Attractant pheromone and allomone from the metathoracic scent gland of a broad-headed bug (Hemiptera: Alydidae)

Females of Alydus eurinus (Say) release an attractant pheromone from their meta thoracic scent gland. Conspecific males and, to a lesser extent, females and nymphs were attracted to blends containing the female-specific essential pheromone components 2-methylbutyl butyrate and (E)-2-methyl-2-butenyl butyrate, whereas individuals of Alydus pilosulus Herrick-Schaeffer were not attracted. When attacked, however, alydid adults emit chemicals for defense-butyric and hexanoic acids in A. eurinus-from the metathoracic scent glands. Mimicry is actually the first line of defense for most broad-headed bugs, including the common North American species studied here, whose nymphs are remarkable ant mimics and whose adults strongly resemble spider wasps (Hymenoptera: Pompilidae). The possibility that disparate heteropterans (Hemiptera) produce sexual pheromones in their metathoracic scent glands must be considered in future pheromone research on heteropterans, especially fur species with the specialized lines of defense indicated by aposematism or mimicry.