Colonization of perspex strips by larvae of Austrosimulium bancrofti (Taylor) near Ipswich, Queensland

Abstract

Larvae of the taxon Austrosimulium bancrofti (Taylor) were collected from perspex strips placed in rapids of the Brisbane River during January (summer) and October (spring). Separation of larvae according to the mixture approach to clustering demonstrated that: a) October cluster I larvae were larger and underwent an additional cluster to those collected in January, b) there was an additional cluster of larvae in each month, which correlated with the percentage of A. bancrofti Ipswich B that were identified cytologically, and c) greater numbers of later cluster larvae were collected from the strips than early clusters.Multivariate analysis demonstrated that distance from the lip of the rapids, strip texture and water velocity had a significant effect on the number of larvae colonizing perspex strips. Numbers increased with: a) decreasing distance from the lip of the rapids, b) increasing surface area of roughened strips and c) water velocity in the range 1.00 < X < 1.38 ms -. The influence of adult female oviposition behaviour, larval behaviour, sampling time and technique are discussed in relation to the parameters that influenced the colonization of artificial substrates.