NUTRITIONAL STUDIES WITH PSEUDOSARCOPHAGA AFFINIS (FALL.), A DIPTEROUS PARASITE OF THE SPRUCE BUDWORM, CHORISTONEURA FUMIFERANA (CLEM.): V. EFFECTS OF VARIOUS CONCENTRATIONS OF THE AMINO ACID MIXTURE, DEXTROSE, POTASSIUM ION, THE SALT MIXTURE, AND LARD ON GROWTH AND DEVELOPMENT; AND A SUBSTITUTE FOR LARD

Abstract

An improved chemically defined diet has been developed for aseptic rearing of the parasitic dipteron Pseudosarcophaga affiuis (Fall.). The time required for 50% of the larvae to develop to the third instar was decreased from nine to five days, and the percentage of larvae that became adults was increased from 19 to 60. These improvements resulted from a reduction in the dextrose concentration to 0.5% of the diet and the inclusion of 0.4% of lard or of a mixture of fatty acids. Reducing the concentration of the salt mixture when the concentration of potassium was increased did not affect growth. The optimum concentration of amino acids was about 2.0% of the medium. Excessive concentrations of amino acids, dextrose, and the salt mixture were toxic.