Submitted to: Entomological Society of America Regional Meetings
Publication Type: Abstract Only
Publication Acceptance Date: 5/1/2004
Publication Date: 6/30/2004
Citation: Baril, R.A., Lenssen, A.W., Blodgett, S., Taper, M.L. 2004. Species distribution, regional assemblages and parasitism of lygus in montana canola fields. In: Proceedings of the Entomological Society of America Regional Meetings. Pacific Branch Annual Meeting of the Entomological Society of America, June 23, 2004, Bozeman, MT.
Technical Abstract: Season-long sweep net sampling of canola (Brassica napus L.) was conducted in 2002 and 2003 to determine lygus (Heteroptera: Miridae) species composition, assemblages and parasitism levels in four regions of Montana. Combined densities of lygus nymphs and adults varied during the season, with physiological developmental stage of canola and region. Canola in all regions had increased lygus population densities as crops matured. The southwest and central regions had infestations that exceeded the economic threshold of 1.5 bugs/sweep. Lygus species composition was identified and analyzed for differences among regions and seasonal change. Regardless of region or season, L. elisus (Van Duzee) was the dominant species in all canola fields sampled, averaging 60 ' 99% of the total adult population across regions and season. Lygus borealis (Kelton), L. keltoni (Schwartz), and L. lineolaris (Palisot) were also found in significant numbers. Species assemblages in the southwest and central regions changed with crop maturity, primarily due to increased proportions of L. elisus. Northeast and southwest regions of Montana had the greatest species diversity. Potential biological control of Lygus by Peristenus spp. (Hymenoptera: Braconidae) was investigated by dissecting nymphal stages III-V. No detectable parasitism was found in dissection of 1,016 nymphs.