Rapid population growth and food-plant exploitation pattern in an exotic leaf beetle, Ophraella communa LeSage (Coleoptera: Chrysomelidae), in western Japan

Abstract

An exotic leaf beetle, Ophraella communa, originating from the Nearctic region, is a multivoltine oligophagous herbivore and was discovered in Japan in 1996. The host-use of the leaf beetle in the field with adult feeding choice and larval performance on some asteraceous plants in the laboratory were surveyed. O. communa showed a hierarchy of food-plant use: The leaf beetle first used Ambrosia artemisiifolia, on which adults preferred to feed and larvae developed well, and its population increased markedly until defoliating this food-plant. Then, the leaf beetle migrated to Am. trifida and Xanthium spp. In the laboratory, Am. trifida was not as preferred by adults as Am. artemisiifolia, although larval performance on Am. trifida was superior. Xanthium was inadequate both in terms of adult feeding choice and larval performance. Neither eggs nor larvae were found on the plant species on which no larvae completed their growth in the laboratory. These findings suggest that the exotic beetle has great mobility and host-discriminating ability. The finding, that Am. trifida was less used than Am. artemisiifolia despite Am. trifida being suitable for larvae, may be attributable to the fact that adults tend to oviposit on Am. trifida subsequently to feeding.