12. New Technologies For Parasite Control Flashcards
What are the key points of consideration for making a pesticide/drug?
- Must be toxic to the pest/parasite
- Must be harmless to us (and domestic animals)
- Must therefore target some metabolic difference (such as the different bacterial ribosome or membrane)
What treatment can we use to stop the mosquito life cycle in water?
- Mosquitoes lay their eggs in ponds
- Air tube goes to the surface so they can breathe
- Hydrophillic hairs down the opening that repel water so that air can go down
- We can put oil on the surface which the water repellent hairs will not work in, they won’t be able to get oxygen
What are the two hormones involved in insect molting?
JH - juvenile hormone and MH - molting hormone
The amount of JH decreases as mosquito grows into an adult
What does the molting hormone control?
- Induces the growth of the new cuticle
- Begins the molting process
- Partial absorption of old cuticle
- Inflation of body to crack cuticle
How do the amounts of each hormone change at each moult?
- MH is constant at each moult while JH reduces with each moult
- Zero JH produces adult
How is the juvenile hormone mimicked?
- Pre-adult fleas killed
Pre-adult fleas in the larval stage are attacked in the home as they scavenge for food. - The larvae that from into pupae are then prevented from developing into fleas
- Adult fleas killed- the hormone mimic will kill adult fleas that have already emerged from the pupae for up to 2 weeks
- Residual effect of the hormone mimic wills top eggs from becoming adult fleas for up to 9 months
What are some methods of biological control other than predators/parasite?
- Drain pools and swaps (for mosquito larvae in ponds)
- Monolayer dispersant on water surface (same)
- Traps baited with food smell (using Tsetse fly)
- Traps/tubes with female pheromones
What are some examples of predators for biological control?
- Predatory insects that may prey on mosquitoes
- Spiders and predatory mites
- Fish
- Parsitoid wasps (used against Tsetse flies)
What are some desirable features of predators?
- Fairly specific to the prey it eats
- Same habitats as pests
- Rapid rate of increase
- Disperse easily
- Population size not kept low by environment
- Survives when the pest is at low levels
- Easily cultured
What is an example of biological control using bacteria as a parasite?
Bt kills many insects
How can nematodes be used as a parasite for biological control?
Nematodes kill infected insects and can carry bacteria too
What are wolbachia?
Wolbachia are bacteria that live inside insect cells
How can the wolbachia be used to take over the population?
- They cause incompatible matings, and this helps them to spread into insect populations
- They get into the immature spermatids and the eggs of the insects, and if sperm from infected insects fertilises uninfected eggs the offspring die, but infected eggs produce offspring
What are some methods to spread a genetic load?
- Recombinant DNA technology (introduce bad alleles)
- Delayed sterility (occurs in later generation)
- Conditional lethal genes
- More sexually active males
- Meiotic drive (one of a pair of chromosomes goes into all the gametes)
- Introduce an incompatible competing strain
How can an incompatible competing strain be introduced as methods to spread a genetic load?
Using wolbachia or compound chromosomes
- A strain that produces dead offspring if it reproduces with wild types
- But it can reproduce with itself, and you can select the alleles it has
