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studies related behavioral effects to levels of inhibition of acetylcholinesterase, and
will be discussed further in the next section.
Behavioral effects of OP insecticides have also been shown in birds (see review
by Grue et al. 1991). Behavioral effects of OCs, OPs, and methylmercury on birds
have been reviewed by Peakall (1985, 1996). A remarkably wide range of behavioral
tests were used in these studies. Tests employed included the following:
adaptive behavior
Introduction of chicks to hens preadapted to
brooding cages.
approach behavior
Reaction to taped maternal call.
avoidance behavior
Distance run after fright stimulus.
detour learning
Food-deprived chicks learning to detour away
from sight of food. Through tunnel to obtain food.
dominance-subordinate
pattern
Placing bird on either side of divided area.
Raising wall and finding dominance.
nest attentiveness
Use of telemetered eggs to record core
temperature.
nest defense
Classed as “aggressive,” “moderate,” or “weak.”
Open field behavior
Movement of chicks monitored by sensors.
Operant behavior
Conditioning to response to lighted key to obtain
food.
predatory behavior
Attack on moving prey model with hidden meat
reward.
Many of these tests gave evidence for changes in behavior following exposure to
neurotoxic pesticides. The author concludes that significant behavioral effects were
often recorded down to one order of magnitude below the LC
50
in question. Some
tests, such as operant tests, were relatively simple and gave reproducible results, but
it was difficult to evaluate the relevance of these to survival in the wild. Other tests,
such as breeding behavior and prey capture, were more complex and less reproduc-
ible, but more relevant to the natural world.
A wide range of sublethal effects of pyrethroids, carbamates, OPs, and neonico-
tinoids have been demonstrated in bees (Thompson 2003). With honeybees (
Apis
mellifera
), effects have been shown on division of labor, conditioned responses, for-
aging, colony development, larval behavior, repellency, and nest mate recognition.
Many effects occurred at or below levels of exposure anticipated in the field. OP,
carbamate, and neonicotinoid insecticides had effects on the “wagtail” dance by
which bees communicate the direction of a source of food to other bees. There has
been considerable interest in developing tests for behavioral effects of pesticides
upon bees. However, there have been reservations about including them in regulatory
testing protocols (Thompson and Maus 2007). It is argued that any behavioral effects
that are ecologically important will be picked up in field or semi-field trials.
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