Behaviour and biology of Chilo partellus (Lepidoptera: Pyralidae) on maize and wild gramineous plants

The ovipositional response, larval orientation, larval settling, feeding, food assimilation, growth and development of maize stemborer ChUo partellus (Swinhoe) (Lepidoptera: Pyralidae) on a susceptible maize (Zea mays L.) genotype (Inbred A) was compared to five wild plant species of the family Poaceae (Gramineae) in the laboratory and greenhouse. The intensity of oviposition differed among the test plants. Pennisetum purpureum Schumach was the most preferred test plant for oviposition when offered in a two-choice situation with maize. Likewise, P. purpureum and Sorghum versicolor Anderss were the most preferred test plant for oviposition when offered in multiple-choice tests. In no-choice tests C. partellus responses to the test plants were not significantly different. The number of first instar larvae that settled on leaf cuts of test plants in Petri dishes was significantly higher on maize and S. versicolor than on the other test plants at 24 h after infestation in a multiple-choice test. No significant differences were observed in larval settling among wild grasses at 4 h and 24 h after infestation in a no-choice test. In a two- choice test there was no significant difference in the number of neonate larvae that settled on maize and S. versicolor at 1 h and 24 h after infestation. Feeding by fourth-instar larvae was significantly higher on maize than on Echinochloa pyramidalis (Lam.) and Hyparrhenia rufa (Nees) Stapf. Larvae fed on maize assimilated significantly more food than those fed on E. pyramidalis, Panicum maximum Jacq. or H. rufa. Larval growth and development was significantly faster on maize and S. versicolor in comparison to other test plants.