Estimation of movement from insectary plants to crop plants in Orius bugs (Heteroptera: Anthocoridae) by molecular gut content analysis

Abstract

The introduction of insectary and banker plants is widely used in agroecosystems to improve the survival and reproduction of natural enemies of pest arthropods. Natural enemies that are attracted to and/or maintained on insectary plants need to move from the insectary plants to crop plants to suppress pest populations effectively. In many cases, however, direct evidence supporting the migration of natural enemies is lacking. To investigate the movement of Orius bugs (Hemiptera: Anthocoridae), which are efficient zoophytophagous predators used in biological control, we performed gut content analyses based on DNA markers. Specific PCR primers were designed to detect the DNA of the insectary plant, Scaevola aemula. We also carried out gut content analyses using prey insect DNA markers to estimate Orius bugs’ predation spectrum. DNA of the insectary plant was detected in the abdomen of Orius bugs collected on eggplant leaves, suggesting that Orius bugs had consumed food resources from the insectary plants and relocated to the crop plants. DNA of three prey insect species—two thrips species, Thrips palmi and Frankliniella intonsa, and cotton aphid, Aphis gossypii—was detected in Orius bugs in the eggplant field, indicating that Orius bugs preyed on them.