Farms.com Home   News

Insect Pest Survival During A Harsh Winter

Christian Krupke and John Obermeyer

  • Most corn and soybean insect pests overwinter beneath the soil surface.
  • Soil and snow insulates insects from wild temperature fluctuations.
  • Insects change their body chemistry to withstand freezing.

The questions abound from farmers and homeowners alike, did the Polar Vortexes of the 2013/2014 winter reduce insect populations? Though the correct answer is, nobody knows with certainty, but it pays to consider some basic facts.

Insects have adapted to varying environments throughout the world, ranging from desert to frozen tundra. They utilize various means to survive harsh temperature extremes, or some die out and return every year, see table below. Insect pests that overwinter in Midwest, do so under plant residues or in the soil, in order to insulate from wild fluctuations. Most of our key pests have lived in the area for many decades. Once the cold sets in, chemical changes within their body occurs that prevent freezing, and allows for them to “sleep” through the winter. Being induced to “wake up” too early, by unseasonable temperatures during the winter, uses precious body fat reserves. Should this happen multiple times, then death by starvation is likely. So in some ways a long, cold winter has advantages in that the temps are relatively consistent.

white grub in wintering earthen cell

White grub in wintering earthen cell

Refer to the chart below. Air and soil (4” depth), temperatures are compared at the Purdue ACRE farm in Tippecanoe County. Average and high/low temperatures are given for the months of December through February. This shows that temperature fluctuations of the air (what we experienced) made for an unbearable winter. Contrast that to the soil temperatures. With the probe just a few inches in the soil, the temperature extremes are greatly tempered. Add to consideration is the snow that was present for much of the state throughout the winter. As you would expect, another insulating blanket to assist the overwinter insect. However, insects that overwinter above the ground, including soybean aphids and bean leaf beetles, will suffer higher mortality as a result of a harsh winter.

So, will insect pests numbers be reduced by the memorable winter of 2013/14? Yes, but they are every winter. For example, rootworm eggs that are laid at, or just below the soil surface, likely desiccate from air exposure. For the female beetles that ventured down soil cracks, earthworm holes, etc. to depths of 6” or more, their eggs will be ready for this season’s corn roots. Same can be said for the assortment of grubs, wireworms and maggots many of which overwinter far below the surface where soil temps are relatively consistent.

Insect Pest

Overwintering Stage

Where

Seedcorn maggot

Pupa

Soil

Japanese beetle

Larva (grub)

Soil

Wireworm

Primarily larva

Soil

Black cutworm

*

-

Other cutworm species

Larva

Soil

Western bean cutworm

Pre-pupa (larva)

Soil

Armyworm

*

-

Slugs

Eggs/adults

Under residues

Corn rootworm

Egg

Soil

Bean leaf Beetle

Adult

Under residues

Potato leafhopper

*

-

Twospotted spider mite

Adult

Under grassy residues

*Don't overwinter in Indiana

graph for winter 2013-14 air and 4" depth soil temperatures ACRE (West Lafayette, IN)

Source : purdue.edu


Trending Video

Using Weather Forecasts to Grow a Crop

Video: Using Weather Forecasts to Grow a Crop


BY: Ashley Robinson

Growing a crop isn’t easy. There’s a lot of variables involved, a major one being weather. And while you can’t control weather, you can use weather forecasts to help you make informed decisions regarding your crop. This could include application of insecticide, herbicide or fungicide treatments, scheduled irrigation or swathing your crop.

On the Nov. 29 episode of Seed Speaks, we’re taking a closer look at how you can use weather forecasts to grow the best possible crop. We’re joined by Chris Manchur, agronomy specialist for eastern Manitoba with the Canola Council of Canada (CCC); David Clay, distinguished professor of soil science at South Dakota State University; and Wade Kent, senior principal digital agronomist for Nutrien.

Manchur provides agronomic advice and support to growers and agronomists in Manitoba. He’s also the sclerotinia stem rot lead for the CCC and helps to manage canola research and innovation through funding programs such as the Canola Agronomic Research Program and the Sustainable Canadian Agricultural Partnership. Manchur received his bachelor of science degree in plant biotechnology and master of science in RNA interference-based next generation fungicides at the University of Manitoba.

Clay is the past president of the American Society of Agronomy, and Corn Councils Endowed Chair in Precision farming. He has spent over 30 years investing soil health, has published and been awarded numerous awards and is a Fellow of the American Society of Agronomy.

Kent is located in North Central Iowa and farms corn and soybeans with his dad in his spare time. He spent his undergraduate and graduate career at Iowa State University and University of Minnesota studying agronomy, crop physiology, and soil science. At Nutrien, Kent works in the digital and precision landscape focusing on bringing together agronomy and technology to improve efficiency, profitability, and sustainability of Nutrien Ag Solution’s customers.

Join us on Nov. 29 at 12 p.m. CST on Seed World U.S., Seed World Canada, Seed World Europe and the Alberta Seed Guide’s Facebook pages, Seed World U.S.’s LinkedIn page and Seed World Group’s YouTube to watch the discussion.