TF写作真题第026套（mm016）

MM_016

Corn rootworms are a widespread type of insect that are one of the most destructive predators of maize in the united states. as their name suggests, corn rootworms feed on corn roots and cause severe damage to corn as both larvae and adults. newly hatched larvae feed primarily on root hairs and outer root tissue. as larvae grow and their food requirements increase, they burrow into the roots to feed. farmers can employ several methods to combat these pests.

The first, and by far the most commonly used method of pest control, is to apply insecticides to soil in areas that have a history of crop damage. insecticides target insect eggs and larvae and have the potential to eradicate an entire generation of pest ensuring that the insect is unable to reproduce.

Another effective method to control the corn rootworm pest is planting corn crops earlier in the growing season. rootworm larvae typically hatch in late may or early june with maturation typically occurring in august. by planting corn crops a few weeks earlier into the growing season young rootworm larvae find they are unable to eat mature corn roots and farmers can avoid a majority of root damage from larvae. without a suitable host plant the rootworm will soon starve to death.

The final method used by farmers to prevent corn rootworm damage is crop rotation. crop rotation is the practice of growing a series of dissimilar or different types of crops in the same area in sequential seasons. in addition to replenishing soil nutrients, crop rotation is effective in mitigating the build-up of pests. corn rootworm larvae must feed on corn roots to develop and mature properly. if they hatch in a field without corn, they starve. for example, alternating corn crops with soybean crops will effectively starve the corn rootworm larvae ensuring that they never fully mature to adulthood.

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