Hiroe YASUI and Mitsuo YAZAWA,
National Institute of Sericultural and Entomological Science, Ohwashi 1-2,
Tsukuba, Ibaraki 305, Japan
Irradiation of mulberry leaves with ultra violet (UV) light (254nm) reduced the feeding response in Bombyx mori, silkworm larvae. It was shown that the decrease of the sucrose content of the foliage by UV irradiation accounts for the reduction in the feeding response in B. mori. 1- An organic extract of UV-irradiated leaves was fractionated and in the acidic fraction which showed antifeedant activity, moracins C, M, N. and 4'-prenyloxyresveratrol, known as phytoalexins, were identified 2- These compounds were induced by UV irradiation and affected the food consumption by acting as feeding deterrents. In addition, feeding tests of other moracin derivatives and chalcomoracin, isolated as phytoalexins, were also investigated.