Toxicity of Chemicals and Entomopathogenic Fungi to Different Stages of Brown Lacewing, Micromus igorotus Banks (Neuroptera:Hemerobiidae)

Studies on toxicity of certain insecticides and entomopathogenic fungi to different stages of brown lacewing, Micromus igorotus Banks were undertaken. Studies on toxicity of insecticides on eggs of M. igorotus revealed that malathion, endosulfan, azadirachtin, monocrotophos, acephate, γ-cyhalothrin, cypermethrin and fenvalerate are safer to eggs permitting 84.3–96.7% eggs hatch. Quinalphos and chlorpyriphos exerted slight toxicity vis-à-vis total killlng of eggs by profenophos. To the second instar larva, γ-cyhalothrin exhibited highest toxicity (LC₅₀ 0.002%) while azadirachtin was least toxic (LC₅₀ 1.52%). Chlorpyriphos, quinalphos, acephate, malathion, fenvalerate, cypermethrin, monocrotophos, profenophos and endosulfan were next to γ-cyhalothrin in the descending order of toxicity. There exists marked variation in the toxicity to M. igorotus pupae. Failure of adult emergence in nndosulfan, monocrotophos, quinalphos, chlorpyriphos, malathion, profenophos and acephate suggest high toxicity to pupae. Among the synthetic pyrethroids, fenvalerate was most toxic followed by cypermethrin and γ-cyhalothrin. Azadirachtin was more safer among all chemicals to permit 70.7% adult emergence. The entomopathogenic fungi, Metarhizium anisopliae (Metschnikoff), Verticillium lecanii (Zimmerman), Beauveria bassiana (Bals.) Vuill. and Nomuraea rileyi (Farlow) Samson @ 1 x 10⁸ conidia mL⁻¹ spared the eegg and larvae of M. igorotus. While the former three fungi caused pupal mortality to 11.2, 7.1 and 6.5%, respectively.