@
Seamaiden, I'll point out a couple of problems with that paper. Firstly, there is a conflict of interest between the funding of the study and the results of the study. If you look at the author information, this is what you'll find:
Dow AgroSciences, Field Exposure and Effects Laboratory, 9330 Zionsville Road, Indianapolis, IN 46268, USA.
Dow Agro produces and sells
spinosad. It is in their best interests to have
spinosad seen in a positive light. This doesn't automatically discredit the results, but it does warrant further research.
Another problem is the measure of toxicity they've used, ie. acute versus chronic. There is no mention of chronic toxicity, yet this is more likely to be a problem for bees. It is chonic toxicity and multiple stressors that have been implicated in CCD. However, other studies have found mixed results on the chronic toxicity of
spinosad to bees, depending on the species of bee and the product being used.
For residual toxicity (supporting information Table S3), contact exposure to dry residues of
spinosad (up to 200 g AI ha−1) on leaves/flowers in crops such as alfalfa, citrus and kiwifruit or glass plates was either slightly harmful or harmless to honey bees up to 100 h after exposure. Although no lethal effects were observed on honey bees, several authors demonstrated that other bee genera, including
Bombus and
Megachile, but not
Protonectarina, were more sensitive. In addition,exposure might also occur via wet residues. For formulated
spinosad (480 g AI L−1) and spinetoram (250 g AI kg−1), high toxicity was obtained after both wet and dry residue exposure, whereas for the fruitfly bait a difference between wet and dry exposure was noted only after 24 h. Taking into account the toxicity seen after exposure to wet residue, Mayes
et al. found that toxicity was not related to the
spinosad volume applied. Furthermore, chronic oral intake of dry residue of real
spinosad field rates via pollen was safe for
B. impatiens colonies.
3.2.2 Sublethal effects on pollinators
For honeybees, dry residues of
spinosad were harmless to larvae. On the other hand, when
B.
impatiens colonies were chronically fed on pollen treated with realistic field rates, the weight of emerging bees was lower, as was the foraging efficiency of adults on artificial flowers (previously fed during their larval development with
spinosad-treated pollen). Recently, Besard
et al. observed that oralexposureof
B.terrestris to
spinosad and spinetoram did not cause adverse effects on reproduction and on foraging behaviour when applied at 1/1000 and 1/100 of their respective field recommended rates. Therefore, the newer spinosyn (spinoteram) may pose less risk to foraging and pollination by bumblebees than
spinosad. However, actual highest recommended field rates induced 100% of mortality in a worst case exposure scenario in the laboratory, and field studies suggested that side effects on brood production and foraging activities of bees may occur depending on field application rate and crop considered (see section 5). However, there is currently a need in studies assessing thoroughly possible sublethal effects of spinosyns on key traits in the honey bee and wild bees.
Besides semi-field tests, several greenhouse studies were conducted to address the effect of a foliar application (residues) of
spinosad on both honey bees and bumblebees. For honey bees, the application of 100 g AI ha−1
spinosad (250 g AI L−1 formulation) in a volume of 1000 L ha−1 on strawberry crops resulted in a delay in pupal formation for young larvae of up to 3 days after
spinosad application, while the survival of older larvae was affected during a longer time period (up to 7 days). For bumblebees, a 2 day exposure of foraging bumblebee colonies to
spinosad residue (120 g AI ha−1; 250 g AI L−1 formulation in a volume of 1200 L ha−1) was also shown to be detrimental for the brood. Eggs and early larval development were inhibited when colonies were placed in the greenhouse on days 0, 2 and 4 after the application of the insecticide.
Th above excerpts are from the following article:
Biondi, A., Mommaerts, V., Smagghe, G., Viñuela, E., Zappalà, L., & Desneux, N. (2012). The non‐target impact of spinosyns on beneficial arthropods.
Pest Management Science,
68(12), 1523-1536.
http://onlinelibrary.wiley.com/doi/...sCustomisedMessage=&userIsAuthenticated=false
I'm not saying
spinosad residues are categorically toxic to bees, as clearly there are a number of variables to be considered which affect the degree of toxicity, but I wouldn't be so sure that
spinosad is actually harmless to bees.