Foraging Bumblebees Selectively Attend to Other Types of Bees Based on Their Reward-Predictive Value

Abstract

Using social information can be an efficient strategy for learning in a new environment while reducing the risks associated with trial-and-error learning. Whereas social information from conspecifics has long been assumed to be preferentially attended by animals, heterospecifics can also provide relevant information. Because different species may vary in their informative value, using heterospecific social information indiscriminately can be ineffective and even detrimental. Here, we evaluated how selective use of social information might arise at a proximate level in bumblebees (Bombus terrestris) as a result of experience with demonstrators differing in their visual appearance and in their informative value as reward predictors. Bumblebees were first trained to discriminate rewarding from unrewarding flowers based on which type of “heterospecific” (one of two differently painted model bees) was next to each flower. Subsequently, these bumblebees were exposed to a novel foraging context with two live painted bees. In this novel context, observer bumblebees showed significantly more social information-seeking behavior towards the type of bees that had predicted reward during training. Bumblebees were not attracted by paint-marked small wooden balls (moved via magnets) or paint-marked non-pollinating heterospecifics (woodlice; Porcellio laevis) in the novel context, indicating that bees did not simply respond to conditioned color cues nor to irrelevant social cues, but rather had a “search image” of what previously constituted a valuable, versus invaluable, information provider. The behavior of our bumblebees suggests that their use of social information is governed by learning, is selective, and extends beyond conspecifics.

Ecological and evolutionary consequences of selective interspecific information use

“…Existing literature (Forsman et al 2014;Loukola et al 2020b;Romero-González et al 2020a) provides examples of how SIIU could lead to similar trait divergence as predicted by our simulation model. To acquire social information, individuals need to coexist, which also increases the probability of competition.…”

“…Selective interspecific information use (SIIU) has gained increased attention and has been observed in birds Seppänen et al 2011;Loukola et al 2013;Szymkowiak et al 2016;Thorogood et al 2018;Tolvanen et al 2018;Morinay et al 2020;Hämäläinen et al 2021a) and insects (Loukola et al 2020b). This interspecific "reject-theunsuccessful" strategy (Forsman et al 2018;Loukola et al 2020b;Romero-González et al 2020a; but see Slagsvold & Wiebe 2017) complements existing literature on selective social information use including "copy-the-successful" strategy (Laland 2004). In this study, we focus on copying and rejecting an observed behaviour due to their relevance in ecological and evolutionary consequences of SIIU.…”

“…When ecologically overlapping individuals coexist and compete for the same resources they may actively observe and use the available information produced by putative competitors. This may facilitate the information user to choose a divergent strategy from the information source (Forsman et al 2014;Loukola et al 2020b;Romero-González et al 2020a), leading to a temporary divergence among the individuals in plastic traits (Fig. 2b).…”

“…Information on high fitness (e.g., large clutch size in birds; Seppänen et al 2011;Morinay et al 2020) or successful nesting (e.g., healthy nest in solitary bees; Loukola et al 2020b) of the information source increases the probability that the information user copies the behaviour of the information source, whereas an association with information on low fitness (e.g., small clutch size; Seppänen et al 2011;Loukola et al 2013) or unsuccessful nesting (e.g., parasitized nest in solitary bees; Loukola et al 2020b) increases the probability to reject the behaviour of the information source. Current theory of social information use does not acknowledge the rejection behaviour, even though many case studies show that a selective decision to either copy or reject a certain trait or behaviour could have adaptive consequences (e.g, Loukola et al 2013Loukola et al , 2020bForsman et al 2014;Szymkowiak et al 2016;Romero-González et al 2020a;Hämäläinen et al 2021a).…”

“…Moreover, there is a well-constructed theory for the adaptive value of intraspecific social information use (Laland 2004;Enquist et al 2007;Kendal et al 2009;e.g., Bocedi et al 2012;Loyau et al 2012;Whitehead et al 2019), and despite of the accumulating number of studies over wide range of species Jaakkonen et al 2015;Forsman et al 2018;Whitehead et al 2019;Keen et al 2020;Loukola et al 2020b;Romero-González et al 2020a;Hämäläinen et al 2021a, b), there are gaps in our understanding on the adaptive value of interspecific social information use. The fitness consequences of social information use depend on the accuracy of the acquired information and the accuracy decreases with ecological and temporal distance between the information source and information user .…”