Exploring the Dynamics of Virulent and Avirulent Aphids: A Case for a "Within Plant" Refuge

TL;DR

This study models the interactions between virulent and avirulent soybean aphids on resistant soybeans, revealing how virulent aphids can indirectly promote avirulent aphid survival, supporting the concept of a "within plant" refuge for sustainable pest management.

Contribution

It introduces a differential equation model to simulate aphid biotype interactions within soybean plants, highlighting the potential of a "within plant" refuge strategy.

Findings

Increased virulent aphids suppress plant resistance.

Avirulent aphids benefit indirectly from virulent aphids.

Model aligns with observed field dynamics.

Abstract

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.