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Change in protective coloration in the striated shieldbug Graphosoma lineatum (Heteroptera: Pentatomidae): predator avoidance and generalization among different  life stages
Stockholm University, Faculty of Science, Department of Zoology.ORCID iD: 0000-0002-3445-3759
Stockholm University, Faculty of Science, Department of Zoology.
Stockholm University, Faculty of Science, Department of Zoology.ORCID iD: 0000-0001-6319-009X
2010 (English)In: Evolutionary Ecology, ISSN 0269-7653, E-ISSN 1573-8477, Vol. 24, no 2, 423-432 p.Article in journal (Refereed) Published
Abstract [en]

There are two major forms of protective coloration, camouflage and warning coloration, which often entail different colour pattern characteristics. Some species change strategy between or within life stages and one such example is the striated shieldbug, Graphosoma lineatum. The larvae and the pale brownish-and-black striated pre-diapause adults are more cryptic in the late summer environment than is the red-and black striation that the adults change to after diapause in spring. Here we investigate if the more cryptic pre-diapause adult and larval coloration may affect the aposematic function of the coloration as compared to the red adult form. In a series of trials we presented fifth instar larvae, pale or red adults to shieldbug-naïve domestic chicks, Gallus gallus domesticus, to investigate the birds’ initial wariness, avoidance learning, and generalization between the three prey types. The naïve chicks found the red adults most aversive followed by pale adults, and they found the larvae the least aversive. The birds did not find the larvae unpalatable and did not learn to avoid them, while they learned to avoid the two adult forms and then to a similar degree. Birds generalized asymmetrically between life stages, positively from larvae to adults and negatively from adults to larvae. We conclude that the lower conspicuousness in the pale forms of G. lineatum may entail a reduced aposematic function, namely a reduced initial wariness in inexperienced birds. The maintenance of the colour polymorphism is discussed

Place, publisher, year, edition, pages
2010. Vol. 24, no 2, 423-432 p.
Keyword [en]
Aposematism, Camouflage, Crypsis, Domestic chick, Ontogenetic colour change, Warning coloration
National Category
Biological Sciences Behavioral Sciences Biology
Research subject
Zoological physiology; Ethology
URN: urn:nbn:se:su:diva-29596DOI: 10.1007/s10682-009-9315-3ISI: 000274109600011OAI: diva2:234358
Available from: 2009-09-08 Created: 2009-09-08 Last updated: 2014-10-28Bibliographically approved
In thesis
1. Seasonal change in defensive coloration in a shieldbug
Open this publication in new window or tab >>Seasonal change in defensive coloration in a shieldbug
2011 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Protective coloration such as aposematism and crypsis occurs in many insects but only a few species alter their defensive strategy during the same instar. We hypothesize the adult shield bug Graphosoma lineatum with an alternating black and non-melanised longitudinal striation exhibit such a change in defensive coloration. In Sweden, the non-melanised stripes of the pre-hibernation G. lineatum are pale brown and cryptic but they change during hibernation to red and aposematic. We have tested the adaptive functions of coloration of the two G. lineatum forms against bird predators. In Paper I we used great tits as predators and measured detection time of the two forms against a background of dry grass and plants, simulating late-summer conditions. We found that the birds took longer time to find the pale than the red form. Thus, the pale form of G. lineatum is more cryptic in a dry environment than the red form. In Paper II and III we used naïve predators and measured attack rate/latency on red and pale adults and fifth-instar larvae (black and brown) to investigate avoidance and generalisation between the stages. In Paper II domestic chicks initially found the red form most intimidating, but both adult forms are more intimidating than the larva. Moreover, there was a broad generalisation among forms. In Paper III naïve great tits did not find the red form significantly more aversive than the pale adult. Neither the chicks nor the tits showed any difference in the speed of avoidance learning between the two adult colour forms. In Paper IV the shieldbugs themselves were the main focus as we compared activity levels in the different colour forms and found that G. lineatum alters behaviour in accordance to their protective strategy. Thus they were significantly less active during the cryptic phase. Taken together, these experiments suggest that the pale brown adult invests in a cryptic strategy at the cost of reduced protection from aposematism, whereas the red adult benefits from aposematism at the cost of reduced camouflage.

Place, publisher, year, edition, pages
Stockholm: Department of Zoology, Stockholm University, 2011. 26 p.
Shield bug, colour change, protective coloration, cryptic, aposematic, behavioural change
National Category
Behavioral Sciences Biology
Research subject
urn:nbn:se:su:diva-62466 (URN)978-91-7447-373-5 (ISBN)
Public defence
2011-11-02, Nordenskiöldsalen, Geovetenskapens hus, Svante Arrhenius väg 12, Stockholm, 10:00 (English)
At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4: Accepted. Available from: 2011-10-11 Created: 2011-09-20 Last updated: 2011-09-26Bibliographically approved

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Gamberale-Stille, GabriellaJohansen, Aleksandra I.Tullberg, Birgitta S.
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