  The soybean aphid, Aphis glycines (Hemiptera: Aphididae), is an invasive pest
that can cause severe yield loss to soybeans in the northcentral United States.
A tactic to counter this pest is the use of aphid-resistant soybean varieties.
However, the occurrence of virulent biotypes can alter plant physiology and
impair the use of this management strategy. Soybean aphids can alter soybean
physiology primarily by two mechanisms, feeding facilitation and the obviation
of resistance, favoring subsequent colonization by additional conspecifics. We
developed a non-local, differential equation population model, to explore the
dynamics of these biological mechanisms on soybean plants co-infested with
virulent and avirulent aphids. We then use demographic parameters from
laboratory experiments to perform numerical simulations via the model. These
simulations successfully mimic various aphid dynamics observed in the field.
Our model showed an increase in colonization of virulent aphids increases the
likelihood that aphid-resistance is suppressed, subsequently increasing the
survival of avirulent aphids, producing an indirect, positive interaction
between the biotypes. These results suggest the potential for a "within plant"
refuge that could contribute to the sustainable use of aphid resistant
soybeans.
