Use of P32 as an Aid in Biological Studies of the Leafhopper, Scaphoideus luteolus

P³² was used to tag the insect vector of elm phloem necrosis and to trace this leafhopper's oviposition habits through activated eggs. Elm plants that were treated with 2 mc P³² absorbed the solution in 2 to 3 hr. Leafhoppers feeding on these plants reached a radioactive level of more than 30,000 cpm per individual in a few days and reached the maximum found (80,000 cpm) in about 8 days. No ill effects to the activated leafhoppers could be detected. Mortality was comparable to that of the controls. Death resulted naturally or because of injury during handling. Females attained an activity twice that of the males, probably because of their larger size. The average activity per egg was 1/36 that of the female body and ranged from 1/24 to 1/50. Few of the eggs studied exceeded 100 cpm; most were around 50 cpm. Eggs were laid 8 to 30 days after mating ad could be traced with the probe of Ihe survey meter to within one-half inch of their exact location. The eggs were laid singly in the corky layer of the bark with 1 or more eggs per spot. Failure to detect eggs after 30 days is attributable to the short half life of the isotope (14.7 days). (H.R.D.)