Bioassay of Crude Extracts for the Factor that Prevents Second Matings in Female Musca domestica

Abstract

Extracts of tissues of the house fly, Musca domestica L., were prepared and injected into virgin female flies to study mating inhibition and mortality. A factor that inhibited mating was extracted from the reproductive systems of the male and newly mated female, male abdomens, and male copulatory duct but not from the testes or the reproductive system of virgin females. An extract of the male copulatory duct caused 50% inhibition of mating at a concentration of 4.3 tissue equivalents. An extract of male abdomens was 53% more effective than an extract of the copulatory duct. All extracts were toxic, and toxicity was enhanced by homogenization, sonification, and oxidation. The most effective bioassay procedure resulted when extracts were prepared from unfragmented tissues, and 1 µliter of the extract containing 4 tissue equivalents was injected into the thorax of 3-day-old virgin females; 3 days later the females were tested for mating inhibition.