Advancing RNAi Technology for Southern Pine Beetle Control

Project Abstract. In spite of growing challenges and shifting dynamics, southern pine beetle (SPB) is among the most pressing of forest management challenges in the eastern US, as populations expand in response to climate change and fragmentation. Endemic SPB populations provide essential ecosystem services, but when populations go into outbreak phases, facilitated by complex chemical communication and adverse environmental conditions, tree mortality is widespread. Innovative strategies are needed to provide resiliency as SPB invades naïve forests in northerly areas. SPB can be killed using RNAi; oral ingestion of SPB-specific dsRNAs designed to silence essential genes kills beetles, is highly specific, and deliverable through the host plant. Further, we know that we can use RNAi to silence verbenone-specific odor receptors (ORs) in female SPB, reducing the beetles’ attraction to males. Similarly, we know that the blue stain fungal associate of SPB, Ophiostoma minus, can be Agrobacterium-transformed to express a dsRNA construct that silences genes in SPB. The discovery that verbenone ORs can be silenced through oral ingestion of exogenous dsRNAs, coupled with the potential for those dsRNAs to be vectored by a ubiquitous SPB fungal associate, creates tremendous potential for its utilization in population regulation. This project will couple these discoveries to pioneer a pest management approach that utilizes a fungal associate to deliver dsRNAs that impede female SPB from detecting males, thereby keeping beetle populations at endemic levels, and reducing their capacity to kill trees. This project is in direct alignment with priorities 6-7 outlined in the SRS Call for Proposals, by addressing SPB as a native invasive expanding into northern forests and impacting disturbance regimes and forest resilience.