ABSTRACT
Fiorinia externa Ferris, elongate hemlock scale, was inadvertently introduced to North America from Japan. This insect is particularly problematic on hemlock, Tsuga spp., though it has been reported in association with several other conifers. The evidence that other conifers might be hosts, capable of supporting growing populations of the insect, has not been previously reviewed. Our review confirms that F. externa is an oligophagous pest of members of Pinaceae. Although species of Cupressaceae and Taxaceae have been reported as hosts of F. externa, they seem unable to support population growth of this pest. Evidence of the tree-killing potential of the insect, even on suitable hosts, is remarkably scant. The degree of pest risk posed by F. externa with respect to tree mortality in areas beyond the geographic range of hemlock seems modest, but uncertain.
ABSTRACT
Knowledge of a species' phenology can assist with timing accurate surveys to detect presence and density in a novel environment. Trichoferus campestris (Faldermann) (Coleoptera: Cerambycidae) has been found in the United States since the 1990s, but its biology and behavior remain poorly understood. This study investigated the phenology of T. campestris in Minneapolis and St. Paul, Minnesota, USA, based on local temperature data. In the summers of 2019 and 2020, 30 and 40 pheromone-baited traps, respectively, were deployed in trees in suburban parks to monitor capture of local individuals. Traps were suspended from branches of mature trees selected at random, with nine genera of trees selected over both years. Early, peak, and late adult abundance were characterized, and the impact of tree genus in which each trap was hung was evaluated. Abundance was found to be unimodal both summers with a peak around 650 degree days (base 10°C) in early July. Significantly more adult T. campestris were caught in traps hung in trees of the genus Tilia than in trees of the genus Quercus. These findings are important first steps to improving monitoring of T. campestris presence and conducting risk assessments.
Subject(s)
Coleoptera , Animals , Minnesota , Pheromones , Seasons , TreesABSTRACT
Sap beetles (Nitidulidae) are considered important overland vectors of the oak wilt pathogen, Ceratocystis fagacearum, in the north central United States. Colopterus truncatus and Carpophilus sayi are thought to be the principal sap beetle vectors in Minnesota. Field studies using windoriented funnel traps baited with aggregation pheromones of the insects were conducted during 2 years in east central Minnesota. The studies compared temporal flight dynamics of Colopterus truncatus and Carpophilus sayi from April through October, measured the proportion of dispersing adults of each species carrying viable pathogen propagules, and estimated the populations of contaminated dispersing beetles in oak (Quercus spp.) stands with and without oak wilt. Abundance of Colopterus truncatus peaked in either April or May, but the pathogen was most frequently isolated (20 to 45%) from beetles obtained from oak wilt sites from July through September. However, the highest contaminated insect population (CIP) generally occurred during April and May. Abundance of Carpophilus sayi peaked in October of both years, but the pathogen was most commonly isolated from beetles collected during May and June. The CIP was highest in June. The infective insect potential, as indexed by CIP, was greatest for both species in the spring and was greater for Colopterus truncatus than for Carpophilus sayi.
