Isolation and identification of the Nuclear Polyhydrosis Virus (NPV) from the cotton leaf worm larvae Spodoptera littoralis (Boisd

Abstract

Cotton leaf worm Spodoptera littoralis (Boisd) larvae reared in lab on tomato leafs, showed illness symptoms which were: slow mobility, stop feeding, swelling and discoloration into pale white. Spodoptera Nuclear Poly Hydrosis Virus was isolated and identified using the electron transmission microscope by the negative staining method and proved to be responsible for the larvae's mortality. Three concentrates of viral suspension were used (25,50,75 %) for the bioassay and the polyhydric inclusion bodies appeared. Toxicity lines were drawn after 24 and 72 hours using the (Log. Dose-propit). The LC50s for the virus were 0.20 % and 0.07 % and the slopes were 1.86 , 1.62 consequently.