Ladybird (Coleoptera, Coccinellidae) communities on nonnative blue spruce in central Europe

Blue spruce (Picea pungens) has been planted in urban greenery as an ornamental tree in central Europe for more than 150 years. We investigated whether this nonnative spruce is a convenient habitat for ladybirds (Coleoptera, Coccinellidae). In 2021 and 2022, adults and larvae were sampled in four towns in Slovakia at monthly intervals throughout the growing season, from April to October. We recorded adults of 27 species and larvae of 11 ladybird species. Conifer specialist ladybird species predominated both in adult and larval communities (adults – 9 species, 85.2% of all individuals; larvae – 7 species, 92.1% of all individuals). Exochomus quadripustulatus and Aphidecta obliterata were the most common in adult (31.8% and 33.5% of all individuals, respectively) and larval (57.5% and 25.1% of all individuals, respectively) communities. The most abundant generalist species was nonnative invasive Harmonia axyridis (adults – 5.6%, larvae – 6.8% of all individuals). Adults and larvae of ladybirds were more abundant on solitary trees than on trees growing in groups. Our results confirmed that blue spruce hosts rich ladybird communities and provides them shelter and food resources.