Colonization of cultivated and indigenous graminaceous host plants by Busseola fusca (Fuller) (Lepidoptera: Noctuidae) and Chilo partellus (Swinhoe) (Lepidoptera: Crambidae) under field conditions.

摘要

Stem borers are generally polyphagous, attacking both cultivated and wild host plants. Two field trials, incorporating four cultivated cereal crops and two grass species, were conducted in South Africa to study colonization of cultivated crops and grasses by stem borers. The first trial, conducted in Potchefstroom over three growing seasons from 1998 to 2001, consisted of maize (Zea mays), sorghum (Sorghum bicolor), sweet sorghum (Sorghum bicolor), pearl millet (Pennisetum glaucum), blue thatching grass (Hyparrhenia tamba) and Guinea grass (Panicum maximum). During the following two seasons, Panicum maximum was replaced by Napier grass (Pennisetum purpureum). In the second trial, conducted in Syferkuil during the 1999/2000 growing season, Pennisetum purpureum was replaced by Panicum maximum. Plots (5x5 m) were arranged in a 6x6 Latin square design. Natural infestation by stem borers was allowed to take place. The stem borers found on host plants were Chilo partellus and Busseola fusca. The incidence of whorl damage, dead heart and stem damage observed indicated that all host plants were susceptible to stem borer attack. Cultivated host plants showed higher incidences of whorl and stem damage than the grasses. The low incidence of whorl damage on the grasses may be ascribed to larval antixenosis at the feeding site. Quicker larval development and increased size were observed on cultivated crops than on the grasses. The results of this study indicated better colonization of cultivated crops by the stem borers compared with the grasses.