Evaluation of predatory mite Amblyseius swirskii and predatory bug Orius laevigatus individually and in combination against western flower thrips Frankliniella occidentalis in greenhouse sweet pepper

In this study, the effectiveness of two important biological control agents [predatory mite, Amblyseius swirskii (Athias-Henriot) (Acari: Phytoseiidae) and predatory bug, Orius laevigatus (Fieber) (Hemiptera: Anthocoridae)] was evaluated indivially and in combination against the western flower thrips [Frankliniella occidentalis (Pergande) (Thysoneptera: Thripidae)] which causes important damages in both indoor and outdoor sweet pepper cultivation in Antalya province. The study was carried out for 2 consecutive growing periods, spring 2013 and fall 2014, in a part (≈100 m2) of a glasshouse, located at Konyaaltı (Karatepe village, 36° 52' 55" N; 30° 33' 12" W, altitude 46 m), near Antalya. The pepper plants in the study area were grouped for treatments in rows and treatments were applied in a completely randomized block design in three replications, with a untreated control plot in each replicate; each plot consisted of sixteen plants. The treatments were termed 'O. laevigatus', 'A. swirskii', 'O. laevigatus + A. swirskii', and 'Untreated control'. One day after transplantation, 50 adults of F. occidentalis per plot were released, and 7-10 days later biological control agents were released into the plots (each to its own plot). Efficiacy of the treatments was evaluated by counting larvae, nymphs and adults) of the thrips from beat tray samples, taken periodically (weekly).during the period of 15 weeks. The results showed that 'O. laevigatus', 'A. swirskii' and 'O. laevigatus + A. swirskii' applications were not significantly different from one another in terms of trips population, but all of them had significantly lower trips populations when compared the those in untreated plots in both growing periods. According to these results, it was concluded that O. laevigatus and A. swirskii, two biological control agents tested for their effectiveness against F. occidentalis in the study, showed no different results in practice and that their control on thrips populations did not statistically (p<0,05) differ from each other when applied individually. Another conclusion is that there are no antagonistic or synergistic effects when these two biological control agents have been used in combination.