Abstract
Bombyx mori is well known as the monophagous insect, which larvae usually grow on leaves of mulberry and a commercial artificial diet. They reject most plants after palpating or a few bites, or even without touching. To investigate this preference mechanisms, the behavioral and electrophysiological analysis were performed on the fifth instar larvae. After inactivation of the maxillary palpus by applying of sulfuric acid on them, larvae began to eat non-mulberry leaves, e.g. Komatsuna (Japanese Mustard Spinach). Furthermore, normal larvae did not eat agar diet containing the Komatsuna juice, but they could eat the agar diet with the heat dried Komatsuna powder. From these result, it was expected that B. mori larvae senses volatile components of non-mulberry leaves by the maxillary palpus. Consequently, sensory responses from a maxillary palpus were recorded upon stimulation with the mulberry leaves and Komatsuna. Small spikes were observed in response to the mulberry leaves entirely, and the amplitude of potentials were decreased gradually. When stimulated with the Komatsuna, large spikes with the frequency of 40 ∼ 50 Hz appeared. Same spikes were observed in response to α-pinene which is common essential oil extracted from many kinds of plant leaves. It was indicated that B. mori larvae distinguish the mulberry leaf from other leaves by detecting the compounds the mulberry leaf doesn't have.
