An Autoradiographic Search for the Site of Fertilization in Spider Mites1

Abstract

The fate of spermatozoa after mating has not been previously investigated in tetranychid mites. Histological evidence indicates that the spermatheca connects with the outside only. Autoradiography was employed in an attempt to trace the passage of spermatozoa from the spermatheca to the egg. Labeled spermatozoa were obtained by rearing males on bean seedlings growing in 8H-thymidine solution. Heavy labeling was found in those mites feeding on the radioactive leaves, anri radioactivity was found to be passed on transovarialy. By mating radioactive males to untreated females and preparing autoradiographs of these females at varying intervals after mating, the seminal material was traced. Labeled seminal material was located in the spermatheca of females recently mated to radioactive mates. General body labeling occurred several hours after copulation. Eggs in these mated females showed patterns of labeling not found in 8H-fed or untreated females. It is hypothesized that the spermatozoa leave the spermatheca, and travel through the haemolymph to the ovary where eggs are fertilized precociously.