Progress towards biological control of Asian longhorned beetle

RNA interference with dsRNA, a gene silencing mechanism targeting genes involved in insect survival, has emerged as a novel pest control tool. We examined the potential effect of a dsRNA targeting an inhibitor of apoptosis of the Asian longhorned beetle Anoplophora glabripennis on its gregarious larval ectoparasitoid Ontsira mellipes, directly on adult wasp’s survival via injection of 1µl (4 µg) dsIAP formulation per wasp, and indirectly on the detectability and suitability of host larvae injected with 0.5, 1 or 2 µl dsIAP formulation per larva. Compared with no injection or injection with a control dsGFP targeting a region of gene coding for a green fluorescence protein, dsIAP did not affect adult wasp’s survival. Ontsira mellipes locates hosts in the wood by sensing their movement. Host larvae did not completely cease movement after the injection of dsIAP and were still detected and parasitized. Clutch size was reduced and only 3.8% of the parasitoid offspring developed into adults on host larvae treated at the highest dose. However, clutch size was not affected and 25.5% of the parasitoid offspring developed into adults on host larvae treated at the lowest dose. The fitness of developed wasps (development time, sex ratio, body size, and fecundity) was not affected when compared to the control treatments. No dsIAP was detected in parasitoid larvae. The results show the potential indirect effect of dsRNA-affected host on its parasitoid, which may be minimized through optimizing dsRNA dosage to promote compatible applications of both management options for this forest pest.