The annual invasive mile-a-minute weed and its biological control agent’s response to moisture and temperature variation

The invasive annual vine Persicaria perfoliata, known as mile-a-minute weed, is established in 12 states in the eastern U.S. where large monocultures disrupt forest succession and compete with native plants. The released biological control agent Rhinoncomimus latipes (Coleoptera: Curculionidae), or mile-a-minute weevil, has been distributed over the range of the weed, but its impact on the plant varies under different conditions. Previous work with mile-a-minute weed has shown the weed capable of outgrowing its control agent during cool, wet conditions in spring. To explore this relationship a series of experiments were conducted under various moisture and temperature regimes. These experiments were designed to not only test the growth and reproduction of the weed, but also the weevil’s, in order to aid in the prediction of the control agent’s population response. Preliminary results suggest that the weed’s biomass, stem thickness, and total seed output is suppressed during moisture stress, but the control agent’s impact is unimpeded and therefore also limits weed growth and reproduction in an additive fashion. Drought may be an important factor in determining future mile-a-minute weed population size, especially when combined with weevil feeding, oviposition, and larval performance.