EFFECTS OF STATIC ELECTRICAL DEVICES ON RED IMPORTED

EFFECTS OF STATIC ELECTRICAL DEVICES

ON RED IMPORTED FIRE ANT BEHAVIOR by

REID MATTHEW IPSER, B.S.

A THESIS

IN

ENTOMOLOGY

Submitted to the Graduate Faculty of Texas Tech University in

Partial Fulfillment of the Requirements for the Degree of

MASTER OF SCIENCE

Approved

Chairperson of the Committee

Accepted

Dear bf the Graduate Sfchool

December, 1998

T3

^ ' ACKNOWLEDGMENTS

I would like to give a sincere thanks to my chairperson, Harlan Thorvilson, for giving me the opportunity to come to Texas Tech to do graduate work. I would also like to give a special thanks to my other conmiittee members, Kent Rylander and Ellen Peffley, for their guidance and making my graduate experience as enjoyable as possible.

To my father, James "the big shot" Ipser, words would fail to express my gratitude for his invaluable guidance and support.

I would also like to thank the fellow student Jo Kirk Newbrough for his help with collecting data. n

TABLE OF CONTENTS

ACKNOWLEDGMENTS ii

LIST OF TABLES vi

LIST OF FIGURES ix

CHAPTER

I. INTRODUCTION OF THE RED IMPORTED FIRE ANT,

ITS EFFECT ON THE ECOSYSTEM, AND

REACTIONS TOWARD ELECTRICAL EQUIPMENT 1

1.1 Introduction 1

1.2 The Effect of Solenopsis invida on Ecosystems 2

1.3 Competitiveness 3

1.4 The Effect ofS. invida on Other Arthropods and Decomposers 4

1.5 Predation on Invertebrates 5

1.6 Predation on Beneficial Insects 5

1.7 The Effect of 5^. /wv/cto on Ant Diversity 6

1.8 Predation on Vertebrates 7

1.9 Impacts of ^. zwv/c/a on Humans 8

1.10 Directional Response of Organisms to Electromagnetic Fields 8

1.11 Insect Behavior Induced by Magnetic Fields 9

1.12 Detection of Magnetic-Containing Tissues and Their

Use for a Biological Compass in Animals 11 ui

1.13 Detection of Magnetite in the RIF A H

1.14 Insect Attraction Induced by Electric Fields 12

1.15 RTFA Response to Electric Fields 12

1.16 RIFA Invasion of Electrical Equipment 14

1.17 RIFA Attraction to Electricity and Contact with

Electrically Charged Bare Wires 15

1.18 Objectives of Research 17 n. MATERIAL AND METHODS 18

2.1 Effects of SED2 of Several Voltages on Fire Ant Colonies 18

2.2 SED2 Repellency Experiments in Choice-Chambers 20

2.3 Fire Ant Attraction to the SED3 22

2.4 Response to Gaster-Flagging Ants on an SED3 23

2.5 Fire ant Aggregation to a Diode Static Electrical Device 25

2.6 Gaster-flagging on a Diode SED and an SED3 26

2.7 Synergistic Aspects of the SED3 27

2.8 Attraction of Alarm Pheromone 28 m. RESULTS 31

3.1 Effects of SED2 of Several Voltages on Fire Ant Colonies 31

3.2 SED2 Repellency Experiments in Choice-Chambers 34

3.3 Fire Ant Attraction to the SED3 37

IV

3.4 Response to Gaster-Flagging Ants on an SED3 37

3.5 Fire Ant Aggregation to a Diode Static Electric Device 37

3.6 Gaster-flagging on a Diode SED and an SED3 39

3.7 Synergistic Aspects of the SED3 39

3.8 Attraction of Alarm Pheromone 42

IV. DISCUSSION 43

V. GENERAL CONCLUSIONS 45

REFERENCES 46

APPENDICES

A. RAW EXPERIMENTAL DATA 52

B. HARVESTING RED IMPORTED FIRE ANT COLONIES 85

C. DESIGNS OF THE STATIC ELECTRIC DEVICE

(SED2&SED3) 87

LIST OF TABLES

3.1 Mean numbers of ants, accumulated number of dead ants, and colony size at termination of single-chamber,

SED2 experiment (Trial 1) 32

3.2 Mean numbers of ants, accumulated number of dead ants, and colony size at termination of single-chamber,


3.3 Mean numbers of ants, accumulated number of dead ants, and colony size at termination of choice-chamber,


3.4 Mean numbers of ants, accumulated number of dead ants, and colony size at termination of choice-chamber,


3.5 Mean number of individuals reacting to SED3 38

3.6 Number of ants crossing designated lines for active SED3 vs. Diode SED 40

3.7 Mean Numbers of ants moving toward a non-working SED3 compared to a diode SED with active grid plates, a transformer, a working SED3, and dead ants 41

A. 1 Ratings of ants within 2.5-cm of SED2

(single-chamber) (Trial 1) 53

A.2 Ratings of ants within 2.5-cm of SED2


A. 3 Ratings of ants within 2.5-cm of brood box


A.4 Ratings of ants within 2.5-cm of brood box


VI

A. 5 Number of gaster-flagging ants on SED2


A. 6 Number of gaster-flagging ants on SED2


A.7 Individual bone pile counts of dead ants (SED2)


A. 8 Individual bone pile counts of dead ants (SED2)


A.9 Ratings of ants within 2.5-cm of SED2

(choice-chamber) (Trial 1) 61

A. 10 Ratings of ants within 2.5-cm of SED2






A. 13 Numbers of gaster-flagging ants on SED2


A. 14 Numbers of gaster-flagging ants on SED2






A. 17 Numbers of ants crossing the 8.0-cm lines for the powered and unpowered SED3 69

A. 18 Numbers of gaster-flagging ants on electrical device for

SED3 experiment 70

Vll

A. 19 Numbers of gaster-flagging ants on electrical device for

SED3 experiment 72

A.20 Ratings of ants within 2.5-cm zone of SED3 74

A.21 Ratings of ants within 2.5-cm zone of SED3 76

A.22 Number of ants behind 8.0-cm line of SED3 and number of ants gaster-flagging on SED3 78

A.23 Number of ants behind the 8.0-cm lines toward diode

(no transformer) and the SED3 79

A.24 Number of ants crossing the 8.0-cm lines toward a non-working SED vs. working transformer, electric grid plates, working SED, and dead ants 82

A.25 Number of ants crossing 8.0-cm lines towards introduced pheromone, plain air, tainted kimwipe paper, and clean kimwipe paper 84 viu

LIST OF FIGURES

2.1 Single-chamber configuration 19

2.2 Choice-chamber configuration 21

2.3 SED3 attraction configuration 24

2.4 Pheromone attraction configuration 29

IX

CHAPTER I

INTRODUCTION OF THE RED IMPORTED FIRE ANT,

ITS EFFECT ON THE ECOSYSTEM, AND REACTIONS

TOWARD ELECTRICAL EQUIPMENT.

1.1 Introduction

The red imported fire ant (RIFA), Solenopsis invida Buren, is native to South

America. Its home range extends north along the Guapore River into Brazil and south along the Paraguay River to northem Argentina (Buren et al. 1974, Rhoads 1977). It was imported into the Mobile, Alabama, area between 1933 and 1941 (Rhoads 1977). Being extremely successful, RIF As have spread throughout the southeastern part of the United

States. The RIFA causes medical problems (Adams and Lofgren 1982, Rhoads 1977) for humans, endangers domestic animals and wildlife species (Mount 1981), and is an agricultural pest (Adams 1986). Adams et al. (1983) reported that plant density and yield of soybeans from fields in Gainesville, Florida, and Gul^ort, Mississippi, infested with fire ants were significantly less as compared to un-infested fields.

Solenopsis invida has several attributes that have enabled it to invade all of the southeastem and part of the southwestern United States. The red imported fire ant not only has high fertility and fecundity rates, but its omnivorous diet and opportunistic behavior allow it to shift among food sources. RIF As also rapidly establish in disturbed areas (Vinson 1994). Such areas are grazed pasture lands, frequently mowed recreation

sites, and man-made natural disturbances such as fires. Pathogens and parasites have failed to follow the RIFA from its native areas, and the RIF As ability to sting allows it to compete and repel larger vertebrate competitors from resources.

1.2 The Effect of Solenopsis invicta on Ecosystems

The effects of invading organisms on an ecosystem can partly be determined by the mechanisms of their invasion (Diamond and Case 1986), which may result fi'om competition, predation, and disease. The impact of an organism on a community can also depend on whether it invades an empty niche, thereby having little impact, or whether it displaces species from occupied niches (Walker and Valentine 1984, Herbold and Moyle

1986). Replacements and substitutions of species within an ecosystem can produce shifts in competition for food and space and can provide other resources for native organisms to exploit. Competition alone, through time, will allow one species to dominate and will limit the number of species in a community. Predation, disturbance, and temporal variability are three factors that can stop competition. Since fire ants eliminate beneficial predators in a community, predator-mediated coexistence is eliminated as well. Predator-mediated coexistence allows many more species to coexist with the presence of a certain predator and/or predators. Although some invasions have little impact, most have serious consequences that are unpredictable.

Although we know that i^. invida is able to replace native ant species and monopolize the food source of an entire guild, current data does not explain its total impact

(Porter and Savingnano 1990). S. invicta may replace many invertebrate predators, scavengers, and decomposers, resulting in a sufficient change in the invertebrate composition (Porter and Savignano 1990). Examples are S. geminata and S. xyloni, which are native predatory ants that have been removed by S. invicta, resulting in a simplified predator component structure of the ecosystem (Vinson 1994). Solenopsis invicta may have established itself sufficiently in the U.S.A. to change the ecological structure, and its removal might cause outbreaks of species that have been suppressed by its presence.

1.3 Competitiveness

Since S. invicta is an efficient forager, workers can dominate in obtaining most food resources. Some ant species, such as Monomorium minimum, can compete with S. invida by emitting a repellent liquid, but S. invicta eventually overcomes the repellent effects due to the many workers that are recruited (Bamoi-Urbani and Kannowski 1974). Other species initially compete with S. invicta, such as Lasius neoniger, but eventually are overcome by the larger numbers ofS. invicta.

