Heterorhabditis bacteriophora: Seasonal dynamics and distribution in a stand of sugar maple, Acer saccharum

The seasonal dynamics of an indigenous entomopathogenic nematode, a new str ain of Heterorhabditis bacteriophora, "Nittany strain," in a stand of sugar maple, Acer saccharun, were examined utilizing a Galleria mellonella bait method. Seasonal dynamics are described in relation to soil temperature; oc currence is related to distance from a tree bole. A correlation between soi l temperature and the number of infected G. mellonella was observed. Soil t emperature had a significant effect on the number of positive samples, i.e. , soil samples containing infected G. mellonella, obtained. In addition, se asonality had a significant effect on whether positive samples were obtaine d on a given date. There was no significant difference in the abundance of positive samples among three distances from a tree bole, namely, at the bas e of the tree, 2 m from the bole, or at the dripline. (C) 2000 Academic Pre ss.