Some notes on the relationship of plant viruses with vector and non-vector insects

Abstract

Extracts of caterpillars and other insects are shown to inhibit the infective power of tobacco mosaic and tobacco necrosis viruses. The inhibitor is not sedimented after spinning for 2½ hr. at 30,000 r.p.m. Experiments with non-vector insects such as caterpillars have shown that the virus of sugar-beet curly-top, of tobacco ringspot and other viruses, are destroyed within the body of the insect. On the other hand, tobacco mosaic virus passes through the body of the caterpillar unchanged though greatly reduced in concentration. By the use of the specific insect vector and artificial feeding methods it was possible to recover the virus of curly-top 24 hr. after it had been injected into the blood of the caterpillar but the viruses of tobacco mosaic and tobacco necrosis could not be so recovered. Experimental evidence is given to show that the virus of beet curly-top is present in the saliva of viruliferous insects.