The effect of storage temperature (9 and 20Â°C) on North West European Heterorhabditis megidis isolate UK211 for control of Otiorhynchus sulcatus larvae at 9Â°C 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 invading the insect larvae increased almost 27-fold. Nematode storage at 9Â°C for 11 to 12 weeks weeks resulted in significantly higher O. sulcatus mortality (41%) than storage at 20Â°C for 2 to 3 weeks (12%). Thus, cold storage does enhance nematode infectivity for O. sulcatus larvae.