Final answer:
In an integrated pest management program, Insect Growth Regulators (IGRs) such as methoprene and pyriproxyfen would be chosen as the least toxic pesticides for use, due to their lower toxicity and lesser environmental impact compared to options like organophosphates.
Step-by-step explanation:
When considering the use of a "least toxic" pesticide for control in an integrated pest management program, the pesticide that would likely be used is D. Insect Growth Regulators. This is because Insect Growth Regulators (IGRs) are designed to mimic hormones in young insects, disrupting their development, and are generally considered to be less toxic and more environmentally friendly than traditional pesticides. In contrast, other options such as repellents and desiccating dusts may be less toxic but are not classified as pesticides, organophosphates and pyrethroids are more traditional pesticides with greater toxicity and environmental impact.
IGRs like methoprene and pyriproxyfen are effective in managing pest populations and are part of an IPM program's strategy to minimize disruption to the environment. They represent a type of pesticide that has a lower risk profile compared to more broadly toxic substances such as organophosphates that can act as nerve agents and are more hazardous to non-target organisms including humans.