COMPARATIVE PHEROMONE CHEMISTRY OF ONCOPELTUSMILKWEED BUGS (HETEROPTERA: LYGAEIDAE: LYGAEINAE).
J.R. Aldrich1, T. Taghizadeh2 and J.T. BarbosaFerreira2
1USDA/ARS, Insect Chemical Ecology Lab., B-007, BARC-West,Beltsville, MD, USA 20705. 2Laboratory de Sintese de ProdutosNaturais, U.F. São Carlos, SP 13565-905 Brazil.
Oncopeltus spp. males produce a pheromone in tubular accessoryglands that are attached to the main reservoir of the metathoracic scentgland complex which, in most Heteroptera, produce purely defensive secretions.The secretions from the tubular accessory glands and metathoracic scentgland reservoirs were analysed for O. fasciatus from North Americaand O. unifasciatellus from South America. The tubular glands inmales of both species were swollen with secretion and the secretions fromeach species contained (E)-2-hexenyl acetate, (E,E)-2,4-hexadienyl acetate,(E)-2,7-octadienyl acetate, (E)-2-octenyl acetate and 1,8-diacetoxy-(E,E)-2,6-octadiene.(E)-2-octenyl acetate and (E)-2,7-octadienyl acetate are the major tubulargland components of both species, but in O. fasciatus the ratioof (E)-2,7-octadienyl acetate to (E)-2-octenyl acetate is about 2.5:1,whereas in O. unifasciatellus this ratio is about 1:1. In addition,1,8-diacetoxy-(E,E)-2,6-octadiene, plus an unidentified isomer, appearedto be relatively more abundant in the secretion of O. unifasciatellusthan that of O. fasciatus. The tubular glands in females were muchsmaller than in males, but did contain traces of the same unsaturated acetatesas identified in the secretions of the males. The metathoracic scent glandreservoirs of males and females were comparable in size for both speciesand the secretions contained the aldehydes corresponding to the alcoholsof esters identified in tubular gland secretions. A synthetic blend oftubular gland esters in proportions mimicking the natural blend of O.fasciatus males was highly attractive to both sexes in field testsin Maryland and to O. unifasciatellus adults in Brazil.