LITERATURE REVIEW
2.1 INSECT PESTS
The concise oxford dictionary of the English language define pest as a
troublesome or destructive person, or things. Williams [1947]state that
an insect pest is any pest in the wrong place.
The classification
of an insect as a pest is a subjective one based on its potential damage
to human purposes or natural habitats and eco-system. Insect pests are
said to be able to kill agricultural crops, ornamental plants etc. They
can also consume and damage harvested food and also cause illness or
unproductively in agricultural animals e.g. Cattle and vector as larvae
while they may be pollinators in adulthood.
Some insects that are
considered as pests are actually more beneficial than pestiferous for
example wasps predate or parasitize many insects. An insect pest may
cause injury which may be physical (bites and stings) or medical
(causing diseases or illness) or economic (monetary lose of goods or
properties). Injury may arise directly from the pest itself or may
develop indirectly as a result of the actions or behavior of the pest.
Insect pest affect us in one way or the other by the following ways:
- They are an annoyance or nuisance e.g. cockroaches
- They endanger human health or safety
- They threaten the welfare of useful plants or domestic animals
- They damage stored products or structural materials.
Although insect pest attract the most attention many insects are
beneficial to the environment and to humans. Some insect like wasps,
bees, butterflies and ants pollinate flowering plants. Insect pests can
be controlled by the use of pesticides, sterilization, destruction of
infected plant, traps, hunting, field burning, poisoned bait and
biological control.
Insect can cause damage directly by their feeding
or making shelters or indirectly by other means. Direct method include
chewing of plants e.g. grasshoppers caterpillars, root chewing beetle
larvae and piercing ant sucking which is the direct removal of plants
sap or animal blood e.g. aphids, mites, bed bugs, lice, vegetable bugs
e.t.c. while the indirect method can be through vectors e.g. plants
viruses and bacteria transmitted via aphids and leafhoppers, malaria
e.t.c.