Characterizing spring emergence of adult Halyomorpha halys using experimental overwintering shelters and commercial pheromone traps

Abstract

To improve our understanding of adult Halyomorpha halys (Stål) (Hemiptera: Pentatomidae) overwintering biology and to better inform models of its population dynamics, its temporal pattern of spring emergence was investigated using experimental overwintering shelters in screened cages within protective structures. In 2012, plastic shelters containing 100 adults were deployed in unheated, unlighted buildings, and adjacent woodlots in Virginia, USA. In 2013 and 2014, wooden shelters containing 300 paint‐marked adults were deployed in pairs in six woodlots across Virginia, West Virginia, and Maryland, USA; one in a closed cage and one in a cage with the top removed, enabling emerged adults to be counted or to disperse, respectively. In 2013 and 2014, pheromone‐baited and non‐baited pyramid traps encircled the shelters at each site. Regular counts of adults that emerged into the closed cage and of marked and ‘wild’ (unmarked) adults captured in traps were conducted from February or March through early July. In 2012, emergence patterns from shelters in buildings and woodlots were very similar and matched those recorded from woodlots in 2013 and 2014. In all years, a small peak of emergence occurred in about mid‐April, a larger and more prolonged peak was observed between mid‐May and early June, and emergence ended by early July. Of the 449 H. halys adults captured in traps between 2013 and 2014, only three were marked individuals from shelters in the open cage, suggesting that adults emerging from overwintering sites may require a dispersal flight before responding to pheromone‐baited traps. In 2013 and 2014, respectively, 98 and 93% of captures were in pheromone‐baited traps, but there was no correlation between the weekly number of adults that emerged from shelters in the closed cages and captures in traps.

Coupling Traditional Monitoring and Citizen Science to Disentangle the Invasion of Halyomorpha halys

“…Our observations of increasing numbers and catch density during fall can probably be explained either by a rising population, or that BMSB sensitivity might be higher during this season, given that their ability to aggregate in suitable shelters during that period directly affects their winter survival. Our results are in accordance with other observations on the phenology of BMSB, in the climatically similar mid-Atlantic region in the United States, where spring-adults also emerge from overwintering sites in late-spring [62]. Females are believed to be reproductively immature in earlyspring, resulting in a delay in reproduction [18], hence the first appearance of nymphs in Trentino followed in summer.…”

“…The rapid decline of nymphal populations in late fall is probably due to fifth instars molting to the adult stage or mortality due to frost [18]. Our results are in accordance with other observations on the phenology of BMSB, in the climatically similar mid-Atlantic region in the United States, where spring-adults also emerge from overwintering sites in late-spring [62]. Females are believed to be reproductively immature in early-spring, resulting in a delay in reproduction [18], hence the first appearance of nymphs in Trentino followed in summer.…”

Nutrient declines in overwintering Halyomorpha halys populations

“…Entire units were in wooden apple crates inside plastic tunnels (Coroplast, Vanceburg, KY, USA) similar to but not identical to Bergh et al (2017). Adult H. halys were hand collected from homes in Aurora (45°13 0 42″N, 122°47 0 09″ W), Boones Ferry (45°26 0 25″N, 122°41 0 31″W), Corvallis (44°31 0 49″N, 123°16 0 09″W), and Estacada (45°17 0 43″N, 122°18 0 03″W), all in OR, in early October 2015.…”

“…Halyomorpha halys enters overwintering sites generally from late September to mid-November in Asia (Lee et al, 2013) and the eastern USA (Bergh et al, 2017), and exits from March to June. These adults spend 6-9 months overwintering out of the 12 months lived as an adult (Figure 1).…”

“…Clearly, this is a convenient, non-destructive method, and these H. halys can be used for additional experiments. Additional labour, chemicals, tubes, and equipment, such as hot plates, vortex, Figure 1 Timing of studies 1-3 and life cycle of Halymorpha halys as observed in Oregon, in the eastern USA (Bergh et al, 2017), and Asia (Lee et al, 2013). centrifuge, and absorbance reader, can total ca. The Nutrient Index only requires a scale with 0.1 mg precision and a microscope or caliper to measure pronotum width.…”