USDA-ARS Insect Chemical Ecology Laboratory, Agricultural Research Center-West, B-007, rm301, Beltsville, 20705 Maryland, USA.
Alydus eurinus (Say) is the most common of the so-called "broad headed" bugs (Heteroptera: Alydidae) in North America. As a first line of defense the nymphs of this and related species are remarkable ant mimics, while adults resemble spider wasps (Pompilidae). However, when disturbed, nymphs and adults produce chemicals as a second line of defense. Allomones in the adult stage -butyric and hexanoic acids in A. eurinus- are released from the metathoracic scent glands characteristic of true bugs. Here we report that females of A. eurinus also release an aggregation pheromone from their metathoracic scent gland: 2-methylbutyl and (E)-2-methyl-2-butenyl butyrates are the female-specific essential pheromone components. In addition to the Alydidae, it is also known that certain seed bugs (Lygaeidae) and plant bugs (Miridae) produce attractant pheromones from the metathoracic scent gland. The mechanism whereby these heteropterans are able to coordinate allomone and pheromone production in the same gland will be discussed, and the implications of this phenomenon for future pheromone research in the group will be considered.