In the struggle between good bug and bad bug, few battles have been won more decisively than that waged by predatory wasps against the Russian wheat aphid.
Washington State University entomologists, who propagated and released more than a million parasitic wasps into wheat-growing areas in the early 1990s, say these tiny beneficials have now virtually eliminated the population of Russian wheat aphids that once affected as much as a half-million acres of wheat and barley crops.
Parasitic wasps aren't a wheat grower's only allies in the battle against insect pests. Beneficial species such as predacious flies and ladybird beetles also feed on aphids. In fact, researchers have found that a single adult ladybird beetle can eat thousands of aphids in a lifetime.
While few beneficial species can take on a crop pest single-handedly, scientists see a synergistic relationship between beneficial insects and the use of seed-applied insecticides like Gaucho, now used by many wheat and barley growers to protect their crops from aphids, wireworms and other insect pests.
Applied directly to the seed coat prior to planting, Gaucho is absorbed systemically into the plant as the seed germinates and starts to grow. So while Gaucho provides control of the insect pests that feed on the seeds and seedlings, it poses essentially no risk to the beneficial species and minimal environmental risk.
“Because Gaucho is applied to the seed at extremely low rates of use, very little material is actually introduced into the soil,” says Bill Hairston, manager of product development at Gustafson LLC. “Research has shown that much of the material is taken up into the plant where it provides protection against feeding insects.
The extremely small amount of material left in the soil doesn't leach in the soil, and it degrades quickly enough to prevent significant soil accumulation, even when seed treated with Gaucho is sown year after year.”
Now labeled to protect corn, cotton, canola, potatoes, sorghum, wheat and barley from a host of early season insect pests, seed-applied Gaucho is also easy on pollinating insects. Research trials around the world have shown that seed-applied Gaucho has no effect on bees and other pollinators that feed on the nectar of plants grown from seed treated with Gaucho insecticide prior to planting.
“Seed-applied insecticides offer a nice fit with the environment,” says John Burns, WSU Extension agronomist.
“Systemic insecticides like Gaucho that are absorbed into the plant tissue pose no risk to the beneficial insects in the field. And because these seed-applied materials go in the seedbed, under the soil, there's very little exposure to the environment.