Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract

A commercially viable low-cost strategy for the management of seed weevil populations on winter oilseed rape in the UK.

Abstract

Application of insecticides to control populations of Ceutorhynchus assimilis on winter oilseed rape in England and Wales is rarely justified; also, on the rare occasions when numbers of weevils exceed economic thresholds, they usually do so by only a small amount. The pteromalid Trichomalus perfectus is a widely distributed and increasingly important enemy of the pest and it is capable of exerting considerable natural control of this pest; control of pest populations will also prevent the development of infestations by Dasineura brassicae. By not spraying with insecticide or, alternatively, by at least avoiding post-flowering insecticide treatments and by minimizing other insecticide applications, natural populations of T. perfectus will be increased. These are then likely to exert sufficient control of the pest that (irrespective of year-to-year cycles in pest abundance) spraying will be unnecessary, and significant savings in pest management costs can then be made. Minimizing or avoiding pesticide use of this important crop is also environmentally desirable.