One revealing study about ant genera in direct competition with S. invicta was conducted by Camilo and Phillips (1990). They examined the population density of ^.

invicta and correlated it with the number of coexisting ant species. A negative correlation was produced, showing a decrease in species composition. When comparing infested plots to un-infested plots, a pattern was found, suggesting species reduction with increased densities ofS. invicta. Their results showed 21 ant species in undisturbed, un-infested plots

and 14 ant species in disturbed, un-infested plots. Yet, with the presence ofS. invicta, onl\ nine species existed in undisturbed plots, and five species occurred in disturbed plots. Not only did S. invicta replace ants in similar niches, but they also out-competed other species as well.

1.4 The Effect of .S'. invicta on Other Arthropods and Decomposers

S. invida has severe effects on other arthropods. However, the interspecific relationship intensity against arthropod predators such as spiders and scorpions to S.

invicta is lower than compared to other ant species. Thus, usually these types of invertebrates are less affected by direct competition by S. invicta. Sterling et al. (1979) reported that fire ants failed to affect the abundance or species composition of predacious arthropods in Texas cotton fields. Agrosystems are disturbed monoculture habitats usually treated with pesticides, and species richness is usually not high. However, Hooper (1976) reported that fire ants reduced numbers of arthropod herbivores and predators and significantly reduced isopod numbers.

Decomposers, which constitute one of the most important trophic assemblages, are also affected by S. invicta (Putnam 1983). Insects constitute one of the major groups of decomposers. Most insects that rely on decomposing material for a food source are highly mobile (Vinson 1991). Flying aduhs and their progeny that break down the resource most completely, generally have a short developmental time (Vinson 1991). Vinson (1991) also found that S. invicta not only preyed upon other decomposers, but became the main users

of the decomposing resource. S. invicta was not only effective in locating decomposing resources, but managed to take over the resources and displace the other competitors.

1.5 Predation on Invertebrates

Solenopsis invicta is an effective invertebrate predator and has attracted attention because of its beneficial aspects. It preys upon economic pests such as the sugar cane borer, Diatraea saccharalis, cotton pests such as Heliothis virescens and Anthonomous

grandis (Sterling 1978, McDaniel and Sterling 1979, 1982), ticks (Harris and Bums 1972,

Bums and Melancon 1977), and several species of dipteran pests (Sunmierlin et al. 1977,

1977b, Howard and Oliver 1978, Summerlin and Kunz 1978, Combs 1982).

RIFA predation on the lone star tick, Amblyomma americarmm, has been documented extensively. Harris and Bums (1972) found that as S. invicta infestations advanced through Louisiana, lone star tick populations declined. S. invicta caused a permanent reduction in lone star tick populations. Lone star tick population decline was also positively correlated with increasing population levels ofS. invicta.

1.6 Predation on Beneficial Insects

Sterling (1978) considered S. invicta an efficient predator without having much effect on other beneficial insects. Although some beneficial insects escape S. invicta by flight, not all are resistant to fire ant predation. S. invicta preys upon eggs of beneficial lacewings and larvae of other aduh beneficial insects, such as ground beetles and parasitic

wasps that help to reduce agricultural pest species numbers (Tedders et al. 1990) Also, many other predatory ants are eliminated by S. invicta, such as S. geminata and S. xyloni

(McCook), which also prey on agricultural pests (Reagan 1986).

Ricks and Vinson (1970) showed that, given the opportunity, S. invicta will consume most insects presented to them, although some were preferred over others. In their laboratory study, RIFA favorite choices included insects such as long-homed grasshoppers, cucumber beetles, some ground beetles, and spittle bugs (Ricks and Vinson

1970). Thus, S. invicta may prey upon stages of beneficial insects that are less mobile as compared to adults. RIF As may also prey on adult beneficial insects that are less mobile than other adult beneficial insects, such as ground beetles compared to parasitic wasps.

Whether predation affects adult beneficial insects is uncertain, but Vinson and Scarborough

(1989) reported that fire ants preferred Trichogramma-parasitized aphids over unparasitized aphids as food. RIFA predation could have an impact on the biological control agents and the livelihood of other natural enemies.

1.7 The Effect of .S*. invicta on Ant Diversity.

The polygyne form of the red imported fire ant may have the greatest negative effect on species diversity of ant communities. Polygyne (muhiple-queen) colonies have greater environmental impact because of larger nest population density. Polygyne colonies often occupy 5-10 times more area than the monogyne form (300-1000 mounds/ha vs. 30-

100 mounds/ha) (Vinson and Sorensen 1986). Polygyne forms have slightly smaller sized

workers and can contain several dozen egg-laying queens (Porter and Savignano 1990)

Polygyne forms can produce other colonies by budding and produce a network among separate colonies. Other exotic species of polygyne ants have severe impacts as well. The

Argentine ant reduced species richness from 8.7 to 3.1 species per site (Porter and

Savignano 1990).

The impact ofS. invicta is proportional to numbers of workers. Thus, polygyne fire ants have a greater impact than the monogyne form. Monogyne fire ants will dominate and simplify native ant fauna, but in a less severe way than polygyne colonies (Summerlin et al.

1977, Apperson and Powell 1984, Phillips et al. 1987).

1.8 Predation on Vertebrates

Pets, domestic animals, and wildlife can be injured as well. Fire ants can invade water and food sources of domestic farm animals, such as cows, sheep, and horses, resulting in starvation and dehydration (Adams 1986). They also attack bird hatchlings and other animals on the ground. Mount et al. (1981) provided experimental evidence that S.

invicta preyed on eggs of two turtle species and speculated that decline in snake, lizard, and ground-nesting birds were associated with S. invicta invasions. Cliff swallows decreased 34% in nesting success due to high densities of *S. invicta (Sikes and Amold

1986). S. invida also preys on some species of birds, such as the wood duck, Aix sponsa, thereby excluding them from their natural nesting sites (Ridlehuber 1982).

1.9 Impacts of .S". invicta on Humans

Although the RIFA will typically nest in the ground and in sunny areas, it has also been found indoors. RIF As have been found in wall voids, under rugs, in the attics of houses, and in clothes (Vinson 1997). They also seek shelter among buildings that provide additional warmth, resources, and breeding space. The venom of the RIFA can cause serious heahh problems. The average reaction is a pustule, yet, some people can suffer anaphylactic shock (Rhoads 1977). One case study included a woman without previous allergic history. She was bitten by two ants on her foot, which produced localized burning and itching. This progressed in a matter of minutes to urticaria, dyspnea, chest pain, and pruritus. Within 30 minutes after the bites, severe dyspnea and dizziness occurred. She was admitted to the hospital and diagnosed with anaphylactic shock. Drees (1995) mentions a case in Houston, Texas, where an elderly woman in a nursing home was discovered at 1 to 2 a.m. with ants on her face, neck, and on the mid and lower extremities of her body. The patient eventually died of heart failure.

110 Directional Response of Organisms to Electromagnetic Fields

Directional orientation of single cells and single-cell organisms in the presence of electromagnetic fields has been well studied. Mosquito development, dragonfly flight behavior, dragonfly naiad directional orientation, honey bee nest constmction and orientation, and other higher organism behaviors are influenced by the natural magnetic fields of the Earth and by electric fields. Bacteria, birds, and honeybees contain magnetite.

8

which allows orientation in magnetic fields (Jungerman and Rosenblum 1980). Neurons detect torque produced by magnetite-containing tissues in connection with an electromotive force generated in moving conductors.

Fish detect electric fields by means of long, conductive canals which connect pores of the skin with extremely sensitive electric field-sensing cells deep in the muscles. The electromotive force generated in a moving conductor is proportional to magnetic field strength, the length of the conductor, and velocity (Jungerman and Rosenblum 1980).

Sharks only need to move a few centimeters per second to generate an electromagnetic force large enough to be detected, using it for their own navigation.

Mosquito larvae and pupae in direct current (DC) electric fields show a varying ambivalent attraction to cathodes and anodes (Riordan 1971). At low levels of DC (14 volts), first and second instars were attracted to the cathode, and third and fourth instars were attracted to the anode. As field strengths were increased, greater numbers of insects moved in both directions. When field strengths were further increased to 800 volts, the second, third, and fourth instars again chose the cathode. Extremely high vohages (1600) caused paralysis and death.

1.11 Insect Behavior Induced by Magnetic Fields

The yellow underwing moth, Noctua pronuba (L.), (Baker and Mather 1982), middle eastem homet, Vespa orientalis, (Kisliuk and Ishay 1977), and the flour beetle,

Tenebrio molitor L., (Arensde 1978), are a few insects that use a geomagnetic compass.

Magnetic fields (MFs) influence homet nest architecture (Kisliuk and Ishay 1977). This magnetic field influence was tested by subjecting hornets in artificial breeding boxes to a steel coil that produced 0.6-0.3 Oersteds (Oe.) 1-5 cm away. The coil's axis was oriented against the horizontal components of the Earth's magnetic field. Homets buih nests under the combined component of the earth's magnetic field and its gravitational force. Yet under the experimental conditions, nest cells were oriented in all directions of the horizontal plane. Cells constmcted further away from the coil gradually faced downwards.

Honey bee (Apis mellifera L.) comb constmction is affected by induced MFs.

Lindauer and Martin (1972) demonstrated that swarms of bees building new combs always oriented their nest stmcture in the same direction as the parent hive. Induced MFs dismpted new nest building, and workers oriented cells in the direction of the induced MFs.

The honey bee waggle dance is another classic example of insect behavior induced by magnetic fields. Lindauer and Martin (1968) proved that the residual misdirection of the waggle dance could be corrected by using an artificial magnetic field. They also found bees to become disoriented, performing dances oriented in the direction of the artificial MF. In addition, magnetic field bursts at a fi^equency of 250 Hz caused jumps of misdirection in honey bee movement of the waggle dance up to 10° (Korall and Martin 1988). A continuous change of the dance angle could be observed in a single bee if it continued to dance in the bursting field.

10

1.12 Detection of Magnetic-Containing Tissues and Their Use for a Biological Compass in Animals

Magnetite (FeO/FcjOj - lodestone) was first discovered in the dental caps of chitons (Lowenstam 1962). Concentrated magnetite has been found in small quantities in honey bees (Gould 1980), turtles (Perry et al. 1981), and pigeons (Moore 1980).

Magnetite is high in ferromagnetic nature and high in conductivity, making it an excellent

MF-sensing device. Other animals that use MFs for navigation probably also have magnetite as a compass (Gould 1984).

