What characteristic defines broad-spectrum insecticides?

Broad-spectrum insecticides are characterized by their toxicity not only to the specific targeted pest but also to a wide range of other organisms, including beneficial insects and other non-target species. This means that when broad-spectrum insecticides are used, they can eliminate or significantly affect a variety of insects beyond just the intended pest.

This broad effect is significant in pest management practices, especially when considering the ecological impact of pesticide use. While such insecticides can be effective in controlling pest populations quickly, their use often raises concerns about the collateral damage they may cause to ecosystems and beneficial species, such as pollinators and natural pest predators.

In contrast, insecticides that have little or no effect on non-target species would be considered selective rather than broad-spectrum. Effective control with limited ecological impact usually involves more targeted approaches, making them separate from the definition of broad-spectrum insecticides. Therefore, the defining characteristic that emphasizes their wide-ranging toxicity aligns specifically with the correct answer.