水深と流速のグァテマラ産ブユ Simulium ochraceum 幼虫の微細分布に与える影響

Abstract

In a quadrat sampling made in a 2.4-m stretch. Simulium ochraceum larvae were recovered only from shallow rapids. Lead plates were designed for collecting larvae attached on them. The highest larval density was recorded from the lowest depth (0.2-2.0cm) and the highest velocity (41-66cm/sec). The density increased with velocity increment, but decreased with depth increment. No larva was recorded in the stream of the current velocity less than 10cm/sec. Comparing among the five sampling stretches of 20m each, the increase in discharge was associated with increase both in depth and current velocity, but decrease in larval density, while increase in slope was associated with decrease in depth but increase in both current velocity and mean larval density.