Biology of Aproida balyi Pascoe, 1863 (Coleoptera: Chrysomelidae: Cassidinae: Aproidini) on its host plant, Eustrephus latifolius R. Br. ex Ker-Gawl (Asparagaceae) in Australia

Abstract

Within the leaf-beetle subfamily Cassidinae (Coleoptera: Chrysomelidae), Aproida Pascoe, 1863 (Aproidini) from Australia has been considered a transitional genus between mining cassidines (“hispines”) and exophagous cassidines (“tortoise beetles”). To illuminate this transition, a detailed study was conducted over one year of the biology of Aproida balyi Pascoe, 1863 on the host plant, Eustrephus latifolius R. Br. ex Ker-Gawl (Asparagaceae). Distribution maps of the host plant and three Aproida species are provided. The life cycle of A. balyi comprises single eggs in a foamy ootheca, three larval instars that feed openly, a pupa suspended from the larva III exuvia, and sexually dimorphic adults. The larva’s green color resembling the host and the narrow body fitted to the narrowed leaf blade allow them to camouflage. They possess a single long caudal process, unlike the paired processes of most other tortoise beetles. Fecal pellets are observed sometimes on this process, but accumulation is rare and lacks the permanent structure of exuvio-fecal shields that distinguishes the ten tribes of tortoise beetles. The larvae exhibit adhesive lobes on the abdominal sternites that appear to help their locomotion, a novel feature in Cassidinae. The pupa is suspended from the larva III exuviae and together they resemble the host’s pendant flower buds, suggesting mimicry. Males have the profemora and protibiae toothed. Both sexes can fly, unlike flightless Aproida cribrata Lea, 1929. These many morphological and behavioral findings contribute potential novel characters that underscore the aberrant nature of Aproidini within Cassidinae and point to another Australian evolutionary oddity.E