Foraging populations of tube building termites, Gnathamitermesperplexus (Banks), Associated with termiticide experiments in Southern Arizona (Isoptera: Termitidae)

In the southwestern desert region of Arizona, a common non-structure invading species is the tube building termite Gnathamitermes perplexus. It is a valuable species from an ecological point of view due to its role in the decomposition of dead wood in desert environments and its capacity to enrich and aerate vast quantities of soil. Since it has no economic importance, very little is known of the effects of termite control measures on it. However, G. perplexus is likely exposed to termiticides used to manage more damaging termite species with which it co-occurs. Since most common termiticides have relatively generalized modes of action, we hypothesized that G. perplexus populations would decrease significantly as a result of termiticide application. The results reported here are part of a larger study in which we were primarily interested in evaluating foraging termite populations of Heterotermes aureus, associated with circular grids that were treated with termiticides. Termites were collected monthly from 9 plots located at the Santa Rita Experimental Range (Pima Co., AZ) over a 3-year period. Plots were equally and randomly assigned to three treatments: a control and two insecticide treatments of either fipronil (Termidor®, BASF) or chlorfenapyr (Phantom®, BASF). Within the chlorfenapyr (Phantom®) treatment, we saw a significant increase in termite foragingpopulations after termiticide application. This effect showed a spatial pattern in which more termites were found near the center of plots. However, the number of G. perplexus collected in the fipronil (Termidor®) plots was reduced with respect to controls. This reduction in the number of termites also showed a spatial distribution with the decrease in termite numbers being stronger near the center of plots within the treated zone.