How do parasites, such as nematodes, affect insects?

Nematodes are microscopic roundworms that are known to act as biological control agents against various insect pests. The correct answer outlines how these parasites function: they enter the insect's body and release bacteria that kill the pest.

This process typically starts when nematodes infect their host. Upon entering the insect, they release symbiotic bacteria from their gut. These bacteria multiply rapidly within the insect's body and create toxic substances that can lead to the insect's death. This method of parasitism allows nematodes to not only consume the host but also to utilize the bacteria to efficiently subdue it, ensuring a steady food source for the developing nematodes.

Other methods of pest control, such as consuming insects from the outside or releasing toxins, do not accurately depict how nematodes operate. Nematodes do not typically feed on plant roots; rather, they target insects directly, which differentiates them from other pests that may affect plants. Understanding this particular interaction helps in appreciating the biological control mechanisms that can be employed in pest management strategies in turf and ornamental settings.