Several insecticidal fungi are being tested in farmer's fields in northern NY for their ability to control the alfalfa snout beetle, a widespread, highly damaging pest that feeds on both foliage and roots of alfalfa.

The alfalfa snout beetle (ASB) is among the more severe pests of alfalfa in North America, capable of destroying entire alfalfa fields within a single growing season. The insect was first discovered in the late 1890's, and currently infests approximately 200,000 acres of cropland (~13% of the total NY cropland), covering 8 counties in Northern New York as well as areas in eastern Ontario along the St. Lawrence River. ASB was introduced from Europe by ships discharging soil/gravel ballast onto the shores of the St. Lawrence River and Lake Ontario. The flightless beetle has been expanding its range ever since by walking, moving along waterways, and hitching rides on farm equipment. Concern over the environmental impact of the more effective chemical pesticides has led to many being discontinued, hence, ASB populations have been expanding rapidly without an effective and ecologically-sound method of control. Research to develop effective, environmentally-friendly and inexpensive biocontrol methods is essential for sustainable agriculture in upstate New York.

We are testing the effectiveness of insecticidal fungi to control ASB outbreaks in northern NY. We selected 3 fungal isolates, two Metarhizium anisopliae and one Beauveria bassiana, that produced 100% beetle mortality in 10-12 days, and 80-90% beetle mortality in 21 days in our laboratory tests. In spring 2003 and 2004, test plots in an infested field in Jefferson County were inoculated with two species of insecticidal fungi. Soil samples taken at several times across each growing season have been used to test the survival of the introduced fungi and to assure that introducing these fungi does not cause any adverse changes in the bacterial, fungal or arthropod populations in the soil. In 2004, we also tested methods of inoculum delivery; a pellet-like treatment that is tilled into the soil prior to planting, or a spore suspension that can be sprayed onto the crops and soil surface much like chemical pesticides. Results of growth chamber studies in 2004 suggested that root secretions from crops in particular plant families may enhance the level and/or persistence of insecticidal fungal populations in the soil, allowing for a more long term control of ASB populations. In 2005, we assessed the effect of crop rotation on persistence of the insecticidal fungi in the soil at the Baker Farm. In 2005, we also started field tests of a commercially available inoculum containing B. bassiana. Crop damage has been assessed in all trials in all years.

The results from these field trials indicate that introduced insecticidal fungi are an effective means of beetle control, but that populations decrease to background levels after two growing seasons, regardless of crop rotation. Thus, more inoculum must be applied in order to maintain significant insect control in areas of heavy infestation. While biological control has the potential to reduce crop losses with less environmental impact than traditional chemical pesticides, it is still more expensive to produce in large quantities and there are regulatory hurdles that must be overcome. The cost to introduce new strains targeted to specific pests are substantial (>$500,000 for regulatory requirements alone). Therefore, we are aiming to test fungal products currently marketed for their efficacy on controlling ASB and are working to develop inoculum production processes that are economically competitive with chemical pesticides. By developing biological control agents that are both cost effective and ecologically sound, it will be possible to implement effective control of ASB. Use of insecticidal fungi must be incorporated into a complete pest management strategy that will help reduce infestation levels in affected regions. This approach has the potential to save the farming community tens of thousands of dollars incurred every year from crop damage.

• Mike Hunter (CCE-Jefferson County)
• Anita Deming (CCE-Essex County)
• John Peck (Peck Farm)
• Crew (Willsboro Farm)
• Chris Jones (CSS-Swedish Agric. Univ.)