Management of the diamondback moth: déjà vu all over again?

The diamondback moth, Plutella xylostella (L.), is considered the most universally distributed of all Lepidoptera and the main insect pest of crucifers worldwide. Although P. xylostella is confined to feeding on plants within the Cruciferae, this diverse family contains a wide host of weed species and cultivated plants that occur throughout the world. Over the last several decades the importance of crucifers in the human diet has increased, resulting in increased crucifer production and changing management practices. Where once crucifers were part of smaller diversified cropping systems, they are often now grown as monocultures under intensive cultivation practices, including year-round production. In areas of China, south-east Asia and other areas where crucifers are important to the human diet, there may be more than 20 generations of P. xylostella annually. As production practices have changed and the demand for damage-free produce has intensified, farmers have relied on intensive use of insecticides which, in turn, has contributed to insecticide resistance, reduced effectiveness of natural enemies, frequent control failures, and some environmental and human health concerns. Because of the health benefits and cultural significance of crucifers, especially in Asian populations, production will continue to increase. What have we learned from the past that will allow us to provide better management of P. xylostella in the future? A central element will be to develop preventative tactics and ‘rescue’ treatments which conserve natural enemies, promote resistance management strategies, and utilize cultural control practices that rely on understanding the agroecology of P. xylostella. Most importantly, successful management of P. xylostella will rely on farmers and scientists taking a more ‘regional perspective’ that includes information on P. xylostella movement and the effects of management tactics on their behaviour and population genetics on a community level.