A solatium beetle on a fabaceous weed: A consequence of the disappearance of an alien host plant from a habitat

摘要

The herbivorous ladybird beetle Henosepilachna vigintioctopunctata (Fabncius) depends basically on solanaceous plants; however, the beetle also utilizes an introduced fabaceous weed Centrosema molle Benth. at several locations in Southeast Asia. The beetle population in Bogor, West Java, Indonesia, once had become a generalist depending on both C. molle and the ordinary host Solarium torvum Sw. More recently, the host use of this population became to be strongly biased to S. torvum because of the decreased abundance otし.molle at the habitat. In 2018, when approximately 30 to 40 generations had passed since the ceasing of frequent use of C. molle, we investigated feeding acceptance of C. molle by adults and survival or larvae on C. molle under laboratory conditions. Results strongly suggested that the ability of beetles to use C. molle was effectively retained. The Bogor population of H. vigintioctopunctata is almost solely depending on S. torvum now as it was before the invasion orしmolle into thehabitat, whereas its host-use ability has been modified through natural selection on C molle which disappeared from the habitat.