Efficacy of female Culex quinquefasciatus with entomopathogenic fungus Fusarium pallidoroseum

This study was conducted to isolate and identify natural entomopathogenic fungi from female Culex quinquefasciatus and to test their adulticidal activity. Field-collected female C. quinquefasciatus died early and were placed on a Saboraud's dextrose agar plates for growth and isolation of natural entomopathogenic fungi. The plates were maintained in an incubator at 24 +/- 2 degrees C for 3 days. Four fungal species were isolated in two genera namely, Aspergillus and Fusarium. The identified fungal species were A. niger, A. flavus, A. nidulans var acristatus (ITCC-6327.04), and F pallidoroseum (ITCC-6324.06). Adult bioassays were carried out using spore-impregnated paper in WHO-holding tubes. F pallidoroseum was found to be more effective than the others. Exposure of C quinquefasciatus to spores of A. flavus and A. niger for 4 h caused 5.53% and 5.51% mortality in the mosquitoes within a week, respectively. All the female C quinquefasciatus were killed within 4 days of exposure to F pallidoroseum at a concentration of 1.11x10(10) conidia per m(2). Significant difference of longevity was observed between the F pallidoroseum-treated C. quinquefasciatus and control mosquitoes. The LT50 of F pallidoroseum was 2.08 days for 4 h exposure to C quinquefasciatus. Results of the present study confirm that F pallidoroseum is one of the alternative biological control agents of adult mosquitoes.