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Response of Phlebotomine Sand Flies to
Light Emitting Diode-Modified Light Traps
in Southern Egypt
LCDR David Hoel
NAMRU-3
Cairo, Egypt
Response of Phlebotomine Sand Flies to
LED-Modified Light Traps in Southern Egypt
• Goals:
– Determine if a preference exists in Phlebotomine
sand flies among different colored light produced
from light emitting diodes (LEDs) and incandescent
light in modified and standard CDC light traps.
– Test prototype LED-modified CDC light trap for
ruggedness/reliability in a desert environment.
– U0009_04_N3 - Sand fly Trap Evaluations to
Determine the Best Surveillance System for
Anthropophilic Sand Flies.
Why research traps? Goals of
trapping…
• Develop highly effective light traps that will increase trap
capture and provide more detailed, accurate surveillance
in an area.
• Provide environmentally-friendly control of nuisance or
vector insects through removal trapping, thus reducing
the impact of broadcast insecticide applications on the
environment (e.g., thermal fog, ULV).
– Trap efficacy may be greatly increased with use of optimal
colors, colored light, trap design, and chemical attractants (Nzi
trap and tsetse flies, Mihok 2002, Green 1994; commercial mosquito traps and
salt marsh mosquitoes, Xue et al. 2005).
• Delay development of insecticide resistance.
Materials & Methods- Traps
J.W. Hock model 512 light traps were wired with twenty
gauge insulated electrical wire routed between a 3-way
toggle switch, LED plug in connectors, and the
incandescent light in parallel.
Materials & Methods- Traps
J.W. Hock model 512 light traps were wired with twenty
gauge insulated electrical wire routed between a 3-way
toggle switch, LED plug in connectors, and the
incandescent light in parallel.
Schematic
Original design
LED-modified design
Materials & Methods- Traps
4 LED plug-in sockets were spaced 90o apart around
the circumference of traps. Flexible, dual lead LEDs
allow for orientation into space (transmitted light) or
towards a reflective surface (reflected light).
• Four 240 Ω, 1/8 W resistors
prevented overdriving the
circuit.
• LEDs are easily replaced as
needed.
Materials & Methods- Traps
• LEDs
– Sold by Digi-Key Corporation (Thief River Falls, MN).
– Color, part number, wavelength and millicandela
(mcd) chosen for testing were:
• blue (P466-ND, 470 nm, 650 mcd)
• green (67-1755-ND, 502 nm, 1,500 mcd)
• red (67-1611-ND, 660 nm, 1,800 mcd)
– LEDs are 8.6 mm in length by 5.0 mm in diameter
with rounded lens and viewing angles of 30o.
Materials & Methods- Traps
• LED Advantages…
– Shock resistant
– Greatly extended operational life of
LED vs. lamp
– Cooler operating temperatures
– Greatly reduced power consumption,
80 ma/hr (4 LEDs) vs. 150 ma/hr lamp
– Doubles battery life (6V, 12 amp/hr)
– Range of colors
Materials & Methods- Location
Bahrif, next to Aswan
Materials & Methods- Location + Design
• Bahrif, Egypt. Farming
village on the banks of
the Nile River 6 km north
of Aswan, 900 km south
of Cairo.
• 4 x 4 Latin square design,
3 repetitions.
• Treatment: blue, green,
red, and incandescent
light.
Materials & Methods- Location
Materials & Methods- Location
Materials & Methods- Location + Design
• All traps baited with ≈ 1
kg dry ice in Igloo
containers.
• Traps set with opening 45
cm above the ground
(knee level).
• Sand flies removed at
sunrise, later IDed using
keys of Lane (1986).
Materials & Methods- Analysis
•
Trap collections were analyzed for month (trial),
position, and treatment (light color) using a 3-way
ANOVA (SAS Institute, 2001).
•
The Ryan-Einot-Gabriel-Welsh Multiple Range Test
was used to delineate significant differences (α = 0.05)
between treatments, months, and positions.
•
All capture data were transformed with log10 (n + 1)
prior to analysis.
