Feeding on cabbage and cherry leaves by maxillectomized silkworm larvae

Abstract

Torii and Morii (1948) have shown that the maxillae are the principal organs in food selection by silkworm larvae, and that extirpation of the maxillae results in feeding on several plants which are normally not touched, or hardly fed on. However, it still remains to be demonstrated that maxillectomized larvae will feed on the wrong plants for continuous periods. This report is concerned with the feeding of maxillectomized larvae on cabbage and cherry leaves. 1. Newly molted 5th instar larvae. a. Operated larvae fed on mulberry leaves normally, except for a few which were thought not to have recovered from the effects of the operation (Table 1). The number of feces collected for each 24-hour period is the criterion of the amount eaten. b. Starved larvae, both operated and unoperated, lost weight, and produced few feces (Table 1). c. Operated larvae fed on cabbage to some extent during the first 24 hours, then fed less (Table 1). Since the variation in the weight of individuals was large and the mortality high, the change in weight was recalculated as per cent of the original weight for those larvae which had survived for two days (Table 2 and Fig. 1). The operated larvae gained weight during the first day, and continued to grow slowly until death. The unoperated ones, however, lost weight more slowly than the starved ones. d. Operated larvae fed on cherry to some extent (Table 1), with a marked loss of weight and earlier death than unoperated larvae, which fed on cherry very slightly when hungry and lost weight more slowly. e. From the above observations it is evident that maxillectomized larvae do not feed on the wrong leaves for continuous periods, and that there appear to be organs of taste besides those on the maxillae. f. Cherry leaves, and to a lesser extent cabbage leaves, seem to contain substances which are detrimental to silkworm larvae. 2. Middle 5th instar larvae. a. Operated larvae fed and grew as well as unoperated ones on mulberry leaves (Table 3). b. Operated larvae fed and grew on cabbage for the first 24 hours, and then began to lose weight (Table 3). Unoperated larvae fed on cabbage very slightly when hungry and grew slightly. The same calculation of the body weight mentioned above was made (Table 4 and Fig. 2). © 1959, The Japanese Society of Sericultural Science. All rights reserved.