Biocontrol potential of Penicillium citrinum and Penicillium chrysogenum against red spider mite, Oligonychus coffeae nietner infesting tea

In the present study, biocontrol efficacy of two entomopathogenic fungi, Penicillium citrinum and Penicillium chrysogenum was evaluated against red spider mites, Oligonychus coffeae in the laboratory. three different concentrations (1 × 10⁶, 1 × 10⁷ and 1 × 10⁸ conidia/ml) of the fungal suspensions were applied to the mite population and 0.01% tween 80 was used as control. Highest mortality of 95.56% was recorded when treated with 1 × 10⁸ conidia/ml of P. citrinum whereas treatment with the same concentration of P. chrysogenum resulted in total mortality of 62.22% after 96 hours. based on probit analysis, Lc₅₀ value after 96 hrs of treatment was calculated to be 4.6 × 10⁶ and 1.4 × 10⁷ conidia/ml for P. citrinum and P. chrysogenum, respectively. Lt₅₀ value for P. citrinum and P. chrysogenum at concentration of 1 × 10⁸ conidia/ml was calculated to be 24.45 and 67.79 hours. P. citrinum was found more pathogenic in activity.