1.13 Detection of Magnetite in the RIFA

Slowik and Thorvilson (1996) demonstrated that RDF As contain ferromagnetic material. Ants were killed using chloroform and immediately dismembered. RIF As were divided into body regions, head fi"om the thorax, and the thorax fi-om the abdomen. Ants were stained with a Pmssian blue reaction stain, which stains for fi-ee iron or its oxides in the tissue. Sections of the head and thoracic regions of the three S. invicta worker sizeclasses did not show consistent iron staining. Some workers' abdomens showed clear, granular staining localized in subcuticular regions; whereas, other abdominal segments revealed inconsistent staining or more difluse, nonspecific staining areas (Slowik and

Thorvilson 1996). Results indicated that queen and alate fire ants did not possess localized ferric concentrations outside the gut and ommatidia. However, workers of all size classes showed subcuticular ferromagnetic material in the anterior region of the abdomen. RIF As may use MFs to navigate, and strong MFs could influence the RIFA to elicit behaviors that

11

show special attraction to MF- producing equipment. The RDF A, like other insects, uses light, chemicals, and visual perception as the main means for navigation (Stratton an

Coleman 1973), but MFs may be used when visual perception is poor.

1.14 Insect Attraction Induced by Electric Fields

A positive relationship exists between strong electric fields and the number of attracted individual insects. Beetles, locusts, and dragonflies are attracted to electric fields, but the orders Diptera and Hymenoptera are the most attracted. Collections of insects in sticky traps under power lines were greater where the electric field intensity exceeded 10 kV/m (Orlov 1990). Greater numbers of hymenopteran and dipteran insects were collected than other orders, and numbers increased in traps closer to power lines. Bindokas et al.

(1988) discovered electric field currents affected honey bee activity, increased hive temperature, impaired hive weight gain, and caused colony failure. Also, honey bees that contacted electric wires experienced enhanced current densities resulting in the perception of shock.

115 RIFA Response to Electric Fields

Recent research has been conducted to determine ant attraction to electric fields.

MacKay et al. ( 1992) constmcted 16 sets of one-cm-diameter copper disks located 1.0 mm apart. Both altemating current (AC) and direct current (DC) was applied to copper wires connected to the disks, ranging between 0 and 350 VDC and 0 and 140 VAC.

12

Workers were placed inside these boxes and exposed to the charged disks for ten minutes and counted at the disk site. Ten species of ants were tested: Solenopsis invicta Buren,

Crematogaster punctulata Emery, Forelius foetidus (Buckley), Formica pallidelfulva

Latreille, Monomorium minimum, Pheidole hyatti Emery, Pogonomyrmex barbatus

(Smith), Pogonomyrmex comanche Wheeler, Solenopsis geminata, and Tetramorium

caespitum. All ants were attracted to both AC-and DC-powered disks, with an increasing response to higher voltages. Most ants showed a threshold between 50 to 60 vohs, below which response was negligible. One species, F. pallidelfulva, whose workers were observed attacking each other, indicated an unusual aggressive response.

MacKay et al. (1992) constmcted similar trials with RDF As, using control relay switches as the experimental apparatus. Relay switches used in the experiment are commonly used in traffic control cabinets in Texas. Switches were powered with 120 VAC and mn with a rate of 1.0 Hertz (Hz) for 14 hours. This was an exact simulation of how highway switches operate. Inactive relay switches were used as controls. Direct current

(DC) and altemating current (AC) electric fields caused accumulation of RDF As, and accumulation increased proportionally to voltages up to 120 ACV (MacKay et al. 1992).

Ants aggregated on and between electrified metal disks and bridged gaps between electrical wires. Ants left the gap between disks after four to five hours of equipment being tumed off, and when electrical disks were covered with a plastic wrap, ants stopped accumulating. This suggested that ants must touch conductmg material to respond

(MacKay et al. 1992). Although their response was directly proportional to voUage, ants

13

had little response to <10 ACV (MacKay et al. 1992). Responses increased up to 100

ACV, and individual ants were usually electrocuted at voltages >60 ACV.

1.16 RIFA Invasion of Electrical Equipment

Eagleson (1940) reported as early as 1939 that Solenopsis xyloni damaged telephone equipment. Three types of damage occurred, such as fouling of working parts by ants themselves, consummation of wire insulation, and nesting inside equipment, eventually causing corrosion. Other problems have occurred in Texas Highway Department's signal cabinets and in residential air-conditioning units in Texas (Vinson and MacKay 1990).

Other states in the Southeast have documented fire ant damage to traffic equipment, causing minor problems for utility workers and field signal technicians (MacKay et al.

1989).

Ants can accumulate in such large numbers that proper movement of mechanical portions of devices is prevented (MacKay and Vinson 1990). Large accumulation of fire ants results in equipment failure in telephone ringers and signal cabinets (MacKay and

Vinson 1990). Ants often nest inside electrical equipment (MacKay et al. 1989), and bring in foreign matter, food particles, and debris. RIF As will bring enough foreign matter to bury electrical v^res of electricity-producing equipment, causing corrosion and eventually system failure. This has been observed in Houston, TX, in instances where ants have invaded electrical transformer boxes and nested near the electrical circuitry (R. Ipser, personal observation, 1996).

14

Ants can damage equipment in several other ways. Ants can accumulate in such large numbers that they prevent the mechanical movement (Little 1984). Little (1984) also mentions the possibility that ants scavenging for nest mate corpses may account for casualties when attempting to retrieve a body lying between the contacts of active wires of electric switches. Telephone ringers (Eagleson 1940) and signal cabinets (Vinson and

MacKay 1990) are damaged in this manner. Ants also short-circuit equipment in several ways. They will consume insulating material fi'om wires (Eagleson 1940) and bridge electrical contacts (Little 1984, MacKay et al. 1989). When ants bridge electrical gaps, they get electrified and accumulate, which results in the fouling of the equipment (Eagleson

1940).

1.17 RIFA Attraction to Electricity and Contact with Electrically Charged Bare Wires

Slowik (1996) demonstrated that RIF As were not directly attracted to electric fields. However, RIFA aggregated when in contact with bare, active wire. Experiments consisted of wire sets divided into three sectors by strip-taping at 4-cm intervals along the length of wires. Each sector had a different wire separation distance and a corresponding weaker EF. Ants only aggregated and clumped together in sectors where they could simultaneously touch both wires. This was a distance of 5 mm, and ants also accumulated in dense numbers at this distance, making accurate counting of individual ants impossible.

RDFA response and accumulation became less as gaps widened between electric wires.

15

Slowik (1996) also concurred that ants were attracted to electrical currentproducing equipment, including low levels of voltage in electric fields. A level of five vohs was the lowest to induce a response. The biological effects of current passing through an ant's body was probably the main factor in inducing their behavior toward electrical equipment (Slowik 1996). Also, ants did not necessarily respond proportionally to increasingly strong EFs. Two wire sets, each with 6.0-cm of parallel, copper leads were used; one set was powered with 120 VDC containing one wire sheathed in tape. This set produced a strong EFs, but simuhaneous contact between wires was restricted. The second set of wires were powered with voltages of 20, 10, 5, and 2.5 VDC, but simultaneous contact was possible. Ants aggregated in large numbers on the wire sets producing 10 and 20 V/mm fields. Less vigor was shown for the 5 and 2.5 VDC sets. The

120 VDC/sheathed set did not attract larger amounts of ants or produce unusual behavior.

This also concurred that simultaneous contact of bare, active wires was needed for an aggressive response.

RIFA colonies invade electric transformer boxes in residential and comercial neighborhoods, causing corrosion of transformers and attacks on utility workers. Can the red imported fire ant be repelled and/or be prevented fi'om invading transformer boxes with the use of high voltage electric current? Will high vohage electric current produce high colony mortality? If mortality rate and colony disturbance is increased, will this cause the invading colony to relocate?

16

1.18 Objectives of Research

In collaboration with Texas Tech engineers, a static electric device (SED) was constmcted to prevent RIF As from invading electrical equipment. For the constmction of the optimal design, the following objectives were defined.

1. To determine the effects of SED2s of different voltages on red imported fire ant colonies and to conclude which vohage is optimal.

2. To quantify red imported fire ant attraction to powered SED3s.

3. To determine what aspect of the SED3 attracts red imported fire ants and if any synergistic effects are produced by the SED3. Aspects are a working transformer, grid plates, pheromone emission from shocked ants, and dead ants on the SED.

17

CHAPTER II

MATERIALS AND METHODS

2.1 Effects of SED2 of Several Voltages on Fire Ant Colonies

Attraction, behavioral changes, and mortality of RIFA colonies in contact with different vohages of the SED2 were measured in the laboratory. These data helped determine the optimal vohage for eliciting gaster-flagging in RIFA and in constmction of the next design (see Appendix C).

Experiments were completed in separate plastic trays (55cm x 44cm x 13cm) (Fig.

2.1). SED2 treatments consisted of four RIFA colonies each introduced to one 50 VAC,

60 VAC, 69 VAC electrical device, or one unelectrified device (control). Devices were electrified continuously during the trial. Colonies used were determined to be the same size through observation.

Bone piles of dead ants were collected weekly or biweekly, and observations were conducted on behaviors such as number of gaster-flagging ants on electrical devices, number of individuals within a 2.5-cm zone around a brood box, and number of individuals within a 2.5-cm zone fi'om an electrical device. A mean rating index was constmcted for estimating numbers of ants around the designated zones: One corresponded to 1-25 individual ants; two, three, four, and five corresponded to 25-50, 50-75, 75-100, and > 100 mdividuals, respectively. Each observation of a specific behavior for each colony was conducted in five-minute intervals once every other day.

18

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There were 28 and 35 observations for the first and second trial, respectively. Both trials lasted approximately 65 days.

Because ants rear brood continuously, calculation of percent mortality for each colony was not possible without counting newly reared individuals. Notwithstanding, a

"death rate index" was constmcted by dividing the total number of dead ants into the whole colony number exterminated at the end of each experiment. Thus, comparisons between treated and untreated colonies permitted detection of differences in mortaUty for colonies exposed to electrical devices. Initial experiments of single-chamber experiments began on 6 Sept. 1996 and were terminated on 26 Nov. 1996. A second trial was initiated on 25 January and terminated 4 April 1997. Unpaired t-tests was used to determine differences among colonies treated by each device.

2.2 SED2 Repellency Experiments in Choice-Chambers

There was a question whether RIFA colonies would abscond to a new location due to the presence of a SED2. This experiment tested if colonies would be repelled from the

SED2 and abscond to a different proximity.

