Seasonal Abundance of Cereal Leaf Beetles (Coleoptera: Chrysomelidae) in Virginia Small Grains and Corn

Abstract

Fields of soft red winter wheat, winter barley, and spring oats grown in eastern Virginia were monitored every 3 to 7 days in April and May during 1980–1982 to determine the incidence of Oulema melanopus (L.). Population peaks were attained in wheat and barley around mid-May and reached densities of 31.7 and 14.7 beetles per 0.3 m of row, respectively. Populations reached 196.7/0.3 m of row in spring oats in late May. ‘Coker 747’ and ‘McNair 1003’ wheat varieties had higher mean population levels than the other three varieties surveyed. ‘Barsoy’ barley had lower infestations than ‘Boone’ and ‘Rapidan.’ Fields with highest O. melanopus densities, regardless of variety, were those expressing poor growth characteristics. Egg deposition in mid-April contained a higher incidence of multiple-egg clusters (two or more laid touching end to end) than during May. First preaestival adults were observed in field corn in early June. Peak population densities of over 24/0.5 m of row occurred between 10 and 15 June, then populations rapidly declined. Oulema melanopus were significantly more abundant on corn field edges than in the interior. Significantly more beetles were observed on field corn margins next to small grain than were observed adjacent to wooded areas.