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

Abstract

The effects of nitrogen and silica application to maize plants on various aspects of the bionomics of the maize stem borer, Sesamia calamistis Hampson, 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, r m , 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 of S. calamistis were not affected by silica application.

Assessment of Grain Yield Losses in Pearl Millet Due to the Millet Stemborer, Coniesta ignefusalis (Hampson)

“…The low effect of borer attack on yield might also result from good plant growth conditions. Stemborer infestations associated with better plant growth was reported by Setamou et al (1993), who showed that nitrogen fertiliser not only increased yields but also survival and, thus, final densities of S. calamistis on maize. Increase in yield may also result in attack having a growth hormonal effect (Walker, 1983).…”

Biology and Management of Economically Important Lepidopteran Cereal Stem Borers in Africa

“…In South Africa, where E. saccharina is a problem on sugarcane, a reduction in nitrogen-fertilization rate from 50 kg per hectare to 30 kg per hectare is recommended (158). An increase in the survival of S. calamistis larvae and acceleration in larval development with increased nitrogen content of maize was observed, and this may result in an increase in the number of generations per year (171).…”

Diversity of alternative hosts of maize stemborers in Trans-Nzoia district of Kenya

“…In a recent study however, 20-40% C. partellus larvae were found to pupate on wild grass species comprising P. purpureum, S. arundinaceum and H. rufa, but these pupation rates were significantly lower than those recorded on maize (Sétamou, unpublished data). Because of its higher nitrogen content, maize is generally more succulent and nutritious than many wild grass species, thus providing a better food source for stemborers (Sétamou et al, 1993).…”