Did the Functional Extinction of the American Chestnut, Castanea dentata, Result in the Extinction of the Greater Chestnut Weevil, Curculio caryatrypes?

Michael A. Charles^1,2,* and Duane D. McKenna^1,2

¹Department of Biological Sciences, University of Memphis, Memphis, TN 38152. ²Center for Biodiversity Research, University of Memphis, Memphis, TN 38152. *Corresponding author.

Northeastern Naturalist, Volume 30, Issue 4 (2023): 511–520

First published early online: 26 December 2023

Abstract
The larvae of Curculio caryatrypes (Greater Chestnut Weevil) are only known to feed on the nuts of Castanea dentata (American Chestnut). The introduction of the fungus Cryphonectria parasitica, causal agent of chestnut blight, to North America in 1904 resulted in the functional extinction of the American Chestnut and the extinction of several of its host-specialist insect associates, possibly including the Greater Chestnut Weevil. We examined American Chestnut trees in Pennsylvania and Maryland during September 2022 for evidence of Greater Chestnut Weevils. Historically, these areas were at the core of the distribution of American Chestnut and were known to host the Greater Chestnut Weevil. Only 6 of the 61 American Chestnut trees examined were reproductive. No evidence of the Greater Chestnut Weevil was encountered at any of the sites visited, and we consider it likely that this species is no longer present in the areas surveyed during this study. However, it is possible that the species may persist elsewhere, such as in southern Maine, where there are records of mature, fruiting trees, or in Wilkinson County, GA, where the last known Greater Chestnut Weevil was collected in 1997.

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