Herbivorous arthropod community of an alien weed Solanum carolinense L.

Abstract

Herbivorous arthropod fauna of the horse nettle Solanum carolinense L., an alien solanaceous herb of North American origin, was characterized by surveying arthropod communities in the fields and comparing them with the original community compiled from published data to infer the impact of herbivores on the weed in the introduced region. Field surveys were carried out in the central part of mainland Japan for five years including an intensive regular survey in 1992. Thirty-nine arthropod species were found feeding on the weed. The leaf, stem, flower and fruit of the weed were infested by the herbivores. The comparison of characteristics of the arthropod community with those of the community in the USA indicated that more sapsuckers and less chewers were on the weed in Japan than in the USA. The community in Japan was composed of high proportions of polyphages and exophages compared to that in the USA. Eighty-seven percent of the species are known to be pests of agricultural crops. Low species diversity of the community was also suggested. The depauperated herbivore community, in terms of feeding habit and niche on S. carolinense, suggested that the weed partly escaped from herbivory in its reproductive parts. The regular population census, however, indicated that a dominant coccinellid beetle, Epilachna vigintioctopunctata, caused a noticeable damage on the leaves of the weed.