Environmental Entomology (2019) 48, 882-893

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Karandeep Chahal, Romina Gazis, William Klingeman, Denita Hadziabdic, Paris Lambdin, Jerome Grant and Mark Windham (2019)
Assessment of alternative candidate subcortical insect vectors from walnut crowns in habitats quarantined for thousand cankers disease
Environmental Entomology 48 (4), 882-893
Abstract: Thousand cankers disease (TCD) results from the combined activity of the fungal pathogen, Geosmithia morbida Kolarik, Freeland, Utley, and Tisserat and its principle vector, Pityophthorus juglandis (Blackman) (Coleoptera: Curculionidae: Scolytinae) in Juglans L. spp. and Pterocarya Kunth spp. host plants. TCD has been reported from the eastern and western United States. To evaluate potential for other beetle species to vector the fungus in east Tennessee, specimens were collected using ethanol-baited traps that were suspended beneath crowns of TCD-symptomatic trees. Associations of G. morbida with insect species collected in traps were assessed in an unsuccessful, preliminary culture-based fungal assay, and then with a molecular-based detection method. For culture-based assays, rinsate from washed, individual insects was plated on nutrient media and growing colonies were subcultured to obtain axenic G. morbida cultures for identification. For the molecular-based method, G. morbida presence was detected by amplifying the previously developed, species-specific microsatellite locus GS004. Capillary electrophoresis was used to detect the amplified amplicons and representative reactions were validated using Sanger sequencing. Eleven beetle species were found to carry G. morbida, including Cnestus mutilatus (Blandford), Dryoxylon onoharaensum (Murayama), Hylocurus rudis (LeConte), Monarthrum fasciatum (Say), Monarthrum mali (Fitch), Xyleborinus saxesenii (Ratzeburg), Xylosandrus crassiusculus (Motschulsky), Xylosandrus germanus (Blandford) (all Coleoptera: Curculionidae: Scolytinae), Stenomimus pallidus (Boheman) (Coleoptera: Curculionidae: Cossoninae), Oxoplatypus quadridentatus (Olivier) (Coleoptera: Curculionidae: Platypodinae), and Xylops basilaris (Say) (Coleoptera: Bostrichidae). These findings raise concerns that alternative subcortical insect species that already occur within quarantined habitats can sustain incidence of introduced G. morbida and contribute to spread within the native range of black walnut, Juglans nigra L., in the eastern United States.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Paris Lambdin

Research topic(s) for pests/diseases/weeds:
transmission/dispersal of plant diseases


Pest and/or beneficial records:

Beneficial Pest/Disease/Weed Crop/Product Country Quarant.


Xyleborinus saxeseni U.S.A. (SE)
Xylosandrus germanus U.S.A. (SE)
Xylosandrus crassiusculus U.S.A. (SE)
Monarthrum fasciatum U.S.A. (SE)
Cnestus mutilatus U.S.A. (SE)
Monarthrum mali U.S.A. (SE)
Geosmithia morbida Walnut/butternut (Juglans) U.S.A. (SE)
Pityophthorus juglandis Walnut/butternut (Juglans)