Effects of Temperature and Relative Humidity on the Vertical Distribution of Stink Bugs (Hemiptera: Pentatomidae) within a Soybean Canopy and Implications for Field Sampling

Abstract

Stink bugs (Hemiptera: Pentatomidae) are suspected to change their intraplant vertical distribution in response to changes in environmental conditions. As a result, this could influence sweep-net sampling efficiency in a soybean canopy. We examined the effects of both ambient and within-soybean canopy temperature and relative humidity on stink bug vertical distribution in 2 0.38m row spaced commercial soybean fields with full canopies in Virginia, one in 2010 and one in 2011. Temperature and relative humidity were monitored in the upper and lower plant canopy. The within-canopy vertical distribution of a minimum of 20 stink bugs was documented at each of 4 different observation times: observations were replicated on different days 14 times in the morning, 14 around noon, 15 during the midafternoon, and 5 observations were replicated in the early evening. Chinavia hilaris Say was the primary species observed with 88% of the total in 2010 and 59% in 2011; the remainder was primarily Euschistus servus Say. No significant relationship was observed between the environmental parameters measured or time of day on the vertical distribution of stink bugs in the canopy. Regardless of environmental conditions, an average of 15 - 20% of stink bugs was located below the typical 38cm zone of a sweep net sampling. Efficiency of sweep net sampling for stink bugs in soybean did not appear to be significantly affected by changes in temperature, relative humidity, or time of day, and sweep netting the upper canopy accessed approximately 80% of the total population.