Roberto,

are there any data supporting your statement?
Thanks!

I don't know about the assertion that they are toxic to bees in sub-detectable amounts, but neonicotinoids have been found to have an extremely deleterious effect on bees of all stripes, interfering with their ability to navigate, slowing colony growth, and greatly affecting the ability of the colony to rear new queens, meaning that when the current queen goes, so goes the colony. Exposure to neonicotinoids can also increase the susceptibility of bees to other common agricultural chemicals and decrease their ability to deal with natural threats such as the parasitic fungus Nosema. Add to this the fact that the neonicotinoids are systemic, migrating to pollen and nectar, and quite persistent (some studies have found that woody portions of plants, at least, may retain them for years - not that they are a threat to bees while sequestered there, but just evidence of their persistent nature) and there is real cause for concern. For popular reading, search Wired Science for a couple good overview articles, while the scientific literature is extensive.

As for alternatives, spinosad, while actually highly toxic to bees, seems to only pose a threat for a short duration after application - three hours, give or take, is the number I've come across. So if you apply at night, while bees aren't foraging, it is not much of a concern (it is also highly toxic to lepidoptera - like CLM - and there, are, of course, nocturnal moth pollinators; I'm not sure if any favor citrus or not). Neem is generally safe for pollinators and other beneficials, but should probably also be applied at periods of low activity. Pyrethrins pose few threats to bees if applied at non-forage hours, due to the fact that the degrad rather quickly in sunlight This, however, also means they have little residual effectiveness, and I don't know whether they would kill established CLM larvae or not, as I never use them. Insecticidal soaps and horticultural oils are also completely bee-safe, as long as the bees aren't sprayed directly. Of course, none of the aforementioned products is systemic, and as mentioned previously, the overuse of any one (except perhaps soaps and oils, which act in ways that would be difficult for pest insects to overcome through incremental mutations) can lead to resistance in the pests. Rotating what you use can help on this second count.

From what I've read and heard and my meager two year's experience, CLM just isn't enough of a threat to the health of the tree for me to worry too much about it, although I am sure that the resulting leaf contortions reduce the surface area available for capturing sunlight. Earlier this summer, I used sesame oil from the cupboard, diluted to roughly 1:20 oil:water ratio on the one small tree the CLMs seemed to favor at the time (it received filtered sunlight in the afternoon, so burning wasn't an issue). As the CLM population mounted over the past two months I used one night-time application of spinosad and one of a horticultural oil that combined sesame and fish oils (and was, surprisingly, only marginally more expensive than mineral oil), and some mechanical control, but again only on the small trees (seedlings and two-year trees). Both worked well, and this was said by others in the area to be a bad year for CLM. Next year perhaps I will just build a small fine-mesh-screened hoop-house for the seedlings. Is all this practical for a commercial orchardist? Perhaps, perhaps not, but for a dooryard grower it's working just fine for now. Only my brief experience, though.

Perhaps, too, fertilizing aggressively early on and decreasing N applications, in particular, as the summer proceeds might shift foliar growth earlier in the summer, before the CLM populations mount. Just a thought; any one else have input on this tactic?

Certainly when you feed almost any insecticide directly to a bee, it's deleterious -- bees are highly susceptible to many classes of insecticides. However, imidacloprid, applied to the root system of a citrus tree, seems to be fairly safe if used according to the label. The Florida industry uses incredible amounts of it, and we do not commonly see bee kills. The so-called "sudden-death" syndrome of bee colonies, which was at one time attributed to imidacloprid, now seems to have nothing to do with that material.

An interesting aspect of that product is that it does not move very well into flowers. That's a real problem in the flower-production industry, in that you can't get it to control thrips or other flower-feeding insects -- it just won't go there. But in this case, that's a good thing -- it also doesn't seem to affect the bees collecting from our citrus flowers.

Orange Blossom Honey used to be quite popular. I don't really buy any so I'm not sure if it is still sold. If it is the honey industry would be raising cain if the Imidacloprid was having an effect on the bees as that is their livelyhood.

I think as Dr. Manners stated it once was THOUGHT to have a bad effect on the bees but actual usage in the field not in the labs does not support the lab findings.

Additionally in France where a lot of the studies were done, areas not in the test program still have CCD even though there are no users of Imidacloprid.

The field studies just don't support the lab results.

elsedgwick,

with all my respect, can you refer to a recent comprehensive study published in a reputable journal (Nature, Science, etc.) that would support your statements? From all I read about imid, I learned the opposite to your post.

Dr. Manners, Darkman, thank you very much for the confirmation!

Also, perhaps CLM is of little concern for GA growers (or mature trees)... I observed the opposite and have a couple of small recently grafted plants defoliating after a CLM attack because I did not spray them at the right moment.

