Biodiversity provides whitefly biological control based on farm management

Abstract

Management of the whitefly Bemisia tabaci biotype B (Hemiptera: Aleyrodidae) has challenged scientists and famers worldwide because this insect is highly polyphagous and resistant to traditional control methods. Innovative management tools, such as the use of the ecosystem service of biological control, are necessary, especially in a century in which sustainable crop systems are emerging. We investigated how management practices and farm diversity within the property limits affect the relationship between biodiversity conservation and the biological control of B. tabaci. We determined the mortality factors of whitefly nymph cohorts on 33 small farms growing tomatoes. The sampled farms formed a gradient of increasing farm diversity and decreasing management intensity. The diversity of natural enemies increased from conventional to agroecological farms, and predation was identified as the key mortality factor of B. tabaci nymphs on all farm types except the conventional farms. Biological control provided by biodiversity components (predators, parasitoids and pathogens) was enhanced on more diverse and less intensively managed farms. Higher predator richness and abundance resulted in more effective biological control and made it less variable among farms. Different components of natural enemy biodiversity were conserved and acted in a complementary way on agroecological farms, and the enhanced ecosystem services reduced the need for insecticides.