Virulence of Local isolates of Entomopathogenic Fungi on the common agricultural pest Spodopteralitura (Fabricius) Lepidoptera:Noctuidae

Abstract

The polyphagous insect pest Spodoptera litura is known to cause huge losses to agriculture all over the world. Its increasing resistance to chemical insecticides necessitates the use of biological options such as Entomopathogenic fungi. Strains of Entomopathogenic fungi, Beauveria bassiana, Metarhizium anisopliae and Lecanicillium lecanii are known to control the incidence of the pest. Laboratory bioassay was conducted to evaluate the effect of different local isolates of M. anisopliae and L. lecanii on the growth and development of S. litura. Results indicate that the susceptibility of the insect pest depends on various factors like the fungal isolate, dosage of the infective propagule, age of the insect larvae and the developmental stage tested. Among the isolates studied, M. anisopliae isolate PaCo4 was found to be most virulent on S. litura neonates and the isolate ArCo3, the least virulent. In a subsequent study on the 3 rd instar larvae of insect pest, the isolates were found to prolong the larval duration, lower the pupation but the pupal period remained unchanged. A lowered adult emergence and longevity was also observed. Further study of the field efficacy of the Entomopathogenic fungal isolates are needed so that they can be successfully used for controlling the pest on the field.