-Anne L Nielsen, Ph.D., Specialist in Fruit Entomology
The early warm temperatures have given some pests a "jump" on the season. But temperature is not the only factor influencing insect development. Our new Fruit Entomologist, Anne Nielsen, explains the science behind why - despite early season warm temperatures - we are not seeing Brown Marmorated Stink Bug reproduction pushed to earlier dates.
The early spring has fast tracked plant development, insect activity, and damage. For many insect pests, we have reliable monitoring programs to track insect activity and/or development in crops using traps or degree-day models. Such programs are unavailable (or being developed) for new or recent pests like Brown Marmorated Stink Bug. Growers are faced with questions about when/if to start managing brown marmorated stink bug in their orchards, especially because of the accelerated weather this spring. We know that at this time of year, adults are leaving overwintering sites in search of food: agricultural crops and wild host plants.
BMSB are Searching for Host Plants
Through multiple collaborative efforts we are working to refine the biofix for a BMSB degree-day model so that we can better predict adults and their offspring in crops to time management programs. As part of this effort we have been monitoring BMSB in peaches, apples, and grapes with visual samples and a new pheromone trap developed by USDA researchers. We have found sporadically low numbers of BMSB in peach and they are already attractive to the trap, indicating that they are searching for host plants.
A key part to refining the degree-day model is looking at reproductive development of BMSB females through dissection. Insect development is influenced by both temperature and photoperiod. While the early spring may have increased activity, the females that we have caught are still sexually immature and not producing eggs (as of May 10). In previous years, the earliest we have found egg masses in New Jersey has been the first week of June. The warm weather may speed maturation up slightly, but the literature suggests that diapause termination is largely driven by photoperiod. Therefore, while we do have some adult presence in orchards, BMSB is not yet reproducing in our area.