Submitted to: Florida Entomologist
Publication Type: Peer reviewed journal
Publication Acceptance Date: 4/7/2009
Publication Date: 6/1/2009
Citation: Shapiro, J.P., Shirk, P.D., Reitz, S.R., Koenig, R. 2009. Sympatry of Orius insidiosus and O. pumilio (Hemiptera: Anthocoridae) in North Central Florida. Florida Entomologist. 92:362-366. Interpretive Summary: Minute pirate bugs are beneficial predatory insects used worldwide as biological control agents to consume pest insects feeding on ornamental and crop plants. Scientists at the USDA ARS, Center for Medical, Agricultural and Veterinary Entomology identified two closely related species of pirate bugs in collections from flowers of false Queen Anne’s lace/large bullwort growing on an organic farm near Gainesville, Florida. Adults of both the insidious flower bug (Orius insidiosus) and the relatively unknown species Orius pumilio were apparently feeding on a pest insect, the Florida flower thrips. This is the first documentation that these species can live together on the same plant. Additionally, there were distinct population differences: 1)O. insidiosus adults outnumbered O. pumilio on the flowers, 2)O. insidiosus had a skewed sex ratio with more males than females and 3) no eggs or immatures of either species were observed on the plants. These findings raise significant questions about ecological interactions between the species, developmental changes in their behaviors, and their biogeography. Most critically for vegetable and ornamental growers, the study offers cautions and promise of employing these predators for biological control on Florida organic farms, in greenhouses, and potentially on field crops.
Technical Abstract: Two closely related species of Anthocoridae, the minute pirate bugs Orius insidiosus and Orius pumilio, were collected together from false Queen Anne’s lace/ large bullwort (Ammi majus) planted on an organic farm in Gainesville, Alachua County, Florida, over a period of five successive weeks. The presumptive prey on the Queen Anne’s lace was a single species of thrips, Frankliniella bispinosa. In the first four weekly collections from the flower heads, the O. insidiosus adults occurred at more than three times the population of O. pumilio. There were no eggs or nymphs of either species observed on the plants. An unusual sex ratio of 0.38 O. insidiosus females to males was observed while for O. pumilio it was a normal 1.0. A colony of O. insidiosus was established from field-collected specimens and the sex ratio of the F1 generation was 1 suggesting that the skewed field sex ratio was not a genetic phenomenon but instead reflected a sampling bias. These data demonstrate that these sympatric predators coexist at least temporarily on pests of Ammi majus but do not complete a life cycle on this plant.