Professor University of Memphis Memphis, Tennessee
The larvae of Curculio caryatrypes (large chestnut weevil) are only known to feed in the nuts of Castanea dentata (American chestnut). The introduction of Cryphonectria parasitica (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 large chestnut weevil. We examined American chestnut trees in Pennsylvania and Maryland during September 2022 for evidence of large chestnut weevils. Historically, these areas were at the core of the distribution of American chestnut and were known to host the large chestnut weevil. Only six of the 61 American chestnut trees examined were reproductive. No evidence of the large chestnut weevil was encountered at any of the sites visited, and we consider it likely that this species is extinct across its former range in eastern North America or at least no longer present in the areas surveyed during this study. However, it is possible (though unlikely) that the species may persist elsewhere, such as in southern Maine, where there are records of mature, fruiting trees, or in Wilkinson County, Georgia, where the last known large chestnut weevil was collected in 1997. Progress towards reconstructing the phylogeny of Curculio includes 40 species in-hand for DNA extraction and sequencing using target enrichment methods, and a first small set of species already successfully sequenced, including the large chestnut weevil.