Reduced insecticide use in soybean fields: A look into the development of site-specific strategies to manage Dectes texanus

The soybean stem borer, Dectes texanus Leconte (Coleoptera: Cerambycidae), is a native North American beetle that has become an important pest in soybean (Glycine max L.). Current management practices targeting adult D. texanus can reduce infestations in the field; however, adult distributions within the field through time and their relation to larval distributions have not yet been studied. Understanding larval-adult distribution relationships can potentially aid in the development of site-specific pest management strategies that can increase the effectiveness of insecticide applications and mitigate loss due to larval feeding. Therefore, the objective of this study was to monitor changes in the spatial distributions of adult D. texanus in soybean production fields through time and correlate these patterns with larval distributions at the end of the growing season.  Two D. texanus infested soybean production fields in Kansas were sampled from June to August in 2012. Fields were grid sampled and swept for adults at all waypoints (n = 69 and 90 respectively). Before harvest, a meter row of soybean plants was collected from each waypoint and stems were processed to determine presence/absence of D. texanus larvae. We hypothesize that adult D. texanus will display an aggregational pattern along field edges during early colonization, dispersing throughout the field towards the end of adult activity; larval distributions will mirror adult aggregational patterns. Preliminary results suggest that adult colonization patterns vary between fields and through time; this might influence larval distribution accordingly and confound the development of site-specific pest management strategies.