Tuesday, February 21, 2012

An Invasion?

Mike Gray, University of Illinois Extension entomologist, has some insect predictions for the coming growing season 2012. 

"Japanese beetle infestations will continue to vex producers this year," Gray said.  The Japanese beetle grubs will burrow down at least two foot if the ground freezes that deep.  With such a mild winter, I can't imagine many grubs died.

David Voegtlin, a retired entomologist with the Illinois Natural History Survey said soybean aphid populations may be down.  Gray observed, "The fungal epizootic swept through the impressive aphid buildup on buckthorn and decimated the population." 

The European corn borer reached all-time population lows across Illinois last year.  Gray expects them to be hardly noticeable this year.  The western corn rootworm densities are low.

“Considerable speculation has arisen regarding whether or not the large-scale increase in Bt usage may be suppressing corn rootworm populations, similar to what happened with European corn borer densities,” he said.  He suspects environmental conditions last season served as the major contributor to the collapse of the corn rootworm population.  The wet soil conditions last spring resulted in high mortality of western corn rootworm larvae soon after hatch occurred."

It’s too early to assess the potential impact of insects that migrate into Illinois such as black cutworms, corn leaf aphids, potato leafhoppers, fall armyworms and corn earworms. Weather is a critical factor surrounding if insect populations will have successful migrations.

For insects that overwinter above ground the mild winter temperatures have been good.  If we should get a freeze, the lack of snow cover will leave them exposed and in danger.

Having sunny mild winter days may cause overwintering insects to become active before they have food.  This activity causes them to use stored energy and they could starve before spring. An insect gradually winterizes it's body.  Having swings between 0-50 can increase death rates.

Should there be a late hard freeze, many migrating insects could be killed. And should there be a cold snap later when the leaves are on the trees, that could cripple the insect population for lack of food.  Gray adds , they’re all pretty hardy, in fact a lot of insects actually need a cold snap to develop, so don’t count on that.

To the sadness of all out door people, the mosquitoes will survive.

Death due to weather conditions affect both beneficial and destructive insects.  This can be good as populations may even out.  More than the mild/harsh winter factors, what happens in the spring can cause more insect damage.  Cool damp springs encourages the development of fungi that attack insects.

It's predicted, critters may double their populations this year due to mild winter weather.  Not especially good news for gardens where deer frequent.

Bee populations have drastically decreased over the years.  Loss of habitat and insecticide use are blamed for much of that decrease.  Having a prolonged late winter freeze might cause them to starve.

Bottom line:  those in the know are making their predictions and all of them hedge their bets right along with your favorite weatherman.  The science of prediction is still a guess; even if based on history, science, data and observation.   

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