Chemically Defined Dietary Media for Larvae of the Mosquito Culex Pipiens (Diptera: Culicidae): Effects of Colloid Texturizers

Abstract

Aseptic, fully-defined dietary media which support growth of Culex pipiens from egg to adult are described. Unless low concentration of certain colloid texturizers was incorporated in media, development was slow with heightened mortality. Agar was the best of 3 colloids studied, having an optimal effect at a concentration of about 0.08%; such agartexturized media supported growth rates and development over larval cycle comparable to good growth rates typical in crude culture. Methylcellulose, optimally effective at concentrations of 0.05 to 0.2%, also greatly improved development, though it was inferior to agar. Polyhall, a polyacrylamide viscosizer, improved development only moderately, with an optimal effect at about 0.4%. Because the major effect of colloids was to increase larval growth rates rather than to much increase the average stage of development ultimately achieved, and because comparative short-duration feeding tests indicated that media were ingested more efficiently when containing colloid, it is concluded that improved overall development in colloidtexturized media resulted mainly from a mechanical facilitation of feeding. Larvae were able to ingest dissolved nutrients at a rate approaching that necessary for normal growth. It is to be noted that these synthetic diets are possibly deficient in some, as yet, unrecognized trace nutrient(s), since adults obtained are weak and short-lived.