Forest microhabitat effects on the field reproductive biology of Oobius agrili (Hymenoptera: Encyrtidae), an egg parasitoid of the invasive emerald ash borer

The solitary egg parasitoid, Oobius agrili Zhang and Huang (Hymenoptera: Encyrtidae), is one of several parasitoids that has been introduced to the United States to manage the invasive emerald ash borer (EAB) Agrilus planipennis Fairmaire (Coleoptera: Buprestidae). To improve release strategies and establishment of this parasitoid, a better understanding of factors influencing its phenology and fitness is needed. Here we report the effects of forest microhabitat on the longevity, realized fecundity, and progeny diapause rate of O. agrili. In fall 2019, five reps of two biotypes of laboratory-reared, diapausing O. agrili were deployed at one of three sites: 1) open-air insectary, 2) semi-urban landscape forest and 3) more mature mix-hardwood forest. Beginning spring of 2020, the emergence phenology of overwintered O. agrili from each microhabitat type was monitored daily until its completion.  O. agrili progeny emerging from each microhabitat were continuously reared with fresh EAB eggs in the same microhabitats until late summer and their reproductive fitness parameters (longevity, fecundity, diapause rate, and population growth) were determined. Results are discussed in the context of ongoing EAB biocontrol efforts and can be used to optimize future O. agrili releases and EAB biological control.