Better Control With More Food: Continuous Provision of Alternative Food Enhances Thrips Control by Predatory Mites

ABSTRACT

The use of alternative food has become an integral component of biocontrol, allowing the introduction and establishment of predators into a crop before pest invasion and sustaining populations even when pest densities are low. The addition of alternative food also has a positive long‐term effect in decreasing the densities of the pest. It has been suggested, however, that the supply of alternative food should be discontinued upon pest invasion to ensure that the natural enemies concentrate their attacks on the pest. Here, we investigate the effect of adding alternative food ( Carpobrotus edulis L. pollen), or interrupting it, on the densities of the thrips pest Scirtothrips dorsalis (Hood) and of the predatory mite Amblyseius swirskii (Athias‐Henriot) on sweet pepper plants in a greenhouse experiment. We found that providing small amounts of alternative food at regular intervals resulted in excellent control of S. dorsalis and had a positive effect on the densities of A. swirskii. When the supply of alternative food was stopped upon pest introduction, however, pest densities increased, causing extensive damage to the plants, while predator densities declined. This study thus confirms that supplying alternative food to generalist predators before pest invasion and continuing provision at regular intervals is an effective strategy for control of this thrips pest.