UC San Diego

The Vespidae is a diverse family of wasps and hornets that are formidable predators of insects, including social bees¹, and includes a number of invasive species². Recently, the world's largest hornet, Vespa mandarinia Smith (Hymenoptera: Vespidae), which occurs naturally in the Indomalayan region, has been found in Canada and the United States². Some simulations indicate that it could rapidly spread throughout Washington and Oregon in the western US, as well as some eastern parts of the country^2,3, threaten native bees and honeybees, and harm bee-pollinated crop production worth over $100 million annually³. There is consequently an urgent need to learn more about V. mandarinia's reproductive biology and to develop trapping methods to locate its nests and to control its reproduction. We identified V. mandarinia queen-produced sex pheromone from the 5^th and 6^th intersegmental sternal glands of virgin queens. The major active compounds were hexanoic acid, octanoic acid, and decanoic acid. When placed in field traps, the synthetic compounds and a queen-equivalent mixture rapidly attracted hundreds of males but no females or other species.