Choice-chambers were two plastic trays, each measuring 27 x 36 x 18 cm, connected by a 20.5-cm passageway of clear tygon tubing (i.d. 2.5 cm) (Fig. 2.2). Colony movement between choice-chambers was recorded through observation. If colonies moved fi'om chambers containing an SED2 device, this would be evidence of repellence.

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SED2 treatments consisted of one RIFA colony introduced to one 35-\\\C device, two

RIFA colonies each introduced to one 70-VAC electrical device, and one colony with one unelectrified device (control). All colonies were approximately the same size at the beginning of the experiment.

Initial experiments of choice-chamber experiments began on 6 Oct. 1996 and were terminated on 26 Nov. 1996. Trial two was initiated on 25 January and terminated 16

March 1997. Bone piles of dead ants were collected weekly or biweekly, and observations were conducted on behaviors such as number of ants gaster-flagging on electrical devices, number of individuals within a 2.5-cm zone around a brood box, and number of individuals within a 2.5-cm zone from an electrical device. A mean rating index was used to estimate numbers of ants around the designated zones. One corresponded to 1-25 individual ants, two, three, four, and five corresponded to 25-50, 50-75, 75-100, and >100 individuals, respectively. Each observation of a specific behavior for each colony was conducted in five-minute intervals, once every other day. There were 21 and 18 observations for the first and second trial, respectively. Both trials approximately lasted 40 days. An indication of colony mortahty at the end of each experiment, based on bone pile counts, was calculated after termination of each colony. An unpaired t-test was used to determine differences among electrical device treatments.

2 3 Fire Ant Attraction to the SED3

Seventy vohs was determined to be the optimal AC vohage within the range of 35-

70 vohs to be used for the SED3. This vohage ehcited significantly more gaster-flagging

22

and pheromone emission from the ants (see Appendix C). However, did RIF As have an immediate attraction to an active SED3 as compared to an unpowered one? This experiment would determine if RIF As were immediately attracted to a powered SED3 without gaster-flagging and the release of alarm pheromone emission from shocked ants.

One tray (55 x 44 x 13cm) was cleaned and disinfected with 70% EtOH. Two

SED3 devices were placed in the tray, one each on opposite ends lengthwise (Fig. 2.3).

One SED3 was powered and one was unpowered. A piece of nylon string was used to draw a Une 8.0-cm from each device. A brood box filled with ants was placed in the center of the tray. The ants had equal access to both devices. Both SED3s were 17.0-cm from the brood box. After placement of ants into the tray, counts began; whereby, ants that crossed each designated line toward either SED3 were aspirated and placed in a corresponding container. Each observational period lasted for five minutes, and 10 replications (colonies) were conducted. Students' t-tests were used to determine differences in mean numbers collected between the SED3s.

2.4 Response to Gaster-Flagging ants on an SED3

Ten experimental colonies were subjected to a powered 70 VAC SED3, and ten controls were subjected to an unpowered SED3. Bone piles of dead ants were removed from colony trays, and observations were conducted on specific behaviors. Examined behaviors included numbers of gaster-flagging ants on the SED3s and numbers of individuals around a 2.5-cm zone from an SED3. Each colony was observed five times daily, for ten minutes, for four days (n=16). Colony numbers were estimated throughout

23

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the experiment. A mean rating index was constmcted for estimating numbers of ants around the designated zones: One corresponded to 1-25 individual ants; two, three, four, and five corresponded to 25-50, 50-75, 75-100, and >100 individuals, respectively An unpaired t-test was used to determine differences among the treatments.

2.5 Fire Ant Aggregation to a Diode Static Electrical Device

The diode SED is different from the SED3. Instead of a transformer to convert 120

VAC (line current) to 70 VAC, a diode was used to supply power to grid plates. The diode allowed direct current (50 DC) and altemating current (50 AC) to charge grid plates

(B. Green, P.E., personal communication). This could possibly affect ants in different ways and cause more gaster-flagging, alarm pheromone emission, and disturbance in colonies. If so, higher amount of alarm pheromone would attract more fire ants.

One tray (55 x 44 x 13 cm) was cleaned and disinfected v^th 70% EtOH. Two devices were placed in the tray, one each on opposite ends lengthwise. The powered transformer of an SED3 touched the tray floor. The grid perimeter area was 70.0 cm. The second device (diode SED) had a diode to regulate current to the electrified grid plates.

The grid peremiter area of the diode SED was 57.0 cm. A piece of nylon string was used to draw a Une 8.0-cm from each device. A brood box filled with ants was placed in the center of the tray. The ants had equal access to both devices. After placement in the tray, ants were given 30 minutes to accUmate to the environment. Once accUmated, both devices were tumed on. After 30 minutes, observations started. Numbers of gasterflagging individuals on devices and numbers of individuals behind the 8.0 cm line of each

25

SED were counted. Each observational period lasted ten minutes. Thirty minutes lapsed between each observational period, and three periods were conducted for each of the eight repHcations (colonies). After each replication the tray was cleaned with 70% EtOH. A

Students t-test was used to detect differences between the diode SED and the standard

SED3 for mean numbers of gaster-flagging ants and for mean numbers of ants behind the

8.0-cm designated line.

2.6 Gaster-flagging on a Diode SED and an SED3

Will more gaster-flagging from sister workers on the diode SED cause a greater aggregation of ants to this device? Significantly greater numbers of ants drawn to the diode SED would indicate that gaster-flagging and pheromone emission had a significant effect in ant aggregation toward the SED.

One tray (55 x 44 x 13 cm) was cleaned and disinfected with 70% EtOH. One

SED3 and one diode SED were placed in the tray, one each on opposite ends of the tray, lengthwise. The transformer of the SED3 touched the tray floor. A piece of nylon string was used to draw a line 8.0-cm from each device. A brood box filled with ants was placed in the center of the tray. Each SED was 17.0-cm from the edge of the brood box, and ants had equal access to both devices. After placement into the tray, ants were given 30 minutes to acclimate to the environment, after which both devices were tumed on. The ants were then given 30 minutes to readjust, to explore, and to become shocked on grid plates. Afterwards, a new brood box of ants from the same colony was placed in the middle of the tray. All ants that crossed the 8.0-cm designated line were counted. There

26

were ten replications using a random selection of different sized colonies. Eight, tenminute observational periods were conducted for each colony, every 30 minutes for eight hours (n=84). A Students' t-test was used to determine differences in mean numbers of gaster-flagging ants and mean numbers of individuals that crossed the 8.0-cm designated line.

2.7 Synergistic Aspects of the SED3

The question of synergism was still up in the air. An experiment was conducted to determine if a synergism tmly existed among four aspects of the SED3. Dead ants on devices could significantly affect ant attraction, but would recently dead ants produce enough aromatic decay products to attract ants without the action of any other agent?

Would dead ants in combination with alarm pheromones have a synergistic effect on RIFA behavior? Did the transformer or electric grid plates produce any synergistic effects? The answers to these questions needed to be determined.

One individual tray (55 x 44 x 13 cm) was cleaned and disinfected with 70% EtOH.

Four experiments were conducted; one measured the attractiveness of active diode SED grid plates compared to an unpowered SED3, and the other three each measured separately a powered SED3 transformer without grid activity, a powered SED3 with gaster-flagging ants, and a pile of dead ants compared to a non-working SED3. Dead ants were collected by scraping individual ants off a SED grid with a fine bmsh or tooth pick; this process lasted between one and two hours. Piles of dead ants ranged from 200 to 300 individuals.

Both the non-working SED3 and the corresponding treatment object were placed in the

27

tray, one each at opposite ends of the tray, lengthwise. A piece of nylon string was used to draw a line 1 O-cm from each device. A brood box filled with ants was placed in the center of the tray. All experimental objects were 17.0-cm from the brood box, and ants had equal access to both test objects. After placement of ants into the tray, counts began; whereby, ants that crossed each designated line toward either experimental object were aspirated and placed in a corresponding container. Each observational period lasted for five minutes, and

10 replications (colonies) were conducted for each experiment. Students' t-tests were used to determine differences in mean numbers collected between the experimental objects.

2.8 Attraction of Alarm Pheromone

Alarm pheromone was tested alone to determine its effect in ant attraction. Two experiments were conducted to determine significant effects of alarm pheromone on fire ant workers. The first experiment consisted of two plastic trays, each measuring 27 x 36 x 18 cm, connected by a passageway of a 30.5-cm piece of clear tygon tubing (i.d. 1.5 cm) (Fig.

2.4). One tray was covered with a piece of cardboard and contained gaster-flagging ants on a powered SED3. An air pump (V.W.R. Scientific, model U522-U4F-G180DX,

Benton Harbor, Michigan) was used occasionally to lightly waft air on the gaster-flagging ants and transfer the airbome alarm pheromone through the tygon tubing into the second tray. A piece of nylon string was used to mark designated lines 1.0 cm from the source of the incoming pheromone. A brood box of ants was placed in the middle of the second tray, after which counting started. Each observational period lasted five minutes, 11 repUcations

(colonies) were completed, and the experiment lasted one day.

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X 6.5 cm pieces of Kimwipes (Kimberly-Clark, Roswell, GA., no. 34155) paper were placed in the tray, one each at opposite ends of the tray lengthwise. A piece of nylon string was used to draw a line 1.0 cm from each piece of paper. One piece was tainted with alarm pheromone. This was achieved in two ways, by firmly restraining ants with forceps and allowing them to gaster-flag on the fiher paper, and by allov^ng shocked ants on an SED3 to gaster-flag on paper. A brood box filled with ants was placed in the center of the tray.

Both pieces of paper were 17.0 cm from the brood box. Ants had equal access to both pieces. Counting started after ants were placed into the tray. Each observational period lasted five minutes, there were 11 replications (colonies), and the experiment was conducted in a single day.

30

CHAPTER m

RESULTS

3.1 Effects of SED2 of Several Voltages on Fire Ant Colonies

Differences among treatments existed (Table 3.1). In the first trial, t-tests indicated that the numbers of gaster-flagging ants and the numbers of individuals near the electrical devices exposed to both the 60 and 69-VAC were significantly greater than the numbers exposed to the 50-VAC and the control. Significantly more ants were attracted to, and gaster-flagged upon, the 69 VAC device compared with the 60 VAC device. For numbers of mdividuals around the brood box, no differences among the treatments were detected.

In the second trial (Table 3.2), more ants accumulated near the 50 VAC device.

