In biocontrol, the terms 'parasitoid,' 'parasite,' and 'predator' refer to different types of organisms that play distinct roles in controlling pest populations.
Parasites live at the expense of their hosts but usually do not kill them outright.
Steinernema feltiae, a parasitic nematode, is commonly used for managing fungus gnats. The nematodes enter the pest larvae through natural body openings and release symbiotic bacteria from their gut. These bacteria convert host tissue into products that the nematodes can digest. As a result, the pest larvae die within a few days, and the nematodes reproduce inside the dead host.
Predators actively hunt and consume prey organisms, often attacking a wide range of prey types.
Orius insidiosus, a predator known for managing thrips, also helps against other soft-bodied pests such as aphids and whiteflies.
Parasitoids develop on or within a host, leading to the host's death, and are very specific in their host choices.
Aphidius colemani is a wasp that lays its eggs in specific aphid species. Once hatched, the larvae consume the aphid from the inside out, mummifying the aphid in the process.
Each of these organisms plays a different role in biological control programs. Some are best used for targeting a specific pest issue, while others are more suited for general preventative treatment. Understanding these options will help you make the right decision.