Shades of yellow: interactive effects of visual and odour cues in a pest beetle
- Published
- Accepted
- Subject Areas
- Agricultural Science, Animal Behavior, Entomology
- Keywords
- visual preferences, locomotion compensator, odour preferences, storage pest, insect behaviour, Sitophilus zeamais, Servosphere, host orientation
- Copyright
- © 2016 Arnold et al.
- Licence
- This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ Preprints) and either DOI or URL of the article must be cited.
- Cite this article
- 2016. Shades of yellow: interactive effects of visual and odour cues in a pest beetle. PeerJ Preprints 4:e2110v1 https://doi.org/10.7287/peerj.preprints.2110v1
Abstract
Background. The visual ecology of pest insects is poorly studied compared to the role of odour cues in determining their behaviour. Furthermore, the combined effects of both odour and vision on insect orientation are frequently ignored, but could impact behavioural responses.
Methods. A locomotion compensator was used to evaluate use of different visual stimuli by a major coleopteran pest of stored grains ( Sitophilus zeamais ), with and without the presence of host odours (known to be attractive to this species), in an open-loop setup.
Results. Some visual stimuli – in particular, one shade of yellow, solid black and high contrast black-against-white stimuli – elicited positive orientation behaviour from the beetles in the absence of odour stimuli. When host odours were also present, at 90° to the source of the visual stimulus, the beetles presented with yellow and vertical black-on-white grating patterns changed their walking course and typically adopted a path intermediate between the two stimuli. The beetles presented with a solid black-on-white target continued to orient more strongly towards the visual than the odour stimulus.
Discussion. Visual stimuli can strongly influence orientation behaviour, even in species where use of visual cues is sometimes assumed to be unimportant, while the outcomes from exposure to multimodal stimuli are unpredictable and need to be determined under differing conditions. The importance of the two modalities of stimulus (visual and olfactory) in food location is likely to depend upon relative stimulus intensity and motivational state of the insect.
Author Comment
This is a submission to PeerJ for review.
Supplemental Information
Spectral composition of light source in the experimental room
a) Over the whole insect-visible spectrum; b) expanded view of the near-UV region(with an increased integration time) showing the availability of < 400nm light in addition to human-visible light. Spectra were measured with an Avantes AvaSpec-2048 with an integration time of a) 15ms and b) 50ms respectively, in the centre of bench areas where work took place.
Analysis of insects' directions of movement
a) Results of Rayleigh test analysis (z-scores) of S. zeamais orientation vectors and b) binomial test probabilities (Bonferroni-corrected to a significance value of 0.0016) in the presence and absence of host odours. Visual stimuli were presented at 90° to the camera azimuth and odour stimuli at 180° to the camera azimuth. (In a), * indicates p < 0.05, ** p < 0.01, *** p < 0.001; in b) # indicates significance after correction.)