Clean, cool and dry bins treated with the right insecticide are the key to preventing bug troubles, says Paul Fields, a research scientist with Agriculture Canada.
Fields told the Agronomy Update meeting here that if grain is warm and moist, a small number of insects can increase exponentially.
Of about 20 insects that live in grain, one of the most common is the rusty grain beetle, which can go from egg to adult in three weeks under ideal conditions. The adults can live for almost a year and the female produces 400 eggs.
The flour beetle is another common insect found in grain bins. It matures in three to eight weeks and lives for about 45-70 weeks.
Fields said many of the insect species are very hard to detect, and are often only found in the dockage tester during sampling at elevator delivery.
Mites and psocids, which are about the size of a period, can also live in grain.
“If you see this sort of fuzz moving around on your grain, it’s probably mites or psocids and the grain is too moist,” said Fields.
Producers can detect insects in their own bins by using a Berlese funnel, which uses a screen and a light bulb to find larva in the grain. Traps using cones and probes can also be used to find insects.
“The insects walk around, fall down holes and then collect in the bottom and you can pull them out,” said Fields. The traps are 10 times more effective than just taking samples of the grain because the traps are continuously in operation.
Another way to detect insects is to measure carbon dioxide levels. Increased carbon dioxide indicates the presence of insects.
Cold winters give Prairie farmers an advantage over their warm-climate competition.
“If you can reduce the grain to -15 C and keep it there for a month, you will kill all the insects,” Fields said.
Before binning, producers can apply insecticide to empty bins to reduce the possibility of residual insects or insects living in the false floors or aeration units. However malathion should not be used in bins to be used for canola, as residue could contaminate overseas shipments. Resistance problems are also being reported in Western Canada.
Diatomaceous earth, which can be mixed with dry grain and kills insects on contact, is a non-toxic option for stored grain.
Fumigants such as phosphine are quick and leave minimal residues, but are very toxic. Use is restricted and a licence is required. It can be used when the grain temperature is -5 C. “This is not air temperature, that’s grain temperature,” said Fields.
The chemical is delivered in pellets and water is added to transform it into a gas.
Fields said there has been some phosphine resistance detected in the U.S. and in Australia.