(a) Discuss seven economic importance of insect pests in crop production. (b) Name two hosts of cotton stainer. (c) List two soil-dwelling insect pests of c...

Answer Details

(a) Seven economic importance of insect pests in crop production

Although mostly harmful, insects have both negative and positive economic effects:

• They reduce crop yield by feeding on leaves, stems, roots, flowers and fruits.
• They lower the quality and market value of produce.
• They transmit plant diseases (act as vectors of viruses and other pathogens).
• They cause storage losses by damaging stored grains and produce.
• They increase the cost of production through spending on pesticides and control.
• On the positive side, some (for example bees) pollinate crops, increasing fruit and seed set.
• Also positively, some produce useful products (honey, wax, silk) and predatory/parasitic insects control other pests biologically.

(b) Two hosts of the cotton stainer

• Cotton plant.
• Okra (also hibiscus/kola).

(c) Soil-dwelling insect pests and general control measures

Two soil-dwelling insect pests:

• Termites.
• Cutworms (also white grubs/beetle larvae).

Five general control measures of insect pests:

• Use of insecticides (chemical control).
• Practise crop rotation and clean cultivation (cultural control).
• Use resistant/tolerant crop varieties.
• Biological control using natural enemies (predators and parasites).
• Early planting, proper spacing and destruction of crop residues and alternate hosts.