تاثیر سه فرمولاسیون قارچ Beauveria bassiana (Balsamo) Vuillemin در مدیریت تریپس غربی گل Frankliniella occidentalis (Pergande)

Sucking pests are important pests of greenhouse environments. In addition to direct feeding, they are often vectors of many plant viruses. Currently, in order to reduce application of chemical insecticides on greenhouse products, which are mostly consumed fresh, biological control agents play a special role. Insect-pathogenic fungi are suitable options for biological control of greenhouse pests because conditions in greenhouses are controllable and the requirements of germination as high relative humidity and suitable temperature can easily be provided. Furthermore, the fungi have mainly contact effects and can penetrate through the cuticle of the sucking pests such as thrips. In this study, the impact of three formulations of Beauveria bassiana (Balsamo) Vuillemin was investigated on the second instar nymphs of Frankliniella occidentalis (Pergande) in laboratory condition (at 26 ± 5°C, 60 ± 5% RH and a photoperiod of 16L/8D). The propagation of this fungal isolate was done on rice bran inside heat-resistant nylon bags. Fungus conidia were separated using a manual sieve and kept at refrigerator (4°C) for use in formulation. Three types of formulations were prepared for the experiments. In the first formulation, concentrated fungal suspension was prepared based on mineral oil containing conidia, mineral oil (industrial paraffin) and tween 80, carboxymethyl cellulose and talc powder. In the second formulation, the conidia were added to a mixture of 95% mineral oil (industrial paraffin) along with 5% emulsifier. In the third treatment, the conidia were mixed in a mixture of sterile distilled water and 0.05% Tween 80. The concentrations of 104, 105, 106, 107 and 108 conidia/ml were prepared and used on second instar nymphs of F. occidentalis by direct spray method in laboratory conditions. LC50 of these formulations was calculated using SPSS Probit Analysis. In all formulations, with the increase in conidia concentration, the mortality of thrips nymphs also increased. At the concentration of 108 conidia/ml in the first to third formulations, 88.50, 85 and 78.25 percent mortality was caused on thrips second instar nymphs, respectively. The LC50 of the first to third formulations were 4.2×104, 2.05×105, and 9.3×105 conidia/ml, respectively. The results showed that the oil formulation of conidia has been able to increase the efficiency of the formulations and reduce the lethal concentration.