Predation and parasitism of naturally occurring and sentinel stink bug egg masses ofHalyomorpha halys(Stål) andNezara viridula(L.) (Hemiptera: Pentatomidae) in various southeastern habitats

Abstract

Stink bugs, including Halyomorpha halys (Stål) and Nezara viridula (L.), are agricultural pests that feed on fruit in a variety of crops. Monitoring predation and parasitism of stink bug egg masses furthers our understanding of potential biological control tactics. However, best practices for laboratory and field assessments of parasitism and predation of egg masses require further attention. We carried out a series of laboratory and field experiments to test whether parasitism and predation for three types of sentinel H. halys egg masses, fresh, frozen, and refrigerated, varied in agricultural commodities. In addition, we asked if predation and parasitism differed between sentinel and naturally occurring H. halys and N. viridula egg masses in soybean. In the laboratory, more H. halys eggs were parasitized by Trissolcus euschisti (Ashmead) (Hymenoptera: Scelionidae) if they were frozen or refrigerated compared to fresh eggs. Similarly, in the field, parasitism was higher for frozen egg masses than fresh. In 2018 and 2019, H. halys natural egg masses had higher parasitism and lower predation compared to sentinel egg masses in soybean. In a paired field test during 2020 and 2021, there was no difference in parasitism between H. halys natural and sentinel eggs, but much higher incidence of parasitism was detected in natural N. viridula egg masses than sentinel eggs. Collecting natural egg masses is the best methodology for field assessment of parasitism of stink bug egg masses; however, if natural egg masses are not easily available, deploying refrigerated sentinel egg masses is a good alternative.

Seasonal density and natural mortality ofHalyomorpha halys(Stål) and indigenous stink bugs (Hemiptera: Pentatomidae) in a field crop agroecosystem

“…Host suitability may also play a role; although Te. podisi can successfully develop in natural H. halys egg masses, as observed here, it often fails to complete development in this host (Cornelius et al 2016b, Ogburn et al 2016, Dieckhoff et al 2017, Tillman et al 2023).…”

“…2020). Unlike some previous studies, parasitism and predation of stink bug egg masses in crops in our study were assessed solely from naturally laid egg masses of H. halys and indigenous stink bug species existing together in an agroecosystem, for an earlier study at this site revealed that H. halys and N. viridula natural egg masses can have higher parasitism and lower predation compared to sentinel egg masses in soybean (Tillman et al 2023).…”

“…Egg masses were chilled at 2.8–3.3 °C for approximately 36 h to kill them. Unlike frozen egg masses, refrigerated H. halys eggs retain their typical shape and color when deployed in the field, but will not hatch, eliminating the risk of eclosing nymphs feeding on parasitized eggs (Tillman et al 2023). Prior to deployment, the number of eggs were counted, and any damaged eggs were carefully removed.…”

“…Several indigenous parasitoid species parasitize naturally laid and sentinel H. halys egg masses in the southeastern United States (Tillman et al 2020, 2023). Trissolcus euschisti , Tr.…”