Submitted to: Annals of the Entomological Society of America
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/8/2015
Publication Date: 1/7/2016
Citation: Horton, D.R., Lewis, T.M., Garczynski, S.F., Thomsen Archer, K.L., Unruh, T.R. 2016. Morphological and genetic reappraisal of the Orius fauna of the western United States (Hemiptera: Heteroptera: Anthocoridae). Annals of the Entomological Society of America. doi: 10.1093/aesa/sav155. Interpretive Summary: The minute pirate bugs (Orius) are primary sources of biological control in agricultural crops worldwide. Scientists with USDA-ARS, Yakima Agricultural Research Laboratory, Wapato, WA found that the minute pirate bug fauna in western North America includes numerous specimens whose body traits differ from traits of previously described species, suggesting that the minute pirate bugs of western North America are actually a complex of described species and several undescribed cryptic species. Body traits allowing identification of these undescribed species are summarized, and separation of species using these newly defined characteristics was confirmed by an analysis of DNA-sequences. These results will help scientists, field biologists, and others interested in biological control to correctly identify minute pirate bugs found in agricultural crops of western North America, leading to more efficient use of these species in biological control.
Technical Abstract: Examination of minute pirate bugs, Orius spp. (Hemiptera: Heteroptera: Anthocoridae) from a broad geographic range in the western U.S. prompted a reappraisal of the taxonomic composition and geographic distribution of the fauna native to the western U.S. and Canada. Collecting efforts led to the discovery of specimens having traits not fully consistent with descriptions of known species. We categorized these unresolved specimens into one of eight phenotypic groups based upon combinations of body size, genitalia, plant association, and geographic source. Genitalia were then measured in 382 specimens to determine whether phenotypic groupings were confirmed by statistical analysis of genitalic morphology. Size and shape of the male’s paramere differed among phenotypes. Parameres of unresolved specimens also often diverged from parameres of described species. Length of the female’s copulatory tube differed between several of the unresolved phenotypes and described species. Analysis of DNA-sequences showed that five of the eight phenotypes diverged genetically from other unresolved phenotypes and from described species. The combined morphological and genetic evidence leads us to suggest that the Orius fauna native to the western U.S. is composed of a mix of two or three described species and possibly five undescribed cryptic species. We summarize the known distributions of described and cryptic undescribed species, and discuss the implications of our work for the biological control community.