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Evaluation of Entomopathogenic Fungi and Delivery Methods for Management of Thrips in Chillies

Hemalatha, S., Ramaraju, K., Jeyarani, S.
International journal of vegetable science 2017 v.23 no.3 pp. 246-259
Beauveria bassiana, Capsicum frutescens, Lecanicillium, Metarhizium, Scirtothrips dorsalis, applicators, bioassays, entomopathogenic fungi, hot peppers, leaves, lethal concentration 50, mortality, mycoinsecticides, pot culture, spores, sprayers, virulence
Successful use of entomopathogenic fungi as microbial control agents of thrips depends on strain virulence, an appropriate delivery system, and timing of application. Use of fungal entomopathogens can be an alternative to synthetic insecticides and could play an important role in bio-intensive pest management. Entomopathogenic fungi may be able to be used for management of chilli thrips, Scirtothrips dorsalis Hood. Laboratory bioassays were performed to evaluate fungal isolates of Beauveria, Metarhizium, Lecanicillium against chilli thrips using different delivery systems. The LC₅₀ values against S. dorsalis indicated that the Beauveria bassiana isolate, Bb 112, had the highest virulence with the lowest LC₅₀ values of 0.6 × 10⁶ spores·mL⁻¹. The time mortality response of S. dorsalis to fungal pathogens indicated that isolate Bb 112 had the lowest LT₅₀ value, 97.68 h. In pot culture on chilli (Capsicum frutescens L., cv. K2), among the entomopathogenic fungal isolates (Bb 111, Bb 112, Bb 101, B2, Bb NBAIR, Bb SBI, and Ml flavoviride var. minus), application of Bb 112 at 10⁸ spores·mL⁻¹ had the highest cumulative mean thrips population reduction, 59.73% and 53.88% in both pot culture experiments. The controlled droplet applicator (CDA) delivery system was effective for application of Bb 112 at 10⁸ spores·mL⁻¹ against S. dorsalis. Mycoinsecticides applied with the CDA sprayer can be used in management of low to moderate populations (two to three thrips per leaf) of S. dorsalis.