A Bumblebee's optimism is contagious to other bumblebees

Amazing stuff!

"... This phenomenon, known as affective contagion, had previously been demonstrated in a variety of social animals—but only ones with bones. Meanwhile, wee bumblebees have demonstrated remarkable cognitive complexity, including different emotional states, learning by watching, and even a penchant for play. So, researchers wondered if these bees might similarly pick up on their hive members’ vibes.

They trained bees to associate certain colored flowers with a food reward, then put some of them in a good mood by giving them an extra sugary treat. The bees that received this yummy bonus more readily landed on ambiguously colored flowers, indicating they were feeling optimistic about getting a treat. But so, too, did bees that simply observed their fellow insects excitedly rushing towards these flowers. ..."

From the editor's summary and abstract:

"Editor’s summary

Being able to adopt a knowledgeable conspecific’s perspective is highly adaptive. Likely for this reason, emotional contagion, or the spread of emotion from one individual to another, is widely distributed among vertebrates. Such an ability, however, would also be adaptive in nonvertebrates, especially those that are social. Whether insect brains are capable of such coordination has been unknown. Romero-González et al. looked at this behavior in bumble bees, whose tiny, but seemingly mighty, brains have already been shown capable of many unexpected cognitive feats. They found that a demonstrator’s positive attitude toward the potential for a reward was readily picked up by an observer. ...

Abstract

Affective contagion, a core component of empathy, has been widely characterized in social vertebrates but its existence in any invertebrate is unknown. Using a cognitive bias paradigm we demonstrate positive affective contagion in bumble bees.

After being trained on colored flowers with different reinforcements, bees that interacted with a conspecific in a positive affective state were quicker and more likely than controls to land on ambiguous colored flowers, indicating the transfer of a positive judgment bias between bees.

Additional observations and experiments showed that affect could be transmitted between bees without physical contact, i.e., through visual modality alone. Our findings suggest that affective contagion may be an evolutionarily widespread mechanism present in both social vertebrates and social insects."

ScienceAdviser

Positive affective contagion in bumble bees (no public access)

The Bee Lab At Southern Medical University, China

Ants are masters of disease prevention

Amazing stuff!

"... Researchers have found yet another way ants are masters of disease prevention: They restructure their nests to stop pathogens from spreading.

Ant hills look like a series of chambers connected by tunnels, where each chamber serves a purpose, for example storing food or housing the young. Since real ant hills are built underground and are hard to study, researchers placed about 200 worker ants in 10-centimeter jars to dig in the lab. Half the colonies were control groups, and half had ants exposed to an infectious pathogen. When the researchers imaged the ant hills’ structures using micro CT scans, they found that the disease-exposed colonies built entrances that were further apart, and that their chambers were less easily connected, providing fewer opportunities for a healthy ant to bump into an infected one.

The team then simulated how a pathogen would spread within the lab-built structures, finding that the disease-exposed colonies’ architecture reduced transmission. The effect strengthened when they simulated ants also implementing social distancing, a behavior the same team had previously discovered. ..."

From the editor's summary and abstract:

"Editor’s summary

Sociality is essential to many species, but it can come with the downside of increasing the transmission of disease. Many species have thus evolved strategies that limit disease transmission, even within highly social species. Leckie et al. tested whether the introduction of a pathogen through nest mate exposure altered patterns of nest construction in black garden ants. They found that the presence of individuals exposed to a pathogen led to architectural changes within the nest, such as an increase in the distance between entrances, and models showed that these changes reduced disease transmission. ...

Abstract

In animal groups, spatial structure shapes social interaction patterns, thereby influencing the transmission of infectious diseases. Active modifications to the spatial environment could therefore be a potent tool to mitigate epidemic risk. We tested whether Lasius niger ants modify their nest architecture in response to pathogens by introducing control- or pathogen-treated individuals into nest-digging groups and monitoring three-dimensional nest morphogenesis.

Pathogen exposure led to architectural changes, including faster nest growth, increased interentrance distance, transmission-inhibitory changes in nest network topology, and reduced chamber centrality.

Simulations confirmed that these changes reduced transmission and highlighted a synergy between architectural and behavioral responses to disease. These results provide evidence for architectural immunity in a social animal and offer insights into how spatial organization can be leveraged to decrease epidemic susceptibility."

ScienceAdviser

Architectural immunity: Ants alter their nest networks to prevent epidemics (no public access)

Architectural Immunity: ants alter their nest networks to fight epidemics (preprint, open access)

Figure 1. Experimental protocol and nest network extraction.

Figure 3. Pathogen-induced architectural modifications 6 days after treatment.

Older and grumpier: Aging sparrows have fewer friends

Amazing stuff! But how much is due to effect of natural changes in demography (older ones dying off)?

"... Researchers have tracked every house sparrow on tiny Lundy Island in the U.K. from egg to death since 2000, so they know exactly how old each animal is. From 2013 to 2017, they also collected detailed social data by noting interactions between individuals at video-monitored bird feeders. In all, they tallied more than 1600 observations of 615 different individuals, finding that the number of “friends” (defined as individuals a given bird is often observed with) decreased with age. Not only did old birds lose touch with old friends, they formed fewer new social connections. ..."

From the abstract:

"Humans become more selective with whom they spend their time, and as a result, the social networks of older humans are smaller than those of younger ones. In non-human animals, processes such as competition and opportunity can result in patterns of declining sociality with age. While there is support for declining sociality with age in mammals, evidence from wild bird populations is lacking. Here, we test whether sociality declines with age in a wild, insular bird population, where we know the exact ages of individuals. Using 6 years of sociality data, we find that as birds aged, their degree and betweenness decreased. The number of same-age birds still alive also decreased with age. Our results suggest that a longitudinal change in sociality with age may be, in part, an emergent effect of natural changes in demography. This highlights the need to investigate the changing costs and benefits of sociality across a lifetime."

ScienceAdvisor

Not so social in old age: demography as one driver of decreasing sociality (open access)

Figure 1.
(a) The number of repeated observations of individuals.
(b) The ages of Lundy house sparrows (y-axis, in years) in relation to the percentage of fledged individuals of their own cohort that were still alive (x-axis), 2013−2017.