Factors associated with winged forms of soybean aphid and an examination of North American spatial dynamics of this species in the context of migratory behaviour

Soybean aphid is a severe invasive pest of soybeans in North America. From 2005 onward, a network of 47 suction traps in North America, each approximately 7 m in height, has monitored aerial populations of this species. Suction trap captures of alate viviparous Aphis glycines in summer, and gynoparae and males in the autumn, were subjected to negative binomial regressions with environmental parameters. Models were ranked by using information-theoretic methods to determine which parameters best explained aerial density of aphids. Multiparameter models incorporating the best parameters were constructed. Best-fit models were used to compute peak values of each parameter, where a quadratic relationship between captures and that parameter occurred. Data were subjected to non-metric multidimensional scaling and analysis of similarity to observe patterns in the geographical and temporal distribution of captures. Summer flight activity A. glycines was explained best by the level of aphid infestation in fields local to the trapping site, although the autumn female flight activity peak and male activity was best explained by photoperiod. Seven-metre tall suction traps are useful for determining when flight activity of A. glycines occurs within a region.