Developing proactive IPM strategies the invasion of Tuta absoluta into California

The South American tomato leafminer, Tuta absoluta, is a devastating pest of tomatoes globally and poses a significant threat to tomato production in the United States. Broad-spectrum insecticides and indigenous natural enemies have had some success in controlling T. absoluta in invaded regions, however insecticide resistance is widespread, variation in natural enemy communities across regions makes reliance on biological control difficult, and resistant tomato varieties have not yet been developed. To improve the U.S. tomato industry’s response to T. absoluta invasion into the US, our studies will i) determine the efficacy of organic and conventional insecticides against appropriate life stages of T. absoluta, ii) identify indigenous parasitoids that may attack T. absoluta and the potential role of parasitoid control in California, and iii) evaluate resistance characteristics of wild tomato relatives from T. absoluta’s native range. We have developed an assay to evaluate insecticides registered for lepidopteran pests in tomatoes on colonies of T. absoluta within the Contained Research Facility at UC Davis. Using a closely related endemic moth, Keiferia lycopersicella, we infested sentinel tomato plants to survey parasitoid communities in the Sacramento and San Joaquin Valleys and have identified several candidates for biological control of T. absoluta. Additionally, we conducted resistance assays on 12 accessions of wild tomato (Solanum habrochaites) collected throughout T. absoluta’s native range. Further testing of insecticide and biological control efficacy, alongside identification of resistance traits for future breeding programs, will help to enable a rapid response to invasion by T. absoluta into the US.