The importance of pollinators to ensure successful harvests and therefore global food security is widely recognized. However, specific pollinators for even the most important crops – such as cocoa – have not yet been identified and there remain many questions about the sustainability, conservation and management of plantations to improve their populations and hence , pollination services. Today, an international research team based in central Sulawesi, Indonesia and led by the University of Göttingen, found that in fact ants and flies – but not ceratopogonid midges as previously thought – seem have a crucial role to play. In addition, they found that promoting biodiversity-friendly landscapes, fallen leaves and trees providing shade in agroforestry systems was important for improving small cocoa pollinators. The research was published in Biological conservation.
The team, in collaboration with Tadulako University in Palu, conducted two separate experiments involving 42 cocoa agroforestry farms in the Napu Valley in central Sulawesi. The work included applying sticky glue to over 15,000 flowers in over 500 trees over an eight-month period and recording visitors’ identities and abundance of captured flowers. In an experiment involving 18 farms, they studied the effect of the distance between the forest and the farm, and the amount of forest cover of shade trees, on the abundance of key pollinators. In the second experiment in 24 different cocoa farms, they measured the effect of leaf litter management on pollinators. In both experiments, they quantified the amount of forests and agroforests surrounding the 42 cocoa farms.
Researchers found that ants were the most common flower visitors. This highlighted their potential as pollinators, either directly (by carrying pollen), or indirectly (by disturbing pollinators and promoting their movement). The study also shows that the preservation of landscapes favorable to biodiversity, such as forests and agroforests, and the promotion of agroforestry systems are crucial for the conservation of pollinators. This in turn promotes pollination and sustainable cocoa production. “We were surprised not to have caught any cerato-pogonid midges, even though these tiny midges were considered the most important pollinators of cocoa. This highlights that cocoa pollinators are more diverse than previously known, but also that there is still a lot to learn, “said Dr Manuel Toledo-Hernández, University of Göttingen and first author of the study. “Current global cocoa initiatives should take into account the role of biodiversity-friendly habitats for pollinator conservation, as their pollination services are an environmentally friendly alternative to current commitments to combine high yields with conservation. Added Toledo-Hernández and his co-authors Teja Tscharntke Thomas C. Wanger.
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