Submitted to: Journal of Insect Behavior
Publication Type: Peer reviewed journal
Publication Acceptance Date: 9/27/2013
Publication Date: 6/10/2014
Citation: Lee, D., Nielsen, A.L., Leskey, T.C. 2014. Dispersal capacity and behavior of nymphal stages of Halyomorpha halys (Hemiptera: Pentatomidae) evaluated under laboratory and field conditions. Journal of Insect Behavior. DOI: 10:1007/s1095-014-9456-2. Interpretive Summary: The invasive brown marmorated stink bug (BMSB) is a highly polyphagous and mobile pest causing perimeter-driven crop damage in many specialty and row crops. Understanding the dispersal biology of BMSB is critical for the development of site- and crop-specific monitoring and management programs. For this, dispersal capacity and behavior of BMSB was studied under laboratory and field conditions. First, laboratory trials demonstrate that BMSB nymphs (i.e. 2nd through 5th instars) have strong walking capacity on horizontal and vertical surfaces. In both horizontal and vertical walking arenas, all nymphal stages of BMSB showed equivalent or significantly greater distances moved compared to adults. Second, direct observations provide practical measurements on dispersal capacity and behavior of BMSB nymphs in the field. We found that 5th instars showed ca. two-fold greater walking distances compared with 3rd instars in grassy field plots and their walking distance was affected by temperature. Shorter bouts of movement were common at surface temperatures below 25 degrees C, whereas individuals showed longer walking distances, e.g. greater than 3 m per 30 min above 25 degrees C. Lastly, mark-release-recapture studies demonstrate that BMSB nymphs can be successfully recaptured by pyramid traps baited with pheromone-based stimuli. Indeed, strong dispersal capacity of nymphs, coupled with their response to the olfactory stimuli, yielded up to a 60 percent recapture rate within 12 h, during which insects walked greater than 20 m on the grassy ground. Further studies are warranted to determine seasonal movement patterns of BMSB nymphal populations at larger spatial scales and it implications towards site-specific management programs.
Technical Abstract: The invasive brown marmorated stink bug, Halyomorpha halys (Stål) (Hemiptera: Pentatomidae), is a highly polyphagous and mobile pest causing perimeter-driven crop damage over the growing season. Understanding the dispersal biology of H. halys is critical for the development of reliable monitoring systems and site-specific management strategies. However, virtually no attempt has been made to examine dispersal capacity or behavior of nymphal stages of this species. In this study, dispersal ecology of H. halys was studied under laboratory and field conditions. In the laboratory, horizontal and vertical walking capacity was quantified for mobile nymphal stages (i.e., 2nd through 5th instars) compared with that of adults. There was a significant difference in the horizontal distance moved by H. halys among the life stages tested. Third instars exhibited significantly greater walking distances compared with adults; horizontal walking distances by other nymphal stages were not significantly different from adults. A similar pattern was observed from vertical climbing tests of H. halys. Third and 4th instars climbed significantly greater distances compared with 2nd instars and adults, while distances climbed by 5th instars were intermediate. In the field, the walking distance of 3rd and 5th instar nymphs on mowed grass was quantified based on direct observation of individuals for 30 min. Under these conditions, 5th instars moved nearly two-fold greater distances compared with 3rd instars, but ground temperature affected both nymphal stages similarly. Shorter bouts of movement were common at surface temperatures below 25 degrees C, whereas individuals showed longer walking distances above 25 degrees C. H. halys also expressed heat-avoidance behavior by moving beneath the grass and closer to the ground surface when the temperature was greater than 40 degrees C. In mark-release-recapture studies, 4th and 5th instars were released and successfully recaptured in traps baited with attractive pheromonal-based stimuli allowing us to estimate dispersal rates under field conditions. When insects were released 5 m from traps, both instars were first recaptured within 2 h after release, with the recapture rates of 54 and 69 percent for 4th and 5th instars over 24 h, respectively. When insects were released 20 m from traps, 4th and 5th instars were first recaptured in less than 5 h, with the recapture rates of 27 and 51 percent, respectively. The results of this study indicate that H. halys nymphs have strong dispersal capacity with which populations can easily move among host plants and other attractive stimuli at farmscape levels.