The economic importance and control of the adult blister beetlePsalydolytta fuscaOlivier (Coleoptera: Meloidae)

Abstract

Psalydolytta fusca is the most serious pest of pearl millet among ten meloid species feeding on millet spikes in The Gambia. It occurs countrywide with distinct ‘hot spot’ areas. The average abundance varies from 0·lb2 to 2·lb4 beetles per millet hill, but maxima of 30 beetles per hill have been recorded. Screen‐house experiments showed a destruction capacity per beetle of one 35–40 cm sized early millet spike in 15 days. With an average of 5 spikes per hill, the total damage to early millet in The Gambia may range between 4 and 48% per year. Varieties of millet with long‐bristled spikes were shown to be far less susceptible to P. fusca than varieties with very short‐bristled spikes. A local long‐bristled variety of early millet was not only less susceptible to P. fusca than the normafly used short‐bristled varieties in various parts of the country, but also to the millet spike borer Raghuva weaverbirds and, possibly, smut. The long‐bristled variety yielded more in most localities. A traditional control method using fires in the fields was shown to repel P. fusca from spikes when a fuel which produced heavy smoke (groundnut Shells, moist wood) was used. Pesticide control trials showed that carbaryl, trichlorphon and probably malathion can control P. fusca satisfactorily.