Hybrids of two destructive subterranean termites established in the field, revealing a potential for gene flow between species

Abstract

Hybridization between invasive pest species may lead to signi cant genetic and economic impacts that require close monitoring. The two most invasive and destructive termite species worldwide, Coptotermes formosanus Shiraki and Coptotermes gestroi (Wasmann), have the potential for hybridization in the eld. A three-year eld survey conducted during the dispersal ight season of Coptotermes in Taiwan identi ed alates with atypical morphology, which were con rmed as hybrids of the two Coptotermes species using microsatellite and mitochondrial analyses. Out of 27,601 alates collected over three years, 4.4% were con rmed as hybrid alates, and some advanced hybrids (>F1 generations) were identi ed. The hybrid alates had a dispersal ight season that overlapped with the two parental species 13 out of 15 times.Most of the hybrid alates were female imply that backcross mating opportunities beyond F1 may primarily be possible through female hybrids. However, the incipient colony growth results from all potential mating combinations suggest that only backcross colonies with hybrid males could sometimes lead to brood development. The observed asymmetrical viability and fertility of hybrid alates may critically reduce the probability of advanced-hybrid colonies being established in the eld.