Alfalfa snout beetle (ASB), Otiorhynchus ligustici (L.), is a very severe pest of alfalfa, grown in areas of northern New York and southeastern Ontario, Canada, bordering Lake Ontario and the St. Lawrence River. ASB often kills out entire fields in a single year from larval root feeding when populations are high. This parthenogenetic insect was first reported in North America in 1896 in Oswego Co., NY,where it was introduced by the dumping of sailing ballast between 1848 and 1896. ASB was

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... fied as an alfalfa pest when alfalfa was introduced into the area in the 1920's. With ASB adults and larvae spending all of their 2-year life cycle in close association with soil, a biological control strategy focused on the use oflocally adapted persistent entomopathogenic nematodes (EPNs) appeared to be a logical research direction. Research was initiated in 1989 and these studies were conducted primarily on a single farm (the John Peck Farm, located in Great Bend, Jefferson Co., New York) that historically contained extremely high populations of ASB. In 2002, the Peck Farm experienced an unexpected and sudden collapse of the ASB infestation. Subsequent studies on the Peck Farm revealed that the combination of two locally adapted nematodes had dispersed throughout the entire Peck Farm. We believe that the coexistence and soil residence partitioning of H. bacteriophora 'Oswego' with the native S. carpocapsae 'NY001' together exposed a wider range oflife stages of ASB to nematode attack and subsequently applied enough biological control pressure on snout beetle to reduce the population to sub-economic levels. This research suggests that using locally adapted EPNs in a multi-species application provides a more effective approach to the biological control of ASB and potentially that of other soil pests.