Effects of high temperature and soil moisture on survival of first-instar larvae of the scarab Anoplognathus porosus (Dalman) (Coleoptera).
Abstract
A laboratory experiment testing survival of first instar larvae of Anoplognathus porosus (Dalm.) at high temperatures and various soil moistures is described. High-temperature stress appears to begin above 32.5 deg C. The mean survival rates for different durations of exposure suggest a gradually increasing level mortality above 30 deg C. The upper lethal temperature is considered to be 40 deg C. In the soil moisture experiments, the very dry soil (2.3% soil moisture, pF 5.6) resulted in total larval mortality after three days. The relatively low soil humidity (75%) caused desiccation. The highest survival was obtained at 4.9% soil moisture (pF 4.2); the concomitant high soil humidity (99%) preventing desiccation. In the very wet soil (40% moisture content, with a layer of water on top of the soil) mortality was high.