SUMMER LIGHT-TRAP CATCHES OF ADULT TRICHOPTERA IN HILL-COUNTRY CATCHMENTS OF CONTRASTING LAND-USE, WAIKATO, NEW-ZEALAND

The distribution of adult Trichoptera in light traps was investigated alongside nine streams draining catchments under native forest, pine f orest, or pasture near Hamilton, Waikato, New Zealand. The aim of the study was to determine the relationship between abundance, taxonomic r ichness, and community composition with respect to land use during sum mer, and to evaluate the use of adult Trichoptera compared with benthi c invertebrates as potential bio-indicators of the effectiveness of la nd-management changes. Adult Trichoptera faunas alongside the native s treams were dominated by Hydrobiosidae, Conoesucidae, and Helicopsychi dae (each >10% of total Trichoptera numbers for at least two of the th ree sites), whereas Leptoceridae, Oeconescidae, and Hydrobiosidae were relatively abundant alongside at least two of the pine sites. Adult T richoptera faunas at the pasture sites were strongly dominated by Hydr optilidae which made up 47-85% of numbers caught at all sites. The mea n number of individuals and taxa caught in light traps increased from November to January and then declined in February for all land-use typ es. Overall, total numbers and taxonomic richness of adult Trichoptera were significantly lower at the pine sites compared to the pasture or native sites. TWINSPAN classification of benthic invertebrates collec ted in November clearly differentiated sites based on land use for pre sence/absence and percentage abundance data. A similar pattern was evi dent for most sites when adult Trichoptera faunas were used for the fo ur sampling dates combined, suggesting that light trapping has potenti al as a tool for bio-monitoring.