THE INFLUENCE OF HOST PLANT ON THE SUSCEPTIBILITY OF SPODOPTERA-LITTORALIS (BOISD) (LEP, NOCTUIDAE) LARVAE TO SPODOPTERA-LITTORALIS NPV (BACULOVIRIDAE, BACULOVIRUS)

The influence of 5 host plants, castor bean, alfalfa, mulberry, cotton and potato, on the susceptibility of the cotton leaf worm, Spodoptera littoralis (Boisd.) to a nuclear polyhedrosis virus (NPV) was investigated. Median lethal dose's (LD50's) of NPV were determined in third-instar larvae by a leaf-disk bioassay. Any statistically significant difference in the third-instar S. littoralis larvae susceptibility to the S. littoralis NPV was observed when fed on mulberry, cotton or potato. On the other hand the larvae were significantly less susceptible to the NPV when fed on castor bean than when fed on alfalfa, mulberry, cotton or potato and were also significantly less susceptible when fed on alfalfa than when fed on mulberry, cotton or potato. No differences were observed in the infection process due to the plant on which the NPV was presented.