Oviposition preference and survival of the maize stem borer, Busseola fusca (Lepidoptera: Noctuidae), on Napier grasses, Pennisetum spp., and maize.

摘要

Napier grass, Pennisetum purpureum, is used successfully as a trap crop for lepidopterous stem borers in Africa. This paper reports on the evaluation of the suitability of Napier grass genotypes and cultivars as trap crops for B. fusca. This was carried out through oviposition preference tests and evaluation of larval survival on the different genotypes (P. purpureum x P. glaucum, Bana Grass, Pennisetum sp., Rietondale, Taiwan Dwarf and Gold Coast Napier). Napier grass genotypes were collected from the wild, from research institutions and farmers growing them as forage crops. In multiple-choice tests with the different Napier grass genotypes, differences in oviposition preference were observed. Results from 2-choice tests with Napier grass and maize plants indicated that B. fusca moths have no marked difference in oviposition preference. However, compared to maize, larval survival on Napier grasses was low and a rapid decline in larval number was observed over the first week after inoculation on the grasses. A scanning electron microscope study of trichomes on Napier grass and maize leaves was conducted and the relationship between trichome number and larval survival determined. Significant negative correlations (P<0.03) were observed between trichome number and larval survival..