Preference of three scarab beetle species to floral cues

Abstract

The role of floral visual cues was studied in both sexes of three nocturnal scarab beetle species (Holotrichia oblita, Holotrichia parallela, and Anomala corpulenta). Flower patterns were designed using n-petal rose curve and radial gradient tools. Bioassay of plain colored patterns showed that both sexes of H. oblita and H. parallela preferred yellow and white. In contrast, A. corpulenta showed sexual differentiation in preferences. Comparison between given radial gradient patterns and their color components indicated that a radial gradient was necessary in both sexes of H. oblita rather than both sexes of H. parallela to elicit the highest response. Sexual differentiation was found in A. corpulenta. Among 4-, 8-, and 12-petaled patterns, the 4-petaled patterns were most preferred by all of the test insects, regardless of species and sex. Choice assays that provided both odor and visual cues suggest that olfaction may be the primary sensory modality in the three scarab species.