Epsilon Open Archive

Abstract

Olfactory learning may allow insects to forage
optimally by more efficiently finding and using favourable
food sources. Although olfactory learning has been shown
in bees, insect herbivores and parasitoids, there are fewer
examples from polyphagous predators. In this study,
olfactory learning by a predatory coccinellid beetle is
reported for the first time. In laboratory trials, adults of the
aphidophagous ladybird Coccinella septempunctata did not
prefer the odour of one aphid-infested barley cultivar over
another. However, after feeding on aphids for 24 h on a
cultivar, they preferred the odour of that particular cultivar.
The mechanism appeared to be associative learning rather
than sensitisation. Although inexperienced ladybirds preferred
the odour of an aphid-infested barley cultivar over
uninfested plants of the same cultivar, after feeding experience
on a different cultivar this preference disappeared.
This may indicate the acquisition and replacement of
olfactory templates. The odour blends of the different
aphid-infested barley cultivars varied qualitatively and
quantitatively, providing a potential basis for olfactory
discrimination by the ladybird. The results show that
predatory coccinellids can learn to associate the odour of
aphid-infested plants with the presence of prey, and that this
olfactory learning ability is sensitive enough to discriminate
variability between different genotypes of the same plant.