Trap sites
Results & Discussion
• 2,298 sand flies were collected over 3 repetitions (12
nights, 48 trap-nights).
• Phlebotomus papatasi was the most abundant species in
the field and comprised 94.39% of the entire catch
(2,169 of 2,298 adults).
• Other species collected included P. sergenti (1.31%),
Sergentomyia schwetzi (4.0%), S. clydei (0.17%), S.
tiberiadis (0.09%), and S. antennata (0.04%).
Results & Discussion
• Analysis of data yielded highly significant results (F =
10.62; df = 8, 39, P < 0.0001).
• Sand fly collections differed significantly between...
– treatments (F = 17.67; df = 3, 8; P < 0.0001)
– collection positions (F = 6.53; df = 3, 8; P = 0.0011)
– trials (F = 6.19; df = 2, 8; P = 0.0046)
P. Papatasi response to colored light
Treatment
Trial 1 (May)
Trial 2 (June)
Trial 3 (July)
Total (%)
Red
297
466
467
1230 (56.7)
Control
70
167
237
474 (21.8)
Blue
92
97
51
240 (11.1)
Green
26
128
71
225 (10.4)
Total
485 (61.2)
858 (54.3)
826 (56.5)
2169
P. papatasi response to colored light
225 (10%)
227 (11%)
Red
Control
474 (22%)
1230 (57%)
Blue
Green
Sand fly species composition (means ± SEM) from light emitting diodemodified CDC light traps (J. W. Hock Co. model 512). Means within each
row followed by the same letter are not significantly different
(Ryan-Einot-Gabriel-Welsh Multiple Range Test). n = 12 nights.
Species Incan.
Blue
Red
Green
P-value
P. papatasi1,2
39.50 ± 11.19b
20.00 ± 3.81bc
102.50 ± 10.01a
18.75 ± 5.27c
< 0.0001
P. sergenti
0.58 ± 0.26a
0.58 ± 0.34a
0.83 ± 0.27a
0.5 ± 0.14a
0.96
S. schwetzi1
2.50 ± 0.93a
1.75 ± 0.69a
2.08 ± 0.96a
1.33 ± 0.51a
0.08
S. tiberiadis
0.08 ± 0.08a
0.08 ± 0.08a
0.0 ± 0.0a
0.0 ± 0.0a
0.78
S. clydei
0.17 ± 0.11a
0.0 ± 0.0a
0.08 ± 0.08a
0.08 ± 0.08a
0.63
S. antennata
0.0 ± 0.0a
0.0 ± 0.0a
0.08 ± 0.08a
0.0 ± 0.0a
0.45
1Significant
2Significant
position effect (P < 0.05)
day effect (P < 0.05)
Sex ratios
• P. papatasi sex ratios were approximately the same, with
slightly more females captured than males.
• Sex ratio was consistent over 3 reps.
• Males highly attracted to red light as well as females.
papatasi + red light
300
250
216
250
200
150
269
198
142155
female
male
100
50
0
1
2
3
Spectral sensitivity
Only one study measured spectral sensitivity to light in
Phlebotomine sand flies (Lutzomyia longipalpis) using
electroretinograms (Mellor et al. 1996). They found that:
-male and female flies demonstrated greatest sensitivity to light
in the UV and a secondary sensitivity to light in the green-yellow
spectrum (520 nm ♀, 564 nm ♂).
-typical bimodal response seen in “slow eye”, slow flight insects
such as mosquitoes.
-no studies found pertaining to Phlebotomus sand flies and
spectral sensitivities.
Luminosity
One possible answer for slow flying P. papatasi to respond
strongly to red light (660 nm):
-High luminosity of red LEDs were more attractive than
less bright competitors (prior published work with
mosquitoes seems to confirm this (Breyev 1963, Barr et
al. 1963)).
• Blue (470 nm,
• green (502 nm,
• red (660 nm,
650 mcd)
1,500 mcd)
1,800 mcd)
Luminosity?
