UNUSUAL THERMAL DEFENSE BY A HONEYBEE AGAINST MASS ATTACK BY HORNETS

THE giant hornet Vespa mandarinia japonica (Hymenoptera: Vespidae) is the only hornet species known to have evolved en masse predation of ot her social bees and wasps. Here we show that hornets is initiated by s ecretion of a foraging-site marking pheromone from the van der Vecht g lands (metasomal sternum VI glands) by a single foraging hornet. The l one hornet rubs the basal tuft of the terminal gastral sternite around a prey food resource, such as a honeybee colony, and the hornet nestm ates then congregate and attack the marked site ea masse. The sympatri c Japanese honeybee Apis cerana japonica (Hymenoptera: Apidae) can det ect the hornet marking pheronome, and responds by increasing number of defenders at the nest entrance. When an invading hornet is captured b y a defending bee, more than 500 other bees quickly engulf the hornet in a ball which contains isoamyl acetate. Thermography showed that the ball temperature is very high (similar to 47 degrees C), which proves lethal to the hornet but not to the bees. Defenders patrolling the ne st entrance also generate high temperatures. These findings suggest th at aspects of the interaction between V. mandarinia japonica and A. ce rana japonica are specifically coevolved.