Significantly more ants gaster-flagged on the device with greatest charge, and no difference was detected in numbers upon the 50 and 60 VAC devices. Significantly more ants were around the brood box in the tray with the 50 VAC device, and fewer ants were near the brood box in the 69 VAC treatment. Differences also existed between the 60 and the 69

VAC devices. Different colonies were used for each trial, and the variation in size among the different colonies may have contributed to the differences in statistical means when subjected to the same device.

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3.2 SED2 Repellency Experiments in Choice-Chambers

In the first trial of the SED2 choice-chamber experiments, significantly more ants gaster-flagged on the 70 VAC device #1 and 70 VAC device #2 compared to the 35 VAC or the control (Table 3.3). Also, more ants gaster-flagged on the 35 VAC as compared to the control. Significantly more numbers of ants were near the brood boxes between the 70

VAC #1 and 35 VAC and the 70 VAC #1 and control. Regarding number of ants around electrical devices, differences existed for numbers of ants around the 35 VAC and 70 VAC

#1, and 70 VAC #1 and the control. In the second trial, differences in mean numbers of ants around an electrical device existed between the 35 VAC and control, 70 VAC#1 and

70 VAC#2, and 70 VAC #1 and control device (Table 3.4). Regarding the mean number of gaster-flagging ants, 70 VAC device #1 initiated significantly more gaster-flagging, and more ants gaster-flagged upon all devices as compared to the control. Regarding numbers of individuals around brood boxes, the 35 VAC and 70 VAC #1 were both significantly different from the 70 VAC #2 and control.

No colony relocated to a choice-chamber without an SED2 present. Gasterflagging ants on the SED2 did not repel the colony; however, the response to the electrical devices was mdicated by debris piUng, which may represent an attempt to "defeat" the disturbing presence of the device. Also, when colonies had less debris in the colony tray to pile up around a device, they seemed to cluster in greater numbers on the electrical device.

The debris may limit the sensation of magnetic field produced by the device.

34

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3.3 Fire Ant Attraction to the SED3

No significant differences were detected between mean numbers of ants crossing the designated lines between the active (17.8 ± 7.2) and inactive (17.2 ± 6.6) SED3

(t=0.36; df=9; P=0.72) (see Table A. 17). Therefore, RIF As were not attracted to a powered SED3 as compared to an unpowered SED3 from a relatively long distance.

3.4 Response to Gaster-Flagging ants on an SED3

Significantly greater numbers of gaster-flagging ants and individuals within a 2.5cm zone on powered SED3 treatments compared to unpowered SED3 treatments were detected (Table 3.5). No ants gaster-flagged on the unpowered SEDs (see Tables A. 18-

21). In addition, the RIFA colonies apparently responded to electrical devices by debris piling, which may be an attempt to "defeat" the disturbmg presence of the grid plates.

Also, when colonies had less debris in the colony tray to pile up around a device, they seemed to cluster in greater numbers on the SED3. RIFA may use debris to buffer the electric grid plates where ants get shocked.

3 5 Fire Ant Aggregation to a Diode Static Electrical Device.

Significant differences were detected between mean numbers of gaster-flagging ants and between mean numbers of ants behind the 8.0-cm designated line. More ants were behind the line toward the diode SED (100.5 ± 70.4) as compared to the transformerpowered SED3 (45.7 ± 43.4) (t=7.2; d^25; P<0.0001). The mean number of ants gasterflagging on the diode SED (4.8 ± 3.4) was significantly greater than the mean numbers of

37

Table 3.5: Mean number (± SD) of individuals reacting to SED3'.

Treatment Mean ranking of individuals** Mean number of individuals

<2.5 cm zone gaster-flagging

Electrified 4.0(±0.9)a 7.8(±3.6)a

Non-electrified 1.0(±0.0)b 0.0 (± 0.0)b

^ Static electrical device, 3'** generation, vohage=70 VAC.

^ Mean numbers with different lower case letters within columns are significantly different

(t-test; d^l68;P<0.05).

38

ants that gaster-flagged on the transformer powered SED3 (1.5 ± 2.0) (t=6.8; df=25:

P<0.0001) (see Table A.22).

3.6 Gaster-flagging on a Diode SED and an SED3

Significant differences were detected for mean numbers of individuals crossing the designated lines between the diode SED and the SED3. Significantly more ants were attracted to the diode SED that had no working transformer (t=14.2; df=83; P<0.001)

(Table 3.6). Thus, a synergistic effect with pheromones and a working transformer was not produced in this experiment. The direct resuh of more gaster-flagging on the diode SED was more alarm pheromone emission, which may be the most significant factor in ant attraction to an SED (see Table A.23).

3.7 Synergistic Aspects of the SED3

A paired t-test only detected significant differences (P<0.05) between mean number of ants attracted to a powered (grid on) and an unpowered SED3 (grid off) (Table 3.7).

Significantly more ants were attracted to a working SED3 with gaster-flagging ants. This supports previous work that pheromones used for conmiunication and released by shocked ants are mainly responsible for fire ant attraction and aggregation to the SED3. Ants were only observed to be attracted to the SED when sister workers were ah-eady on the device being shocked, hence, releasing pheromones by gaster-flagging (see Table A.24).

39

Table 3.6: Number of ants (± SD) crossing designated lines for active SED3 vs Diode

SED.

Treatment Meannumber of Individuals^ t-value P<t ^

Standard SED3 23.1 (± 15.6)a

14.2 0.001

Diode SED 99.7(±62.0)b

" Mean numbers with different lower case letters are significantly different (t-test; df=83;

P<0.001)

40

Table 3.7: Mean numbers of ants moving toward a non-working SED3 compared to a diode SED with active grid plates, a transformer, a working SED3, and dead ants.

Treatment

EXP#1

Grid Plates on (diode)

SED3 Off

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SED3 Transformer only 24.7 (14.1)

SED3 Off 24.0(14.8)

0.43 0.681

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33.7(13.7)a

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EXP #4

Dead Ants 34.8(51.8)

1.01 0.339

SED3 Off 25.2 (28.5)

" Mean numbers with different lower case letters are significantly different (t-test; df=9;

P<0.05)

41

3.8 Attraction of Alarm Pheromone

For the first experiment, a paired t-test detected significant differences between mean numbers of ants attracted to the side with the pheromone (43.4 ± 28.1) as compared to the side of the tray with clean air (22.8 ± 17.0). More ants were significantly attracted to the side of the tray where alarm pheromone was introduced (t=4.23; df=10; P=0.002).

For the second experiment, significantly greater mean numbers of ants were attracted to tainted kimwipe paper(42.8 ± 22.0) as compared to the clean kimwipe paper (19.7 ± 9.0)

(t=4.84; df=10; P=0.001) (see Table A.25). Due to these resuhs, alarm pheromone from shocked, gaster-flagging ants is the only factor in ant attraction to a powered SED3.

42

CHAPTER IV

DISCUSSION

The resuhs clarify several aspects of the effects of static electric devices on red imported fire ants. Through comparisons of various vohages, 70 VAC was determined to be the optimal vohage of these tested, which caused more gaster-flagging and release of alarm phermone. Powered devices that shocked ants and caused gaster-flagging attracted more ants than devices that were unpowered. The emission of alarm pheromone was the cause for such attraction.

Gaster-flagging is a behavior where workers disperse venom as an aerosol by forming droplets of venom on the tips of their sting and vibrating their abdomen vertically

(Wilson and HoUdobler 1990). The diode SED used DC in combmation with AC, and this combination induced more gaster-flagging and pheromone emission from RIF As. Hence, the more gaster-flagging ants on the diode SED caused a significantly greater attraction of sister workers to the device. In addition, not only did more ants gaster-flagg but also more nest-mate clamping was produced. Nest-mate clamping is a behavior where ants clamp and lock on each other with their mandibles. This eventually produces a clump of ants clamped on each other, to whatever body part can be gripped with the mandibles. Some shocked ants on the SED3 and diode SED died instantly, thus remaining on the device as part of the active circuit.

These resuhs support previous work conducted by Slowik (1996). He was able to show that when ants contact active bare wire, ants either were electrocuted and died, or

43

remained on the live active wires as part of the active circuit. Similar behaviors were also produced such as nest-mate clamping and involuntary gaster-flagging. No synergistic effects were produced by the SED3, and, pheromone emission was the only characteristic that immediately attracted ants. Thus, pheromone emission was the only significant factor in ant attraction to an SED.

^

44

CHAPTER V

GENERAL CONCLUSIONS

The effect of a static electric device on red imported fire ants {Solenopsis invicta

Buren) is unique. Based on the observations conducted in these experiments, the following may describe RIFA attraction and accumulation to an SED. As workers scour and forage for food and other needed materials, one or several individuals randomly contact the SED.

Given time, ants will recruit workers to the active transformer; however, foraging workers on the SED will become shocked within seconds of initial contact. This will produce gaster-flagging and the release of alarm pheromone. Also, heavy colony communication will resuh, and RIF As will proceed to defeat the disturbing presence of the device.

This gaster-flagging behavior is initiated to release alarm pheromones. These pheromones cause a chaotic frenzy among the colony, attracting sister workers, which respond in an aggressive manner toward the disturbing stimuli. This is considered an

"aggressive alarm" according to Wilson and HoUdobler (1990). In aggressive alarm, colony workers are drawn toward the threatening stimulus and venture to attack it. Slowik

(1996) also determined that the physical properties and characteristics of electricity do not eUch aggregation. Rather, the flow of current of the active circuit, when accessible to ants by bare contact, affects the ants by electrocuting them. This alone causes the release of chemicals, voluntary or involuntary, which draw more ants to the source.

45

REFERENCES

Adams, C. T., and C. S. Lofgren. 1982. Incidence of stings or bhes of the red imported fire ant and other arthropods among patients at Fort Stewart, Georgia, USA. J.

Med. Entomology. 19: 366-370.

Adams, C. T., W. A. Banks, C. S. Lofgren, B. J. Smitle, and P. P. Harlan. 1983. Impact of the red hnported fire ant, Solenopsis invicta Buren, on growth and yield of soybean. J. Econ. Entomol. 76:1129-1132.

Adams, C. T. 1986. Agricultural and medical impact of the imported fire ants, pp. 48-57.

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Apperson, C. S., and E. E. Powell. 1984. Foraging activity of ants (Hymenoptera:

Formicidae) in a pasture inhabited by the red imported fire ant. Florida

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Arendse, M.C. 1978. Magnetic field detection is distinct from Ught detection in the invertebrates Tenebrio and Talitrus. Nature. 274: n. 27: 358-362.

