دراسة إمراضیة نسیجیة لتأثیرات العزلة المحلیة لفیروس Spodoptera littoralis Nucleopolyhedrovirus على یرقات دودة ورق القطن Spodoptera littoralis (Boisd.) فی العراق

Abstract

The aim of this current study is to focus on the histopathological changes that happens to the midgut of the cotton leaf worm Spodoptera littoralis (Boisd) larvae especially in the Peritrophic membrane as a main defense line against the occulosion bodies OBs (A crystalline protein matrix which occludes the nucleocapsids) of the Spodoptera littoralis nucleopolyhedrovirus from a local Iraqi isolation that was used as a biological control factor to control this pest. The high specialty of the baculovirus when used as a biological control factor for certain insect families has an important role in full control programs to control pests, especially the SpoNPV virus which is highly specialized in infecting the cotton leaf worm S. littoralis larvae. And it was pointed out by results that there was dissociation and disintegration in the midgut Peritrophic membrane of the larva of the cotton leaf worm at the forth larva stage after 24 hours of exposing them to semi-synthesized nutrition with OBs of the SpoNPV. The microscopic test of the cross section of the larva's midgut showed that after 72 hours of viral infection virus particles have speeded through the rest of the inner tissue of the digestive system and invaded it to reach the fat bodies and tracheal system up to the dermis tissues and the outer cuticle cells of the larva. According to the results of the histopathological study of the infected S. littoralis with the SpoNPV, the virus is considered to be an effective, specialized and ecological safe biological control factor to control this serious pest.