Abstract:
Parasitoids are a diverse group of insects that contribute to several dimensions of biodiversity, including biological control of arthropod pests. Understanding parasitoid ecology, behavior, reproduction, habitat selection, and preferred pest host is crucial to increasing their populations for natural pest control. The invasive brown marmorated stink bug, Halyomorpha halys (Stål) (Hemiptera: Pentatomidae) is a significant insect pest in agricultural systems, including pecan orchards. Natural enemies, such as stink bug egg parasitoids, may help control H. halys outbreaks in pecan. The addition of floral resources, such as crimson clover, which attract parasitoids, may also increase rates of parasitism as well as parasitoid abundance. For my thesis, I tested whether parasitoid rate of attack, abundance, and diversity differed with and without crimson clover in pecan tree canopies or on the ground next to trees. I monitored rate of attack with sentinel egg masses and abundance with yellow sticky cards. From H. halys sentinel egg masses, five native stink bug egg parasitoid species were detected, including one new species for the state of Georgia, Anastatus pearsalli (Ashmead), as well as Trissolcus brochymenae (Ashmead), Trissolcus euschisti (Ashmead), Telenomus podisi (Ashmead) (Hymenoptera: Scelionidae), and Anastatus reduvii (Howard) (Hymenoptera: Eupelmidae). From sticky cards, I also detected five native stink bug egg parasitoid species, including A. reduvii, T. brochymenae, T. euschisti, T. podisi, and Ooencyrtus species (Hymenoptera: Encyrtidae). Overall, rate of attack in sentinel egg masses was higher in orchards with crimson clover compared to the control and was higher in the canopy compared to the ground. Parasitoid abundance was similar whether crimson clover was present or not. Despite similar abundance, increased rates of attack suggest that crimson clover improves biological control of H. halys in pecan orchards. Importantly, planting crimson clover in pecan orchards is a simple, sustainable approach for growers to control H. halys.