A FLOWER IN FRUIT'S CLOTHING: POLLINATION OF JACKFRUIT (ARTOCARPUS HETEROPHYLLUS, MORACEAE) BY A NEW SPECIES OF GALL MIDGE, CLINODIPLOSIS ULTRACREPIDATA SP. NOV. (DIPTERA: CECIDOMYIIDAE)

摘要

Premise of research. Jackfruit (Artocarpus beterophyllus, Moraceae) is an emerging but underutilized crop whose pollination is poorly understood. We present a multidisciplinary investigation of the reproductive biology and chemical ecology of jackfruit and a putative pollinator, Clinodiplosis ultracrepidata Gagne new species (Dip-tera: Cecidomyiidae)-newly described here-which likely originated in Asia. Methodology. We employed observations, insect trapping, gas chromatography-mass spectrometry analysis of floral volatiles, behavioral bioassays, and quantitative electroantennography to investigate the relationship between jackfruit and C. ultracrepidata in Miami, Florida. Pivotal results. Results indicated that C. ultracrepidata female gall midges visit both male and female jackfruit inflorescences. They oviposit in fungus-infected male inflorescences, and their larvae feed on the fungus; female inflorescences provide no apparent reward. Behavioral assays indicated that the gall midges are attracted to both male and female inflorescences by scent. The main components of jackfruit floral volatiles in both inflorescences are aliphatic esters, primarily methyl 2-methylbutyrate, methyl isovalerate, and methyl tiglate, all of which elicited strong antennal elecrophysiological responses in C. ultracrepidata females. Most of the esters in jackfruit floral volatiles also exist in jackfruit fruit volatiles, suggesting a link between adaptation to pollinators and adaptation to seed-dispersing mammals, which are sensitive to aliphatic esters. Conclusions. We have documented a tripartite pollination mutualism involving gall midges and a fungus in an understudied crop, a result that may inform proper pollinator management. While male inflorescences provide a brood site and nutritional resources, attraction of gall midges to female inflorescences is the result of deceit by scent. Our results support the existence of insect pollination in jackfruit but do not negate the possibility of wind pollination, which warrants further study.