Nitrogen Status of Sugar-cane Leaves and the Fecundity of a Hemipterous Pest

Abstract

IN Jamaica, cane-fly (Saccharosydne saccharivora (Westw.) Hom.: Delphacidae) has long been known as a pest of sugar-cane, with records of occasional outbreaks dating back to the nineteenth century. In recent years, however, it has become so prevalent in certain areas that outbreaks can be prevented only by resort to aerial spraying of insecticides on a large scale. Work on the epidemiology of cane-fly has shown that the initial buildup in population occurs most often in plant cane, despite the fact that in such cane the biological pressure of natural enemies is as great as elsewhere^1,2. The tentative conclusion was, therefore, that the rate of reproduction is an important variant. It is well known that an adequate supply of organic nitrogen is essential for the reproduction of most insects³, and that the level of nitrogen in leaf lamina material changes with, inter alia, fertilizer treatments, the age of the leaf and the age of the plant⁴. Accordingly, an experiment was designed to determine whether the fecundity of cane-fly was related to the nitrogen content of the leaf.