Location: Insect Behavior and Biocontrol ResearchTitle: Potential use of the fungus Beauveria bassiana against the western flower thrips Frankliniella occidentalis without reducing the effectiveness of its natural predator Orius sauteri (Hemiptera: Anthocoridae)) Author
Submitted to: Biocontrol Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/2/2012
Publication Date: 6/18/2012
Citation: Gao, Y., Reitz, S.R., Wang, J., Tamez-Guerra, P., Wang, E., Xu, X., Lei, Z. 2012. Potential use of the fungus Beauveria bassiana against the western flower thrips Frankliniella occidentalis without reducing the effectiveness of its natural predator Orius sauteri (Hemiptera: Anthocoridae). Biocontrol Science and Technology. 22:803-812. Interpretive Summary: Western flower thrips are among the most damaging insect pests of horticultural crops in the USA and in China. Because insecticides do not provide effective and sustainable management of this pest, scientists with the Chinese Academy of Agricultural Sciences, the University of Nuevo Leon, Mexico, and the USDA, Agriculture Research Service, Center for Medical, Agricultural and Veterinary Entomology, Gainesville, Florida, have been developing biologically-based approaches for management of western flower thrips. Predatory insects and entomopathogens are promising options for biological control of western flower thrips; however, it must be determined if entomopathogens are compatible with the use of predators. The present research demonstrates that a particular strain of the fungus Beuaveria bassiana, which is highly virulent to western flower thrips, has minimal adverse effects on an important predator. Therefore, it is not expected that Beauveria bassiana strain would negatively affect the predator. Consequently, it appears that these two biological control agents could be combined to more effectively manage western flower thrips.
Technical Abstract: Orius sauteri (Poppius) (Hemiptera: Anthocoridae) is an important predator of western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae). Orius sauteri would be directly exposed to the entomopathogenic fungus Beauveria bassiana (Bals.) Vuillemin in the field should the fungus be used as a biopesticide. If the fungus were to negatively affect O. sauteri in agroecosystems, predation of F. occidentalis by O. sauteri may be limited. The present study was undertaken to evaluate the insecticidal activity of the strain Bb-RSB of B. bassiana, which is highly virulent to F. occidentalis, on the predator under laboratory conditions. Results showed that, regardless of the concentration applied to first instars, Bb-RSB was not insecticidal against O. sauteri, nor did direct applications affect the developmental rate of the predator. Significant differences in developmental rates and adult longevity were observed between O. sauteri that fed on Bb-RSB-infected F. occidentalis cadavers and those that fed on untreated thrips. Developmental time (from first instar to adult) increased from 0.33 – 0.70 days and adult longevity decreased by 0.84 – 1.23 days for predators fed thrips treated with low and high concentrations of strain Bb-RSB, respectively, compared with predators fed on untreated thrips. However, these differences were only 3 – 13 % of mean values for the controls, suggesting that the effects of Bb-RSB on O. sauteri are relatively minor. These findings highlight the potential use of O. sauteri in combination with B. bassiana for the biocontrol of F. occidentalis, but field tests must be performed to confirm their compatible use.