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You might think of pollinators as bees or butterflies, but for many crops, it’s humans, according to a review published in Basic and Applied Ecology. The study by Annemarie Wurz and colleagues finds that hand pollination is used on twenty crops.
The primary reason for hand pollination is due to a lack of pollinators, say Wurz and colleagues. In the case of vanilla (Vanilla planifolia), the authors note that while Spanish explorers took the plant from Mexico to Europe, they did not take its pollinators. They record that a slave, Edmond Albius, discovered a method to hand pollinate the plants. This method continues to be used in Madagascar, where many smallholders depend on vanilla production.
They also mention date palm (Phoenix dactylifera). This tree is a plant with male and female forms. The males don’t produce dates, so they tend to be weeded out to favour the female plants. However, you do need some males for pollination and fruit set to occur. “The pollination of date palm is often ritualized and also used for demonstrations of strength, pride, and skills of male laborers making it a culturally important practice,” write Wurz and colleagues. Climbing the date palms to pollinate the trees is dangerous, and they point out that hand pollination remains a health and safety issue.
Elsewhere humans can drive out pollinators with pesticides or by introducing honey bees that might not be as efficient. Passion fruit production in Brazil is affected by low numbers of carpenter bees. Here, hand pollination has increased production costs by 12%. One way to reduce hand pollination costs would be to develop new technologies. Still, the review authors note that often there is another option — pollination by low-paid workers, possibly children, under poor working conditions.
“Therefore, hand-pollination must be accompanied by socio-ecological standards that include the protection of natural pollinators and ways to ensure safe and fair work practices,” said Professor Ingo Grass of the University of Hohenheim in a press statement.
Annemarie Wurz, Agroecologist at the University of Göttingen and lead author of the study, added: “Where natural pollination is available or can be restored, it has to be a priority, as it is the most efficient, cost-effective and biodiversity-friendly option.”