Nutrient declines in overwintering Halyomorpha halys populations

Abstract

Brown marmorated stink bug, Halyomorpha halys (St al) (Hemiptera: Pentatomidae), has become a major pest for agricultural growers since it arrived in the USA and Europe. To better understand the energetic requirements of overwintering, dispersal, and reproduction of this invasive pest, we monitored the weight, egg load, lipid, glycogen, and sugar levels of adult H. halys populations in western Oregon, USA, over 2 years. In the first study, overwintering H. halys collected monthly from inside shelters exhibited a consistent decline in weight, glycogen, and sugar levels from October to June. In the second study, post-overwintering adults that exited shelters in late spring had lower lipid, glycogen, and sugar levels than those that exited in early spring. Also, adults that just exited shelters had lower weight, glycogen, sugar, and sometimes lipids than adults that remained in diapause. Sugar levels declined the most during winter, followed by lipid and glycogen. These findings suggest that nutritional depletion may cause H. halys to emerge from diapause. In the third study, overwintered and first-generation adults (G 1 ) were simultaneously collected from holly in July and August. Overwintered adults often had lower nutrient levels than G 1 adults, which may reflect overwintered adults having expended energy for dispersal and reproduction. In the fourth study, we evaluated whether the Nutrient Index [weight (mg)/prothorax width (mm) 3 ], a convenient index of physiological status, correlated with nutrient reserves. The Nutrient Index correlated with the adults' lipid, glycogen, or sugar levels in 57% of cases, ranging from weakly negative to moderately positive correlations.

Monitoring Nutrient Status of Brown Marmorated Stink Bug Adults and Nymphs on Summer Holly

“…First, an explanation for these fluctuations is that it reflects the generational change in the population dynamics. As the overwintered generation of adults expend their energy in summer, they later die off in July/August upon which the newly emerging adults are often sampled with higher energetic reserves [ 12 ]. Secondly, another explanation for the fluctuations in nutrient levels could be the quality of food available and adult movement at different times of the summer.…”

“…Monitoring the energetic reserves of field-collected adults has revealed that extensive nutrient depletion occurs during overwintering. In spring, emerged BMSB adults have lower glycogen and sugar reserves than concurrently overwintering BMSB [ 12 ]. Furthermore, overwintering adults exhibit a 12–25% decline in lipid, a 48–70% decline in glycogen and a 54–79% decline in sugar levels from October–June [ 12 ].…”

“…In spring, emerged BMSB adults have lower glycogen and sugar reserves than concurrently overwintering BMSB [ 12 ]. Furthermore, overwintering adults exhibit a 12–25% decline in lipid, a 48–70% decline in glycogen and a 54–79% decline in sugar levels from October–June [ 12 ]. Given that BMSB have low reserves upon emergence from diapause, adults must feed on host plants to replenish their reserves.…”

Responses of Overwintering Halyomorpha halys (Hemiptera: Pentatomidae) to Dead Conspecifics

“…In addition to the fall search for harborage, H. halys may leave their harborage and become active in homes through winter and spring, likely in response to poor nutritional state (Funayama 2012, Skillman et al 2018. During active periods, some become trapped and die in window frames, light fixtures, and ventilation systems.…”

Size Restrictions on the Passage of Overwintering Halyomorpha halys (Hemiptera: Pentatomidae) Through Openings

“…They crawl around the exteriors while searching for entry points and may quickly enter when doors and windows are opened. In spring, they exit, triggered at least in part by the depletion of their fat bodies (Skillman et al 2018). Throughout the colder months, individuals may exit their hiding places and move around indoors.…”