Coccinella septempunctata avoids the generalist entomopathogenic fungus Beauveria bassiana.

Beauveria bassiana (Ascomycota: Hypocreales) is an entomopathogenic fungus with a wide host range which includes coccinellids. Seven-spot ladybirds, Coccinella septempunctata, predominantly overwinter in leaf litter and B. bassiana causes high winter mortality of adults in temperate regions. Beauveria bassiana is ubiquitous in soil environments but at varying densities and virulence. Behavioural assays were conducted to assess whether adult C. septempunctata avoided lethal densities of B. bassiana spores in soil or on leaves, or behaved differently in their presence. Behaviours assessed were intensive searching, extensive searching, cleaning and stationary. An additional assay considered avoidance by C. septempunctata of mycosed (B. bassiana) C. septempunctata cadavers compared to uninfected C. septempunctata cadavers or in vitro B. bassiana. Experiments were conducted at both summer (20C) and winter simulated temperatures (4C). The resulting behavioural data were compositional and, so, there was a lack of independence between the times an individual devoted to the behavioural options available. We therefore modelled the ratios of pairs of behaviours, logarithmically transformed, using recently-developed methods in which trials where a behaviour was not recorded (leading to zero-valued observations) were regarded as censored observations bounded above by an arbitrarily small number. The analysis showed that adult C. septempunctata avoided contact with leaf and soil surfaces inoculated with B. bassiana and mycosed cadavers. Indeed, C. septempunctata adults were positioned further away from mycosed cadavers than either uninfected C. septempunctata cadavers or in vitro B. bassiana. So in conclusion C. septempunctata appears to detect and avoid B. bassiana spores on leaves and soil and also mycosed conspecifics.