Evaluation of biological activity of biopreparations containing nematodes from the genera Steinernema and Heterorhabditis used for reducing large pine weevil Hylobius abietis L. population in pine Pinus sylvestris L. stumps

Przemysław Szmit

The use of entomopathogenic nematodes (EPNs), such as Steinernema and Heterorhabditis spp., against the large pine weevil Hylobius abietis has been mainly studied in the United Kingdom and Ireland. The results of these studies show a great potential of nematodes for H. abietis control. Similar research conducted in Poland aimed at evaluating effectiveness of commercially produced biopreparations that contained entomopathogenic nematodes and were applied against the large pine weevil. The treatments consisted of spraying soil around Pinus sylvestris stumps with an aqueous suspension of Steinernema carpocapsae, S. feltiae and Heterorhabditis bacteriophora, H. downesi, H. megidis at a dose 3.5 million IJs/1000ml of water per stump. The roots of experimental stumps were analyzed 4 weeks subsequent to the treatments. After roots debarking, H. abietis larvae were isolated and the percentage of insects parasitized by EPNs was assessed. All tested nematodes showed ability to parasitize H. abietis larvae overwintering in P. silvestris stumps. The highest extensivity of parasitizm was observed in H. abietis larvae parasitized by S. carpocapsae and H. downesi, and the lowest - in the case of larvae collected from the roots of the stumps sprayed with H. megidis. There were no nematodes found in H. abietis larvae collected from untreated – control stumps.