Baker, Robin R., and Janice G. Mather. 1982. Magnetic compass sense in the large yellow underwing moth, Noduapronuba L. Animal. Behav. 30: 543-548.

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Bindokas, V. P., J. R. Gauger, and B. Greenberg. 1988. Exposure scheme separates effects of electric shock and electric field for honey bees. Apis mellifera L.

Bioelectromagnetics. 9: 275-284.

Bindokas, V. P., J. R. Gauger, and B. Greenberg. 1988. Mechanism of biological effects observed m honey bees (Apis mellifrea L.) hived under extra high-voltage transmission lines. Bioelectromagnetics. 9:285-301.

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Zoogeography of the imported fire ant. J. New York Entomol. Soc. 82: 113-124.

46

Bums, E. C , and D. G. Melancon. 1977. Effect of imported fire ant (Hymenoptera:

Formicidae) invasion on lone star tick (Acarina: Ixodidae) populations. J. Med.

Entomol. 14: 247-249.

Camilo, G. R., and S. A. PhiUips. 1990. Evolution of ant communities in response to invasion by the fire ant Solenopsis invicta, pp. 190-198. In R. K. Vander Meer, K.

Jafife, and A. Cedeno [eds.], AppUed Myrmecology: a worid persepctive.

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Combs, R. L., Jr. 1982. The black imported fire ant, a predator of the face fly in

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Diamond, J., and T. J. Case. 1986. Overview: Introductions, extinctions, exterminations, and invasions, pp. 65-67. In J. Diamond and T. J. Case [eds.]. Community

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Eagleson, C. 1940. Fu-e ants damage to telephone equipment. J. Econ. Entomol. 33:

700.

Gould, James, L. 1980. The case for magnetic senshivity m birds and bees (Such as it is ).

American Scientist. 68: 256-267.

Gould, James, L. 1984. Magnetic field sensitivity in animals. Ann. Rev. Physiol. 46: 585-

598.

Harris, W. G., and E. C. Bums. 1972. Predation on the lone star tick by the imported fire ant. J. Environ. Entomol. 1: 362-365.

Herbold, B., and P. B. Moyle. 1986. Introduced species and vacant niches. Am. Natur.

128: 751-760.

Hooper, M. W. 1976. The effects of the red imported fire ant, Solenopsis invicta, on the

East Texas arthropod community. Thesis, University of Texas at Austin, Austin

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Howard, F. W., and A. D. Oliver. 1978. Arthropod populations in permanent pastures treated and untreated with mirex for red unported fire ant control. J. Environ.

Entomol. 7: 901-903.

47

Jouvenaz, D. P., G. E. Allen, W. A. Banks, and D. P. Wojcik. 1977. A survey of pathogens of fire ants, Solenopsis spp., in the southeastem United States. Fla.

Entomol. 6: 275-279

Jungerman, R. L., and B. Rosenblum. 1980. Magnetic induction for the sensing of magnetic fields by animals-an analysis. J. Theor. Biol. 87: 25-32.

Kisliuk, M., and J. Ishay. 1977 Influence of an additional magnetic field on homet nest architecture. 885-887.

Korall, H., T. Leucht, and H. Martin. 1988. Bursts of magnetic fields induce jumps of misdirection in bees by a mechanism of magnetic resonance. J. Comp. Physiol. A.

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Lindauer, M., and H. Martin. 1968. Die Schwereorientiemng der Bienen unter dem

Emfluss des Magnetfelds. Z. Vergl. Physiol. 60: 219-243.

Lindauer, M., and H. Martin. 1972. Magnetic effects on dancing bees, pp.559-567. In S.

R. Galler [ed]. Animal orientation and navigation, NASA sp-262. USGPO,

Washington DC.

Little, E.C. 1984. Ants in electric switches: Note. N.Z. Entomol. 8: 47.

Lowenstam, H. A. 1962. Magnethe in denticle capping in recent chitons

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MacKay, W. P., S. Majdi, J. Irving, S. B. Vinson, and C. Messer. 1992. Attraction of ants

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48

McDaniel, S. G., and W L. SterUng. 1979. Predator determination and efiBciency on

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49

Sikes, P. J., and K. A. Amold. 1986. Red imported fire ant (Solenopsis invicta) predation on cliff swaUow (Hirundo pyrrhonota) nestlings in east-central Texas. Southwest.

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50

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MA.

51

APPENDIX A

RAW EXPERIMENTAL DATA

52

Observation period

21

22

23

24

17

18

19

20

11

12

13

14

15

16

25

26

27

5

6

7

8

9

10

1

2

3

4

28

Mean ± (SD)

Table A. 1: Ratings of ants within 2.5-cm of SED2 (single-chamber) (Trial 1)

50 VAC

1.0±1.0

Treatments

60 VAC 69 VAC

3

3

3

4

3

2

4

3

2

2

3

3

5

2

2

2

4

2

4

3

3

4

3

4

2

3

2

3

2.9 ±0.8

3

3

2

3

2

3

2

2

2

3

2

2

2

3

2

2

3

4

2

4

1

2

3

2

2

2

3

3

2.4 ±0.6

Control ^

1 L

;

1.0 ±1.0

53

Observation period

29

30

31

32

33

34

25

26

27

28

18

19

20

21

22

23

24

8

9

10

11

5

6

7

12

13

14

15

16

17

1

2

3

4

35

Mean ± (SD)

Table A.2: Rating of ants within 2.5-cm of SED2 (single-chamber) (Trial 2

Treatments

60 VAC 50 VAC

5

5

5

5

5

5

5

5

5

5

5

4

5

5

4

1

5

5

5

5

5

5

5

4

4

4

5

4

4

5

4

4

4

4

5

4.0 ±0.7

69 VAC

1

2

2

5

3

4

2

1

2

1

1

1

2

1

1

2

2

2

2

2

5

5

5

3

3

5

5

5

5

5

4

4

4

4

2

2.9±1.5

54

2

2

1

1

5

2

2

3

1

4

2

2

2

5

4

4

4

4

2

2

4

2

4

4

5

4

5

5

4

5

5

5

5

5

3

3.4+1.3

Control

1.0+1.0

Observation period

18

19

20

21

22

23

24

25

26

27

28

11

12

13

14

15

16

17

5

6

7

8

9

10

1

2

3

4

29

Mean ± (SD)

Treatments

60 VAC 69 VAC 50 VAC

5

5

5

5

5

5

4

5

5

5

5

5

5

5

5

5

5

4

5

5

5

5

5

5

4

5

5

5

5

4.8 ±0.3

5

5

5

4

4

5

5

5

5

5

5

5

5

5

5

4

5

5

5

5

5

5

5

5

5

5

5

5

5

4.8 ±0.3

4

4

5

5

5

4

4

5

5

5

5

5

5

5

5

5

5

5

5

5

4

4

4

5

5

5

5

5

5

4.7 ±0.4

Control

5

5

5

5

4

5

4

5

4

5

5

5

5

5

5

4

4

5

5

5

4

4

4

5

5

5

5

5

5

4.7 ±0.4

55

Table A.4: Ratings of ants vyithin 2.5-cm of brood box (single-chamber) (Trial 2).

Treatments

50 VAC

5

5

5

5

5

5

5

5

5

5

5

5

5

5

5

5

5

5

5

5

4

4

5

5

5

5

5

5

5

5

5

5

5

5

5

Observation period

19

20

21

22

15

16

17

18

23

24

25

26

27

28

9

10

11

12

13

14

29

30

31

32

33

34

1

2

3

4

5

6

7

8

35

60 VAC

1

1

1

3

5

3

4

3

3

3

3

3

4

5

4

5

5

5

5

5

5

5

5

5

5

4

5

5

5

5

5

5

5

5

5

Mean±(SD) 4.9 ±0.2 4.1 ±1.2 3.7 ±1.4 4.5 ±0.6

69 VAC

4

1

3

5

5

5

5

5

4

5

3

3

3

3

2

2

1

1

1

1

3

4

5

5

5

4

5

5

5

5

4

5

5

5

5

Control

5

5

2

4

5

5

5

5

4

5

4

4

5

5

5

5

4

4

4

4

5

4

5

5

5

4

4

5

5

5

4

5

5

5

5

56

Observation period

20

21

22

23

24

16

17

18

19

12

13

14

15

25

26

27

28

29

30

31

32

6

7

8

9

10

11

1

2

3

4

5

33

Mean ± (SD)

Table A. 5: Number of gaster-flagging ants on SED2 (single-chamber) (Trial 1)

Treatments

50 VAC

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0.0 ±0.0

69 VAC

8

3

4

4

2

5

2

3

4

4

4

2

1

4

4

5

2

2

2

2

6

3

4

4

4

6

5

3

5

5

5

4

2

3.7±1.5

60 VAC

6

2

2

3

4

4

4

2

0

1

3

3

3

0

0

3

5

6

4

7

0

0

7

3

3

3

4

2

3

3

0

4

5

2.9 ±1.9

Control

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0.0 ±0.0

57

Observation

Period

6

7

8

9

10

11

12

13

14

15

16

17

1

2

3

4

5

22

23

24

25

18

19

20

21

26

27

28

Mean ± (SD)

Table A.6: Number of gaster-flagging ants on SED2 (single-chan^ • r > (Trial 2).

