Biology subjects

Nehring, V.

Publications and source records attributed to Nehring, V..

5 recordsLinked to original sources

bioRxiv2025

Exposure to non-nestmate odours changes the odorant receptor profile in Acromyrmex echinatior ants

Insects depend on a broad olfactory perception ability that involves many sensory receptors. Social insects, in particular, use olfactory cues to maintain colony cohesion (Lenoir et al., 1999; Leonhardt et al., 2016). They recognize nestmates through colony-specific olfactory labels that individuals store as neural templates in their memory (Sherman et al., 1997). Learning continuously optimises the nestmate recognition template to keep up with the constant changes in colony labels (dEttorre and Lenoir, 2010; Errard and Hefetz, 1997; Wilgenburg et al., 2012). The template is often considered to be located in higher brain centres and potentially a product of learning (Bey et al., 2025; Brandstaetter et al., 2011; Esponda and Gordon, 2015; van Zweden and dEttorre, 2010). However, some authors suggest it might be in the neural periphery, i.e. the antennae or antennal lobes, formed by habituation or receptor adaptation (Guerrieri et al., 2009; Ozaki and Hefetz, 2014; Stroeymeyt et al., 2010). Here we investigate a potential mechanism for the construction and functioning of the colony template in the peripheral nervous system: the antennas odorant receptor (OR) profile and its dynamics. We exposed Acromyrmex echinatior leaf-cutting ants to non-nestmate odours and analysed the consequences on their behaviour and antennal gene expression. Consistent with other studies, prolonged exposure to non-nestmate odours reduced worker aggression towards the non-nestmate label, indicating habituation to the non-nestmate odour (Carlin and Holldobler, 1983; Errard and Hefetz, 1997; Stroeymeyt et al., 2010). Exposure also altered the expression of the OR genes. Notably, the OR profiles were colony-specific, mirroring the colony-specific recognition labels. When we exposed two different colonies to the same non-nestmate odour, the colony-specificity of the odorant receptor gene expression vanished. This indicates that the olfactory machinery used to perceive nestmate recognition cues is flexible and adapts to the current nest-specific olfactory environment. The OR profiles could either become more sensitive to the nestmate recognition cues by increasing the number or ORs for the nest-specific substances, or less sensitive by decreasing the expression of these ORs. The latter would in turn increase the sensitivity to non-nestmate cues. This would be a mechanism explaining habituation to nestmate recognition cues that has been described across the social insect literature.

animal behavior and cognition↗

bioRxiv2024

Queen loss fails to elicit physiological and transcriptional responses in workers of the invasive garden ant Lasius neglectus

Insect colonies with morphologically distinct castes have been called superorganisms because their queens and workers are functionally analogous to the germline and soma in metazoan bodies. In the haplodiploid ants, workers typically lost the sperm storage organ but retained ovaries so they can lay unfertilized eggs. Worker reproduction often occurs after queen loss and is accompanied by a number of physiological changes. However, in some evolutionarily derived ants, workers have become functionally sterile and in many of these species colonies contain multiple queens and can readily raise replacement queens - a syndrome characteristic for invasive ants. We hypothesized that the combination of full worker sterility and regular queen replacement should have eliminated important aspects of the physiological interdependence between queens and workers. We tested this hypothesis by analysing fat body gene expression and worker resistance to oxidative stress in colonies of the invasive ant Lasius neglectus with and without queens. We found age-related transcriptional shifts between young and old queens and young and old workers, suggesting rapid ageing in all castes. However, the removal of any queens in controlled experiments failed to elicit changes in the transcriptional activity and oxidative stress resistance of workers, consistent with our hypothesis. The invasive syndrome of this ant may thus have led to a somatic work force that evolved to be physiologically independent of queen presence.

evolutionary biology↗

bioRxiv2023

Ants hold a grudge: Associative learning of non-nestmate cues improves enemy recognition

Recognition protects biological systems of all scales, from cells to societies. Social insects recognize their nestmates by colony-specific chemical labels, which individuals store as "templates" in their memories. The distributed model of nestmate recognition predicts that individual experiences cause variation between the recognition templates that different individuals store in their memory. Here, we show for the first time that ants associatively learn recognition labels of both friends and enemies during brief encounters. Because different individuals will accumulate different experiences throughout their lives, their later decisions on whether to accept or reject other individuals will also vary. Individual associative learning can thus explain many phenomena from nasty neighbour effects to age polyethism. To avoid chaos caused by inconsistent decisions across individuals, decisions are made in a distributed manner at the colony level. Group-level decision can thus be much more accurate than any individual decision alone.

animal behavior and cognition↗

bioRxiv2021

Cryptic diversity within the Poecilochirus carabi mite species complex phoretic on Nicrophorus burying beetles: phylogeny, biogeography, and host specificity

Coevolution is often considered a major driver of speciation, but evidence for this claim is not always found because diversity might be cryptic. When morphological divergence is low, molecular data are needed to uncover diversity. A taxon for which this holds true are the mites, which are known for their extensive and often cryptic diversity. We studied mites of the genus Poecilochirus that are phoretic on burying beetles (Silphidae: Nicrophorus). Poecilochirus taxonomy is poorly understood. Most studies on this genus focus on the evolutionary ecology of Poecilochirus carabi sensu lato, a complex of at least two biological species. Based on molecular data of 230 specimens from 43 locations worldwide, we identified 24 genetic clusters that may represent species. We estimate that these mites began to diversify during the Paleogene, when the clade containing P. subterraneus branched off and the remaining mites diverged into two further clades. One clade resembles P. monospinosus and P. austroasiaticus. The other clade contains 17 genetic clusters resembling P. carabi s.l.. Among these are P. carabi sensu stricto, P. necrophori, and potentially many additional cryptic species. Our analyses suggest that these clades were formed in the miocene by large-scale geographic separation. Diversification also seems to have happened on a smaller scale, potentially due to adaptation to specific hosts or local abiotic conditions, causing some clusters to specialize on certain beetle species. Our results suggest that biodiversity in this genus was generated by multiple interacting forces shaping the tangled webs of life.

zoology↗

bioRxiv2021

Appetitive learning relies on octopamine and dopamine in ants

Associative learning relies on the detection of coincidence between a stimulus and a reward or punishment. In the insect brain, this process is thought to be carried out in the mushroom bodies under control of octopaminergic and dopaminergic neurons. It was assumed that appetitive learning is governed by octopaminergic neurons, while dopamine is required for aversive learning. This view has been recently challenged: Both neurotransmitters seem to be involved in both types of memory in bees and flies. Here, we test which neurotransmitters are required for appetitive learning in ants. We trained Lasius niger ant workers to discriminate two mixtures of linear hydrocarbons and associate one of them with a sucrose reward. We analysed the behaviour of the trained ants using machine learning and found that they preferred the rewarded odour over the other, a preference that was stable for at least 24 hours. We then treated the ants before learning with either epinastine, an octopamine receptor blocker, or with flupentixol, a dopamine receptor blocker. Ants with blocked octopamine receptors did not remember the rewarded odour. Octopamine signalling is thus necessary for the formation of appetitive memory. In contrast, ants with blocked dopamine receptors initially learned the rewarded odour but failed to retrieve this memory 24 hours later. Dopamine is thus required for long-term memory consolidation during appetitive conditioning, independent of short-term memory formation. Our results show that appetitive learning depends on both octopamine and dopamine signalling in ants.

animal behavior and cognition↗