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ARS Home » Pacific West Area » Hilo, Hawaii » Daniel K. Inouye U.S. Pacific Basin Agricultural Research Center » Tropical Crop and Commodity Protection Research » Research » Publications at this Location » Publication #310364
Title: A qPCR-based method for detecting parasitism of Fopius arisanus (Sonan) in oriental fruit flies, Bactrocera dorsalis (Hendel)

Author
item LIANG, GUANGHONG - Fujian Agricultural & Forestry University
item Jang, Eric
item Heller, Wade
item Chang, Chiou
item CHEN, JIAHUA - Fujian Agricultural & Forestry University
item Geib, Scott

Submitted to: Pest Management Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/7/2015
Publication Date: 2/4/2015
Citation: Liang, G., Jang, E.B., Heller, W., Chang, C.L., Chen, J., Geib, S.M. 2015. A qPCR-based method for detecting parasitism of Fopius arisanus (Sonan) in oriental fruit flies, Bactrocera dorsalis (Hendel). Pest Management Science. doi: 10.1002/ps.3976.

Interpretive Summary: Parasitism rate detection and parasitoid species identification are necessary in fruit fly biological control. Currently release of mass-reared Fopius arisanus is occurring world-wide, as this species is effective in controlling Bactrocera dorsalis and Ceratitis capitata. While release is occurring, it is difficult to determine parasitism levels in mass reared colonies, and also ultimate establishment in wild populations. A technique has been developed to use quantitative PCR to detect the presence of parasitism of Tephritid fruit flies by the parasitic wasp, Fopius arisanus. This manuscript describes the methodology, and tests the sensitivity and specificity of the method for detecting the wasp. Results show that a single F arisanus egg can be detected from a host egg, showing higher detectability that current methods of manual dissection or rearing the wasps to emergence.

Technical Abstract: BACKGROUND: Parasitism rate detection and parasitoid species identification are necessary in fruit fly biological control. Currently release of mass-reared Fopius arisanus is occurring world-wide, as this species is effective in controlling Bactrocera dorsalis and Ceratitis capitata. While release is occurring, it is difficult to determine parasitism levels in mass reared colonies, and also ultimate establishment in wild populations. To support this, the development of a rapid, specific and sensitive method to detect the parasitoid across all life stages inside host and assess the parasitism rate is important. RESULTS: A species-specific probe was designed for F. arisanus, as well as a universal Tephritid probe. Utilizing rapid DNA extraction techniques coupled with quantitative-PCR, a simple and fast assay has been developed to detect parasitism of Tephritid fruit flies by F. arisanus that is sensitive enough to detect a single egg laid into a single host egg. Parasitism on B. dorsalis was clearly detectible using qPCR methods across all developmental stages. In addition, 0.25 ng of parasitoid DNA in 40 ng of fly DNA can be detected, and detects a higher parasitism rate when compared to rearing or dissection methods where parasitism can be overlooked due to error in dissections or mortality during rearing. CONCLUSION: These results demonstrate a rapid, sensitive and specific technique for determining the parasitism rate of F. arisanus across all life stages of B.dorsalis. This is useful to evaluate the outcome of pest suppression after mass-releasing in the fields, and provides a way to predict parasitoid output from mass-rearing.