A proactive approach to prepare for the invasion of Tuta absoluta into California

The South American tomato leafminer, Tuta absoluta, is a devastating pest of tomatoes that has invaded the Mediterranean Basin and most of the Asian and African continents, posing 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 and variation in natural enemy communities across regions makes reliance on biological control difficult. To improve the ability for the U.S. tomato industry to rapidly respond to T. absoluta invasion into the US, we are conducting a series of experiments to i) determine the efficacy of organic and conventional insecticides against appropriate life stages of T. absoluta and ii) identify indigenous parasitoids that may attack T. absoluta and the potential role of parasitoid control in California. We have developed and tested an assay to evaluate insecticides registered for use against lepidopterous pests in tomatoes on colonies of T. absoluta within the University of California-Davis Contained Research Facility. 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. Further testing of insecticide and biological control efficacy will help to enable a rapid response to invasion by T. absoluta into the US.