Potential effects of RNA interference of Asian longhorned beetle on its parasitoid

Authors: Wang, Xingeng; Faucher, Jessica; DHANDAPANI, RAMESH KUMAR - University Of Kentucky; Duan, Jian; PALLI, SUBBA REDDY - University Of Kentucky

Submitted to: Pest Management Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/13/2022
Publication Date: 12/19/2022
Citation: Wang, X., Faucher, J., Dhandapani, R., Duan, J.J., Palli, S. 2022. Potential effects of RNA interference of Asian longhorned beetle on its parasitoid. Pest Management Science. https://doi.org/10.1002/ps.7328.
DOI: https://doi.org/10.1002/ps.7328

Interpretive Summary: Asian longhorned beetle (ALB) is a high-risk invasive forest pest. Although eradication efforts are ongoing since the beetle was first reported in the US in 1996, invasive ALB populations are still present in several states. The economic, ecological, and aesthetic impacts on the US would be devastating if the beetle continues to spread and becomes permanently established. Should that happen, sustainable management strategies such as biological control need to be developed for ALB. A native parasitic wasp has the potential to be used as a biological control agent against ALB. RNA interference with dsRNA, a gene silencing mechanism that targets genes involved in insect survival, is another potential management option. To evaluate their compatibility, we examined the potential impact of ALB dsRNA on the parasitic wasp. There was no direct impact on the adult wasp survival, but indirect impact may occur when the wasp attacks dsRNA-affected ALB larvae, and wasp offspring failed to develop on ALB larvae treated with high doses of dsRNA. Indirect impact could be minimized by optimizing dsRNA dosage to promote complementary applications of both control methods for ALB.

Technical Abstract: RNA interference is a gene silencing mechanism triggered by dsRNA and has emerged as a novel pest control tool. It is important to understand how non-target insects such as parasitoids may be impacted directly via ingestion of dsRNA products or indirectly via exposure to dsRNA-affected hosts. We examined the potential effect of a dsRNA that targets an inhibitor of apoptosis (IAP) of the Asian longhorned beetle, Anoplophora glabripennis, on its gregarious larval ectoparasitoid, Ontsira mellipes. Like many other larval parasitoids of woodboring beetles, O. mellipes locates hosts concealed in the wood by sensing their movement. We evaluated direct effects on adult wasp’s survival via injection of 1 µl dsIAP per wasp, and indirect effects on the detectability and suitability of host larvae treated with 0.5, 1 or 2 µl dsIAP per larva. Compared with no injection or injection with a control dsGFP (dsRNA targeting a region of gene coding for green fluorescent protein), dsIAP did not affect adult parent wasp’s survival. Host larvae did not completely cease feeding or 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 (blackened < 3 days) 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. There was no dsIAP detected in parasitoid larvae. The results show the potential indirect effect of dsRNA treatment of host on its parasitoid, which could be minimized through optimizing dsRNA dose to promote complementary applications of dsRNA and parasitoids for the control of this high-risk invasive forest pest.