Abstract:Semiochemicals like aggregation pheromones are key components of the ecology of a variety of insect species. Insects also use plant-produced volatile organic compounds as kairomones to find plant hosts. Pheromones and kairomones can also be valuable tools for developing pest management strategies. In the Northern Sacramento Valley of California, cucumber beetles - the western striped cucumber beetle (CB), Acalymma trivittatum, and western spotted CB, Diabrotica undecimpunctata undecimpunctata - are the principal pests of muskmelons, particularly for soft-rind varieties. Adults of both species feed on the fruit surface, rendering fruit unmarketable. Existing management for cucumber beetles relies heavily on broad-spectrum insecticide applications. There is a need for alternative management tools such as semiochemical-based pest management. A novel aggregation pheromone, vittatalactone, was identified and synthesized from semiochemicals produced by the male striped cucumber beetle, Acalymma vittatum, the east coast congener to the western striped CB. Groundwork studies have shown that vittatalactone attracts cucumber beetles in field settings. This presents an opportunity to test vittatalactone as a tool for sampling the western species of cucumber beetle. We conducted a two-year study to test the efficacy of vittatalactone as an attractant for the western striped and western spotted CB. We also tested if pairing a commercial floral lure with vittatalactone increased beetle captures. Clear-sticky traps attached to wooden stakes were deployed at two commercial farms in the Sacramento Valley with organic cucurbit operations with the following treatments: 1) vittatalactone alone, 2) floral lure alone (only for the second year of the study), 3) a combination of vittatalactone plus floral lure (V+F), and 4) an unbaited control. Lastly, we measured differences in response to vittatalactone between males and females for one of the years of the study. We determined that vittatalactone was attractive to both the western striped and western spotted CB. Furthermore, combining the floral lure with vittatalactone enhanced the attraction (?) of both species of cucumber beetle. It also appeared that the floral and vittatalactone treatments were most attractive when the fields were not planted with a crop. We rarely observed significant interactions between treatment x month, and we found no difference in attraction to vittatalactone between females and males. Overall, our studies demonstrated that vitttatalactone is attractive in a field setting to both species of cucumber beetle, while the combination of floral and vittatalactone lures are even more attractive. Additionally, the commercial floral lure was attractive on its own but greatest effects were observed mostly for the western spotted CB in July, August, and September. In general, vittatalactone is promising as a tool for effective integrated pest management of cucumber beetles. Vittatalactone, possibly paired with a plant-odor lure, could be used as an attractant for monitoring. Similarly, these attractants could form the foundation of an attract-and-kill strategy used to remove beetles from a field or farm. Based on these data we believe that the most effective times of the year to deploy these semiochemicals would be in the early and late season of crop production prior to planting or post-harvest.