The Effects of Predation and
Competition on the Mortality and
Hatching Percent of Mosquitoes
and Mayflies
By
Henry Mumford
Kyle Goodwin
Brendan Fogarty
May 28, 2008
Small Minnow Mayfly (Beatidae) Larvae
Diet:
• Algae
•Diatoms
•Settled organic matter
Reproductive Cycle:
Entire generation hatches at once after 3
months in larval stage. Once they mature
they quickly mate.
The females land near shore and
crawl underwater to lay their eggs in
neat little rows on rocks and logs.
Critical Habitat Features: Mayflies require clean, unpolluted water that is well
oxygenated. They are one of the first aquatic species
to disappear when water pollution occurs.
Mosquito (Culicadae) Larvae
Diet:
•Algae
•Protozoa
•Organic Debris
Habitat: Aquatic habitats. Any size
standing body of water.
Reproduction: Eggs are laid either on surface of
water or above the waterline in areas subject to
flooding.
Eggs hatch in spring and larvae complete 4
stages of development before pupating.
Larva stage lasts about a week depending mostly
on temperature. Pupa stage typically lasts less
than a week; adults emerge directly from pupae at
the water surface.
Northern Case Makers (Limnephilidae)
Diet: •Organic Material
•Any type of larvae
•Extremely Voracious
Habitat: Large standing pools.
Reproduction: Caddisfly larvae develop
through four stages (instars) over
several months or even a year. Pupation
is always aquatic.
Eggs are deposited on moist wood
and other debris on the dry pool
bottom in the fall. They need wood
and other debris to make their
protective “homes”.
Dytiscid Beetle (Dytiscidae cybister tripunctatus)
Diet: • Insects (macroinvertebrates)
•Crustaceans
•Small Fish
•Tadpoles
•Both adults and larvae are
predaceous, and will attack a wide
variety of small aquatic organisms.
Habitat: Slow moving or
shallow water, ponds, lakes,
and pools. They breathe air.
Damselfly Larvae (Protoneuridae)
Diet: •Daphnia
•Mosquito Larvae
•Small Aquatic Organisms
Habitat: Small streams,
vernal pools, and lakes.
Underwater vegetation and
water are required for laying
eggs.
Grayback Dragonfly Larvae (Petaluridae tachopteryx)
Diet: •Mosquito Larvae
•Tadpoles
•Bloodworms
•Aquatic Insects
Catching Mechanism:
Dragonfly larvae look like fierce
dragons and crawl about
underwater hunting for food. A
unique feature is their labium, a
lower lip that they project to hook
prey.
•Maturing dragonfly larvae feed very intensively.
Factually Based Assumptions for this Lab
•All predators are known to eat mosquito larvae.
•All predators are known to eat other aquatic
invertebrates so mayflies are assumed to be prey.
Significance
•This study will give further insight into the effects of
competition and predation upon the mosquito. In areas with
high rates of malaria and vector-transmitted diseases, the
natural control of mosquitoes may help decrease disease with
minimal cost.
•The effects of predation on mayflies and their dynamics in
competition will allow a more in depth analysis to the mayflies
presence in certain pools. Mayflies are a great water pollution
indicator species and understanding the predators and
competitors will help water quality assessment in pools with
mayflies.
Possible Correlations
1. Mayflies and Mosquitoes are competitors however the
mosquito is the superior competitor.
2. The Caddisfly is the most effective predator on the mayfly.
3. Presence of a predator and competitor decreases the
hatching percent for mosquitoes.
4. The more aggressive and agile predators like the Dytiscid
beetle and Damselfly are more effective on controlling
mosquito populations.
Methods
Dates
Time
Activity
May 2
3:45 P.M.
Organism Collection
and Separation
May 5
1:05 P.M.
May 5
10:55 A.M.
May 7
2:00 P.M.
May 8
1:15 P.M
May 9
1:45 P.M.
May 10
10:45 A.M.
May 15
2:00 P.M.
Data Collection
Species were collected using dipnets in vernal pools GSP 1 and 2.
The Mayflies were collected from the upper landfill pool.
All predators were collected from Lake Romeyne, with the sole exception of
the Caddis Fly larvae. They were collected in GSP1 and GSP2
After collection, 12 initial treatments were made using a variety of combinations of
species measuring the effects of predation and competition. The treatments were
in glass containers with roughly equivalent water depth. The tops of the
containers were covered with paper towel and sealed with a rubber band to allow
gas exchange but to contain the hatched larvae.
Data Collection
Data was collected by examining the jars visually and attempting to count
the number of larvae of each species still swimming around, as well as the
number of hatched mosquitoes (no mayfly larvae hatched during the
experiment). To obtain the mortality rate, we counted the number of living
larvae (plus hatched adults for mosquitoes) and subtracted that number
from the orginal.
. Detailed descriptions of how variables were measured (including units)-we counted
number of mosquito larvae alive, mayfly alive, and mosquito hatched, and subtracted
that total amount from initial to get number dead.
Error and Bias
The most obvious case of error in this lab is in the counting of specimens.
Because the larvae never actually stopped moving, and there was a large
amount of particles in the large majority of the jars, it was often extremely
difficult to obtain an accurate count of the living larvae. Mosquito larvae were
particularly difficult because of their rapid bursts of movement. The mayfly
larvae were difficult because they favored sitting in the silt at the bottom in the
corner of the jar.
