Current Projects
Together with Jan Oettler, I lead CoRe (Cardiocondyla obscurior Research), an international collaborative effort to establish one ant as a model for the many questions about social life. Our focus within CoRe lies in the study of ageing, behavior, developmental plasticity, endosymbiosis, genome evolution and sexual selection. We've recently incorporated the coffee berry borer Hypothenemus hampei, a major pest of coffee, as a comparative model in CoRe (Coffee berry borer Research). For an overview of all CoRe projects and collaborators, see https://cardiocondyla.com (externer Link, öffnet neues Fenster)
Social traits of developing ants
Ants develop in complex social environments where they interact with adult nest members and other developing individuals (Schultner et al., 2017 (externer Link, öffnet neues Fenster); Schultner & Pulliainen, 2020 (externer Link, öffnet neues Fenster)). In Formica wood ants, larvae actively influence their own survival by engaging in egg cannibalism (Schultner et al., 2013 (externer Link, öffnet neues Fenster)), a prime example of selfish offspring behavior. Whether a larva engages in cannibalism depends on its own sex as well as its genetic relatedness to the egg (Schultner et al., 2014 (externer Link, öffnet neues Fenster)), which suggests that larvae can assess variation in their social environment, likely using similar molecular machinery as adults (Morandin et al., 2018 (externer Link, öffnet neues Fenster); Pulliainen et al., 2022 (externer Link, öffnet neues Fenster)). By adjusting egg consumption behaviour to social environment, larvae may even be able to help defend the nest against social parasites (Pulliainen et al., 2019 (externer Link, öffnet neues Fenster)). Ant larvae also adjust their begging behavior to colony kin structure, underlining their ability to assess their social environment (Pegnier et al., 2019 (externer Link, öffnet neues Fenster)). By taking an approach focused on brood, this axis of our research shines a new light on social evolution. This work has clearly ignited interest in the role of brood in insect societies and has inspired our research on developmental plasticity and larval traits in Cardiocondyla obscurior.
Phenotypic plasticity in ants
Individuals that share the same genes can follow different developmental pathways so that as adults, they differ in shape, size and behaviour. Much of this variation is due to phenotypic plasticity, which allows organisms to express a range of phenotypes in response to variation in their environment. The ant Cardiocondyla obscurior, a species with two female castes (queens & workers) and two male morphs (wingless & winged males), has been successfully established as a model for developmental research (e.g. Oettler et al. 2010 (externer Link, öffnet neues Fenster), 2019 (externer Link, öffnet neues Fenster), Schrader et al. 2015 (externer Link, öffnet neues Fenster), 2017 (externer Link, öffnet neues Fenster)). A recent study suggests that sex differentiation genes have been co-opted to act in caste differentiation in this ant (Klein et al. 2016b) (externer Link, öffnet neues Fenster). In addition, we discovered that female caste is determined by late embryogenesis, and that queen-destined eggs and larvae can be easily identified by the localization of crystalline deposits around the developing ovaries (Schultner et al. 2023 (externer Link, öffnet neues Fenster)). We are now using this unique discovery to investigate the proximate mechanisms that regulate caste determination and differentiation. So far, we've found that caste development is already highly canalized in embryos, with miRNA and mRNA expression patterns suggesting that the sterile workers are neither “female”, nor “male” (Oettler et al. preprint 2023 (externer Link, öffnet neues Fenster)). Currently, we are studying how canalized caste development is linked to developmental hormones (Brülhart et al. 2024 (externer Link, öffnet neues Fenster)). We are also interested in the determination and differentiation of the unique wingless male morphs.
Ants and their symbionts in a changing world
Understanding how organisms cope with environmental change is one of the most important challenges facing biologists. Predicting the effects of extreme environmental conditions is not straightforward because, in addition to genotype and abiotic factors, organisms are influenced by a multitude of biotic interactions, including those with their competitors, predators and microbial symbionts - who themselves are exposed to changing environmental conditions. The cosmopolitan ant Cardiocondyla obscurior is infected with two main endosymbionts: Candidatus Westeberhardia cardiocondylae (Klein et al. 2016a (externer Link, öffnet neues Fenster), Jackson et al. 2022 (externer Link, öffnet neues Fenster)) and Wolbachia (Ün et al. 2021 (externer Link, öffnet neues Fenster)). Populations from Brazil and Japan carry distinct Wolbachia strains, which differ in their infection titres and ability to manipulate host reproduction by inducing cytoplasmic incompatibility (Ün et al. 2021 (externer Link, öffnet neues Fenster)), as well as in their sensitivity to environmental stress (Ün et al. 2022 (externer Link, öffnet neues Fenster)). Currently we are focusing on understanding the functional relationship between the ant, its symbionts and the environment, with particular focus on the effects of stressors such as chemical pollution (Leponiemi et al. 2022 (externer Link, öffnet neues Fenster)) and extreme temperatures. We do this using a holobiome approach incorporating genomic, morphological, and behavioral data.
Evolution and applied biology of the coffee berry borer Hypothenemus hampei
Coffee production is threatened by the coffee berry borer Hypothenemus hampei (CBB), a tiny beetle that develops within the coffee bean and consumes it, destroying both yield and quality. Worldwide, the CBB causes losses of over €450 million in a global market generating ~€65 billion annually. It is paramount that we understand the biology of the beetle to find a sustainable solution for this problem. In projects led by Dr. A. Myrie, we’ve established a lab population of the CBB and investigated three fundamental aspects of CBB biology: behavior (Myrie et al., 2024 (externer Link, öffnet neues Fenster)), cuticular chemistry (Myrie et al., 2025 (externer Link, öffnet neues Fenster)) and population genomics (Errbii, Myrie et al., 2024 (externer Link, öffnet neues Fenster)). We are now testing the influence of heat waves on fitness of the beetle and its symbiotic bacteria, which play a crucial role in caffeine digestion. Further, we have incorporated an applied aspect by comparing the attractiveness of berry volatiles for use in CBB traps, with preliminary laboratory tests conducted in November 2024, and field trials planned in collaboration with various international coffee authorities. Currently, we are also generating data for a collaborative project on CBB population genomics. For more information on these projects, please contact Dr. A. Myrie.