• Blue (470 nm,
• green (502 nm,
• red (660 nm,
650 mcd)
1,500 mcd)
1,800 mcd)
Note however that…
• green and red mcd ratings are within 17% of each other
• green lit-traps collected the fewest number of sand flies
• five species of mosquitoes belonging to 3 genera (Culex,
Ochlerotatus and Anopheles) were collected in the following order of
success:
Green> incandescent> blue> red lit-traps (~5800 mosq.)
during this test period (this data is largely in agreement with Burkett
et al. (1998) concerning collection of mosquitoes with LED-baited
traps in Florida).
Luminosity?
Using low luminosity glow sticks in the
Sinai, Dr. Szumlas found no preference
Date
in P. papatasi for one
7-Jun-05
color over another, in fact, very little
7-Jun-05
response at all.
7-Jun-05
Color
No
Yellow
0
Control
0
Blue
2
7-Jun-05
White
3
7-Jun-05
Red
2
7-Jun-05
Control
7-Jun-05
Orange
1
7-Jun-05
Green
13
9-Jun-05
Blue
3
9-Jun-05
White
1
9-Jun-05
Red
1
9-Jun-05
Control
0
9-Jun-05
Orange
1
9-Jun-05
Green
0
9-Jun-05
Yellow
0
9-Jun-05
Control
0
Low luminosity produced
by both radioactive tritium gas
Luminosity?
lights and chemlites also resulted in few mosquitoes or
sand flies captured in trials in the Panama canal zone.
Order of success was incandescent light> chemical
light> radioactive light (Varva et al. 1974).
Conclusions of study
• Phlebotomus papatasi is very likely more attracted to
long-wavelength light (red spectrum) than short
wavelength light (UV-blue), however, further field testing
is needed in different environments (Riparian vs.
Desert).
• High intensity colored light (from LEDs) is better than low
intensity colored light (chemlights).
• LED-modified CDC light traps performed very well with
no trap or LED failures.
Other work…
• Need to run electroretinograms on male and female
P. papatasi, other Phlebotomus sand flies to
determine spectral sensitivities.
• Our study used reflected light- how about transmitted
light?
• Determine most effective chemical attractants +
match with red-LED traps (Dr. Bernier, CMAVE).
• Test LED traps in wet environments for durability.
References
•
•
•
•
•
•
Barr, A.R., T.A. Smith, M.M. Boreham, K.E. White. 1963. Evaluation of some factors
affecting the efficiency of light traps for collecting mosquitoes. Journal of Economic
Entomology 56:123-127.
Breyev, K.A. 1963. The effect of various light sources on the numbers and species of
blood-sucking mosquitoes (Diptera: Culicidae) collected in light traps. Entomological
Review 42:155-168.
Burkett, D.A., J.F. Butler, D.L. Kline. 1998. Field evaluation of colored light-emitting
diodes as attractants for woodland mosquitoes and other Diptera in north central
Florida. Journal of the American Mosquito Control Association 14(2):186-195.
Green, C.H. 1994. Bait methods for tsetse fly control. Advances in Parasitology
34:229-291.
Lane, R.P. 1986. The sand flies of Egypt (Diptera: Phlebotominae). Bulletin of the
British Museum (Nat. Hist.) Entomol. 52:1-35.
Mellor, H.E., J.C.G. Hamilton, M. Anderson. 1996. Spectral sensitivity in the eyes of
male and female Lutzomyia longipalpis sandflies. Medical and Veterinary
Entomology 10:371-374.
References
•
•
•
Mihok, S. 2002. The development of a multipurpose trap (the Nzi) for tsetse and
other biting flies. Bulletin of Entomological Research 92:385-403.
Vavra, R.W.Jr., R.R. Carestia, R.L. Frommer, E.J. Gerberg. 1974. . News 34(4):382384 . Mosquito News 34(4):382-384.
Xue, R., A. Santoro, D.L. Kline, A. Grant. Mosquito magnets as barrier treatments
against salt marsh mosquitoes around residential houses in marsh area. Technical
Bulletin of the Florida Mosquito Control Association 17 Feb. 2005.