Studies on the methods for massrearing of the mosquito, Culex pipiens pallens

Abstract

Laboratory studies on the developments and rearing methods of mosquito larvae, Culex pipiens (L.) were made under various breeding conditions by using mainly 500ml. of beakers being 57(cm)^2 of water suface. Diet used in the experiments was "the diet for experimental animals". The egg rafts laid within 15 hours were used in the experiment. In non-water-conversion condition, no or little numbers of the larvae were generally developed but the numbers of 18 larvae per 1(cm)^2 of the water surface were developed in the beaker providing 30 egg rafts and 6gr. of the diet at time of the egg stage. In most of the cases, three to six individuals of pupae were obtained from the beakers in which equal amounts of the diet were added every days during the larval stages. Eight to fifteen individuals of the larvae per 1(cm)^2 were developed when the diet and water converted every other days with the exception for large amounts of the diet or few numbers of the egg rafts were used. Larger numbers of the larvae were developed in daily-water-conversion as compared with other water-condition. Thirty four individuals of the pupae per 1(cm)^2 were obtained from the beaker that added daily 6gr. of the diet in daily-water-conversion. These results indicated that the conversion of water or procedures to providing the diet are more important factors that influenced larval developments than the amounts of diet or the numbers of the egg rafts provided. The pupating periods were prolonged with the high larval densities or with the few amounts of the diet. From these investigation the rearing method for the large numbers of the larvae by using 500ml. beaker is summarised as follows : Ten numbers of the egg rafts introduce in a beaker and then 0.3gr. of the diet add in 25℃. Afterthere 0 or 0.3gr., 1.5gr., 3gr., 3gr., 3gr., 3gr., 1.5gr. and 0.8gr. of the diet are added at 2, 3, 4, 5, 6, 7, 8 and 9 days after initiating the breeding. Three hundred ml. of water are usually maintained in the beaker with conversions of water. The conversions of water are made daily without 1 and 2 days after intiating the breeding. The amounts of diet that based on 25℃. are increased under lower temperatures and decreased under higher ones.