Efficacy of the entomopathogenic fungus, Metarhizium anisopliae (Metsch.), against larvae of the cotton leafworm, Spodoptera littoralis (Boisd.) (Lepidoptera: Noctuidae), under laboratory conditions

The efficacy of the entomopathogenic fungus, Metarhizium anisopliae, was assessed through applying different conidiospore concentrations of a local isolate against third and fifth larval instars of the cotton leafworm, Spodoptera littoralis (Boisd.) (Lepidoptera: Noctuidae) under laboratory conditions. The lowest tested concentrations (2 × 101, 2 × 102, and 2 × 103 conidiospores/ml) caused low mortality rates on the tenth day post-treatment (2–14% for L3 and 0–6% for L5). The highest concentrations (2 × 104 2 × 105, 2 × 106, and 2 × 107 conidiospores/ml) induced (52–90%) mortality rate in L3 and (50–100%) in L5 on the seventh day post-treatment. Death of treated larvae started on the fourth day post-treatment with the high concentrations. LC50 and LC90 values were calculated. They were higher for L3 than for L5.