Submitted to: The Canadian Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 15, 2000
Publication Date: N/A
Interpretive Summary: Plant bugs and blood-feeding bugs are members of a group of insects (order Heteroptera) that includes many crop pests and vectors of human disease. These kinds of insects are usually strong fliers whose movements are difficult to detect in nature. The chemical signals these insects produce to find one another (pheromones) offer a means to monitor the insects so that they may be more effectively controlled. The present investigation presents data for one of these species (Alydus eruinus) showing that a potent attractant pheromone is somehow released from the same gland in which chemical irritants are produced for the insect's defense. The mechanism whereby these insects are able to produce pheromones and defensive secretions in the same gland is described. The discovery that some of these kinds of insects produce attractants in what was once thought to be solely a defensive gland is important to scientists looking for pheromones in related insects. Identification of the pheromone for A. eurinus is also of academic interest because individuals of this and closely related species often simultaneously feed on the same plants yet they do not interbreed.
Technical Abstract: Mimicry is the first line of defense for most broad-headed bugs (Heteroptera: Alydidae), including the common North American species studied here, Alydus eurinis (Say) whose nymphs are remarkable ant mimics and adults strongly resemble spider wasps (Pompilidae). When attacked, however, alydid nymphs and adults emit chemicals as a second line of defense. In the adult stage, allomones--butyric and hexanoic acids in A. eurinus--are ejected from the metathoracic scent glands characteristic of all true bugs. Here we report that females of A. eurinus also release an attractant pheromone from their metathoracic 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-buyenyl butyrate, while individuals of the congeneric species A. pilosulus Herrick-Schaeffer were not attracted. In addition to the Alydidae, attractant pheromones from the metathoracic scent gland are known for certain other seed bugs (Lygaeidae) and plant bugs (Miridae). The possibility that disparate heteropterans produce sexual pheromones in their metathoracic scent glands must be considered in further pheromone research on this groups of insects.