Agriculture Reference
In-Depth Information
population, but you should be aware of their influence and take advantage of
them whenever possible. Some forces which affect the pest population in-
clude climate, natural enemies, topography, and food and water supply.
1.
Climate
Weather conditions, especially temperature, day length, and humidity, af-
fect pests' activity and their rate of reproduction. Pests may be killed or sup-
pressed by rain, frost, freezing temperatures, drought, or other adverse weather.
Climate also affects pests indirectly by influencing the growth and devel-
opment of their hosts. The population of plant-eating pests is related to
growth of the host plants. Unusual weather conditions can change normal
patterns so that increased or decreased damage results.
2.
Natural Enemies
Birds, reptiles, amphibians, fish, mammals, and predatory and parasitic
insects feed on some pests and help control their numbers. More than half of
all insect and insect-like species feed on other insects, some of which are
pests. Disease organisms often suppress pest populations.
3.
Topography
Features such as mountains and large bodies of water restrict the spread of
many pests. Other features of the landscape can have similar effects. Soil
type is a prime factor affecting wireworms, grubs, nematodes, and other soil
organisms. Some pests live in heavy, poorly drained soil, others in light,
sandy soils. Soil type also affects the distribution of plants (including weeds),
which in turn affects the population of insects and other plant pests.
4.
Food and Water Supply
Pest populations can thrive only as long as their food and water supply
lasts. Once the food source, plant or animal, is exhausted, the pests die or
become inactive. The life cycle of man pests depends on the availability of
water
