Home Brewed BiocontrolJohn Knecht

IntroductionAlfalfa snout beetle (ASB) is an invasive species that came to New York in shipping ballast in wooden boats. Thus far it is only a problem in a few counties in northern New York and some areas of Ontario.

ASB is a pest of alfalfa. While the adults do feed on leaves, the real damage is done to the roots by the larvae. The larvae eat the roots and a heavy infestation can quickly kill a stand.

Elson Shields’ lab have developed a biological control of ASB larvae using entomopathogenic (insect attacking) nematodes. For the past few years the lab has been rearing nematodes at Cornell and transporting them to the farms, where they were applied to alfalfa fields.

This internship taught growers how to rear and apply their own nematodes.

Infested area as of 2007(red)- the infested area has grown since then, but there is no new survey.

RearingThe process of rearing and applying nematodes is fairly simple. There are two main steps. The first is rearing Cups of wax moth larvae are inoculated with nematodes that are provided to them (see picture below). The nematodes attack the larvae and reproduce. Each cup can produce up to 25 million nematodes! When the cups have been inoculated, they are placed and a warm (70-80°F), temperature controlled room for around 12-14 days.

ApplyingThe final step of biological control with nematodes is applying them to the fields. First the nematodes must be removed from the cups of moth larvae. This is accomplished by sifting out the debris and moth larvae with a window screen and hose (see above center). The nematodes go through the screen with the water, but most of the debris does not. The nematodes are then poured into the sprayer. 8 cups of nematodes (200 million nematodes) will make 50 gallons of spray and covers an area of about an acre.

Now that the nematodes are in the sprayer, the field is sprayed. The field should be sprayed perpendicular to the direction that the field is plowed. This way, when the field is plowed, nematodes will be spread around.

Nematodes can be applied with a regular chemical sprayer (taking certain precautions) or a variety of homemade devices. The sprayer below was gravity fed. The Shields’ lab uses a pickup with two 50 gallon tanks and pumps that run on the truck’s battery.

Doug Shelmidine’s son inoculates wax moth larvae

Gary Sullivan and I strain nematodes photo courtesy of Allyson Jones-Brimmer and Joe Lawrence

Mike Kiechel uses a three point hitch sprayer

Gary Sullivan sprays with a gravity fed sprayer made from PVC pipe photo courtesy of Allyson Jones-Brimmer and Joe Lawrence

2nd (foreground) and 3rd (background) year alfalfa fields that were cut the same date, infested with ASB. The 3rd year stand has extensive damage.