Department of Agricultural Entomology, Agricultural College and Research Institute, Madurai-625 104, Tamil Nadu (India).
Suspending of nuclear polyhedrosis virus (NPV) of groundnut red hairy caterpillar, Amsacta albistriga Wlk. (AaNPV) in different concentrations of Congo red provided significant ultraviolet (UV) protection. Its effect was concentration dependent and wet viruses were comparatively resistant to UV rays than the dry viruses. At 1.0% concentration of the dye, the larval mortality was 61.5 and 71.5 per cent in dry and wet viruses, respectively. This resulted in 83.3 and 100.0% of original viral activity remained (OAR) respectively after 60 min of exposure to UV radiation. With NPV suspended in water, it was 7.3 and 10.4% with OAR of 9.9 and 14.9%. Also, Congo red decreased the incubation period of AaNPV.
