Photoperiodic modulation of diapause induction and termination in Oobius agrili Zhang and Huang (Hymenoptera: Encyrtidae), an egg parasitoid of the invasive emerald ash borer

Publication date: Available online 25 July 2019Source: Biological ControlAuthor(s): Toby R. Petrice, Deborah L. Miller, Leah S. Bauer, Therese M. Poland, Forrest W. RavlinAbstractOobius agrili Zhang and Huang (Hymenoptera: Encyrtidae) is a solitary and parthenogenetic egg parasitoid from China being introduced into North America (NA) as a biological control agent of the emerald ash borer (EAB), Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), an extremely invasive and destructive pest of ash trees (Fraxinus spp.). Oobius agrili is being released over a broad geographical range in NA where photoperiod varies considerably during the season of parasitoid-host activity. We conducted laboratory studies to determine 1) if photoperiod-induced diapause is modulated maternally, grand-maternally, and/or directly in immature parasitoids; 2) interactions of maternal adult age and photoperiod exposure on diapause induction; 3) the critical day length for diapause induction; 4) the critical age at which photoperiod-induced diapause is modulated in developing larvae; 5) the effects of photoperiod and length of chill on diapause termination; and, 6) the effects of photoperiod on O. agrili biology across a latitudinal gradient. We found that photoperiod exposure of O. agrili larvae developing inside host eggs directly induced diapause, and maternal or grand-maternal photoperiod treatments did not affect diapause induction in their progeny. However, older adults that experienced diapau...
Source: Biological Control - Category: Biology Source Type: research