Associate Certified Entomologist (ACE) Practice Exam

What type of hazard does diatomaceous earth pose to insects?

1. Chemical burns

2. Physical abrasion and dehydration

3. Increased reproductive rates

4. Respiratory failure due to choking

The correct answer is: Physical abrasion and dehydration

Diatomaceous earth primarily poses a physical hazard to insects through its abrasive nature and ability to cause dehydration. This natural substance consists of amorphous silica obtained from the fossilized remains of diatoms, which are tiny aquatic organisms. When insects come into contact with diatomaceous earth, it acts mechanically by scratching their exoskeletons. This physical abrasion leads to the loss of bodily fluids, resulting in dehydration. The efficacy of diatomaceous earth as an insecticide is largely due to this physical mode of action rather than any chemical toxicity. Insects, particularly those that rely on a waxy cuticle for moisture retention, are especially vulnerable, as the micro-fine particles accumulate on their bodies and exacerbate moisture loss. Thus, the primary hazard it poses is effectively a combination of physical injury and subsequent dehydration, leading to their eventual demise. Other choices do not accurately represent the nature or action of diatomaceous earth. For instance, while chemical burns highlight the principle of corrosive agents causing damage, diatomaceous earth operates on a physical level without chemical reactivity. Increased reproductive rates is directly contrary to the purpose of diatomaceous earth, as it is designed to eliminate pests, not enhance their proliferation. Lastly, while respiratory issues