Crape myrtle bark scale Acanthococcus lagerstroemiae (Coccidae: Eriococcidae) infestation seasonally alters the insect biodiversity on crape myrtle trees.

Abstract

Understanding changes to local communities brought about by biological invasions is important for conserving biodiversity and maintaining environmental stability. Scale insects (Hemiptera: Coccoidea) are a diverse group of insects well known for their invasion potential and ability to modify local abundance of multiple insect groups. Here, we tested how the presence of crape myrtle bark scale (Acanthococcus lagerstroemiae, CMBS), an invasive felt scale species, seasonally impacted local insect abundance, biodiversity, and community structure on crape myrtle trees. Our field surveys showed that CMBS-infested trees had seasonal changes to local insect abundance and family-level richness, and inverse Simpson's diversity relative to non-infested trees. CMBS infestation resulted in a decrease in community evenness on crape myrtle trees. Community compositions of insect visitors were distinct between infested and non-infested trees. CMBS-infested trees had greater seasonal abundances of Coccinellidae, Vespidae, Dolichopodidae, and Muscidae. Two of the families (Coccinellidae, Vespidae) that responded most strongly to CMBS infestation were dominated by non-native species. Our results show that CMBS-infested trees acted as resource hubs for natural enemies and carbohydrate scavengers, resulting in uneven communities shaped by a few highly responsive taxa. The temporal dynamics of these effects support CMBS as an ecological catalyst, reshaping urban insect communities and highlight its potential for facilitating invasion cascades in anthropogenic habitats. These results emphasize the importance of fine-scale temporal monitoring for understanding and mitigating the ecological impacts of introduced scale insects in urban environments.