Associate Certified Entomologist (ACE) Practice Exam

Which of the following statements about neonicotinoids is true?

1. They are very toxic to mammals

2. They are systemic and water soluble

3. They are effective only against bees

4. They cannot be absorbed by plant roots

The correct answer is: They are systemic and water soluble

Neonicotinoids are a class of neuroactive insecticides modeled after nicotine, primarily used to manage a variety of pest insects. The correct statement highlights that they are both systemic and water-soluble. Being systemic means that when neonicotinoids are applied to a plant, they are absorbed and distributed throughout the plant's tissues, including leaves, stems, and roots. This system, along with their water solubility, allows them to be effective in controlling pests that feed on those parts of the plant. This characteristic sets them apart from many other insecticides that may remain only on the surface of the plant and require direct contact with pests. Other options present misconceptions about neonicotinoids. For instance, while they do pose some level of toxicity to mammals, they are generally targeted to insects, meaning their impact on mammals is much less pronounced. They also affect a broad range of pests beyond just bees, including various harmful insects that might not have any relation to pollinators. Lastly, neonicotinoids can indeed be absorbed by plant roots, which is part of their systemic action, opposing the claim that they cannot be absorbed.