Biological control techniques are commonly used in many horticultural crops in Spain, however the application of these
techniques to Spanish strawberries are relatively recent. In this study the effectiveness of augmentative biological control
techniques to control the two main strawberry (
Fragaria
×
ananassa Duchesne) pest: the two-spotted spider mite (TSSM),
Tetranychus urticae
Koch (Acari: Tetranychidae), and the western flower thrips (WFT),
Frankliniella occidentalis
(Pergande) (Thysanoptera: Thripidae), through releases of the predatory mites
Phytoseiulus persimilis
Athias-Henriot,
Neoseiulus californicus
(McGregor),
Amblyseius swirskii
Athias-Henriot (Acari: Phytoseiidae), and
Orius laevigatus
(Fieber) (Heteroptera: Anthocoridae) were tested. Two-year results on the performance of treatments using combinations
of these biocontrol agents are presented. In both years, all treatments resulted in the reduction of TSSM numbers; but no
treatment was better than the release of
P. persimilis alone (P < 0.05). TSSM suppression varied among crop phases being
greater early in the season. None of the treatments reduced significantly WFT numbers (P < 0.05), and the established
economic injury level (EIL) was surpassed from March to late April in both years. However, EIL was surpassed less times
when treatment included
O. laevigatus (2009: 20.7%; 2010: 22.7% of samples). No effect of
A. swirskii was observed
when this mite was released. Results corroborate that biological control techniques for TSSM and WFT are feasible for
high-plastic tunnel strawberries. Under the conditions in our study no additive effects were observed, and there was not
advantage in the release of multiple natural enemies.
