Division of Entomology, Indian Agricultural Research Institute, New Delhi-110012, (India).
1Present address: Department of Entomology, 219 Hodson Hall, 1980 Folwell Avenue, University of Minnesota, St. Paul, Minnesota-55108, U.S.A.
An in vitro perfusion system was employed to study the permeability of the peritrophic membrane (PM) in relation to maturation resistance to nuclear polyhedrosis virus (NPV) in Spodoptera litura (Fabr.). PM permeability was observed to decrease 21-fold as larvae matured from 7 to 12 days. This 21-fold decrease in perfusion rate was accompanied by an approximately 13-fold increase in chitin content in the PM of 12-day old larvae in comparison to 6-day old larvae. Chitin content of the PM of 6-day old larvae decreased significantly (47.13%) in response to NPY infection, whereas the decrease was not significant (5.32%) in the 12-day old infected larvae.
