(a) Define an insecticide (b) List four groups of insecticides. (c) For each of the following pests, name the class of pesticide used for their control: (i) grasshoppers (ii) rats (iii) weaver birds (iv) eelworms (d) Enumerate two effects of each of the following pest control measures on the environment: (i) chemical (ii) cultural (iii) biological
Explanation
(a) Insecticide: An insecticide is defined as a chemical preparation used to control insect pests.
(b) Group of insecticides: (i) Powder (ii) Liquid (iii) Granules (iv) Tablets (v) Aerosol
(c) Class of Pesticide that Kills Specific Insect Pests:
|
Pest killed |
Pesticide | Pest killed |
Pesticide |
|
(i) Grasshoppers |
Insecticide | (iii) Weaver birds Rodenticides | Avicides |
|
(ii) Rats |
Rodenticides | (iv) Eelworms Avicides | Nematicides |
(d)(i) Effects of Chemical Control on the Environment: (i) Beneficial organism insects like earthworms, bees may be destroyed. (ii) Some chemicals may be toxic to man, domestic animals and plants. (iii) It may lead to pollution of the environment. (iv) It destroys aquatic life.
(ii) Effects of Cultural Control on the Environment: (i) Fire that kills harmful insects may also kill beneficial insects. (ii) Bush burning spreads within a twinkle of an eye to other places and causing excessive damage to structures, crops and animals. (iii) Fire destroys organic matter in the soil. (iv) Tillage operation destroys soil structure and causes erosion.
(d)(iii) Effects of Biological Control on the Environment: (i) Natural enemy (organism) introduced to control pest may abandon the pest and start to attack other crops in the environment originally free from attack. (ii) Predators may feed on other beneficial insects other than the ones intended to control. (iii) Newly introduced organism may cause imbalance in the ecosystem. (iv) Breeding for increased yield may alter genetic resistance of crops to pest and diseases thereby leading to increased pest/disease population in the environment.