Richard Wall - traps Flashcards
7 features of traps
- Attractants (olfactory/visual)
- Non-return mechanism
- Effective against low density populations
- Minimal non-target effects
- Effective over large distances
- Inexpensive & durable
- Catch a large number of target pest (rel. R0)
why are semiochemicals used
eg kairomones, more useful than pheromones which only attract the males, whereas females are more important to trap in controlling the population.
how are tsetse distinguished from other flies?
unique hatchet shaped cell in wings.
both sexes blood feed every 2-4 days
tsetse life cycle
adenotrophic viviparity
1 egg ovulated and retained in common oviduct where it hatches and larvae pass through 3 dev stages, fed by ‘milk’ from accessory glands.
9 days later, larviposition - larva breathe through polypneustic tubes which poke out of female.
larvae pupate and adults hatch. adults climb up branches and wait for host to pass by. feed on mammals and reptiles which are reservior hosts but only show signs of infection when under stress, vector of trypanosomes.
which trypanodsome types affect humans?
T. brucei gambiense - in W africa, more chronic form, riverine habitat.
T. brucei rhodesiense - in E africa, acute form. savannah habitat
what is the tsetse belt?
stretch through central africa
cattle distribution N or S of it
what is nagana
Cattle trypanosomiasis
argument for tsetse being good for environment in africa
kill livestock, so benefits biodiversity?
w/o tsetse, people and livestock would move into tsetse belt.
3 methods of tsetse control
Bush clearence, wildlife eradication, insecticide spraying, eg DDT, pyrethroids, via ground or arial spraying.
start of Trap development for tsetse
1911-14, Island of Principé.
stuck black sticky patched to overalls of workers, and community effort to wipe out feral pig populationwhich are the major hosts.
combination of trapping flies and removing hosts manages to eliminate entire population of glossina palpalis and started trap development.
who first identified importance of olfactory cues to insects
GA Vale,
dug large pits underground to remove visual cue. tube with fan used to vent smell of animal from inside the pit. insects observed to fly upwind towards pit, after which the visual cues kick in.
found a chemical cue in animal breath most important. used this chemical in jars and smell of urine, phenols, in the pit which stimulates long distance orientation and attraction.
who found that at close range, visual cues were important?
CH Green
colour v important in visual cues.
black most attractive, and a particular shade of blue caused flies to go near it but not actually sit on it.
used these colours on a large funnel shape. better than simple non return system with waterbottles.
describe targets used to catch tsetse
and successful regime
black panel sprayed with pyrethroids, blue panels used too.
targets deployed at 3-5km, along 600km of zambezi valley in zimbabwe.
Baited with octenol and acetone, coated with deltamethrin.
traps used to monitor tsetse popualations.
10 months - eradicated both G. moristans and G. pallidipes.
costly in deploying traps in environment and maintaining.
often used in conjunction w other techniques.
traps have a low efficiency. What are consequences of this?
means traps mainly used for pop monitoring and local suppression.
how has trapping been investigated to control sheep blowfly myiasis?
on 12 commercial farms, s.w. England
traps baited w freeze dried liver, fly densities monitored and strike incidence recorded.
4 groups: control x2, trapping only, trapping plus insecticide.
found no significant difference between test groups. concluded trapping can be valuable to blowfly strike control in the UK, But, relatively expensive and labour-intensive compared to insecticides
