Crape myrtle bark scale Acanthococcus lagerstroemiae (Coccidae: Eriococcidae) infestation seasonally alters the abundance and composition of insect assemblages 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, impacted local insect abundance, biodiversity, and community structure on crape myrtle trees. We evaluated seasonal changes in standing honeydew crop on infested crape myrtle trees. Our field surveys showed that infestation of CMBS results in increases to local insect abundance and family-level richness, while negatively affecting community evenness. Community compositions of insect visitors were distinct between infested and non-infested trees. CMBS-infested trees had greater seasonal abundance of Coccinellidae, Vespidae, Halictidae, Sphecidae, Syrphidae, and Muscidae. The two families that responded most strongly to CMBS infestation (Coccinellidae, Vespidae) were dominated by non-native species. Non-infested crape myrtles showed no associations with insect taxa. Honeydew standing crop from landscape and potted trees infested with CMBS peaked during months with low insect visitation to infested crape myrtle trees. Our results show that the introduction of CMBS into local landscapes shifts community dynamics largely by increasing the abundance of generalist and non-native insect species. The cascading biotic effects of an invasive insect on whole communities highlights the importance of establishing more effective methods to prevent the spread of this non-native scale.