Population dynamics of bronze beetle, Eucolaspis spp. (Coleoptera: Chrysomelidae) in relation to other soil macro-invertebrates in organic apple orchards in Hawke's Bay

摘要

The population structure and dynamics of bronze beetle, Eucolaspis spp., and other soil macro-invertebrates were studied in eight organic apple orchards in Hawke's Bay during spring/summer 2007-08. Orchards with high bronze beetle population densitiesalso had higher abundance of all types of soil macro-invertebrates than orchards with low bronze beetle populations. Surface-dwelling generalist predators were more numerous (on average 53.6 versus 40.5 predators per trap) in orchards with low bronze beetle density than in orchards with high beetle density. This result was mainly due to spider numbers in pit-fall traps, which were highest during January. It may be that within orchards where surface-dwelling spiders are most abundant, these spiders maybe predating upon newly emergent adult bronze beetles as they move from the soil to the apple foliage.