STUDIES ON THE NUCLEAR POLYHEDROSIS OF LYMANTRIA XYLINA SWINHOE.
Annotatsiya
The present paper deals with the results of the studies on the nuclear polyhedro-sis of Lymantria xylina, which was tested both in the laboratory and in the woods.This nuclear polyhedrosis is of limited epizootic in nature. The body of dead larvae turns greyish-brown in colour. The liquefied tissues and organs turns into a mess cream in colour.Electron microscopic investigation showed that the polyhedra are irregular in shape; their diameters ranging from 2.38 μ to 3.34 μ, The virus particles consist of 1 to 4 rods either single or in bundles. The size of the virus particles is 435 ×145 mμ.Bioassay conducted in the laboratory showed that mortality of the treated larvae depends on the concentration of the virus suspension as well as the larval instar. The LC50 for the sixth-instar larvae at 25℃ is 1.24 × 106 polyhedra/ml. The larval susceptibility increased with the advance of age, the last instar being the most susceptible.When the 1 × 108 polyhedra/ml deposit had been on the branchlets for 1-2 days, its infectivity has decreased significantly.The results of our study showed that both dead larvae and polyhedral suspension could be stored in the ice-box (0-4℃) for one year without losing infectivity.