Determine which of the following statements concerning treatment of pest populations in agriculture are true.
a. Insecticides are substances used to repel, kill, or control animals that are considered pests.
b. Historically, methods of controlling agricultural pests were not 100% effective at removing pests from agricultural crops.
c. Insect resistance is an issue since the survivors can pass the resistance on to the next generation.
d. Genetically modified Bt corn is designed to control corn pests such as the European corn borer.
e. Natural insecticides are not as effective at controlling species of insects as synthetic chemicals, such as organophosphate insecticides, but without the harmful consequences to humans or livestock.
f. Insecticide-producing GM crops have led to a decrease in spraying insecticides and poisoning of non-targeted species.