Data from: 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.

同种个体线索（conspecific cues）作为决策过程中的社会信息的利用现象在动物界广泛存在，但由于这类社会信息具有间接性，因此极易出现误差。在资源获取过程中，同种个体线索同时也会暗示竞争者的存在；因此，决策个体理应利用来自资源本身的直接信息，并据此调整对社会信息的响应策略。本研究以一种非社会性昆虫为对象，发现缺乏吸引力的产卵资源会使个体对同种个体线索的行为响应从规避转向偏好，进而促成资源共享行为。赤小豆豆象（Callosobruchus chinensis）的雌性个体会规避在已带有同种卵粒的豆子上产卵。然而，当我们向雌性个体提供尺寸与豆子相当、分别带有和不带有同种卵粒的干净玻璃珠时，雌性个体反而更倾向于在带有卵粒的玻璃珠上产卵。若将玻璃珠涂抹上赤小豆的水提取物，雌性个体的行为模式会与面对真实豆子时一致：相较于干净玻璃珠，它们更偏好带有豆子气味的玻璃珠，同时仍会规避带有卵粒的基质。当雌性个体仅能获得缺乏吸引力的产卵基质时，追随行为（即社会模仿）或许会成为有利策略，因为这类行为可以利用目标个体可能遗漏的、关于基质正向属性的信息。本研究结果表明，当仅能获得不尽如人意的选择时，社会模仿的收益将超过资源竞争带来的成本。本研究凸显了整合多源信息在动物决策过程中的重要性。