Visual ability and searching behavior of adult Laricobius nigrinus, a hemlock woolly adelgid predator
1Virginia Tech, Department of Entomology, 216A Price Hall MC 0319 Blacksburg, VA 24061-0002
2Current address: University of Massachusetts, Department of Plant, Soil and Insect Sciences Agricultural
Engineering Bldg., 250 Natural Resources Rd., Amherst, MA 01003-9295
Abstract
Very little is known about the searching behavior and sensory cues that Laricobius spp. (Coleoptera: Derodontidae) predators use to locate suitable habitats and prey, which limits our ability to collect and monitor them for classical biological control of adelgids (Hemiptera: Adelgidae). The aim of this study was to examine the visual ability and the searching behavior of newly emerged L. nigrinus Fender, a host-specific predator of the hemlock woolly adelgid, Adelges tsugae Annand (Hemiptera: Phylloxeroidea: Adelgidae). In a laboratory bioassay, individual adults attempting to locate an uninfested eastern hemlock seedling under either light or dark conditions were observed in an arena. In another bioassay, individual adults searching for prey on hemlock seedlings (infested or uninfested) were continuously video-recorded. Beetles located and began climbing the seedling stem in light significantly more than in dark, indicating that vision is an important sensory modality. Our primary finding was that searching behavior of L. nigrinus, as in most species, was related to food abundance. Beetles did not fly in the presence of high A. tsugae densities and flew when A. tsugae was absent, which agrees with observed aggregations of beetles on heavily infested trees in the field. At close range of prey, slow crawling and frequent turning suggest the use of non-visual cues such as olfaction and contact chemoreception. Based on the beetles’ visual ability to locate tree stems and their climbing behavior, a bole trap may be an effective collection and monitoring tool.
Keywords: biological control, hemlock woolly adelgid, monitoring, predation, Tsuga canadensis, visual cues
Correspondence:
laricobius@gmail.com
Editor: Todd Shelly was Editor of this paper.
Received: 4 September 2010 | Accepted: 1 December 2010 | Published: 29 August 2011
Copyright: This is an open access paper. We use the Creative Commons Attribution 3.0 license that permits unrestricted use, provided that the paper is properly attributed.
ISSN: 1536-2442 | Volume 11, Number 111
Mausel DL, Salom SM, Kok LT. 2011. Visual ability and searching behavior of adult Laricobius nigrinus, a hemlock woolly adelgid predator. Journal of Insect Science 11:111 available online: insectscience.org/11.111
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