A tiny pest known as the wheat log saw fly can overgrow a wheat field in a short amount of time and costs farmers a wad of money every year. In Montana alone, producers are losing more than $ 25 million to this local villain, who of course isn’t hampered by man-made geographic lines. The pest harms producers in northwest North Dakota as well as producers in northeast Montana.
Research ecologist Dr. Tatyana Rand from the USDA-ARS department here in Sydney, who will speak about the wheat log saw fly during MonDak Ag Days.
Rand has looked at a variety of things that could help defeat the wheat stem saw fly over the years, and she is particularly interested in using natural predators against it. Among these are a few braconid wasps – almost as small as the sawfly itself – that could be useful in saving wheat fields from danger.
Bracon cephi and B. lissogaster have a very effective attack on wheat log saw flies. They lay eggs in the pest larvae and paralyze them, which prevents the sawfly from eating the wheat stem.
When a sawfly climbs into a wheat stalk to eat the stalk, it’s all but impervious to more traditional management practices like pesticide application. The sawfly eats up the wheat stem and lays the plant over it before it can be harvested. But if the wasp finds it first, the wheat will be saved and can continue to stand tall.
Some wheat fields are lucky enough to have plenty of these little Superman wasps flying around, while other wheat fields have practically none at all. Figuring out why some fields have wasps and others don’t is one of the many research projects Rand undertook while working at the USDA-ARS research laboratory in Sydney.
Rand speculates that some fields are lacking these useful wasps because they lack flower nectar sources to power the wasps. After all, it takes a lot of energy to fly around in a field and look for exactly the right host for your eggs. Nectar snacks can keep wasps going until they find what they’re looking for.
Goldenrod, sunflowers, and other native plants could be key to attracting beneficial insects that can help farmers keep the sawfly population at bay in their wheat fields.
Another study that Rand is involved in is a collaboration that looks at cover crops. Test strips have been planted with radish, beet, peas, lentils, etc., and several scientists are collecting data from the strips to better understand the pros and cons of cover crops.
Rand examines insect populations in the cover crops and in two oilseeds that could serve as replacements for Chemfallow in two-year wheat field rotations. It tracks populations of both beneficial insects and pests.