Biology subjects

Csata, E.

Publications and source records attributed to Csata, E..

4 recordsLinked to original sources

bioRxiv2026

Isolation and introductions disrupt the homogeneity of Argentine ants in Europe.

The introduction of alien species into new habitats stands as a pressing economic and ecological challenge but it is also essential for unveiling evolutionary processes. The introduction of the Argentine ant (Linepithema humile) led to the spread of a single supercolony through different continents and thousands of kilometres like in Europe, from Northwest Spain to Greece. It was assumed that the high invasiveness of the species mainly relied on the lack of agonism among colonies, an effect derived from its introduction. However, recent studies suggest that local adaptations and evolutionary divergence could involve the disruption of the Argentine ant "empire" into a mosaic of competitive colonies. We investigated how isolation affects population divergence by comparing mainland and island populations in two distant regions colonized in Spain and in Greece with morphology, agonism, cuticular hydrocarbons, and genetic diversity of ant workers. Our results showed that all colonies sampled belonged to the most spread supercolony in Europe (main supercolony) except one sampled in Crete (Heraklion; Greece), which resulted to be a supercolony not registered in Europe. The Heraklian supercolony showed a different chemical and genetic profile and hostile agonism towards the other Greek colonies. Differences between islands and mainland colonies belonging to the main supercolony were higher in Galiza than in Greece. Surprisingly, the chemical profile of the Cretan colony belonging to the main supercolony showed more similarity with the Galizan colonies than with the Greek mainland, suggesting that L. humile may have been introduced into Greece through this island instead of the mainland. Our study suggests that local adaptations in Argentine ant colonies can trigger competition between colonies. Our data strongly support the existence of a candidate supercolony which highlights either ongoing introductions of L. humile in Europe or gaps in our understanding of its metapopulation dynamics.

evolutionary biology↗

bioRxiv2024

Biotic challenges in the city: Dietary restrictions and body fat content of female sexuals in urban ant populations

Urban habitats represent an important challenge for many organisms. Besides the abiotic changes, urban habitats are also characterized by changes in the biotic conditions, such as a more uniform species composition and declining population sizes. For urban ants this can result in dietary shortages. In our study, we tested whether urban ant colonies might suffer from dietary restrictions by carrying out a common garden experiment in which ant colonies from urban and rural habitats were exposed to high carbohydrate, protein, and fat / protein diets. We also investigated the body fat content of individuals from both habitat types. Our findings suggest a lower availability of high-quality carbohydrates in urban areas. Additionally, while not statistically significant, rural colonies exhibited a tendency to consume greater quantities of proteins and fat compared to urban colonies. This trend was in line with a higher body fat content observed in female sexuals (gynes) from rural colonies. These results might indicate the outcome of an evolutionary feedback process in which ant colonies adapt to nutritional constraints in urban environments. They achieve this by minimizing the investment in gynes, which might require fewer reserves for survival during colony foundation due to reduced competition for nesting sites within urban green spaces.

ecology↗

bioRxiv2024

Variability of immune gene expression among different groups within ant colonies shows a multifaceted response to infection by a non-lethal ectoparasitic fungus

Social insect colonies are known to be targeted by a wide variety of different parasites and pathogens because of their high host abundance. However, within a colony, the level of risk to exposure could vary among individuals depending on their role. Unlike many known parasites, which mostly target specific groups of individuals, e.g. foragers, the myrmecoparasitic fungus Rickia wasmannii infects entire ant colonies, being linked to subtle changes in physiology, morphology and behaviour. We investigated how different groups within the colonies respond to being exposed to the fungus by measuring the expression of the genes defensin 1 and prophenoloxidase, both vital components of ant immunity. We found that workers, queens and broods varied in their immune response. Workers displayed diverse profiles, with variable responses to infection: in same-age workers, both prophenoloxidase and defensin 1 levels exhibited increases in correlation with pathogen loads. Queens exhibited a more pronounced immune response. Highly infected queens had a heightened immune response. Larvae did not show a discernible response. Morphological and physiological characteristics had limited effects on gene expression, except in the case of queens, where larger individuals displayed higher defensin 1 expression. Our study shows that these divergent responses likely stem from the differing physiological needs and priorities of various groups within the colony. HighlightsO_LIIn same-age workers, prophenoloxidase and defensin 1 levels increased with pathogen loads. C_LIO_LIBody size affected defensin 1 expression in a caste-specific manner: larger queens displayed higher expression. C_LIO_LIInfection did not elicit any specific response in larvae. C_LIO_LIThe diverse response to infection likely arise from distinct physiological needs and priorities within colony groups. C_LI

zoology↗

bioRxiv2023

Fungal infection alters collective nutritional intake of ant colonies

In many animals, parasitic infections impose significant fitness costs [1-6]. Animals are known to alter their feeding behavior when infected to help combat various parasites [7-12]. For instance, they can adjust nutrient intake to support their immune system [13,14]. However, parasites can also manipulate host foraging behavior to increase their own development, survival and transmission [15-18]. The mechanisms by which nutrition influences host-parasite interactions are still not well understood. Until now, studies that examine the impact of diet on infection have mainly focused on the host, and less on the parasite [12,13, 19-25]. Using Nutritional Geometry [26], we investigated the role of key nutrients: amino acids and carbohydrates, in a host-parasite system: the Argentine ant, Linepithema humile, and the entomopathogenic fungus, Metarhizium brunneum. We first established that the fungus grew and reproduced better on diets comprising four times less amino acids than carbohydrates (1:4 AA:C ratio). Second, when facing food combinations, the fungus exploited the two complementary food resources to reach the same performance as on this optimal diet, revealing the ability of fungal pathogens to solve complex nutritional challenges. Third, when ants were fed on this optimal fungal diet, their lifespan decreased when healthy, yet not when Metarhizium-infected, compared to their favored carbohydrate-rich diet. Interestingly, when the ants were given a binary choice between different diets, the foragers of uninfected colonies avoided intake of the fungal optimum diet, whilst choosing it when infected. Experimental disentanglement of full pathogenic infection and pure immune response to fungal cell wall material, combined with immune measurements, allowed us to conclude that this change of nutritional choice in infected ants did not result from pathogen manipulation but likely represents a compensation of the host to counterbalance the cost of using amino acids during the immune response. The observed change in foraging behavior in infected colonies towards an otherwise harmful diet (self-medication), suggests a collective compensatory mechanism for the individual cost of immunity. In short, we demonstrated that infected ants converge on a diet that is proven to be costly for survival in the long term but that could help them fight infection in the short term. HighlightsO_LIThe insect-pathogenic fungus Metarhizium brunneum performs best on protein-rich diets and is able to solve complex nutritional challenges C_LIO_LIWhile harmful to healthy ants, protein-rich diets did not shorten infected ants lifespan C_LIO_LIContrary to healthy ants, when given a choice, infected and immune-stimulated ants choose a protein-rich diet C_LI

animal behavior and cognition↗