Abstract:
Repeatability, (the consistency with which a given
trait is expressed) of aggressiveness
against prey (attack latency) in gravid females of
the predatory mite
Neoseiulus
californicus
(McGregor) was examined. In two experiments, prey -
conspecific
individuals, the onion thrips
Thrips tabaci
(Lindeman), and the two-spotted spider mite
Tetranychus urticae
Koch- were repeatedly offered in various no-choice
vs.
choice
situations. Throughout the first experiment, the pr
edators were offered conspecific larvae
twice, alone and then together with
Te. urticae
. In a second experiment, the predators
were alternately offered
Te. urticae
and
Th. tabaci
within choice
vs.
no-choice situations.
Latency to the first successful attack (resulting i
n death and consumption of prey) was
recorded as aggressiveness. In the first experiment
, Pearson’s r indicated that the
predators were consistent in aggressiveness against
conspecific prey. Additionally, latency
to attack conspecific larvae and
Te. urticae
were strongly correlated when the former
were offered alone and the latter offered together
with conspecific larvae. In the second
experiment, aggressiveness against spider mites and
thrips was inconsistent, non-
repeatable and varied among contexts. However,
Te. urticae
was attacked more quickly
when offered second, following the first prey
Th. tabaci
than when offered as the first
prey. Both experiments, in concert, suggest that th
e level of behavioral consistency of
N.
californicus
in aggressiveness against prey is strongly context
-dependent. Further in-
depth studies are needed to determine which foragin
g traits, (and why and under what
circumstances) are more repeatable than others.
Keywords:
Aggressiveness,
Cannibalism,
Consistency,
Neoseiulus
californicus
,
Repeatability.
