Field evaluation of Lecanicillium psalliotae and development of an integrated pest management strategy against Sciothrips cardamomi

Cardamom thrips, Sciothrips cardamomi Ramk. (Thysanoptera: Thripidae) cause huge economic losses to cardamom, Elettaria cardamomum (L.) Maton., a high-value spice crop, in all growing regions worldwide. To date, the pest is managed by synthetic pesticides, which results in harmful residues in the produce and also pose a serious threat to the environment. In our studies, we evaluated the biocontrol potential of a recently isolated entomopathogenic fungus, Lecanicillium psalliotae (Treschew) Zare & W. Gams (Ascomycota: Hypocreales) under field conditions for two years in two major cardamom growing states, Kerala and Karnataka in India. The results indicated that four rounds of soil application of the fungus granules reduced capsule damage by thrips significantly compared to control, whereas spray application of the fungus was ineffective. The compatibility of the fungus with commonly used pesticides in cardamom was tested under laboratory conditions and the fungus was found compatible with the pesticides, spinosad, fipronil and copper oxychloride. Further, we evaluated the fungus along with other management options such as application of recommended insecticide (quinalphos), reduced-risk insecticide (spinosad) and soil application of fungal entomopathogen (L. psalliotae) and in combination with insecticides for developing an integrated pest management (IPM) module for the management of the pest. The trials indicated that initial sanitization of the crop with either quinalphos or spinosad sprays followed by three rounds of soil application of the fungus or spray application of spinosad and soil application of L. psalliotae twice alternatively, reduced capsule damage by thrips significantly. Our findings offer a scope for integrated management of cardamom thrips with reduced risk to the environment. This is the first IPM schedule developed against this major pest of cardamom with biological control as a component.