Four Common Pesticides, Their Mixtures and a Formulation Solvent in the Hive
Environment Have High Oral Toxicity to Honey Bee Larvae
Wanyi Zhu mail, Daniel R. Schmehl, Christopher A. Mullin, James L. Frazier.
Published: January 08, 2014
DOI: 10.1371/journal.pone.0077547
Abstract
Recently, the widespread distribution of pesticides detected in the hive has
raised serious concerns about pesticide exposure on honey bee (Apis
mellifera L.) health. A larval rearing method was adapted to assess the
chronic oral toxicity to honey bee larvae of the four most common pesticides
detected in pollen and wax - fluvalinate, coumaphos, chlorothalonil, and
chloropyrifos - tested alone and in all combinations. All pesticides at
hive-residue levels triggered a significant increase in larval mortality
compared to untreated larvae by over two fold, with a strong increase after
3 days of exposure. Among these four pesticides, honey bee larvae were most
sensitive to chlorothalonil compared to adults. Synergistic toxicity was
observed in the binary mixture of chlorothalonil with fluvalinate at the
concentrations of 34 mg/L and 3 mg/L, respectively; whereas, when diluted by
10 fold, the interaction switched to antagonism. Chlorothalonil at 34 mg/L
was also found to synergize the miticide coumaphos at 8 mg/L. The addition
of coumaphos significantly reduced the toxicity of the fluvalinate and
chlorothalonil mixture, the only significant non-additive effect in all
tested ternary mixtures. We also tested the common 'inert' ingredient
N-methyl-2-pyrrolidone at seven concentrations, and documented its high
toxicity to larval bees. We have shown that chronic dietary exposure to a
fungicide, pesticide mixtures, and a formulation solvent have the potential
to impact honey bee populations, and warrants further investigation. We
suggest that pesticide mixtures in pollen be evaluated by adding their
toxicities together, until complete data on interactions can be
accumulated..
For more information:
http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0077547
Kind regards,
Ghislain De Roeck,
Belgium.
***********************************************
The BEE-L mailing list is powered by L-Soft's renowned
LISTSERV(R) list management software. For more information, go to:
http://www.lsoft.com/LISTSERV-powered.html
|
