Arthropod assemblages in tree canopies: a comparison of orders on box mistletoe (Amyema miquelii) and its host eucalypts

Parasitic plants, such as mistletoes, are important components of tree canopies, providing food andshelter for a range of vertebrates and invertebrates. Arthropods from several orders are known to inhabitmistletoes but no direct comparisons between these plants and their host plants have been conducteduntil present. In this study, the composition and abundance of arthropods occurring on hemi-parasiticbox mistletoe, Amyema miquelii ((Lehm. ex Miq.) Tiegh., Loranthaceae), on Eucalyptus (L., Myrtaceae)trees from the south-west slopes region of eastern Australia were investigated. Here a comparison ofthe arthropod assemblages at the ordinal level is presented. Specimens of Insecta and Arachnida weresampled from box mistletoe and three of its most common host species, using restricted canopyfogging, in two consecutive years, in nine remnants of grassy-box woodlands. The same 10 arthropodorders were sampled from the mistletoes and their eucalypt hosts but the total density of arthropods wasgreater on the eucalypt foliage. The latter result might be attributed to the significantly greater nitrogencontent of the eucalypt foliage than the mistletoe foliage. One year after de-faunation, all but one ofthe arthropod orders had re-colonised the mistletoe plants. The total abundance of arthropods (particularlyHemiptera and Hymenoptera) on the mistletoes was greater in the second year of sampling,in which drought conditions occurred. Future research of arthropod assemblages in tree canopiesshould be more inclusive of the full range of substrates or habitats within canopies. Furthermore,investigation of the nutritional quality of mistletoe foliage compared with their host trees is requiredfor a better understanding of the factors driving variation in community composition of arthropodassemblages.