Feeding response of the silkworm,Bombyx mori, to UV irradiation of mulberry leaves.

Ultraviolet irradiation of mulberry leaves caused a reduced feeding response inBombyx mori larvae (ca. 22% reduction in consumption as compared with control). Sucrose content of the foliage decreased after exposure to UV irradiation (0.5 mW/cm(2) for 1 hr. Electrophysiological responses of the sensilla styloconica-I to sucrose concentration (ca. 0-80 mg/g) showed a reduced response to UV-irradiated foliage when compared with the control. From feeding, gustatory, and electrophysiological responses, as well as the measurement of sucrose contents of the leaves, we concluded that the reduced feeding response to UV-irradiated leaves is due to the reduced sucrose content of the mulberry leaves, thus reducing pleogostimulatory levels.