Approaches to Biological Control of Termites

Abstract

Biological control refers to the application or manipulation of preda- tors, parasitoids, or pathogens in order to suppress and manage insect populations. The cryptic habits of subterranean termites limit their susceptibility to predators. Ants are generally considered to be the most effective predators of termites, and under some conditions may be able to exclude them from occupying feeding sites at the soil surface. However, ants are not able to penetrate far into the subterranean gallery system. To date, there is very little documentation of termite parasitism. Thus, the most promising area of biological control research with termites appears to lie with pathogens. Unfortunately, termite social and chemical defenses appear to be strong limiting factors in inhibiting disease outbreaks in termite colonies. Fungi and nematodes have received the greatest attention to date, and a few commercial formula- tions are either available or on the near horizon, but their field efficacy is not well documented. Bacteria are also currently of interest, and manipulation via molecular techniques may be a viable path to devel- opment of efficient microbial agents. Other approaches to enhancing the efficacy of microbial agents may be the use of combinations of pathogens, or insecticide plus pathogen combinations. Microbial con- trol is a balancing act, in that pathogens must not be repellent, and must not have such rapid or dramatic effects upon the infected individuals that others will subsequently avoid contact with them or with the inoculum source. On the other hand, they must be capable of distribution through the colony and induction of either an epizootic or sufficient delayed mortality to essentially destroy the colony. A self- replicating time bomb, akin to a computer virus, would be the ideal microbial control agent.