Fijian Arthropod Survey

Taxonomy, Diversity and Distribution of Canopy Coleoptera (Beetles) along Elevational Gradients on Eastern Viti Levu, Fiji

Hilda Waqa, MSc Research Student, University of the South Pacific, Fiji Email: waqa_h@yahoo.com

University of the South Pacific postgraduate student Hilda Waqa and field assistant Viliame Takalaiyale in the forest at Waisoi, Namosi on the eastern side of Viti Levu, Fiji. Hilda, who's research project involves the taxonomy of beetles, is seen here using a canopy fogging technique to collect insects, that have fallen into white cone traps that were hung approximately 1.5m off the ground.

This study investigates the diversity and distribution of canopy Coleoptera in relation to altitude and forest type on eastern Viti Levu, Fiji. The study was conducted at three locations representing lowland (Nakobalevu), upland (Waisoi) and cloud forest (Monasavu) habitats, with an overall altitudinal range of 200-1000m above sea level. Canopy fogging was used to sample insects - an insecticide was sprayed into the canopy and cone traps used to collect insects which then fell to the ground. Physical factors (including temperature and relative humidity) were recorded on site and detailed records of vegetation type were made. The first survey (June/July, 2005) collected 1720 individual beetles representing 29 families. The most abundant families include Curculionidae (weevils), Staphylinidae (rove beetles) and Chrysomelidae (leaf beetles). These families have been shown to be well distributed along altitudinal ranges as they are well adapted to microclimatic change. Preliminary analyses have shown significant differences in abundances and diversity, revealing peaks at mid-elevation around 600-800m. This is probably due to the net accumulation of photosynthate around these altitudes which results in high resource diversity and leads to high species diversity. Multi-dimensional scaling has been used to identify distinct community types existing at low, mid and high altitudes. A second sampling survey conducted in Jan/Feb 2006 will provide data for seasonal variation (wet/dry). Further analysis on the categorization of vegetation types may reveal further relationships between coleopteran diversity and forest habitat type.