Molecular characterization of interspecific competition of Diachasmimorpha longicaudata (Ashmead) and Fopius arisanus (Sonan) parasitizing the oriental fruit fly, Bactrocera dorsalis (Hendel)

Authors: LIANG, GUANGHONG - Fujian Agricultural & Forestry University; FU, LIEQING - Fujian Agricultural & Forestry University; LIN, HAOYU - Fujian Agricultural & Forestry University; Sim, Sheina; Jang, Eric; Heller, Wade; Geib, Scott

Submitted to: Biological Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/24/2017
Publication Date: 3/20/2018
Citation: Liang, G., Fu, L., Lin, H., Sim, S.B., Jang, E.B., Heller, W., Geib, S.M. 2018. Molecular characterization of interspecific competition of Diachasmimorpha longicaudata (Ashmead) and Fopius arisanus (Sonan) parasitizing the oriental fruit fly, Bactrocera dorsalis (Hendel). Biological Control. https://doi.org/10.1016/j.biocontrol.2017.11.012.

Interpretive Summary: Diachasmimorpha longicaudata (Ashmead) and Fopius arisanus (Sonan), are two of the most abundant and widely used parasitoids for biological control of the oriental fruit fly (Hendel) worldwide. They co-exist in the same landscape in the wild. This manuscript investigates the competition between these two species in successfully parasitizing and reproducing in the host oriental fruit fly. To characterize and detect the competition between these two species in cases where both parasitize the same host at the same time, molecular tools were developed to detect presence of both species with a host. It was found that in cases where both species are competing within a single host, most of the time, the egg parasitoid, F.arisanus, is able to outcompete and successfully reproduce in the host. This method is a reliable and robust technique to determine parasitism by a single species or both species of parasitoid across all life stages within one host. It can be useful to characterize impact of both of these species in augmentative releases and in established wild populations.

Technical Abstract: Diachasmimorpha longicaudata (Ashmead) and Fopius arisanus (Sonan), are two of the most abundant and widely used parasitoids for biological control of Bactrocera dorsalis (Hendel) worldwide. However, interspecific competition between them frequently occurs within a single host once they coexist in same orchard, resulting in reduction of their combined impact. However, thus far, it is difficult to characterize these complex interactions. This paper demonstrates qPCR-methods for detection of parasitism for single D.longicaudata, and methods to determine interspecific interaction with F.arisanus. Utilizing qPCR-based methodologies, a species-specific probe was designed for D.longicaudata, which was coupled with a previously published probe for F.arisanus. An assay was developed that is sensitive enough to detect parasitism of solitary D.longicaudata across all developmental stages including one egg per host larva (0.01ng/40ng parasitoid/host DNA). The detected parasitism of D.longicaudata was higher than that of using traditional rearing-methods. For the lab-reared and wild strain of multiple species parasitization, qPCR-methods also detected higher parasitism by the above two species from one assay respectively when compared to conventional rearing-based methods. In the later experiment, the majority of D.longicaudata larvae were dying or dead within hollow-like host pupae, likely due to interspecific competition. This method is a reliable and robust technique to determine parasitism by a single species or both species of parasitoid across all life stages within one host. It will be useful to evaluate parasitoid output of mass-rearing or combined suppression, and to characterize complex interspecific competition between these two parasitoid species.