It has been in the news, of course, about the severity of the 2013/2014 winter with record breaking low temperatures and higher than normal snow amounts in many locations. So how does all this translate to crop insect pests? As an article that I read last week said, “It’s complicated”.
There are many factors that affect insect mortality through the winter months. It is not only just the cold, but the amount of snow cover, overall fitness of the insects going into the winter diapause (hibernation), how well protected were they from the cold, what the weather conditions are coming out of winter, and so on.
What to Expect
Local native insects are much more likely to survive the winter than southern migratory insects. Corn earworm, Helicoverpa zea, may be one of those casualties. In mild winters, corn earworm survives the winter further north than normal. With very low temperatures extending deep into the south, repeatedly, there is likely going to be a higher mortality than usual. Does that mean we’ll have fewer corn earworm problems this year? Maybe. How well the earworm population rebounds from adverse conditions depends upon another set of factors, such as availability of food sources, how well did predators of the earworm survive and weather conditions across the southern tier of states and Mexico.
How well invasive species, such as brown marmorated stinkbug, emerald ash borer and others survive depends upon the habitat where they originally came from and how well they have been able to adapt to their new surroundings and the natural enemies here.
It isn’t possible to make a blanket statement that there will be fewer crop pests this year. It depends upon each species of insect and what requirements they need to survive the winter. Undoubtedly, this was a stressful winter for many species, but it may have been advantageous to some pests.
Anticipate that early season pests, such as aphids and seed corn maggots, will be there. If the aphids survived better than their natural enemies, there could be more aphids than usual. We’ll have to wait to see how well cabbage looper, corn earworm, fall armyworm and potato leafhopper survived and how much of a problem they’ll be.
So, be happy that we are finally getting some warm temperatures, but don’t be lulled into thinking that the crop pests will be fewer, or gone. Maybe they will but don’t bet the farm on it.