Foraging range expansion and colony genetic organization in the subterranean termite Reticulitermes flavipes (Isoptera: Rhinotermitidae)

Our understanding of foraging and space use in Reticulitermes species is limited because their subterranean colonies are not associated with distinct physical nest structures and the colony affinity of workers cannot be readily identified with behavioral assays. Recently, we found that in Reticulitermes flavipes (Kollar) colonies from Massachusetts, the average colony inbreeding coefficient, measured with five polymorphic allozymes, was significantly greater than zero for non-Mendelian colonies with worker genotypes corresponding with the offspring of multiple inbreeding secondary reproductives rather than male and female primary reproductives. Foraging groups of termites with positive inbreeding coefficients suggest that workers feeding at fallen trees and branches frequently originate from different reproductive centers. The positive inbreeding coefficients appear to result from foraging traffic and not from inbreeding among secondary reproductives. A positive correlation between colony inbreeding coefficients and colony foraging range for non-Mendelian colonies suggested that the number of separate reproductive centers and/or the allele frequency contrasts between reproductives from separate centers increased with the expansion of a colony's foraging area. It is unlikely that an increase in the subdivision of breeding groups in a single reproductive center would closely coincide with an increase in foraging range. However, the extent of mixing between workers from neighboring colonies could have increased with foraging range expansion, especially given the apparent lack of nestmate discrimination in R. flavipes. Nevertheless, foragers from neighboring colonies have high genetic contrasts, and therefore appear to maintain distinct foraging areas.