Predicting average weekly blacklight trap catch of Acrosternum hilare adults using weather parameters

A regression model was developed to predict the flight activity of Acrosternum hilare (Say) using data on the number of adults collected in a single black light trap located in Painter, VA in the 18-yr period from 1990–2007. Eighteen initial weather variables including cumulative precipitation over different time periods, mean monthly precipitation from January to April (PJA), days below freezing (DBF), and average monthly temperatures from December to July were tested in developing the regression model. Stepwise regression analysis showed that a two-variable regression model, log₁₀ Y=0.98 + 0.027 (DBF) – 0.102 (PJA), was sufficient for predicting the mean weekly number of A. hilare adults in black light trap (Y). Validation of the model using five independent black light trap data sets (the observed) resulted in an r=0.98 between observed and predicted mean weekly number of A. hilare adults caught in traps. Three peaks in flights of A. hilare adults were observed when mean trap catch was plotted over time for the 18-yr period. The peaks occurred at 319, 892, and 1331 degree days (DD) from 1 January. Based on known developmental rates, the first peak was attributed to overwintered adults, the second to first generation adults, and the third to second generation adults. This research suggest that A. hilare undergoes two complete and a partial third generation in Virginia. Cumulative trap catch estimated from the 18-yr mean trap catch showed that 10, 50, and 90% of the total seasonal catch should occur by 153, 501, and 1066 DD.