The main source of bias in this experiment involved the collection and
separation of the species. Because species were only sampled from the
shallows, it is possible that better (or worse) competitors were excluded
because of their inability to survive elsewhere in the ecosystem. Furthermore,
when species were separated into jars it is possibly that only the weakest
organisms were collected, because they were the easiest to catch in the pipet
before being transferred into the jars.
Mosquitoes Hatched in Competition
1.00
0.90
Percent Hatched
0.80
0.70
0.60
Hatched in Comp.
Hatched Control
0.50
0.40
0.30
0.20
0.10
0.00
5
7
9
11
Day in May
13
15
1
Mosquito and Mayfly Mortality
1.00
0.90
0.80
0.70
% Mortality
0.60
%Mos Mort in
Comp
%Mos Mort Control
0.50
% May Mort Comp
0.40
%May Mort Control
0.30
0.20
0.10
0.00
5
6
7
8
Date in May
9
10
2
Mosquito Populations under Predation
0.9
0.8
0.7
Percent Mortality
0.6
Mos Control
0.5
Mos Caddis
MosDams
May Drag
0.4
MosDytiscid
0.3
0.2
0.1
0
4
5
6
7
8
Date in May
9
10
11
3
Mayfly Populations under Predation
1.20
1.00
0.80
% Mortality
May Control
May Caddis
0.60
MayDamselfly
May Drag
MayDytiscid
0.40
0.20
0.00
4
6
8
10
Date in May
12
14
16
4
Percent Mosquitoes Hatched
1.00
0.90
0.80
Percent Hatched
0.70
0.60
% Hatched Caddis
% Hatched Control
0.50
% Hatched Damsel
% Hatched Dragon
% Hatched Dytiscid
0.40
0.30
0.20
0.10
0.00
0
2
4
6
8
Day in May
10
12
14
16
5
Discussion and Conclusions
•Mayflies are limited by habitat. They can only
survive in clean water without pollution or intense
particulate matter.
•The mosquito is the superior competitor. The pools
and water utilized eventually became polluted with
organic matter and other detritus. The mayflies died
over time and the cloudy water indicated this. In the
sampled with cloudy water the mayflies died the
fastest. The mayfly is extremely sensitive to pollution
in the water. The upper landfill pool where the mayflies
were collected was extremely clean and has a constant
source of fresh stream water flowing into it.
2
Mosquito Predator
•The Dytiscid beetle is the superior competitor of the mosquito
populations. Most Dytiscid beetles were found in GSP 1 and 2 where the
mosquitoes were most present . The Dytiscids ability to be agile and
swim around enables it to effectively catch mosquitoes with little search
and capture energy expended.
3
Mayfly Predator
•The Caddisfly is the superior predator for the mayfly larvae.
The upper landfill pool was extremely infested with them in
previous weeks because the mayflies were so abundant. The
mayflies are it’s primary food source. It will eat mosquitoes but
it prefers mayflies.
4
Mosquito Management
•The most effective predator on the hatching rate of the mosquito is the
Dytiscid beetle. To control mosquito populations Dytiscid beetles must
be managed. Also, to control mosquito populations, the pollution and
water quality of the pools must be extremely clean to allow mayflies to
take over the pool.
5
Summary
1. Mosquito superior competitor in polluted pools. However, mayfly does
out-compete mosquito in clean permanent pools based on observations.
2. Caddisfly is superior predator of mayflies.
3. Presence of Dytiscid Beetle decreases the hatching percent of
mosquitoes the greatest.
4. Competition increases mortality of both species (mayfly, mosquito) and
decreases hatching percent of mosquitoes.
Literature Cited
http://www.desertusa.com/mag98/nov/papr/drangonflies.html
http://www.ucmp.berkeley.edu/arthropoda/uniramia/odonatoida.html
Image of Dragonfly Larvae: http://csa.springbranchisd.com/clark1e/limnol5.jpg
Image of Dragonfly Adult: http://www.cssplay.co.uk/menu/slides/dragonfly.jpg
http://www.anbg.gov.au/cpbr/WfHC/Dytiscidae/index.html
Dytiscid Beetle Image provided by: http://www.sacsplash.org/cimages/water_beetle2.jpg
http://www.troutnut.com/hatch/4/Insect-Ephemeroptera-Mayflies
http://www.bcadventure.com/adventure/angling/bugs/mayfly/mayfly.phtml
Image Provided by: http://www.samford.edu/schools/artsci/biology/research/images/mayfly_larvae.jpg
http://insects.tamu.edu/fieldguide/cimg245.html
http://www.muhlenberg.edu/cultural/graver/Pools&Ponds/Invertebrates.htm
Caddis Fly Larvae Image provided by: http://images.whatsthatbug.com/images/caddisfly_nymphs_dewaine.jpg
Caddis Fly Adult Image Provided by: http://www.cirrusimage.com/images/Trichoptera_caddisfly_1.jpg
http://en.wikipedia.org/wiki/Damselfly
Damselfly Image provided by: http://cache.eb.com/eb/image?id=24012&rendTypeId=4
Aquatic Entomology: The Fisherman’s and Ecologists’ Illustrated Guide to Insects and Their Relatives.
Copyright by Science Book International 1981. W. Patrick McCafferty.