Improved control of Otiorhynchus sulcatus at 9 degrees C by cold-stored Heterorhabditis megidis UK211

The effect of storage temperature (9 and 20 degreesC) on North West Europea n Heterorhabditis megidis isolate UK211 for control of Otiorhynchus sulcatu s larvae at 9 degreesC is assessed. O. sulcatus mortality increased from -5 .3% (corrected mortality) using freshly produced nematodes, to 27.1% using nematodes that had been cold-stored for 12 weeks. The number of nematodes i nvading the insect larvae increased almost 27-fold. Nematode storage at 9 d egreesC for 11 to 12 weeks weeks resulted in significantly higher O. sulcat us mortality (41%) than storage at 20 degreesC for 2 to 3 weeks (12%). Thus , cold storage does enhance nematode infectivity for O. sulcatus larvae.