Evaluation of the effectiveness of Dicyphus errans (Wolff) as predator of Tuta absoluta (Meyrick)

Abstract

Tomato crop in the Mediterranean Basin and in Europe has been recently affected by the exotic pest Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), which is difficult to control due to its high reproduction rate and potential to develop resistance to insecticides. In this paper, the suitability and effectiveness of the predatory bug Dicyphus errans (Wolff) (Hemiptera: Miridae), an indigenous species usually found in the IPM tomato crop of northwestern Italy, were evaluated on eggs and larvae of T. absoluta under controlled conditions. This generalist predator could be an effective biological control agent against the tomato borer. Both sexes of D. errans were proven to prey actively on T. absoluta eggs and 1st-instar larvae. In particular, compared to males, females showed a significantly higher egg consumption rate (11.0±0.7 vs 8.6±0.8day−1), and were also more effective in preying on 1st-instar larvae (2.4±0.5 vs 1.3±0.3day−1). The mirid was able to develop from egg to adulthood on tomato infested with eggs or with 1st-instar larvae of T. absoluta, even if a high mortality of the predator was recorded in the latter case. Moreover, in olfactometer bioassays predator adults proved to be attracted by tomato either infested or previously infested with tomato borer larvae, independently of larval instars. D. errans can be considered a promising potential candidate for controlling the pest, and further research is needed to assess its effectiveness under field conditions.