Theory question 106
Crop Pests(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.
Show the model answer
(a) An insecticide is a chemical used to kill or control insect pests
(b) Any four: contact insecticides; stomach poisons; systemic insecticides; fumigants; also by chemistry – organochlorines, organophosphates, carbamates, pyrethroids
(c)(i) Insecticide; (ii) rodenticide; (iii) avicide; (iv) nematicide
(d)(i) Chemical: pollutes air, water and soil; kills useful organisms (pollinators, natural enemies, fish); residues in food; pests may become resistant
(ii) Cultural: little or no pollution; burning trash may destroy organic matter and cause air pollution; tillage may expose soil to erosion
(iii) Biological: no chemical pollution; natural balance kept; introduced enemies may attack non-target organisms or become pests
Name the pesticide class for each pest.