Fungal biological control agents for integrated management of Culicoides spp. (Diptera: Ceratopogonidae) of livestock

Abstract

Aim: Entomopathogenic fungi Metarhizium anisopliae and Beauveria bassiana had wide host range against insects and hence these are being exploited as fungal bio-pesticide on a large scale. Both fungi are proved pesticides against many crop pests and farmers are well acquainted with their use on the field. Thus, research was aimed to explore the potency of these fungal spores against larval and adult Culicoides midges, a pest of livestock. Materials and Methods: In-vitro testing of both fungal biological control agents was undertaken in Petri dishes against field collected Culicoides larvae, while in plastic beakers against field collected blood-engorged female Culicoides midges. In-vivo testing was undertaken by spraying requisite concentration of fungal spores on the drainage channel against larvae and resting sites of adult Culicoides midges in the cattle shed. Lethal concentration 50 (LC50) values and regression equations were drawn by following probit analysis using SPSS statistical computerized program. Results: The results of this study revealed LC50 values of 2692 mg and 3837 mg (108 cfu/g) for B. bassiana and M. anisopliae, respectively, against Culicoides spp. larvae. Death of Culicoides larvae due to B. bassiana showed greenish coloration in the middle of the body with head and tail showed intense blackish changes, while infection of M. anisopliae resulted in death of Culicoides larvae with greenish and blackish coloration of body along with total destruction, followed by desquamation of intestinal channel. The death of adult Culicoides midges were caused by both the fungi and after death growth of fungus were very well observed on the dead cadavers proving the efficacy of the fungus. Conclusion: Preliminary trials with both funguses (M. anisopliae, B. bassiana) showed encouraging results against larvae and adults of Culicoides spp. Hence, it was ascertained that, these two fungal molecules can form a part of biological control and alternative to chemical control and, therefore, can be inducted in integrated management programs.

Keywords

• biocontrol agents
• Beauveria bassiana
• Culicoides spp
• integrated pest management
• Metarhizium anisopliae