Luteolin 7-O-glucoside in hozuki leaves, Physalis alkekengi, is involved in feeding stimulation in Epilachna vigintioctopunctata

Abstract

Hozuki, Physalis alkekengi, is one of the host plants of the twenty eight-spotted ladybird, Epilachna vigintioctopunctata. We investigated feeding stimulants for E. vigintioctopunctata in hozuki leaves. The methanol extract of hozuki leaves and its chloroform-soluble fraction stimulated feeding of the adult beetle. Although the butanol-soluble and water-soluble fractions were inactive by themselves, the butanol-soluble fraction or the deposit formed during concentration of this fraction acted synergistically with the water-soluble fraction. The deposit was identified as luteolin 7-O-glucoside. This compound is considered to be one of the factors in hozuki that induce feeding in E. vigintioctopunctata.