Evaluation for Risk of Interspecific Mating among Native and Exotic Orius Species (Heteroptera: Anthocoridae)

Abstract

Importation of exotic natural enemies is a common approach in biological control but they may threaten native natural enemies through interspecific interactions. Orius laevigatus, which is native to Europe, is a commercially available, effective biocontrol agent of pest thrips. The present study was undertaken to assess the effects of exotic O. laevigatus on two Orius species native to Japan, i.e., O. sauteri and O. strigicollis. Specifically, the possibility of interspecific cross and harassment was evaluated in the laboratory. Laboratory tests showed that mating between O. laevigatus and O. sauteri or O. strigicollis was unlikely to occur. Males mostly did not respond to interspecific females, and mounting on interspecific females was rarely observed. No insertion of male genitalia took place even when mounting had occurred. Thus, harassment by interspecific males is not likely to take place in the field. Reproductive isolation appears perfect at least against the two native species. There are however a number of points to be examined in order to assess the potential risk of the importation and use of O. laevigatus. Given the presence of promising native Orius species, importation of exotic species should be decided with great caution.