DISPERSION AND SAMPLING OF AEDES-VIGILAX EGGSHELLS IN SOUTHEAST QUEENSLAND, AUSTRALIA

The density and dispersion of eggshells (also includes live eggs fract ured in processing) of Aedes vigilax in salt marsh and mangrove forest s of southeast Queensland, Australia, were quantified and used to dete rmine sample size. Use of a blender to disrupt soil samples decreased sieving time, although the rate of eggshell recovery was reduced in sa ndy soils. In clay soil, 48.3% and 55.8% of eggshells were recovered b y blender and hand processing, respectively. Subsampling sieved and dr ied soil provided an accurate estimate of eggshell density while reduc ing the amount of material requiring microscopy. Eggshell density was highest in vegetated plains and pond banks rather than bare pond botto ms, with a mean eggshell density of about 2/ml in known breeding sites in salt marsh and mangrove forests. Eggshell dispersion was aggregate d, with a Taylor's b of 1.85, mean crowding of 106, and a mean/varianc e of 72.5. Estimated sample sizes to sample a site with one eggshell/m l ranged from 54 to 9 for respective precision levels of 0.10 and 0.25 .