Arthropod communities associated with gall-inducing Aciurina bigeloviae and Aciurina trixa (Diptera: Tephritidae) in New Mexico

Insect-induced galls are novel structures that serve as habitat to whole communities of associate arthropods that include predators, parasitoids and inquilines. Galling insects are generally under-described, but their associate communities, which can include many specialist organisms, are virtually unknown, particularly in the southwest United States. Aciurina bigeloviae (Cockerell 1890) and Aciurina trixa Curran 1932 are unusually common and abundant galling flies in New Mexico. The 2 species are sister and occur in sympatric areas but have distinct gall morphologies. We reared all arthropods from 3800 galls from 14 sites in the northern and central regions of the state and as a result characterized the complete communities of both species, including barcode sequences and eclosion phenology. We also investigate interactions of A. trixa galls with the abundant inquiline weevil Anthonomus cycliferus Fall 1913 and find no measurable effect of inquiline abundance on the size of the emerged adult fly or gall. The total species count is 24 and includes 6 guilds; both A. bigeloviae and A. trixa communities are richer and more complex than other documented Tephritidae-Asteraceae galling systems. This study highlights the potential of galling insects as ecosystem engineers to maintain large, rich and multi-trophic communities.