crop plants: pest control Flashcards
5.4
what can pests do to crops?
damage crops by eating them
what can weed do to crops?
outcompete crop plants for space, water and soil nutrients
what can fungi do to crops?
infect crop plants and spread diseases- affect growth and yield
what do insecticides do?
kill insects
what do herbicides do?
kill plant pests
what do fungicides do?
kill fungal pests
what do molluscicides do?
kill molluscs (e.g. snails and slugs)
what are the advantages of pesticides?
easily accessible and relatively cheap
have an immediate effect
kills the entire population of pests
what are the disadvantages of pesticides?
organisms they are meant to kill can develop resistance to them
they are non-specific chemicals and often kill other beneficial organisms
they can be persistent chemicals- they do not break down in the body and can accumulate in concentrations in the top of food chains and harm predators- bioaccumulation
need to be repeatedly applied
what is biological control?
using another organism to reduce the numbers of a pest
when are pests only a problem?
when they are present in sufficient numbers to cause economic damage
advantages of biological control?
natural method- no pollution
no resistance
can target specific species
long lasting
does not need to be repeatedly applied
disadvantages of biological control?
may eat other organisms instead of the pest
takes a longer period of time to be effective
cannot kill entire population- the pest may still be present
may not adapt to the new environment and may migrate out
may become a pest itself
how can whiteflies in a greenhouse full of tomato plants be controlled?
by introducing a tiny parasitic wasp- Encarsia
these lay their eggs inside the larvae of the flies, which hatch and then eat the larvae and so reduce the numbers of whitefly
