Abstract
The two-spotted spider mite Tetranychus urticae and the tomato red spider mite Tetranychus evansi are known to cause severe damage in tomato crops. Preliminary laboratory studies showed that a phytoseiid predatory mite from Argentina, Phytoseiulus longipes, could be a potential candidate for the control of those two pests. The present paper aims to assess the effectiveness of this predator for controlling both pests under tomato experimental greenhouse conditions. Six treatments were considered: T. urticae without predators, T. evansi without predators, a high and a low predator–prey ratios (1–5 and 1–25 predator–prey, respectively) used with both prey. Mites were counted twice a week during 35 days after the predators were released. Without predators, plant damage was quickly noticed. P. longipes was able to maintain T. urticae and T. evansi populations under a threshold of 25 mites/leaflet at a high predator–prey ratio. However, at the low predator–prey ratio, plants showed damages in presence of both pests. The predatory mite population considered could constitute a real improvement for the biological control of T. urticae and T. evansi in European tomato greenhouses. Perspectives for the use of P. longipes as a biocontrol agent and the additional work required to make this a reality are discussed.