One thing I can tell you is the new Bayer Advance also has fertilizer in it. You don't want to be adding any fertilizer this time of year to inground trees.

GT, go to http://en.wikipedia.org/wiki/Neonicotinoid and in the chapter "Environmental impact" some studies are cited.

Laaz, it must come in different formuations, then. What we get here has no fertilizer in it.
Malcolm

I really don't want to get into an article war (or any war at all - I'm clearly outnumbered - yikes). However, just thinking of 2012 articles I've come across in Science, try:

Whitehorn et al., Science 336 (6079): 351-352 (April, 2012) Neonicotinoid Pesticide Reduces Bumble Bee Colony Growth and Queen Production, found a nearly 85% decrease in queen bee production in bees exposed to imidiacloprid will note that this study invovles the humble bumble, rather than honey bees. You will also note the exposure was done in labratory conditions, but at levels simulating field exposure.

Henry et al., Science 336 (6079): 348-350 (April 2012) A Common Pesticide Decreases Foraging Success and Survival in Honey Bees, found that thiomethoxam exposure resulted in disorientation, sometimes to a degree that bees were unable to forage and return to the hive.

Is there a smoking gun that would leave Florida's apiaries littered with dead bees. No , especially since they can't find their way back to the hive. That's a joke, but seriously, even most virulently "anti-neonic" studies I have read suggest that field-level exposures would typically result in sublethal effects, not massive dieoffs (they have been observed, to be sure, but generally due to improper application). And on the point of field exposure, although I haven't seen citrus or petal studies, imidacloprid has been found to migrate into corn pollen and sunflower pollen and nectar, even from seed treatments using amounts that are miniscule compared with those used in soil drenches, let alone spraying programs. On the other hand, we have seen honey bee populations in the U.S. decline by half since the mid 1940's (not coincidentally, around the time when pesticide production and use really began in earnest on an industrial scale, as the U.S. turned its swords into ploughshares), with roughly half of that decline occurring since the release of imidacloprid in the early nineties. Other problems have plagued bees over that period - most notably the introduction of varroa, which caused a sharp drop in populations in the mid eighties - but it seems blithe to simply dismiss the possibility that pesticides, including the most widely used class of insecticides in the world - neonicotinoids - are at least partly to blame. When you look at the continued survival of bees in the citrus belt, it is also important to realize that they are buoyed in part by active husbandry - including, notably, queen-rearing operations that are often sited so as to minimize pesticide exposures. The decline in feral populations has been much more stark than the overall decline (again, of course, there are ofter factors involved, as well).

The neonicotinoids are attractive insecticides in a lot of ways: Seed treatments, soil drenches and trunk injections minimize the need for spraying, which is typically less efficient and less targeted. Insect toxicity is high, meaning relatively small amounts must be produced. Toxicity outside of the phylum Arthopoda, and even, I think, the subphylum Hexapoda, is low to very-low, at least in acute terms. They are persistent, resulting in fewer applications (although this last characteristic is also a potnetial concern - imidacloprid has been found to persist for years in soil and months in water). But there is obvious cause for concern when it comes to their effect on pollinators, and as a grower - dooryard, at that - I have found alternatives (including, for large trees, no course of action) preferable for this reason; perhaps if the incidence of greening in the area increases I will reconsider, but probably not for CLM.

Respectfully,
ES

Bob that is correct, that is the only one Lowes & HD now carry.

Sylvain,

thank you very much for the link! Curiously, most of the sources wiki lists simply state that Germany, France, Italy, and Slovenia ban the chemical. The EPA states:

"It is worth noting, however, that though clothianidin was the particular chemical involved in the 2008 incident in Germany, a similar result would be expected if a large amount of any chemical that is toxic to bees was blown into the air on a dry, windy day next to blooming canola fields for which thousands of hives were providing pollination services."

I seriously doubt that any one on this forum will blow large quantities of any chemical in the air! Also, a common consensus is to apply imid AFTER blossom. Just in case... So, bees should be safe, right?

elsedgwick, thank you very much for the references! I did not ask for them to start a war! Unfortunately, I do not have access (right now) to full articles published by Science. The abstract of the "bumblebee paper" states that insects were "exposed" to a chemical. However, per Dr. Manner's post, imid does not reach flowers. Since I did not read the paper and do not know the methods used to poison poor creatures, I may only suspect that the experimenters sprayed them... Per Bayers' label, the chemical is not applied to foliage or flowers. So, it should be safe for bees, right?

Sincerely,
GT

Bob, I use Amazon.com all the time. I'm a Prime member. The $50.00 membership is quickly realized by using Prime sellers who don't charge shipping (I still price-shop, though, whatever option is least expensive), plus my gasoline costs realized by not having to drive somewhere to get what I want. I use amazon.com all the time. Same with Ebay.com.