Effect of plant nitrogen and silica on the bionomics ofSesamia calamistis(Lepidoptera: Noctuidae)

Abstract

AbstractThe effects of nitrogen and silica application to maize plants on various aspects of the bionomics of the maize stem borer,Sesamia calamistisHampson, were studied in the laboratory. Increasing nitrogen doses significantly increased larval survival (from 18.7% (control) to 37.3% at 2.25 g N/plant), larval weight (from 49.0 mg (control) to 99.5 mg at 2.25 g N/plant), and female fecundity (from 77 eggs per female (control) to 365 eggs per female at 1.69 g N/plant). A significant, positive relationship was found between moth fecundity and female pupal weight. Nitrogen had no effect on larval and pupal developmental time but increased adult longevity. Intrinsic rate of increase, rm, and the net reproductive rate, Ro, were positively related to leaf and stem nitrogen, while generation time, G, was negatively related. Silica had the opposite effect from nitrogen on larval survival. Increasing silica supply reduced ultimate larval survival from 26.0% (control) to 4.0% at 0.56 g Si/plant. Immature developmental time, larval and pupal weight, pupal survival, female fecundity, egg viability and adult longevity ofS. calamistiswere not affected by silica application.