Seasonal Abundance of Limothrips denticornis (Thysanoptera: Thripidae) on Spring Barley

Abstract

The seasonal abundance of Limothrips denticornis Haliday on spring barley ( Hordeum vulgare L.) was examined during the growing seasons of 1987 and 1988 to aid in the development of an efficient sampling scheme. In 1987,78% of the immature population occurred during growth stage 10.4–11.1 (Feekes scale) (inflorescence three-quarters emerged-milk stage). In 1988, 81% of the immature population occurred during growth stage 10.54–11.2 (early milk stage–dough stage). The difference may be attributed to the drought conditions present in 1988, increasing the rate of plant development. When immature and adult counts were examined based on Julian day rather than on plant developmental stage, population trends occurred on similar dates in both years. Both adult and immature populations were concentrated on the top two leaf sheaths of barley regardless of plant development stage. There were significant differences between adult counts in quadrats within growth stages; a field edge effect was present both at the beginning and end of the season.