Location of curly-top virus in the beet leafhopper, Eutettix tenellus

Abstract does not appear. First page follows.

Introduction

The curly-top virus is sometimes transmitted by the beet leafhopper, Eutettix tenellus (Baker), many days after the insect has had an opportunity to acquire the virus by feeding on an infected plant. The retention period of the virus in the insect has been reported to be as long as 151 to 180 days (Freitag, 1936).3 The question of where the virus is during this time has interested a number of investigators.

Earlier attempts to determine the location of the virus in the leafhopper were failures. In experiments at this station (Severin, 1922), not a single case of curly top was obtained by inoculating healthy beets with various internal organs from infective beet leafhoppers dissected in physiological salt, Ringer’s and Locke’s solutions, and in juice expressed from healthy beets. The excrement from infective beet leafhoppers inoculated into the petioles of healthy beets also failed to produce curly top. (Carsner and Stahl (1924)) dipped the points of steel needles into drops of fresh excreta from infective beet leafhoppers and then pricked the excrement into two beet seedlings, but no disease resulted.

Later, however, (Carter (1928a), ^(b) succeeded in demonstrating curly-top virus in leafhopper saliva. He transmitted the virus by previously noninfective leafhoppers which had fed on a solution on which infective insects had previously fed, the incubation period of the disease in the beets in these instances being, as a rule, prolonged. An attempt (Severin, 1931) to demonstrate its presence in feces by a similar technique was unsuccessful: previously non-infective nymphs after feeding on a feeding solution containing the feces from infective beet leafhoppers failed to transmit curly top to sugar beets.