Effect of soil acidity on the entomophilic nematodeSteinernema krausseiSteiner

摘要

The free-living stages ofSteinernema kraussei(Rhabditida), an endoparasite ofCephalcia abietisL. (Hymenoptera), are exposed to different soil conditions when searching for host nymphs. Field studies and laboratory experiments showed that soil acidity plays a major role in the nematode's ability to parasitizeCephalcianymphs. Under field conditions inPicea abiesforests positive correlations between soil pH and both nematode density and insects parasitized were found. Acidic soil with pH levels below 4.0 may limit the nematode's host-finding. Controlled experiments in the laboratory under different pH conditions confirmed these correlations.