Abstract
The relationship between feeding and gustatory responses to plants was investigated in the silkworm larvae, Bombyx mori L. The leaves of nine plant species, Morus alba, Cudrania triloba, Ulmus pumila, Lactuca laciniata, Ricinus communis, Ailanthus altissima, Prunus donarium, Quercus acutissima and Liquidambar formosana, were used in the experiments. The feeding responses to aqueous leaf-extracts in an agar diet were examined. The response to M. alba was strongest; C. triloba came second. Next in order were U. pumila and L. laciniata. No response was found to R. communis, A. altissima, P. donarium, Q. acutissima and L. formosana.
In electrophysiological studies, the frequencies of the LS-impulse (basic feeding stimulation signal), LI-impulse (synergistic signal for feeding stimulation), and R-impulse (feeding deterrence signal) were used as indices of the gustatory response to the aqueous leaf-extracts. The results could be classified into four types: LS-LI, LS-LI-R, LS-R, and R. The feeding responses of the silkworm larvae were influenced by the reciprocal interactions between the LS-impulse, LI-impulse and R-impulse. A “bitter substance” both activated the R-receptor as a feeding deterrent and inhibited the sensitivity of the LS-receptor.
