BIO-INTENSIVE INTEGRATED PEST MANAGEMENT (BIPM) OF GREENHOUSE VEGETABLE PESTS USING LOCAL STRAINS OF BEAUVERIA PSEUDOBASSIANA, AMBLYSEIUS SWIRSKII AND PHYTOSEIULUS PERSIMILIS

Abstract

Tomato (Lycopersicum esculentum) and cucumber (Cucumis sativus L.) are the most commonly produced vegetable crops in Lebanon in protected cultivation. However, their production has been seriously constrained by different factors including arthropod pests. Major arthropod pests include whiteflies, thrips, spider mites, aphids and leafminers; the management of which remains a challenge due to resistance development against synthetic pesticides. Given the limited studies on the effectiveness of bio-control agents in Lebanon, the objective of this research was to assess the control efficacy of locally collected entomopathogenic fungus Beauveria pseudobassiana Rehner and Humber (Hypocreales: Cordycipitaceae) and the predatory mites Amblyseius swirskii and Phytoseiulus persimilis Athias-Henriot (Mesostigmata: Phytoseiidae) for the management of greenhouse arthropod pests in two large-scale commercial greenhouse trials on cucumber and tomato. A third trial was conducted in insect-proof cages to assess the compatibility between B. pseudobassiana and A. swirski against Bemisia tabaci (Gennadius) (Hemiptera; Aleyrodidae). In field trials, three greenhouses were selected at Rmeileh area, South Lebanon. In the control greenhouse, the farmer followed his normal plant protection practices while the other two greenhouses were subject to IPM practices; IPM-A and IPM-B to evaluate the efficacy of B. pseudobassiana and the two local predatory mites, respectively. In the 1st trial on cucumber, the populations of Frakliniella occidentalis (Pergande) (Thysanoptera: Thripidae) and Myzus persicae (Sulzer) (Hemiptera: Aphididae) were maintained below ETL in the control, while that of B. tabaci exceeded the ETL and an outbreak among Tetranychus urticae Koch (Acari: Tetranychidae) occurred, forcing the farmer to stop the production cycle despite the application of six sprays of pesticide mixtures. In IPM-A, five B. pseudobassiana sprays showed the highest control level by suppressing B. tabaci, F. occidentalis, T. urticae, and M. persicae to below their respective ETL, allowing 100% reduction in pesticide applications. Four releases of A. swirskii and three hotspot treatments of P. persimilis in IPM-B successfully maintained B. tabaci and F. occidentalis below ETL, despite elevated temperatures (T. average 32ºC and Max. 54-41 ºC) recorded in September-October and (T. average 26ºC and Max. 40-49 ºC) in November. In the tomato trial, Bacillus thurigiensis var. kurstaki (Btk) was used as a microbial biocontrol agent instead of the predatory mites in IPM-B since Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) was the major pest. In the control greenhouse, the farmer applied 20 pesticide sprays using 2-3 active ingredients per spray, yet obtained the lowest level of control against T. absoluta; 3.8 eggs/leaf and 3.6 larvae/leaf at the end of the trial. In IPM-A, five B. pseudobassiana sprays outperformed all treatments against T. absoluta; 0.4 eggs/leaf and 1.9 larvae/leaf; representing significant reductions of 89.5% among eggs and 47.2% among larvae as 3 compared to the control. Meanwhile, five applications of B. thuringiensis in IPM-B reduced the number of T. absoluta eggs and larvae by 80 and 27%, respectively. Both bio-control agents reduced leaf miner (Liriomyza spp.) populations by 80% with respect to the control. The small scale greenhouse experiment revealed 97.85% efficacy of A. swirskii against B. tabaci nymphs, which increased to 99.2% when combined with B. pseudobassiana, indicating high compatibility. B. pseudobassiana was also active against B. tabaci; 86.3% mortality rate. Overall, adopting biologically-integrated pest management (BIPM) for pest population in greenhouse cucumber and tomato production appears promising under Mediterranean environmental conditions