Visual and olfactory location of biotopes, prey patches, and individual prey by the ladybeetleChilocorus nigritus |
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Authors: | Vaughan Hattingh and Michael J Samways |
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Institution: | (1) Department of Zoology and Entomology, University of Natal, PO Box 375, 3200 Pietermaritzburg, South Africa;(2) Present address: Outspan Citrus Centre, PO Box 28, 1200 Nelspruit, South Africa |
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Abstract: | Foraging behaviour of the predatorChilocorus nigritus (Fabricius) (Coleoptera: Coccinellidae) at the three spatial levels of biotope, prey patch and individual prey, was studied
in the laboratory, and related to behaviour in the field. Vertically oriented parallel lines were more attractive than the
same shapes in a horizontal position. A simulated horizon with a tree line was preferred to a simulated flat horizon. They
were attracted to a tree image for the first 2 h of exposure, but were less attracted after longer exposure, possibly due
to habituation. Leaf shape was recognised, and simple ovate leaves were preferred to compound bipinnate leaves and to squares.
These responses were associated with biotope selection for feeding and aggregation at aestivation sites. The location of prey
patches by adults involved prey odour but the location of such sites by larvae did not. Adults detected individual prey visually
and olfactorily over short distances but physical contact with prey was required for detection by larvae. Location of individual
prey and prey patches by adults and larvae was facilitated by alternation between intensive and extensive search. The differences
in the ability of larvae and adults to locate prey, stem from the adults being the active locators of biotope and patch, whereas
the comparatively immobile larvae depend on their parents’ ability for long-range location of prey. Two hypotheses concerning
coccinellid foraging behaviour are proposed. Firstly, the duration of response to a visual cue is related to the distance
over which such a cue may be perceived. It follows that habituation to closer range cues occurs more rapidly than to longer
range cues. Secondly, visual cues used by adults at the different spatial levels of prey location, and the location of mates
and aggregation sites, have the same or similar shape. These results also provide guidelines for orchard management to maximise
the biocontrol value of this species. |
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Keywords: | foraging behaviour Chilocorus Coccinellidae |
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