Viral diversity in predatory insects used for biological control: Insights from a multi-country meta-viromic analysis

Predatory insects such as ladybirds, green lacewings, and an aphid midge have been commercialized and deployed worldwide to deal with the challenge of pest control. However, limited information is available on their associated viruses. To start filling this gap, this study employed an integrative bioinformatics approach with 21 publicly available RNA-seq libraries, from six countries, of eight natural enemy species used to control aphids. A total of 41 putative novel viruses were identified and classified into 16 families and 1 genus. In addition, 13 known viruses were detected, including aphid and phytopathogenic viruses, and a virus from the invasive harlequin ladybird (Harmonia axyridis). The Aphid lethal paralysis virus was the most common virus, detected in several species at different trophic levels, including plants, aphid vectors, and predatory insects, suggesting potential host sharing or dietary/environmental origin. In summary, this unique bioinformatic assessment of eight agriculturally significant predatory insect species demonstrates substantial viral diversity and suggests the potential for interspecies viral transmission. Further studies on viruses associated to agricultural insect populations are essential to elucidate possible effects on biological control strategies based on trophic interactions, determine their functional roles in agroecological systems, promote biodiversity conservation, and comprehend viral evolutionary trends.