Single versus double field rate: Do different rates of fenoxycarb in chronic Oomen bee brood feeding tests cause different effects sizes?

Autor/innen

  • Sabine Hecht-Rost
  • Annika Alscher
  • Christian Claßen
  • Andrea Klockner
  • Tobias Schlotz
  • Jörg Staffel
  • Johannes Lückmann

Abstract

Background: EFSA (2013) recommends to modify the Oomen bee brood feeding test (Oomen et al., 19922) from an acute to a chronic feeding test, but proposals regarding the concentration of the reference item fenoxycarb in such trials are missing. For the chronic Oomen bee brood feeding ring-test (see Lückmann & Schmitzer 2014) the double field rate was used. Due to the lack of information about the effect size of the single field rate two separate bee brood feeding tests (following the method given by the ring-test protocol) were conducted: one in July 2013 (study 1) and one in April 2014 (study 2). The single and the double field rate of fenoxycarb were applied each at both times. As endpoints effects on brood termination rate (BTR) of marked eggs, young and old larvae, pupal mortality and colony development (i.e. number of brood cells and colony strength) were recorded and evaluated.
Results: The chronic administration of the double field rate caused reproducible results whereas those of the single field rate were more variable. Distinct (i.e. ≥ 50%) and statistically significant increased BTRs of eggs were observed for the single rate in study 2 only, and for the double rate in both studies. Pupal mortality was statistically significantly increased at both rates in both studies and also bee brood and colony strength development was affected at both rates in both studies. Distinct dose-related differences between the two test rates were present for the BTRs of eggs in study 1 and for pupal mortality and colony development in study 2.
Conclusion: The chronic feeding of the single rate of fenoxycarb did not cause reproducible, doserelated effects. Therefore it is recommend using the double field rate of fenoxycarb as the toxic reference item dose in chronic Oomen bee brood feeding studies as long as no further data are available on the effect size of the single rate.

Keywords: honeybees, chronic Oomen bee brood feeding test, fenoxycarb, single rate, double rate

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Veröffentlicht

2015-10-12

Ausgabe

Nr. 450 (2015): "Hazards of pesticides to bees", 12th International Symposium of the ICP-PR Bee Protection Group

Rubrik

Section II: Developments in laboratory, semi-field and field testing for honeybees

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