Phenology and Cold Tolerance of Megacopta cribraria: An Invasive Soybean Pest at its Northern Limit

Abstract

Megacopta cribraria, kudzu bug, is an invasive pest of soybeans in the Southeast United States, with a northern distribution limit in Maryland. Soybeans, however, are grown north of Maryland, which places producers at risk of future range shifts. Additionally, producers in the current distribution need a development model to aid management. To address both concerns, I studied the cold tolerance of the kudzu bug and its phenology. I examined the supercooling point (SCP) and lethal temperature to kill 50% (LLT50) of three populations over the fall of 2015 to determine the cold tolerance. I found the kudzu bug is a freeze avoidant species with an average SCP of -12.6°C and LLT50 of -5.1°C. I also determined that the kudzu bug moves to thermally protected leaf litter in late November to overwinter. To address phenology, I determined the kudzu bug requires 625 degree-days at a minimum temperature of 16°C to complete egg and nymphal development. Field validation fit the model well with a biofix of May 1st and 30 days for a preoviposition period. The phenological degree-day model indicates two generations per year and allows producers evaluate and time pest management strategies within a year. Cold tolerance enables producers to predict the surviving population each year as well as the potential for northward range expansion.