Which type of organism is NOT used in the biological control of turf insects?

In the context of biological control for turf insects, the primary organisms used are predators, parasites, and pathogens. Predators actively hunt and feed on pest insects, effectively reducing their populations. Parasites lay eggs in or on their hosts, and the developing offspring consume the host, leading to its demise, further controlling pest populations. Pathogens, including bacteria, fungi, and viruses, can infect and kill pest insects.

While fungi are indeed used as biological control agents, they're typically classified under pathogens due to their ability to cause disease in pest insects. Therefore, the answer indicating that fungi are not used in biological control would be misleading, as they are recognized as a significant method of control under the broader category of pathogens.

With this understanding, the correct identification of the organism not used in the biological control of turf insects would involve recognizing that fungi, while a component of the pathogenic control tactics, are very much involved in controlling pest populations. Hence, specifying that fungi are not utilized reflects a misunderstanding of their role in the ecosystem and biological control methods.