Which of the following organisms are NOT considered a biological control agent for mosquito larvae?

Biological control agents for mosquito larvae are organisms that help reduce mosquito populations by preying on or harming them during their developmental stages. Fish, insects, and certain types of bacteria are commonly used as biological control agents in integrated pest management.

Fish, such as Gambusia affinis (mosquito fish), are effective because they consume mosquito larvae and pupae. Certain insects, like the dragonfly larvae or predatory beetles, also contribute to controlling mosquito populations by feeding on them.

Bacteria, particularly the bacterium Bacillus thuringiensis israelensis (Bti), are used to kill mosquito larvae. This bacterium produces toxins that are specific to mosquito larvae and other dipterans, making it a safe and effective biological control method.

On the other hand, viruses are not typically considered biological control agents for mosquito larvae. While there are viral diseases that affect adult mosquitoes, these viruses do not target the larval stage in a way that helps manage populations effectively. Therefore, viruses do not fit into the category of biological control agents for mosquito larvae, which is why they are the correct choice in this context.