In an effort to control a snout beetle population of more than one million beetles per acre, we released persistent entomopathogenic (insect-attacking) nematodes on the John Peck farm in Great Bend, N.Y., in a series of research plots during the 1990s. The farm`s snout beetle population crashed in 2002 and has remained very low since then, while neighboring farms still harbor these extremely high snout beetle populations. A farmwide soil survey documented the presence of the released nematodes throughout the Peck farm, including in fields where they were not released. The frequency of nematodes in soil samples from the Peck farm is very similar to the frequency of nematodes in soil samples taken in Hungary, where the snout beetle is not considered an economic problem.

Alfalfa snout beetle (ASB), Otiorhynchus ligustici, is the most destructive insect pest of alfalfa in North America. This insect was first discovered in the 1930s infesting 3,000 acres, and has currently spread to more than 500,000 acres. Fortunately, this insect is currently confined to a nine-county region of northern New York and a small infested area in Canada where it invaded across the St. Lawrence River. Feeding on alfalfa roots by the larvae of this pest causes severe alfalfa yield and stand losses. New infestations are often mistaken for winter injury since the majority of plants die after the last harvest and before spring growth. This is the only alfalfa insect in the United States that frequently kills entire alfalfa fields in a single season. To date, there are no effective methods of controlling this destructive insect pest.

Research was initiated in the early 1990s focused on developing a successful management strategy for this very serious and economically damaging insect. Since insecticides were ineffective and alfalfa is a relatively low-value crop, a major emphasis was placed on the identification, evaluation, and establishment of a biological control organism that would become permanently established within the infested area and would spread naturally throughout the farm. Soil surveys throughout the snout beetle-infested region yielded three species of entomopathogenic nematodes at barely detectable numbers. These nematode species were reared and tested for efficacy in the laboratory and greenhouse before being released on the Peck farm. Multiple field plots were established in multiple years to test field efficacy of these nematodes and application timing and to develop application techniques.

A snout beetle population of more than one million beetles per acre on the John Peck farm in Great Bend, N.Y., first crashed in 2002 and has remained very low in the subsequent years of 2003-2006. Neighboring farms still harbor these extremely high snout beetle populations. Persistent entomopathogenic (insect-attacking) nematodes were released on the Peck farm in a series of research plots during the 1990s to examine the field efficacy of these nematodes and application timing and to develop application techniques. A farmwide soil survey documented the presence of the released nematodes throughout the farm, including in fields where they were not released. We believe that this nematode movement was a combination of soil movement during normal farming practice, natural nematode movement, and the movement of infected beetles before they died. The frequency of nematodes in soil samples from the Peck farm is very similar to the frequency of nematodes in soil samples taken in Hungary, where the snout beetle is not considered an economic problem. We believe that the data indicate that biological control of the alfalfa snout beetle has been successful on the John Peck farm. Future research will be directed toward spreading the success achieved on the Peck farm throughout the nine-county region in northern New York, covering more than 500,000 acres of agricultural land, that is infested with the beetle.

NNYADP

• Elson Shields (Dept. Entomology, CALS)
• Tony Testa (Dept Entomology, CALS)