John D. Stein

Interruption of Semiochemical-Mediated Attraction of Dendroctonus valens (Coleoptera: Scolytidae) and Selected Nontarget Insects by Verbenone

Abstract We tested two formulations of verbenone for efficacy in protecting ponderosa pine trees from attack by the red turpentine beetle, Dendroctonus valens LeConte: (1) polyethylene bubblecaps filled with 800 mg of neat verbenone, and (2) a sprayable water suspension of microencapsulated verbenone. We baited artificial trees (cardboard cylinders coupled with Lindgren pheromone traps) with host kairomones and the verbenone formulations. Efficacy was measured by numbers of beetles captured in baited traps. Both release systems significantly reduced trap catch, and there was no significant difference between them. Both systems have promise for use in forest stands, depending on management objectives and land use. Verbenone was an interruptant for some nontarget insects, especially Coleoptera, and none were consistently attracted to verbenone. We report on verbenone as an interruptant to host attraction in the red turpentine beetle, and also on the efficacy of a microencapsulated scolytid semiochemical.

Acetophenone as an anti-attractant for the western pine beetle, Dendroctonus Brevicomis LeConte (Coleoptera: Scolytidae).

Host location and colonization by bark beetles is dependent upon the relative and absolute amounts of attractant and antiattractant compounds available. Many investigations have lead to use of antiattractants for the management of these pests and have been especially focused on verbenone. However, recent studies have identified new antiattractants for several species of bark beetles. We report results of recent investigations of the response of western pine beetle, Dendroctonus brevicomis LeConte, to two recently identified antiattractants, acetophenone, and fenchyl alcohol, with verbenone as a standard of comparison, in northern California. Release of both acetophenone and verbenone resulted in significantly lower trap catches of D. brevicomis in aggregation pheromone-baited traps, while fenchyl alcohol was inactive. Acetophenone was the only antiattractant that did not reduce numbers of the most abundant predator of D. brevicomis, Temnochila chlorodia (Mannerheim), responding to the attractant pheromone of its prey. Aggregation pheromone-baited traps with acetophenone also had the highest predator/prey ratio. Our results suggest that acetophenone may be part of the intra- and interspecific interactions among sympatric species of bark beetles and may have application in their control.

Identification of Dioryctria (Lepidoptera: Pyralidae) in a Seed Orchard at Chico, California

Abstract Species of Dioryctria Zeller (Lepidoptera: Pyralidae) are important pests of conifers, particularly in seed orchards, and accurate species identification is needed for effective monitoring and control. Variable forewing morphology and lack of species-specific genitalic features hinder identification, prompting the search for additional diagnostic characters. Mitochondrial DNA (mtDNA) sequences from the cytochrome c oxidase I and II genes (COI and COII) were obtained from specimens collected at lights, pheromone traps, and host plants in the Pacific Northwest, focusing on a U.S. Forest Service seed orchard in Chico, CA. A 475-bp fragment of COI was used to identify eight distinct genetic lineages from 180 Dioryctria specimens, and these were identified as eight described species. Comparisons among mtDNA variation, adult morphology, larval host association, and pheromone attraction were used to assign individuals to species groups and to identify diagnostic characters for species identification. A 2.3-kb fragment of COI-COII was sequenced for 14 specimens to increase resolution of phylogenetic relationships. Species groups were well resolved using both the 475-bp and “DNA barcode” subsets of the 2.3-kb sequences, with the 475-bp fragment generally showing lower divergences. The zimmermani and ponderosae species groups were sister groups and had similar male genitalic morphology and larval feeding habits. The pentictonella group was sister to the zimmermani + ponderosae group clade, and all species have raised scales and a Pinus sp. larval host (where known). Combining molecular characters with morphological and behavioral characters improved identification of Dioryctria species and supported previous species group relationships.

Systematics of the Dioryctria abietella Species Group (Lepidoptera: Pyralidae) Based on Mitochondrial Dna

Abstract Coneworms of the genus Dioryctria Zeller include several serious pests of conifer seeds that are notoriously difficult to distinguish as species. We surveyed mitochondrial DNA variation within the abietella species group by sequencing 451 bp of cytochrome oxidase subunit 1 (COI) and 572 bp of cytochrome oxidase subunit 2 (COII) genes from 64 individuals of six major species in the group. In addition to examining phylogenetic relationships within European members of the group, the study focused on the two most damaging species, D. abietivorella Grote from North America and D. abietella Denis & Schiffermüller from Europe and Asia, which have been considered taxonomically synonymous in the past. To detect different levels of divergence, we extensively sampled in seed orchards and natural forests for D. abietella on different hosts. Maximum parsimony and maximum likelihood analyses confirmed the monophyly of the abietella species group and its separation into three clades. The grouping of North American species (clade A) received strong support in both analyses, whereas relationships between clade A and the two European clades were weakly supported. Dioryctria simplicella Heinemann could not be unambiguously separated from D. abietella populations. The diverse haplotypes observed in the network analysis conducted with eight populations of polyphagous D. abietella suggested the presence of two distinct lineages in France.