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Title: Regional assemblages of Lygus (Heteroptera: Miridae) in Montana canola fields

item RITTER, REBECCA - Montana State University
item Lenssen, Andrew
item BLODGETT, SUE - South Dakota State University
item TAPIR, MARK - Montana State University

Submitted to: Journal of Kansas Entomological Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/1/2010
Publication Date: 12/1/2010
Citation: Ritter, R., Lenssen, A.W., Blodgett, S.L., Tapir, M.L. 2010. Regional assemblages of Lygus (Heteroptera: Miridae) in Montana canola fields. Journal of Kansas Entomological Society. 83:297–305.

Interpretive Summary: Lygus bug infestations can cause serious yield loss in canola production. We determined populations, species assemblages, and parasitism levels of lygus bugs infesting canola in four regions of Montana in 2002 and 2003. As canola crops matured, lygus populations increased. Regardless of region or crop stage, Lygus elisus was the dominant species. Potential biological control of lygus bugs by Peristenus pallipes (Curtis) (Hymenoptera: Braconidae) was investigated by dissecting Lygus nymphal stages III-V. No parasitism was detected in the dissection of 1,230 nymphs representing all four regions of Montana.

Technical Abstract: Sweep net sampling of canola (Brassica napus L.) was conducted in 2002 and 2003 to determine Lygus (Heteroptera: Miridae) species composition and parasitism levels in four regions of Montana. Regardless of region or seasonal change, Lygus elisus (Van Duzee) was the dominant species in all canola fields sampled, averaging 60 – 99% of the total adult populations. Lygus borealis (Kelton), Lygus keltoni (Schwartz) and Lygus lineolaris (Palisot) were detected at much lower levels. Total lygus population density was greatest in the southwest and central regions. The northeast and southwest regions had the greatest lygus species diversity. The proportion of L. elisus increased from early to late crop maturity stages in the southwest and central regions while there was no change in northeast and southwest canola production regions. Nymphal stages III – V were dissected to detect parasitism. Parasitism was found to be negligible in the dissection of 1,230 nymphs. Lygus population densities in canola are likely to have economic consequences for Montana canola producers especially in years when moisture is limited.