This work studies the acute contact toxicity of oxalic acid (OA) on a
honeybee polyhybrid subspecies ( Apis mellifera ), which is the
dominant biotype in southwestern zone of Uruguay (SWZU) and the
country’s most important honey-producing region. We determined
the mean lethal dose (LD50), as well as the no observed effect level
(NOEL) and the lowest observed effect level (LOEL) values. We also
estimated the total number of honeybees per hive in the test area. The
aim was to assess the relationship between the maximum OA dose used in
Uruguay (3.1 g OA per hive) and the toxicological parameters of
honeybees from SWZU. The current dose of 3.1 g OA per hive corresponds
to 132.8 μg OA per honeybee since determined NOEL is 400 μg
OA per honeybee; our results indicate that the current dose could be
increased to 9.3 g OA per hive. The results also highlight some
differences between the LD50 value in SWZU honeybees (548.95 μg OA
per honeybee) and some published LD50 values for other honeybee
subspecies
