Lecture 25 Flashcards
mosquitos are vectors of what diseases? (2)
Western Equine Encephalitis
West Nile Virus
what spp does Western Equine Encephalitis effect?
humans & horses
what spp does West Nile Virus effect?
birds, horses & humans
what spp seem to be the most susceptible to west nile virus?
corvids
what is the vector spp of the west nile virus?
blood-fed culex tarsalis
describe the Blood-Fed Culex Tarsalis lifecycle
females suck blood (engorged), lay eggs & fly away from host
When larvae hatch, there is a cap that they use to emerge & they then go into the water
develop into a pupa
Emerge as an adult mosquito from the water
how does the female Culex Tarsalis lay eggs
Lays eggs all at once
Laid in a raft on the surface of the water – initially white & then darken
how does the Culex Tarsalis larva breathe in water?
Have 2 spiracles that break through the surface tension & creates an opening of air directly into the spiracles
how does the Culex Tarsalis larva feed?
Mouthparts are brushes that vibrate & filter out fine particles in the water
what type of development does Culex Tarsalis have?
holometabolous
describe the pupa stage of Culex Tarsalis
No longer breathe from abdomen
Breathe from 2 holes in the thorax
Abdomen is used for buoyancy
what are the 2 nuisance mosquito pests of MB?
o 1) Spring snow-melt species
o 2) Summer floodwater species
what are the 2 vector spp of mosquitos?
o Culex spp. o Anopheles (not a vector in MB)
how do the spring snow-melt spp lay their eggs?
Lay a hole batch of eggs, but are laid indiv on a moist substrate (not on the surface of water)
Wetland, marsh
how many gens do spring snow-melt spp have?
1 gen/year
what is the result of a spring snow-melt mosquito laying eggs?
female dies
when do the spring snow-melt spp eggs hatch?
just above freezing temp
Once winter is over & they become flooded in the marsh/wetland then they are ready to hatch
do the spring snow-melt spp go into obligate diapause?
yes
where do the summer floodwater spp lay their eggs?
on the side of depressions where water accumulates
ex: sides of ditches
which type of mosquito spp egg’s hatch at a wamer temp?
summer floodwater spp
when do the summer floodwater spp lay their eggs?
june
how many gens of mosquitos do summer floodwater spp have?
several gens
what triggers diapause in the summer floodwater spp?
fall
does the culex spp lay eggs over winter?
no, they overwinter as adults
how many gens of mosquitos do culex spp have?
several
describe how culex spp lay their eggs
as rafts
what mosquito spp is a vector of malaria?
Anopheles
how do you distinguish Anopheles from other mosquitos?
Lift abdomen
Prediuresis & who uses this method?
expel serum from blood to get rid of mass to permit better movement & acquire more blood
Anopheles - done during & after feeding
describe how Anopheles lay their eggs
Lay eggs singly on the surface of water
describe how Anopheles overwinters
as adults
what spp of mosquitos overwinter as adults
anopheles & culex
what spp lay their eggs over winter?
- Summer floodwater species
* Spring snow-melt spp.
what spp have several gens?
Summer floodwater species
culex
what spp eggs are triggered to hatch by flooding?
- Summer floodwater species
* Spring snow-melt spp.
describe the relationship b/w the pitcher plant mosquito & its plant
Plant grows in soils low in N, supplement N by consuming it from insects
Insect will fall to the ground & the plant observes nutrients from the decomposing insect
Mosquitos lay larvae in the plant
what is an ex of a carnivorous plant feeding on mosquitos?
pitcher plant
what are the factors why mosquitos are so abundant in MB? (5)
Topography
Seasonal weather patterns
Urban development
Rural drainage networks
Blood-host availability
how does topography contribute to the abundance of mosquitos in MB?
mosquitos develop only in standing water
Flat prairies facilitate this
Since humans try to drain everything (ditches etc.) there are perfect envrs for mosquitos
how do seasonal weather patterns contribute to the abundance of mosquitos in MB?
a lot of snowmelt, require a lot of snow to raise water level & triggers the mosquitos to hatch
Thunderstorms also fill areas with water
what happens if there’s a drought & the mosquito eggs aren’t triggered to hatch?
they will just wait for the following year
how does blood-host availability contribute to the abundance of mosquitos in MB?
cattle adjacent to ditches
Ditches are in close proximity to pasture animals
what are the costs of mosquitos? (6)
Losses to livestock production
Losses in tourism & trade
- Reduction in outdoor activity
- Impact of vector-borne pathogens
- Impact on fitness in wildlife (vector disease)
- Costs of control
how does an abundance of mosquitos affect cattle?
When mosquitos are abundant they cause cattle to stampede
Cattle Out run mosquitos, stop & start grazing
When the mosquitos increase in numbers they flood them again & the cattle continue to stampede
what are the steps in mosquito control? (6)
Surveillance
Larviciding
Source reduction
Public awareness
Baited traps & repellents
Adulticiding
what is the surveillance step of mosquito control?
knowing where they lay eggs
the surveillance of mosquitos is divided into 2 sections: _____ & _____
larval mosquitos - still in the aquatic stage
adult mosquitos - mobile
how is surveillance done on aquatic mosquitos?
dipping
how is surveillance done on adult mosquitos? (4)
Light/CO2 traps
Oviposition traps (gravid trap)
Landing-biting counts
Surveillance flocks
Light/CO2 traps
lightbulb with a fan, attracted to the light at night & sucked to the bottom from the fan
Attracted to CO2 b/c females release it, adding CO2 near fan will increase efficiency
Oviposition traps
used for vector spp of culex lay eggs on rafts, so you provide a water surface for them to lay their eggs
what trap targets the culex spp & why?
oviposition traps
they lay eggs on rafts
gravid trap
form of an oviposition trap except it has a fan on it that sucks up the mosquitos when they lay eggs
land-biting counts
have a tube with suction, when they land on you then you suck them up
surveillance flocks
used for vector species
Put chickens in a cage & count how many land on them
Take blood samples from the birds to determine if they extracted a pathogen
what traps are used for vector spp?
surveillance flocks
larviciding
spray on larval sites manually, with trucks or helicopters
what does public protection consist of?
personal protection:
- Behaviour modification
- Protective clothing – light coloured, long sleeves & pants
- Repellents – DEET most effective forms, citroses plant not effective
what are mosquito baited traps & repellents used?
Mosquito magnet
Electronic mosquito repellers
when does adulticiding occur?
when adult numbers are so high & control program has failed
how do they determine when it is approproate or adulticiding?
Threshold # of mosquitos in night traps