Treatments

50 VAC

1

2

5

3

0

2

2

3

1

1

6

1

1

0

13

4

3

2

0

0

1

0

8

3

0

2

0

0

2.2 ±2.8

60 VAC

1

0

0

2

1

0

0

0

4

0

7

7

4

1

10

0

2

2

0

1

2

0

1

3

0

0

2

1

1.8 ±2.5

Control

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0.0 ±0.0

69 VAC

3

5

4

4

14

0

1

2

1

5

0

4

4

12

6

3

0

1

1

9

3

5

4

5

3

0

11

2

4.0 ±3.6

58

Table A.7: Individual bone pUe counts of dead ants (SED2) (single-chamber) (trial 1)

Treatments

Date 50 VAC 60 VAC 69 VAC Control

6 Sept.

20 Sept.

4 Oct.

18 Oct.

2 Nov.

16 Nov.

26 Nov.

70

320

400

220

176

154

220

600 220 390

520 760 370

760 840 750

320 1276 440

1710 1543 560

400 750 400

200 261 440

59

Table A. 8: Individual bone pUe counts of dead ants (SED2) (smgle-chamber) (trial 2)

Treatments

Date 50 VAC 60 VAC 69 VAC Control

30 Jan.

8 Feb.

15 Feb.

18 Feb.

4 Mar.

18 Mar.

29 Mar.

4 Apr.

750

650

1275

1546

650

530

461

513

256 1520 160

542 3117 530

756 1000 0

423 70 440

350 580 420

425 0 0

365 0 0

383 0 0

60

^

.1-:

Table A. 9: Ratings of ants within 2.5-cm of SED2 (choice-chamber) (Trial 1). t

%

Treatments

Observation period

6

7

8

9

10

11

1

2

3

4

5

17

18

19

20

12

13

14

15

16

21

Mean ± (SD)

35 VAC

4

4

4

2

2

2

2

1

4

4

3

0

0

0

0

0

0

0

0

0

0

1.5 ±1.6

70 VAC #1

4

5

5

4

3

4

5

4

0

1

0

0

2

1

2

0

0

0

0

0

0 i . 9 ± :

>.o

69 VAC#2 Control

4 1

5 1

4 1

5 1

5 1

2 1

2 1

3 1

2 1

0 1

0 1

0 1

0 1

0 1

0 1

0 1

0 1

0 1

0 1

0 1

1.6±1.9 1.0±1.0

61

Observation period

8

9

10

11

12

13

14

15

16

17

4

5

6

7

1

2

3

18

Mean ± (SD)

Table A. 10: Ratmgs of ants within 2.5-cm of SED2 (choice-chamber) (Tnal 2)

Treatments

35 VAC

1

1

1

2

2

1

1

2

1

1

2

3

1

2

1

1

1

1

1.3 + 0.6

70 VAC # 1 69 VAC#2 Control

1

3

2

1

1

1

1

2

3

2

2

4

3

3

1

1

1

1

2

2

0

2

1.8 + 0.9 1.1+0.3 1.0 + 0.3

62

Table A. 11: Ratings of ants within 2.5-cm of brood box (choice-chamber) (Trial 1)

Treatments

Observation period

8

9

10

11

12

13

14

15

16

17

18

19

20

21

1

2

3

4

5

6

7

22

35 VAC

4

4

4

4

0

0

0

0

1

0

0

0

0

0

4

4

3

2

2

2

2

0

70 VAC #1 69 VAC#2 Control

4

5

4

0

0

0

0

2

0

0

1

4

4

5

5

4

3

2

1

0

0

4 1

5 1

4 1

4 1

5 1

5 1

3 1

2 1

2 1

3 1

2 1

0 1

0 1

0 1

0 1

0 1

0 1

0 1

0 1

0 1

0 1

0 0 1

Mean ± (SD) 1.6+1.7 2.0

+ 2.0 1.7+1.9 1.0+ 1.0

63

Observation period

11

12

13

14

15

16

17

5

6

7

8

1

2

3

4

9

10

18

Mean ± (SD)

Table A. 12: Ratings of ants within 2.5-cm of brood box (choice-chamber) (Trial 2)

Treatments

35 VAC

1

1

1

1

2

1

2

2

3

2

1

2

1

1

1

1

1

1

1.3+0.6

70 VAC # 1 70 VAC#2 Control

1 1 1

1 1 1

2 2 1

1

1.8 + 0.9

I 1

1.0 + 0.2 0.9 + 0.4

64

Observation period

8

9

10

11

12

13

14

5

6

7

1

2

3

4

15

16

17

18

19

20

21

22

Mean ± (SD)

Table A. 13: Numbers of gaster-flagging ants on SED2 (choice-chamber) (Trial 1)

Treatments

35 VAC

0

1

0

0

0

0

0

1

0

2

1

2

0

0

0

0

0

0

0

0

0

0

0.3 ±0.6

70 VAC #1 70 VAC#2

0

0

1

0

0

1

0

0

0

0

0

0

0

0

0

2

2

2

3

4

3

0

2

1

2

2

3

1

1

0

0

0

0

3

4

4

0

0

0

0

0

0

0

0

0.8 ±1.2 1.0±1.3 0.0 ±0.0

Control

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

65

Observation period

8

9

10

11

12

13

14

15

16

4

5

6

7

1

2

3

17

Mean ± (SD)

Table A. 14: Numbers of gaster-flagging ants on SED2 (choice-chamber) (Trial 2)

Treatments

35 VAC

0

1

0

1

4

1

3

3

0

0

0

2

0

0

3

3

0

1.2±1.4

70 VAC #1 70 VAC#2

2

4

2

7

0

6

2

1

3

3

2

0

0

0

5

5

1

0

0

0

1

1

0

0

0

5

0

1

1

2

3

1

0

0

2.5 ±2.2 0.8 ±1.3 0.0 ±0.0

Control

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

66

Table A. 15: Individual bone pile counts of dead ants (SED2) (choice-chamber) (Trial 1).

Treatments

Date 35 VAC 70 VAC #1 70 VAC#2 Control ^

10 Oct.

17 Oct.

31 Oct.

6 Nov.

18 Nov.

26 Nov.

350

521

276

315

427

456

1276 780 125

2345 440 135

700 476 220

853 356 99

659 364 76

557 324 60

67

Table A. 16: Individual bone pile counts of dead ants (SED2) (choice-chamber) (Trial 2).

Treatments

Date 35 VAC 70 VAC #1 70 VAC#2 Control

30 Jan.

5 Feb.

14 Feb.

28 Feb.

7 Mar.

333

226

315

217

256

450 654 895

462 720 745

520 652 650

387 589 420

333 476 226

16 Mar. 195 202 416 249

68

Table A. 17: Numbers of ants crossing the 8.0-cm lines for the powered and unpowered

SED3.

Numbers of ants

Observation

Period Active SED3 Inactive SED3

1 21 22

2 23 25

3 28 17

4 16 19

5 22 27

6 25 21

7 14 12

8 9 12

9 5 9

_10 15 8

Mean±(SD) 17.8 ±(7.2) 17.2 ±(6.6)

69

Table A. 18: Numbers of gaster-flagging ants on electrical device for SED3 experiment.

1997

Date/Tune

5/6-8:00 a.m.

5/6-9:00 a.m.

5/6-1:00 p.m.

5/6-2:00 p.m.

5/7-8:00 a.m.

5/7-9:00 a.m.

5/7-1:00 p.m.

5/7-2:00 p.m.

5/8-8:00 a.m.

5/8-9:00 a.m.

5/8-1:00 p.m.

5/8-2:00 p.m.

5/9-8:00 a.m.

5/9-9:00 a.m.

5/9-1:00 p.m.

5/9-2:00 p.m.

Mean ± (SD)

1

5

2

4

4

2

1

0

3

4

0

0

5

2

7

4

2

2.8 ±2.0

2

2

6

5

6

12

10

10

10

15

15

14

12

7

6

4

4

8.6 ±4.1

3

2

5

4

5

5

11

9

11

15

14

13

11

10

9

5

8

8.5 ±3.8

4

3

4

5

2

6

12

15

11

12

11

10

10

12

14

8

7

8.8 ±3.9

5

2

8

6

8

7

12

14

12

12

10

9

7

6

9

7

8

8.5 ±2.9

70

Table A. 18 (continued): Numbers of gaster-flagging ants on electrical device for SED3 experiment.

1997

Date/Time

5/6-8:00 a.m.

5/6-9:00 a.m.

5/6-1:00 p.m.

5/6-2:00 p.m.

5/7-8:00 a.m.

5/7-9:00 a.m.

5/7-1:00 p.m.

5/7-2:00 p.m.

5/8-8:00 a.m.

5/8-9:00 a.m.

5/8-1:00 p.m.

5/8-2:00 p.m.

5/9-8:00 a.m.

5/9-9:00 a.m.

5/9-1:00 a.m.

5/9-2:00 p.m.

Mean ± (SD)

6

8

5

9

4

7

2

4

8

12

12

10

17

12

10

8

12

8.7±3.8

Experimental Colonies

7

9

4

8

5

5

9

11

12

10

3

5

12

11

9

8

5

7.8 ±2.9

8

8

5

8

5

17

15

9

9

8

2

6

5

6

14

9

6

8.2 ±4.0

9

9

5

7

7

8

5

8

15

10

8

9

5

5

4

9

7

7.5 ±2.6

10

6

6

7

7

6

7

5

8

14

12

7

7

8

7

12

9

8.0 ±2.5

71

1997

Date/Time

5/6-8:00 a.m.

5/6-9:00 a.m.

5/6-1:00 p.m.

5/6-2:00 p.m.

5/7-8:00 a.m.

5/7-9:00 a.m.

5/7-1:00 p.m.

5/7-2:00 p.m.

5/8-8:00 a.m.

5/8-9:00 a.m.

5/8-1:00 p.m.

5/8-2:00 p.m.

5/9-8:00 a.m.

5/9-9:00 a.m.

5/9-1:00 p.m.

5/9-2:00 p.m.

Mean ± (SD)

1

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0.0 ±0.0

Control Colonies

2

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0.0 ±0.0

3

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0.0 ±0.0

4

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0.0 ±0.0

5

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0.0 ±0.0

72

Table A. 19 (continued): Numbers of gaster-flagging ants on electrical device for SED3 experiment.

1997

Date/Time

5/6-8:00 a.m.

5/6-9:00 a.m.

5/6-1:00 p.m.

5/6-2:00 p.m.

5/7-8:00 a.m.

5/7-9:00 a.m.

5/7-1:00 p.m.

5/7-2:00 p.m.

5/8-8:00 a.m.

5/8-9:00 a.m.

5/8-1:00 p.m.

5/8-2:00 p.m.

5/9-8:00 a.m.

5/9-9:00 a.m.

5/9-1:00 p.m.

5/9-2:00 p.m.

Mean ± (SD)

6

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0.0 ±0.0

Control Colonies

7

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0.0 ±0.0

8

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0.0 ±0.0

9

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0.0 ±0.0

10

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0.0 ±0.0

73

1997

Date/Time

5/6-8:00 a.m.

5/6-9:00 a.m.

5/6-1:00 p.m.

5/6-2:00 p.m.

5/7-8:00 a.m.

5/7-9:00 a.m.

5/7-1:00 p.m.

5/7-2:00 p.m.

5/8-8:00 a.m.

5/8-9:00 a.m.

5/8-1:00 p.m.

5/8-2:00 p.m.

5/9-8:00 a.m.

5/9-9:00 a.m.

5/9-1:00 p.m.

5/9-2:00 p.m.

