ABSTRACT Pollination efficiency is a major determinant of productivity of cacao, Theobroma cacao L., with ceratopogonid biting midges ( Forcipomyia spp.; Diptera: Ceratopogonidae) recognized as key pollinators. However, temporal variation in pollinator availability and the sensory cues mediating attraction to cacao flowers remain poorly quantified. Here, we investigated the emergence dynamics of Forcipomyia sp., floral colour traits, and behavioural responses to visual and olfactory cues associated with cacao flowers using field surveys and laboratory bioassays. Emergence from decomposing cacao husks was temporally associated with the flowering intensity, rainfall, and temperature, although this pattern was not fully synchronized across all months. Floral colour analysis based on RGBA values identified four representative hues: dark yellow, light yellow, beige, and purple. Field trapping showed that Forcipomyia sp. was captured across all colour categories, with no significant preference detected among the tested hues. In Y‐tube assays, adults oriented preferentially towards the cacao floral volatile extract rather than the solvent control. In arena assays, visual choice was limited in the absence of odour cues, whereas the presence of floral extract concentrated responses on the purple stimulus. Together, these results suggest that attraction of Forcipomyia sp. to cacao flowers is mediated by multimodal sensory cues, with olfactory signals contributing to initial orientation and visual cues contributing to final localisation. This integrative perspective provides novel understanding of cacao pollination ecology and highlights the role of combined visual and chemical signals in pollinator–plant interactions.
Jordão et al. (Wed,) studied this question.
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