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A bit about Imidacloprid Bees and such.

Posted by IpmMan none (My Page) on
Sun, Sep 11, 11 at 11:14

The fact that I recommended this for a scale problem in another post does not mean that I am not only aware of, but also concerned about the possible link between Imidacloprid and Bee deaths. In my practice and in my writings I always recommend that oils and other methods be the first choice for controlling Scale and many other insects.

Imidacloprid is used far too frequently for insects that don’t exist are not a problem, or can be controlled by other methods. People chuck this stuff around for lawn grubs that have populations too low to cause damage or as preventatives and cure all's for trees and shrubs, without identifying a problem. Indeed I hear one local host of a radio show recommending this for just about every problem. That said there are places and reasons where this chemical is an appropriate choice.

Oil, my first choice is not always easy to apply properly, especially for the homeowner.
You need to get one hundred percent coverage to kill scale and have to treat several times. Timing is critical to get the crawlers (juvenile scale). Even with my spray rig I cannot treat all trees due to size or location. So taking the case of say the Cherry that this discussion originally came from. Yes by all means use the oil first. However, if a one-time treatment with Imidacloprid for a scale that will kill the tree is preformed then I proffer this justification. Assuming that I will knock off a few bees in the short term, but completely rid this tree of the problem, then the tree will live for many more years and supply countless bees with pollen long into the future.

In addition whether I use oil or Imidacloprid, I then will teach my customers how to avoid scale problems. Most scale and many other pests have numerous natural enemies that are frequently killed by unknowing homeowners. One Lacebug problem I had with a customer persisted even with several Oil treatments. It was not until I saw a note on the door that I figured out why. The note was from a Mosquito control company and it read that the yard was treated with Bifenthrin, a notorious predator killer. So I was killing pests and they were killing predators.
Other things that will help the survival of predators are such things as trying to keep something flowering all season, and having some fresh water available.

So before turning to Imidacloprid or any other chemical treatment please at least.
1. Identify the problem.
2. Decide whether the problem needs to be treated. Are the populations high enough to cause damage? Which and how many predators are present? Is the insect at the end of its damaging stage? Is the insect at a treatable life stage? Are other conditions such as weather about to control the pest?
3. See if this insect can be controlled using cultural or mechanical means? And think if you are encouraging it.
4. If you do need to treat, treat with the least hazardous option first.
5. If nothing else works and you have a plant that is worth saving, then you can turn to an effective, and labeled chemical option.
By the way just for the sake of discussion, Spinosad the bio-rational pesticide has a very similar mode of action to Inidacloprid.

Follow-Up Postings:

RE: A bit about Imidacloprid Bees and such.

  • Posted by hortster 6A southcentral KS (My Page) on
    Sun, Sep 11, 11 at 13:06

In this area we have had a serious onslaught of lecanium scale, especially on oaks but now also many other species. The "one cure fits all" attitude has been suggested as the reason for the spread of lecanium - obscure scale on oaks was the initial plague so neighborhoods were doused with products for control; unfortunately populations of predatory insects were greatly reduced.
Now, along comes lecanium, almost unhindered by the dearth of predatory insects and now even more species of trees are affected.
A shingle oak in my yard has a heavy infestation of lecanium, and my treatment for two years has been...nothing. The tree looks fine. Inspection of the scales shows predatory action (entry holes in most of the scales). The point is, most of the time nature will take care of insect population imbalances by itself if we don't douse everything with products and mess with the natural cycle.
Having said that, I agree with IpmMan that sometimes, to save a plant or tree it may need to be treated, but start with the environmentally gentlest solution and work up from there. More is less.

RE: A bit about Imidacloprid Bees and such.

I have been seeing a lot more scale problems in the last few years. I am convinced, but have no scientific evidence that this has a lot to do with the increased use of Bifenthrin and other chemicals for mosquito control. Many so called practitioners of IPM use Bifenthrin for everything.
One large nursery I work with was plagued with Scale of all types. They were serviced by a large outfit who frequently treated with Talstar. I have stopped this practice for the most part, they still sneak it in under other names but it is still Bifenthrin. The scale populations have definitely been reduced and predator activity has increased. That is not to say that Bifenthrin should not ever be used, I have used it myself, but it should not be generally sprayed around to control everything.

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