A comparative study on the distribution of adult Dectes texanus in continuously planted soybean fields

The soybean stem borer, Dectes texanus Leconte (Coleoptera: Cerambycidae) is a species native to North America that has become an important pest in soybean (Glycine max L.). It is common for growers to continuously plant soybean without rotating to other crops, which can increase the liklihood of reinfestation of soybean stem borer within their soybean field. Monitoring adult densities within a field during times of peak activity is useful for determing the utulity of site-specific management practices; however, it is also imperative to understand year-to-year variability in adult distribution within continually planted soybean. Therefore, the objective of this study was to examine the within-field spatial distribution of adult D. texanus within a season and between multiple growing seasons. A single soybean field infested with D. texanus was selected for modeling the spatial distribution of adults for two consecutive years (2012 and 2013). Geostatistical software was used to create a sampling grid (69 sample points). Each waypoint was sampled using a sweep net by collecting 20 sweeps in each cardinal direction at all waypoints within the field. Ordinary kriging in program R was used to interpolate denisties of adult D. texanus between sampled waypoints to construct a distribution map within the field using ArcMap. Maps between dates and years were compared using multivariate analysis. Preliminary results from 2012 showed adult aggregration along edges neighboring previous years soybean crops or edges near alternative plants host prior to dispersing throughout the field. Changes in spatial patterns between both years and implications from these initial results on current management strategies will be discussed.