Genomic perspectives on the evolution of fungal entomopathogenicity in Beauveria bassiana

The ascomycete fungus Beauveria bassiana is a pathogen of hundreds of insect species and is commercially produced as an environmentally friendly mycoinsecticide. We sequenced the genome of B. bassiana and a phylogenomic analysis confirmed that ascomycete entomopathogenicity is polyphyletic, but also revealed convergent evolution to insect pathogenicity. We also found many species-specific virulence genes and gene family expansions and contractions that correlate with host ranges and pathogenic strategies. These include B. bassiana having many more bacterial-like toxins (suggesting an unsuspected potential for oral toxicity) and effector-type proteins. The genome also revealed that B. bassiana resembles the closely related Cordyceps militaris in being heterothallic, although its sexual stage is rarely observed. A high throughput RNA-seq transcriptomic analysis revealed that B. bassiana could sense and adapt to different environmental niches by activating well-defined gene sets. The information from this study will facilitate further development of B. bassiana as a cost-effective mycoinsecticide

Invasion success of a widespread invasive predator may be explained by a high predatory efficacy but may be influenced by pathogen infection

Invasive alien species (IAS) can drive community change through ecological interactions. Parasites and pathogens can play an important role in community function including mitigating or enhancing IAS impacts. Despite this, the degree to which pathogen pressure influences IAS impacts remains poorly understood. We quantified the predatory behaviour of the highly invasive alien harlequin ladybird (Harmonia axyridis) and two UK native species, the 7-spot (Coccinella septempunctata) and 2-spot (Adalia bipunctata) ladybirds, using comparative functional response experiments. We investigated the impacts of pathogen infection on the predatory ability of the ladybirds by exposing individuals to Beauveria bassiana, a widespread entomopathogen. Invasive H. axyridis was a more efficient predator than both the native A. bipunctata and C. septempunctata, often having higher attack and/or lower prey handling time coefficients, whereas native A. bipunctata were the least efficient predators. These differences were found in both adult and larval life-stages. Beauveria bassiana infection significantly altered the predatory efficiency of adult and larval ladybird predators. The effects of pathogenic infection differed between species and life-stage but in many cases infection resulted in a reduced predatory ability. We suggest that the interactions between IAS and pathogens are integral to determining invasion success and impact