Effects of trap height on captures of arboreal insects in pine stands of northeastern United States of America

Knowledge of the effects of variables that can influence trapping results should help to optimise efforts in exotic species detection and other surveys. Two vertical trap placements (understorey, canopy) were tested to determine influence of these two heights on captures of Scolytinae (Coleoptera: Curculionidae), Cerambycidae (Coleoptera), and Siricidae (Hymenoptera) using semiochemical-baited multiple-funnel traps. Traps were baited with α-pinene, ethanol, ipsdienol, and ipsenol. A total of 8463 insects from 65 species and one genus were captured during the study. Average species richness, species diversity, abundance, number of unique species, and expected diversity were higher in understorey compared with canopy traps. Jaccard (0.94 ± 0.05) and Sørensen abundance (0.97 ± 0.03) similarity indices suggested highly similar communities sampled at the two trap heights. Dendroctonus valens LeConte, Dryocoetes autographus Ratzeburg, Hylastes opacus Erichson, Orthotomicus caelatus (Eichhoff), Gnathotrichus materiarius (Fitch), Asemum striatum (Linnaeus), Monochamus scutellatus scutellatus (Say), Rhagium inquisitor (Linnaeus), and Xylotrechus sagitattus sagitattus (Germar) were more abundant in understorey traps. In contrast, Ips pini (Say), Pityogenes hopkinsi Swaine, Monochamus carolinensis (Olivier), Acmaeops proteus (Kirby), and Astylopsis sexgutatta (Say) were more abundant in canopy traps. The common practice of trapping in the understorey may be optimal for sampling arboreal insects as part of survey efforts. However, additional species may be found by trapping at other vertical placements.

The effect of sex and maturation on cuticular semiochemicals in Monochamus scutellatus (Coleoptera: Cerambycidae)

Contact pheromones are a subset of a complex mixture of hydrocarbons secreted on the cuticle and play an important role in the mating behaviour of several cerambycid species (Coleoptera: Cerambycidae). In this study, we investigated the relationship between maturation (newly eclosed and sexually mature) adult Monochamus scutellatus (Say) beetles and sex and the composition of the cuticular hydrocarbon blend to determine if this information is encoded in the blend and potentially available for communication purposes. Whole-body extracts of unfed females, and both mature females and males were analysed by gas chromatography mass spectrometry to identify and quantify the components of the cuticular hydrocarbons. There were no unique compounds present in any of the three groups, but discriminant analysis indicated that the relative proportions of the cuticular hydrocarbon components were unique for each group.

2-Undecyloxy-1-ethanol in combination with other semiochemicals attracts three Monochamus species (Coleoptera: Cerambycidae) in British Columbia, Canada

Two species in the genus Monochamus Dejean (Coleoptera: Cerambycidae: Lamiinae) have recently been shown to have the same male-produced sex pheromone, 2-undecyloxy-1-ethanol (monochamol), suggesting that other congeners may share the same pheromone. We tested that hypothesis by conducting field bioassays of monochamol, in combination with bark-beetle pheromones and the host plant volatiles ethanol and α-pinene, in southern British Columbia, Canada. We captured 603 Monochamus clamator (LeConte), 63 Monochamus obtusus Casey, 245 Monochamus scutellatus (Say) (tribe Monochamini), and 42 Acanthocinus princeps (Walker) (tribe Acanthocinini). All three Monochamus species were significantly attracted to the combination of monochamol and host plant volatiles, whereas bark-beetle pheromones plus plant volatiles and plant volatiles alone were minimally attractive. Adding bark-beetle pheromones to the monochamol plus plant volatiles treatment synergised attraction of M. clamator, but not the other two Monochamus species. Acanthocinus princeps was most strongly attracted to the combination of bark-beetle pheromones and plant volatiles, and did not appear to be affected by the presence or absence of monochamol in baits. We conclude that monochamol is a likely pheromone component for the three Monochamus species, and that monochamol plus host plant volatiles is an effective attractant for these and perhaps other North American Monochamus species.

The natural history of mites (Acari: Mesostigmata) associated with the white-spotted sawyer beetle (Coleoptera: Cerambycidae): diversity, phenology, host attachment, and sex bias

Little is known about the acarofauna associated with wood-boring beetles in Canada, including long-horned beetles (Coleoptera: Cerambycidae). Herein, we assessed the prevalence, abundance, diversity, phenology, and attachment location of mesostigmatic mites (Acari: Mesostigmata) associated with Monochamus scutellatus (Say), and tested whether the abundance and prevalence of mites differed between male and female beetles. A total of 176 beetles were collected in two sites in eastern Ontario in 2008 and 2009 using Lindgren funnel traps baited with α-pinene and ethanol lures, and 71% of hosts had mesostigmatic mites. A total of 2486 mites were collected, representing eight species, four genera, and three families (Digamasellidae, Trematuridae, and Melicharidae). Average prevalence was variable across mite species, and the number of mites per infested beetle also varied across species. Many of the mite species collected in this study have been reported from other cerambycid species, as well as from other wood-boring beetles, such as bark beetles. There was no significant sex bias in the abundance or prevalence of mites between male and female M. scutellatus, which suggests that there is no selective advantage for mites to disperse on females. This study represents the first quantitative investigation of the mites associated with M. scutellatus in Canada.

An improved trap for large wood-boring insects, with special reference to Monochamus scutellatus (Coleoptera: Cerambycidae)

Commercially available multiple funnel traps have three potential limitations for trapping large wood-boring insects: (i) escape by captured insects from the dry collecting cup, (ii) low catches of insects that fall outside the trap, and (iii) poor visual orientation to the narrow funnel column. To test the importance of these limitations, we compared conventional multiple funnel traps to multiple funnel traps with water-filled collecting cups or large bottom funnels and to crossvane traps with a prominent silhouette. The experiment was conducted in a mill yard in the southern interior of British Columbia between 5 July and 2 October 2000. Differences in catch among different trap types indicated that the first and third of the three potential limitations were important for the capture of most target species. Crossvane traps captured significantly greater numbers of most Cerambycidae and Siricidae, and similar numbers of most Buprestidae, compared with the other traps. Of the two most abundant species, Xylotrechus longitarsus Casey was captured in consistently greater numbers in crossvane than in other traps, but Monochamus scutellatus (Say) showed little discrimination early in the flight season and much higher captures in crossvane traps late in the season. The change in behaviour of M. scutellatus may be related to a transition from maturation feeding to searching for oviposition sites.

lnfestation of four coleopteran species by the pine wood nematode Bursaphelenchus xylophilus (Nematoda, Aphelenchoididae) living in wood chips

Six coleopteran species were tested for their susceptibility to infestation by dauerlarval or propagative stages of Bursaphelenchus xylophilus (Steiner & Buhrer 1934), living in wood chips: Monochamus scutellatus (Say), Rhagium inquisitor (L.), Asemum striatum (L.) (Cerambycidae), Hylobius pales (Herbst) (Curculionidae), Dendroctonus valens (LeConte) (Scolytidae) and Pytho sp. (Salpingidae). M. scutellatus and R. inquisitor very frequently became infested by dauerlarvae, though the numbers of larvae per beetle were low. A. striatum and H. pales also became infested by dauerlarvae, but the frequency of infestation and the numbers per beetle were considerably lower. In addition, one male of H. pales became infested by 20 individuals of propagative stages.