The American Chestnut was once the dominant tree species in much of the eastern United States. Breeding efforts following the devastating chestnut blight in the early 1900s have made growing chestnuts an increasingly viable option for producers. Pest pressures still limit production, however. Lesser Chestnut Weevil (Curculio sayi) larvae feed inside of chestnuts rendering them unmarketable and causing substantial losses. This project evaluates the viability of two biological control agents, entomopathogenic nematodes and entomopathogenic fungi, for the control of Chestnut Weevil. The entomopathogens have proved effective in controlling other, related, weevils. We seek to establish their effectiveness as an attractive, environmentally friendly, control option for organic chestnut production. Success in this project would remove a primary barrier to productive chestnut production and facilitate economic development in this nascent industry.

Into the Field

Trapping

A good start with any field project is monitoring the environment to get a read on the initial conditions. When working with insects, quantifying current populations is essential, usually accomplished via trapping. We employed three types at our test site at Rose Valley Farms in Clyde, NY: cone traps, pyramid traps, and trunk traps.

Pyramid Trap

A pyramid trap nestled next to a chestnut tree at
Rose Valley Farms in Clyde, NY

Trunk Trap

A trunk trap tied around a chestnut
tree at the same location

Cone Trap

A cone trap fastened to a microcosm
buried in a chesnut grove

Collections occur weekly to survey not only the chestnut weevil populations but also any other insects found in the area. Ecosystems are large, multivariate equations, and collecting as much data about the environment can help us to understand the ecology.

Soil Samples

Chestnut weevil larvae overwinter in the soil beneath the trees. This behavior makes them prime candidates to be controlled by entomopathogenic nematodes (EPNs) and entomopathogenic fungi (EPF). Before applying our EPNs, we sampled the grove to evaluate the presence of native nematodes and fungi. In this particular grove, we did not find any EPNs in our sampling but did detect the presence of two EPF: Metarhizium and Beauveria.