Efficacy of the entomopathogenic fungus, Paecilomyces fumosoroseus (Wise) Brown and Smith (Ascomycota: Hypocreales) against Geotrogus deserticola (Coleoptera: Melolonthidae)

Different conidial concentrations of isolate P 83 of Paecilomyces fumosoroseus ranging from 1 × 10⁶ to 1 × 10¹⁰ conidia/ml were injected through the anus of geotrogus deserticola on the 2nd and 3rd instars larvae. The larval mortality caused by fungal infection differed significantly and increased with increasing conidial concentrations. Results revealed 100% mortality of 2nd instar larvae at 1 × 10¹⁰, 1 × 10⁹, and 1 × 10⁸ conidia/ml and the lower mortality 93.33% was obtained at 1 × 10⁶ conidia/ml, 6-day post treatment. For the 3rd instar larvae the higher mortality (93.33%) was noticed at 1 × 10¹⁰ and the lower (53.33%) at 1 × 10⁶ conidia/ml 8 day of post inoculation. The estimated LC₅₀ was 4.73 × 104 and 2.13 × 10⁵ conidia/ml and the LT₅₀ values was 3, 64 days and 3, 90 days respectively for the 2nd and the 3rd instar larvae treated.