Mean ± (SD)

1

3

2

2

2

5

2

2

2

2

2

2

2

5

4

5

3

2.8 ±1.2

2

5

5

5

4

5

5

5

5

5

5

5

5

5

5

5

4

4.8 ±0.3


3

4

5

4

4

4

5

4

3

4

5

4

4

4

5

4

4

4.1 ±0.5

4

4

4

5

4

5

4

5

5

4

3

5

4

4

4

5

5

4.3 ±0.3

5

3

3

4

4

3

3

3

5

5

5

5

4

4

5

5

4

4.0 ±0.8

74

Table A.20 (contmued): Rating of ants within 2.5-cm zone of SED3.

1997

Date/Time

5/6-8:00 a.m.

5/6-9:00 a.m.

5/6-1:00 p.m.

5/6-2:00 p.m.

5/7-8:00 a.m.

5/7-9:00 a.m.

5/7-1:00 p.m.

5/7-2:00 p.m.

5/8-8:00 a.m.

5/8-9:00 a.m.

5/8-1:00 p.m.

5/8-2:00 p.m.

5/9-8:00 a.m.

5/9-9:00 a.m.

5/9-1:00 p.m.

5/9-2:00 p.m.

Mean ± (SD)

6

4

4

4

5

3

4

5

5

3

2

4

4

5

5

4

3

4.0 ±0.8


7

3

5

3

4

4

2

3

3

5

5

5

4

5

5

2

4

3.8±1.0

8

5

4

4

4

4

5

4

5

5

4

3

5

5

5

4

5

4.4 ±0.6

9

2

4

3

4

4

4

4

4

5

4

4

4

4

4

3

4

3.8 ±0.6

10

5

5

4

5

4

4

3

5

5

4

4

4

4

5

4

4

4.3 ±0.6

75

1997

Date/Time

5/6-8:00 a.m.

5/6-9:00 a.m.

5/6-1:00 p.m.

5/6-2:00 p.m.

5/7-8:00 a.m.

5/7-9:00 a.m.

5/7-1:00 p.m.

5/7-2:00 p.m.

5/8-8:00 a.m.

5/8-9:00 a.m.

5/8-1:00 p.m.

5/8-2:00 p.m.

5/9-8:00 a.m.

5/9-9:00 a.m.

5/9-1:00 p.m.

5/9-2:00 p.m.

Mean ± (SD) 1.0 ±0.0

Control Colonies

2 3 4

1.0 ±0.0 1.0 ±0.0 1.0 ±0.0

5

1.0 ±0.0

76

Table A.21 (continued): Rating of ants within 2.5-cm zone ofSED3.

1997

Date/Time

5/6-8:00 a.m.

5/6-9:00 a.m.

5/6-1:00 p.m.

5/6-2:00 p.m.

5/7-8:00 a.m.

5/7-9:00 a.m.

5/7-1:00 p.m.

5/7-2:00 p.m.

5/8-8:00 a.m.

5/8-9:00 a.m.

5/8-1:00 p.m.

5/8-2:00 p.m.

5/9-8:00 a.m.

5/9-9:00 a.m.

5/9-1:00 p.m.

5/9-2:00 p.m.

Mean±(SD) 1.0 ±0.0

Control Colonies

8

1.0 + 0.0 1.0 + 0.0 1.0 + 0.0

0

1.0 + 0.0

77

Table A.22: Number of ants behind 8.0-cm Une of SED3 and number of ants gaster-

Observation period

22

23

24

25

16

17

18

19

11

12

13

14

15

20

21

8

9

10

5

6

7

1

2

3

4

26 x/Toon -1- /'Qn^

<2.5 cm

250

200

220

93

100

153

134

156

207

24

26

31

33

60

90

101

160

36

48

110

34

150

130

23

23

21 inn s + 70 4

Diode gaster-flagging

9

6

6

3

5

3

4

0

3

0

3

0

5

10

9

9

7

5

10

7

7

10

3

1

0

1

4.8 + 5.4

<2.5 cm

130

126

101

19

34

50

100

120

120

7

3

0

2

22

23

27

81

8

19

35

54

35

33

12

17

11

45.7 + 43.4

^FD^ gaster-flagging

4

0

0

1

1

0

0

0

0

0

5

1

0

0

0

1

4

6

4

0

0

4

5

1

3

0

1.5 ±2.0

78

Table A.23: Number of ants behind the 8.0-cm lines toward diode (no transformer) and

SED3.

Number of ants

Observation period Diode SED3

1 35 16

2 35 14

3 35 9

4 40 9

5 32 9

6 30 10

7 27 9

8 37 6

9 120 16

10 128 14

11 142 30

12 164 31

13 168 32

14 157 22

15 157 19

16 164 20

17 93 25

18 101 27

19 120 29

20 132 22

21 141 19

22 149 20

23

164 24

24

175 23

25

15 8

26 28

5

7

27 28

28

32 6

6

29 35

5

30 42

6

31 48

3

32 46

40

33 120

35

34 150

35 157 37

36 162 38_

79

Table A.23 (continued): Number of ants behind the 8.0-cm Unes toward the diode SED

(no transformer) and SED3.

Number of ants

Observation period

55

56

57

58

59

60

48

49

50

51

52

53

54

61

62

63

64

65

66

67

68

69

70

37

38

39

40

41

42

43

44

45

46

47

71

Diode

42

45

51

52

52

50

57

54

70

60

65

63

62

165

130

160

160

170

220

240

248

264

30

37

67

74

78

84

92

30

37

42

50

. 50

46

SED3

14

13

9

12

11

17

17

16

14

13

9

10

7

61

52

48

46

14

13

12

10

57

40

35

47

52

14

20

27

14

16

11

10

9

7

80

Table A.23 (continued): Number of ants behind the 8.0-cm lines toward the diode SED

Number of ants

Observation period

80

81

82

83

84

72

73

74

75

76

77

78

79

Mean ± (SD)

Diode

172

169

38

37

154

147

154

162

175

170

120

135

138

99.4 ± 62.3

SED3

52

42

11

11

45

40

37

45

44

47

37

42

60

22.9 ±15.7

81

Table A.24: Number of ants crossing the 8.0-cm lines toward a non-working SED vs.

Trans. on vs. SED3 off

Replication

(colony)

1

6

7

8

9

2

3

4

5

10

Mean ± (SD)

Trans. on

28

38

7

14

21

41

5

17

31

45

24.7 ±14.1

SED3 off

22

36

6

16

20

27

45

11

9

48

24.0 ±14.8

Grid plates on vs SED off

Plates on

42

65

37

60

35

20

18

3

35

32

34.7 ±18.6

SED3 off

14

31

6

61

36

54

50

46

27

27

35.2 ±17.6

82

Table A.24 (continued): Number of ants crossing the 8.0-cm Unes toward a non-working

SED vs. working transformer, electric grid plates, working SED, and dead ants.

SED3 on vs SF.D3 nff

RepUcation

(Colony)

1

2

3

4

5

6

7

8

9

10

Mean ± (SD)

47

54

25

27

35

43

38

4

32

32

SED3 on

33.7± 13.7

SED3 off

35

12

4

13

32

16

17

12

24

16

18.1 ±9.5

Dead ants vs SED3 off

Dead ants

9

38

24

42

23

24

5

177

1

5

34.8 ±51.8

SED3 off

15

1

88

1

15

59

35

27

8

3

25.2 ±28.5

83

Table A.25: Number of ants crossing 8.0-cm Imes towards mtroduced pheromone, plain air, tainted kimwipe paper, and clean kimwipe paper.

Replication

(colony) Pheromone No Pheromone Clean paper Tainted paper

1 17

12 13 25

2

3

4

5

6

7

64

9

40

83

24

88

19

39

12

15

55

6

50

19

15

9

21

34

26

28

32

35

42

37

96

54

34

66

8

9

10

57

18

13

9

14

17

32

33

11

59 21 8 17

Mean ± (SD)

43.4

±28.1 22.8

±17.0 19.7 ±9.0 42.8

+ 22.0

84

APPENDIX B

HARVESTESTG RED IMPORTED FIRE ANT COLONIES

85

Materials and Methods for Harvesting RIFA.

Red imported fire ant colonies were coUected near Lake Kirby in Abilene, Taylor

Co., Texas, and from the campus of Texas Tech University, Lubbock, TX, by shoveling mounds mto 18.9-Uter plastic buckets. A thin fiUn of baby powder was sprinkled along the top 10 cm of each pail to provide a slippery surface over which ants could not climb. Once m the laboratory, colonies were retained and accUmated for several days in the buckets.

After five days, ants and brood were separated from soil by water-dripping (Jouvenaz et al.

1977). Ants were then placed m separate plastic trays (55 cm x 44 cm x 13 cm). Each tray had at least one plastic brood box measuring (12x12x3.5 cm) for the ants to rear brood.

Dental plaster fiUed the bottom 1/3 of the brood boxes and was used in the constmction of the abodes. The top edges of trays were coated with Fluon (Northem Products,

Woonsocket, RI) to prevent ants from escapmg. Colonies were fed three times each week, on an altematmg diet of dog food, cockroaches (Blaberidae), jelly, and other meat products. Water was continuously supplied in test tubes with cotton plugs.

86

APPENDIX C

DESIGNS OF THE STATIC ELECTRIC DEVICE (SED2 & SED3)

87

The SED2 consisted of one soUd sheet of stainless steel and one sheet of perforated stamless steel. These material changes were made to reduce the oxidation potential and helped mcrease the uhimate service life, and reduce the manufacturing cost. Also, a layer of latex paint was used on one side of the perforated piece to insure that the only circuit that could be made on the SED2 was by ants when in contact with the base plate and the perforated plate. The SED2 was 12.7 cm x 17.8 cm and used a 2-to-l, center-tapped transformer. The voltage of the SED2 was 70 VAC. The SED2 drew about one kilowatthour of power per year.

The SED3s design caUed for more effective insulation between energized plates and more self-cleaning so ants could not pUe up debris. Gaster-flagging occurred most around the perimeter of charged surfaces, so the charged surface of the SED3 consisted of two stainless steel strips without perforations. Strips were 1.3 cm apart and were separated from the steel base by 1.5 mm of insulation, which prevented ant access and debris accumulation between charged plates. EssentiaUy, SED3 devices were self-cleaning because dead ant bodies and debris did not accumulate between charged surfaces and cause short cu'cuits. The two separate charged strips also increased the perimeter in relation to the charged surface area.

88

EFFECTS OF STATIC ELECTRICAL DEVICES ON RED IMPORTED

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