Copy if dissatisfied, innovate if not: contrasting egg-laying decision making in an insect
The use of conspecific cues as social information in decision making is widespread among animals; but, because this social information is indirect, it is error-prone. During resource acquisition, conspecific cues also indicate the presence of competitors; therefore, decision makers are expected to utilize direct information from resources and modify their responses to social information accordingly. Here, we show that, in a non-social insect, unattractive egg-laying resources alter the behavioural response to conspecific cues from avoidance to preference, leading to resource sharing. Females of the adzuki bean beetle Callosobruchus chinensis avoid laying eggs onto beans that already have conspecific eggs. However, when we provided females with bean-sized clean glass beads with and without conspecific eggs, the females preferred to add their eggs onto the beads with eggs. The glass beads, once coated with water extracts of adzuki beans, enabled the females to behave as if they were provided with the beans: the females preferred bean-odoured glass beads to clean glass beads and they avoided the substrates with eggs. When females are provided with unattractive egg-laying substrates only, joining behaviour (i.e. copying) might be advantageous, as it takes advantage of information about positive attributes of the substrate that the focal animal might have missed. Our results suggest that given only unsatisfactory options, the benefits of copying outweigh the costs of resource competition. Our study highlights the importance of integrating multiple information sources in animal decision making.
KeywordsInsect cognition Oviposition Scent marking Seed beetle Information cascade
We thank Ken Cheng and three anonymous referees for constructive comments on earlier drafts. We also thank K. Matsuura, members of Laboratory of Insect Ecology and Y. Toquenaga for their discussion and laboratory support.
This study was partly supported by the Japan Society for the Promotion of Science (15K18609 to S.D.).
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
All applicable international, national, and/or institutional (Regulation on Animal Experimentation of Kyoto University) guidelines for the care and use of animals were followed.
- Gokhale VG, Honda H, Yamamoto I (1990) Role of physical and chemical stimuli of legume host seeds in comparative ovipositional behaviour of Callosobruchus maculatus (Fab.) and C. chinensis (Linn.) (Coleoptera: Bruchidae). In: Fujii K, Gatehouse AMR, Johnson CD, Mitchel R, Yoshida T (eds) Bruchids and legumes: economics, ecology and coevolution. Springer, Kluwer Academic Publishers, Dordrecht. https://doi.org/10.1007/978-94-009-2005-7_4 CrossRefGoogle Scholar
- Ishii S (1951) Studies on the host preference of the cowpea weevil (Callosobruchus chinensis L.). Bull Natl Inst Agric Sci Ser C1:185–256Google Scholar
- R Core Team (2017) R: a language and environment for statistical computing. R Foundation for Statistical Computing, Vienna. https://www.R-project.org/)
- Shinoda K (1989) Studies on life cycle of azuki bean beetle in the field. Ph. D. thesis, Okayama University, Japan. http://ousar.lib.okayama-u.ac.jp/en/7774 (in Japanese)
- Utida S (1941) Studies on experimental population of the azuki bean weevil, Callosobruchus chinensis L. Kyoto. Memoirs of the College of Agriculture, Kyoto Imperial University, KyotoGoogle Scholar
- Yoshida T (1990) Historical review of bruchid studies in Japan. In: Fujii K, Gatehouse AMR, Johnson CD, Mitchel R, Yoshida T (eds) Bruchids and legumes: economics, ecology and coevolution. Springer, Kluwer Academic Publishers, Dordrecht. https://doi.org/10.1007/978-94-009-2005-7_1 CrossRefGoogle Scholar