Steinernema kraussei, a parasite of the body cavity of the sawfly, Cephaleia abietis, in Czechoslovakia

Abstract

During an outbreak of Cephaleia abietis in southern Bohemia, nematodes identified as Steinernema kraussei were recovered from diapausing infected larvae. A description is given of a giant generation and of larval stages. Diagnostic characters distinguishing Steinernema from the genus Neoaplectana are the presence of submedian papillae, the absence of a masticatory apparatus in the bulb, and a gubernaculum with a hook at its base. Giant females are no more than four times larger than normal ones. Typical characters of the family Steinernematidae are: The first generation includes giant females while subsequent generations are normal. Moreover, the buccal cavity is short, the metacorpus is not swollen, and the valve of the esophagus is reduced. The spicules are arcuate and the gubernaculum is wedge-shaped. Invasive larvae of members of this family carry symbiont-like bacteria of the genera Achromobacter and Flavobacterium. These nematodes are obligatory parasites of insects and are without a free-living sexual generation.