Studies on environmental factors for breeding of grain mites VII : Relationship between reproduction of mites and kind of carbohydrates in the diet

Abstract

In the previous paper, the author reported on the differences in activities of various enzymes in the body of typroglyphoid mites, and that remarkable differences by the species were seen those which acted on carbohydrates. The present study was intended to see mode of utilizations of various carbohydrates as nutrients by different species of the grain mites as observed from the rates of reproductions in food composed of mixtures of dried yeast and various carbohydrates. Cultures of three species of the grain mites, Tyrophagus dimidiatus, Aleuroglyphus ovatus and Carpoglyphus lactis were made in media composed of the mixtures of dried yeast and carbohydrates (glucose, lactose, sucrose, dextrin and starch) at the ratios of 10 : 0, 8 : 2, 6 : 4, 4 : 6, 2 : 8 and 0 : 10. They were kept in separate containers regulated at relative humidity of 75% in an incubator at 25℃. The densities of mites in the cultures were counted at two weeks intervals. Carpoglyphus was found to breed best in the media containing 40 to 60% glucose or sucrose, while the diets containing dextrine and starch were less adequate as food than dried yeast alone. On the other hand, the rate of reproductions of Aleuroglyphus ovatus was the highest in cultures composed of the mixtures of starch and yeast at about equal ratios. However, the mite was estimated to be unable to utilize glucose and lactose for its reproduction. Tyrophagus was found to be intermediate type in its nutritional requirements between the above two species, and the addition of any of the carbohydrates to the yeast was had the effects to increase its rates of reproductions. The results shown above seem to indicate that Caropoglyphus lactis is the mite that utilize glucose or sucrose as the nutrients but not the starch, while Aleuroglyphus is the reverse in its requirements, and that Tyrophagus has broader allowances and can utilize a variety of carbohydrates from glucose to starch.