ヨトウガの相変異 : IV 異なる飼育温度下での幼虫形質の相変異

抄録

In this paper the writer describes the results of observations on the phase variation in the larval characters of the cabbage armyworm, Mamestra (Barathra) brassicae, under different conditions of rearing density and temperature. The materials used for the experiments were offsprings of non-diapausing individuals of the first brood of the Noheji strain (Aomori Pref.) Details of experimental design are given in Table 1. The larvae were fed on young leaves of the goose foot, Chenopodium centrorubrum MAKINO, one of the wild plants. High mortality was encountered at the final larval stage in crowded cultures and this tendency was intensified at 28℃ (Fig. 1). As shown in Fig. 2,temperature influences the skin color of the final instar larvae, the highest percentage of dark colored larvae was obtained at 20〜22℃ and the lowest one at 28℃. Furthermore, the larval coloration was affected by rearing density and the percentage of dark colored larvae in a culture increased with the increase of density (Figs. 2 and 3). Crowding induces rapid development at 25 and 28℃ and slow development at 20〜22℃ (Table 2), and produces lighter female purae at each temperature employed in the experiment (Table 3). Fig.44 indicates that the larvae in crowded cultures grew at the same rate as those in solitary cultures both at 25 and 28℃ and that there was a difference in the rate tf growth between density cultures at 20〜22℃.