The assessment of arboreal insect fauna: comparisons of knockdown sampling and faunal lists

Abstract. 1. A comparison is made between the fauna of six British tree species sampled by pyrethrum knockdown and the faunal lists in the literature for the same tree species.
2. Conspecific trees vary both in abundance of arthropods and their proportional distribution across taxa, but there are important overriding differences between tree species.
3. The percentage similarity in faunal composition between tree species reflects the ecological specificity of the arthropod groups used for the comparison.
4. The similarity in species composition between tree species is least for phytophages, the guild most closely associated with particular tree species, The two species of Salix are most similar in their fauna for most guilds.
5. About 40% of the entirely phytophagous species in the faunal lists for native trees were found in the knockdown samples.
6. The proportion of individuals of predominantly phytophagous taxa collected that belong to the relevant faunal lists ranges from 0.39 to 0.99.
7. Those species found in the knockdown samples which are not included in faunal lists none the less contribute to the trophic web of the tree.
8. The relative species richness of arboreal faunas assessed from knockdown samples parallels that derived from faunal lists.
9. The two approaches to the categorization of arboreal faunas, knockdown sampling and faunal lists, provide comparable data.