Submitted to: Annals of the Entomological Society of America
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/27/2010
Publication Date: 11/1/2010
Citation: Shapiro, J.P., Shirk, P.D. 2010. Ovarian development in the predaceous minute pirate bug Orius pumilio: relationship to diet and mating. Annals of the Entomological Society of America. 103(6):971-978. Interpretive Summary: As elusive as they are, predatory insects such as minute pirate bugs are integral to the balance in an agro-ecosystem, and they play key roles in managing pest populations, whether or not a grower is aware of their presence. Scientists at the USDA ARS, Center from Medical, Agricultural and Veterinary Entomology, Insect Behavior and Biocontrol Research Unit have examined the effects of nutrition and mating on the development of eggs in a female pirate bug, Orius pumilio. A protocol to produce virgin, unfed adult bugs from the nymphal stage was developed which was critical for establishing that both adult feeding and mating are required before egg production can begin. This information will facilitate the conservation of these useful and critical beneficial insects for the control of damaging thrips and whitefly pests. It will also be employed in commercial rearing facilities that provide these predators to establish or augment greenhouse or field Orius populations.
Technical Abstract: Adult female minute pirate bug, Orius pumilio (Champion), were found to require food and mating to achieve maximum egg production. A protocol for isolating last-instar nymphs of Orius spp. was established to provide newly-eclosed, virgin, unfed adults as a resource for examining the importance of nutrition and mating on egg development. Using morphological characters in nymphs, correct sex identification was achieved with 96% accuracy. Isolation of last instar nymphs in single wells of 96-well microtiter plates resulted in a low mortality rate. Regulation of food availability as Ephestia kuehniella Zeller eggs and of a mate was conveniently managed for these isolated females. Egg production under these conditions was determined by ovarian morphology or assessed by a yolk protein ELISA. Unfed adult females, whether mated or not, did not produce detectible yolk protein or show any follicle development. Fed but unmated females produced a significant, detectible amount of yolk protein but had no fully mature eggs although minimal follicle development was observed. Fed and mated females fell into two categories: 44% produced mature eggs at a rate of 6.4 eggs/female, while 56% had ovaries similar to those of fed and unmated females. We conclude that there is a two stage process to egg development in adult female O. pumilio where entrance into previtellogenesis is dependent on acquiring a nutritious adult diet and initiation of vitellogenesis requires mating and both nutrition and mating must occur before egg development can be completed.