Another View on New Insecticide - Flupyradifurone Still Concerning for Honey Bees

American Bee Journal    By Michele Colopy, Program Director, Pollinator Stewardship Council January 22, 2014

The Pollinator Stewardship Council is gravely concerned another systemic insecticide with similar insecticidal activity to neonicotinoids has been registered for seed, soil, and foliar treatments across a variety of crops. This new insecticide is proposed for use before, during and after bloom, three to five times per season.

Our concerns are derived from EPA’s own analysis of this butenolide insecticide.   Flupyradifurone has greater persistence in the water column than sediment, thus exposing honey bees through the ingestion of water with a Flupyradifurone half-life of 330.1 days.  What is also concerning is the research submitted to EPA showed this systemic insecticide may not be acutely toxic upon the first exposure, but the second and third applications show effects upon honey bee mortality, behavior, brood development, and food storage. 

The research concerning the residues of Flupyradifurone in nectar and pollen found different levels of the chemical in pollen and nectar, the level varied per plant, and if the plant had extra nectaries.  Pollen appeared to contain higher levels of Flupyradifurone, than nectar (3.5-106x), and the levels increased with the number of applications of Flupyradifurone.   Table 28 in EPA’s documentation further highlighted this concern as studies showed pollen in various crops showed an increase of Flupyradifurone at the second, and third applications during the same growing season.  Further, the concentration remained high for 1-7 days after the second and third applications (depending on the crop). 

Studies of caged honey bees fed Flupyradifurone do not reflect the real world of honey bees.  Flupyradifurone will be utilized in a tank mix, and effects of Flupyradifurone, its degradates, mixed with herbicides, and fungicides is unknown.  The synergistic effects of these chemicals upon honey bees is unknown; yet that will be how honey bees will encounter this compound.  While a ten-day honey bee feeding study was conducted, what happened at day 16, 21, and 24—developmental stages of honey bees?  To state there were “no consistent adverse effects” except “some increases in mortality and decreases in foraging activity immediately following applications . . . and in some cases there was recovery from the effects on mortality by test termination,” does not inspire confidence in the use of this compound.  EPA questioned the “large variation in starting colony size” and the “low number of replicates per treatment group” which limit the ability to detect the effects of Flupyradifurone.  One study mixing Flupyradifurone with a tebuconazole formulation enhanced the toxicity of Flupyradifurone increasing the toxicity “116-fold and 6.1 fold via the contact and oral routes.”   Relying on the label guideline to protect against mixing Flupyradifurone with azole fungicides is unrealistic.

According to EPA registration review documents,  “Maximum residues in comb pollen, nectar, and wax varied, but generally occurred one week to several months after the second application indicating that residues were translocated within the hives to varying extents.”  Flupyradifurone appears to have pre-lethal effects which long term, replicated studies would reveal.  Even when the studies prescribed Flupyradifurone based on the body weight of the honey bee there was increased worker mortality, decreased flight activity, and brood numbers varied widely during the evaluation periods and after over-wintering.  In one study it showed the “mortality of the test group was 5 times greater than the control group during the 7-day period after 3rd (full bloom) application.” 

While Flupyradifurone is “practically non-toxic to bees on an acute contact exposure basis,” “the greatest area of uncertainty surrounding the potential risk to bee pollinators is for foliar application at full bloom.”  “In addition, pollen, nectar, and wax residue data from one of the full field studies with Flupyradifurone (MRIDs 48844517) indicate that average residues did not reach their maxima until up to several months after the pesticide was applied.
 
The use of Flupyradifurone upon such a wide array of crops will translocate to pollinator forage areas developed through Federal and State initiatives.  Its mobility in water will affect honey bees, and other pollinators.  The repeated use of Flupyradifurone has shown to increase its toxicity with each application with a half-life of one application lasting 3-951 days in the plants, soil, and water.  The use of this compound will further exacerbate the concerns over the honey bees’ food supply: pollen, nectar, and water.
 
For more information about the EPA’s registration of this pesticide go to http://www.regulations.gov/#!docketDetail;D=EPA-HQ-OPP-2013-0226

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