Our latest eco-physiological study shows that hemolymph parameters in ladybirds, partly reflecting the state of their immune system, decline markedly from summer to autumn but are not affected by infection of the ectoparasitic fungus Hesperomyces harmoniae. In contrast, tolerance to thermal extremes is strongly influenced by both season (and thus acclimatization) and infection status: infected ladybirds exhibit reduced tolerance to low temperatures, which may partly explain the lower overwinter survival we observed in a previous study. The fungal infection did not affect movement activity or preferred temperature, and we therefore found no evidence for “behavioural fever”, i.e. the ability of insects to mitigate infections by actively selecting higher (or lower) temperatures than those preferred by healthy individuals. Further details of the study published in Oecologia are available here.
