Root-Inhabiting Bark Beetles (Coleoptera: Curculionidae) and their Fungal Associates Breeding in Dying Loblolly Pine in Alabama

Abstract

Root feeding bark beetles in the family Curculionidae and the ophiostomatoid fungi they vector contribute to root disorders of Pinus species around the world. In the southeastern United States root feeding beetles in the genus Hylastes (Coleóptera: Curculionidae), including Hylastes salebrosus and Hylastes tenuis, are associated with stands of Pinus taeda experiencing premature mortality. Despite this, direct evidence of Hylastes species breeding, with their associated ophiostomatoid fungi, in Pinus taeda has not been observed until this point. In one P. taeda stand experiencing increased mortality in Alabama, roots were excavated and dissected from pines exhibiting a range of crown conditions in order to determine if Hylastes breeding and feeding damage could be detected and to investigate the relationship between beetles, ophiostomatoid fungi, and tree crown condition. Hylastes salebrosus and H. tenuis represented the majority of beetles collected (94%) and were found nearly exclusively in root of trees with dying crowns. Adult beetles and beetle galleries were associated with a host of ophiostomatoid fungi, including Leptographium terebranis, Grosmannia huntii, L. procerum, and L. serpens. These observations suggest roots of dying trees represent a valuable host substrate for expanding H. salebrosus and H. tenuis populations. A more comprehensive study is required to confirm these findings.