The effect of radioactive phosphorus on the growth and development of Culex pipiens molestus Forsk. (Diptera, Culicidae)

Abstract

SummaryIn a study of the effect of different concentrations of radioactive phosphorus (32P) in the larval medium on the growth and development of Culex pipiens molestus Forsk., 32P was found to have little noticeable effect on the growth of the larvae up to a concentration of 3·0 microcuries (μc.) of 32P per ml., but, above this concentration, larval growth was greatly retarded.The period of larval development was increased at concentrations greater than 1·0 μc. of 32P per ml., and pupation occurred two weeks later than in the controls. In concentrations higher than 5·0 μc./ml., pupation was completely inhibited, larvae became sluggish, stopped feeding and finally died.The effect of 32P in the larval medium on the emergence and radioactivity of the resulting adults was also studied. On the basis of this study, it is recommended that, for efficient utilisation of radio-phosphorus in large-scale field experiments, a concentration of 32P of 1·0 μc./ml. be employed so that emerging adult mosquitos may be sufficiently radioactive to be readily detectable.