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Kirjoittajat osallistuivat syksyllä 2022 Oslossa kahteen tilaisuuteen, joissa kuultiin hedelmien ja marjojen kasvinsuojeluun ja laatuun liittyvää uutta tietoa. Pohjoismainen omenan laatuverkosto piti työpajan 7.-8.11.2022. Suomesta mukana oli seitsemän henkeä. Työpajasta siirryttiin suoraan hedelmän- ja marjanviljelyn neuvojien järjestämään seminaariin (Frukt- og bærseminaret, Norsk Landbruksrådgiving). Tapahtumissa esityksien pääpaino oli erityisesti omenan laatumittauksissa, fungisidiresistenssissä sekä hyönteistuhoojissa.

Increasing antimicrobial resistance (AMR) poses a challenge for treatment of bacterial diseases. In real life, bacterial infections are typically embedded within complex multispecies communities and influenced by the environment, which can shape costs and benefits of AMR. However, knowledge of such interactions and their implications for AMR in vivo is limited. To address this knowledge gap, we investigated fitness-related traits of a pathogenic bacterium (Flavobacterium columnare) in its fish host, capturing the effects of bacterial antibiotic resistance, coinfections between bacterial strains and metazoan parasites (fluke Diplostomum pseudospathaceum) and antibiotic exposure. We quantified real-time replication and virulence of sensitive and resistant bacteria and demonstrate that both bacteria can benefit from coinfection in terms of persistence and replication, depending on the coinfecting partner and antibiotic presence. We also show that antibiotics can benefit resistant bacteria by increasing bacterial replication under coinfection with flukes. These results emphasize the importance of diverse, inter-kingdom coinfection interactions and antibiotic exposure in shaping costs and benefits of AMR, supporting their role as significant contributors to spread and long-term persistence of resistance. peerReviewed

Hosts can defend themselves against parasites either by preventing or limiting infections (resistance) or by limiting parasite-induced damage (tolerance). However, it remains underexplored how these defense types vary over host development with shifting patterns of resource allocation priorities. Here, we studied the role played by developmental stage in resistance and tolerance in Atlantic salmon (Salmo salar). This anadromous fish has distinct life stages related to living in freshwater and seawater. We experimentally exposed 1-year-old salmon, either at the freshwater stage or at the stage transitioning to the marine phase, to the trematode Diplostomum pseudospathaceum. Using 56 pedigreed families and multivariate animal models, we show that developmental transition is associated with reduced resistance but does not affect tolerance. Furthermore, by comparing tolerance slopes (host fitness against parasite load) based on additive genetic effects among infected and unexposed control relatives, we observed that the slopes can be largely independent of the infection, that is, they may not reflect tolerance. Together, our results suggest that the relative importance of different defense types may vary with host development and emphasize the importance of including control treatments for more confident interpretations of tolerance estimates. peerReviewed