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| Figure 1. Sampling locations for click beetles and wireworm larvae (Coleoptera: Elateridae) submitted for wireworm surveying from 2004-2017. |
Approximately 600 samples were submitted, with the number of larvae per sample typically less than five (Fig. 1). More samples are welcome, particularly from areas currently not well represented on the maps. Please provide either the legal land description or latitude and longitude coordinates with a sample. Any information on the cropping history or whether fields were irrigated is helpful.
The main findings of this survey are that:
1. Wireworms are re-emerging as primary pests of cereals and other crops, particularly in southern Alberta and Saskatchewan. This can be attributed to several factors, including changes in seeding and cultivation resulting in higher soil moisture and increased food availability, and therefore greater wireworm survival; the elimination of effective insecticides such as lindane and the decline of organochlorine residues in the soil; and the present lack of insecticides that actually kill wireworms.
2. Limonius californicus is generally the predominant pest species in fields reporting heavy wireworm damage, occasionally building up to very high populations and resulting in complete crop wrecks (Fig. 2). This was not the case when Glen et al. (1943) or Doane (1977) conducted their surveys; L. californicus was considered a minor species at those times. Selatosomus destructor (Fig. 3) and Hypnoidus bicolor (Fig. 4) are still the most common species. The pest status of another commonly found species, the predaceous Aeolus mellillus (Fig. 5), is unclear. The following species listed by Glen et al. (1943) as pests of agriculture in the Prairie Provinces were found also, but infrequently: Agriotes mancus, A. criddlei, A. stabilis, Hemicrepidius memnonius, L. pectoralis, and various Dalopius sp.
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| Figure 2. Distribution of Limonius californicus (Coleoptera: Elateridae) submitted for wireworm surveying from 2004-2017. |
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| Figure 3. Distribution of Selatosomus destructor (Coleoptera: Elateridae) submitted for wireworm surveying from 2004-2017. |
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| Figure 4. Distribution of Hypniodes bicolor (Coleoptera: Elateridae) submitted for wireworm surveying from 2004-2017. |
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| Figure 5. Distribution of Aeolus mellillus (Coleoptera: Elateridae) submitted for wireworm surveying from 2004-2017. |
3. Multiple pest species are frequently found in the same fields where damage is reported (i.e. about 25% of the time, despite the small number of larvae per sample). This is particularly important as pest species can vary considerably in the type of damage they cause (e.g. it remains unclear if H. bicolor is damaging to potato), their life history (e.g. duration of the larval stage), and susceptibility to insecticides.
Details related to the biology and management of these species are reviewed in van Herk and Vernon (2014) and Vernon and van Herk (2013).
Acknowledgements:
These maps are only possible thanks to the collections done by a large team of local entomologists and agrologists. We are extremely grateful to them; thank you to everyone who participated! A special thank you to Ted Labun and colleagues at Syngenta Crop Protection (Canada), and to Bayer CropScience, for providing the bulk of the samples.
Disclaimer:
Please do not distribute or use the contents of this post, including any maps, without obtaining prior permission.
Obtain further information or arrange shipment of wireworm or click beetle samples by contacting:
Dr. Wim van Herk
Agriculture and Agri-Food Canada
Agassiz Research and Development Centre
6947 Highway 7, Agassiz, BC, V0M 1A0
wim.vanherk@agr.gc.ca
Further wireworm reading:
Burrage RH (1964) Trends in damage by wireworms (Coleoptera: Elateridae) in grain crops in Saskatchewan, 1954–1961. Canadian Journal of Plant Science, 44: 515–519. https://doi.org/10.4141/cjps64-102
Doane JF (1977) Spatial pattern and density of Ctenicera destructor and Hypolithus bicolor (Coleoptera: Elateridae) in soil in spring wheat. The Canadian Entomologist 109: 807–822. https://doi.org/10.4039/Ent109807-6
Doane JF (1977) The flat wireworm, Aeolus mellillus: studies on seasonal occurrence of adults and incidence of the larvae in the wireworm complex attacking wheat in Saskatchewan. Environmental Entomology 6: 818–822. https://doi.org/10.1093/ee/6.6.818
Glen R, King KM, Arnason AP (1943) The identification of wireworms of economic importance in Canada. Canadian Journal of Research 21: 358-387. https://doi.org/10.1139/cjr43d-030
van Herk WG, Vernon RS (2014) Click beetles and wireworms (Coleoptera: Elateridae) of Alberta, Saskatchewan, and Manitoba. In: Arthropods of Canadian Grasslands (Volume 4): Biodiversity and Systematics Part 2. (Edited by D.J. Giberson and H.A. Carcamo). Biological Survey of Canada, pp. 87-117. https://biologicalsurvey.ca/monographs/read/17
Vernon RS, van Herk WG (2013) Wireworms as pests of potato. In: Insect pests of potato: Global perspectives on biology and management. (Edited by P. Giordanengo, C. Vincent, A. Alyokhin). Academic Press, Elsevier, Amsterdam, pp 103–164. https://www.elsevier.com/books/insect-pests-of-potato/alyokhin/978-0-12-386895-4
Zacharuk RY (1962) Distribution, habits, and development of Ctenicera destructor (Brown) in western Canada, with notes on the related species C. aeripennis (Kby.) (Coleoptera: Elateridae). Canadian Journal of Zoology 40: 539–552. https://doi.org/10.1139/z62-046
