Losses of canola seeds from feeding by Lygus species [Heteroptera: Miridae] in Manitoba

Publisher Website
Google Scholar
Abstract
Pods of canola plants (Brassica napus L., mostly cv. Westar) were sampled annually from 11–40 canola fields in Manitoba in 1985–1991. The effects of temperature, precipitation, and lygus bug density (in 1989 and 1990) on seed classes (normal, aborted, and collapsed) were determined. In 1991, all pods from 10 racemes sampled from each of 11 canola fields in Manitoba were examined, and the collapsed seeds were classified as injured by lygus bugs or not. The proportion of aborted seeds was not related to lygus bug densities or to weather conditions. The proportion of collapsed seeds varied from 2 to 53% among fields and was related to the number of lygus bugs in the field at the time the pods were collected. Collapsed seeds increased by 1.5% for each lygus bug per sweep. In 2 yr, the proportion of collapsed seeds increased with the mean monthly temperature and decreased with the total precipitation in July, but these weather factors accounted for little of the variation in the proportion of collapsed seed in most years. Collapsed seeds occurred at low frequency in many pods at all canopy levels, but they were most common in small pods in the upper part of the canopy. The proportion of seeds injured by lygus bugs was estimated to be 3–5%, on average, and in some fields, 20%. In addition, lygus bug feeding on other parts of the host plant may induce seed collapse. Key words: Insecta, Lygus, Brassica napus, seed damage, canola

This publication has 0 references indexed in Scilit: