Winter survival in Sweden of L 3-stage larvae of the ostrich wireworm Libyostrongylus douglassii

Abstract

Libyostrongylus douglassii, a pathogenic trichostrongylid nematode of the ostrich, was recently identified as a potentially important parasite in ostriches on Swedish farms. This parasite is well adapted to the hot and dry climates of sub-Saharan Africa, the natural habitat of the ostrich. The influence of low temperatures in colder climates, such as in Sweden, on free-living stages of L. douglassii is however insufficiently known. In this study, parasite free ostrich faeces were mixed with infective L 3-stage larvae of L. douglassii, which had been cultured from eggs obtained from two Swedish farms. Samples of the mixture were placed on a grass surface, and analyses for L 3-stage larvae were performed at regular intervals. The results of the study showed that L 3-stage larvae may remain alive during a period of at least 97 days on pasture during the winter season in Sweden, even when the temperature within the samples was repeatedly below −0.1 °C, and the air temperature varied between −19.6 and +14.9 °C. It was concluded that L 3-stage larvae of L. douglassii probably have the ability to remain viable on pastures during winter in Sweden.