Is Fennel Crop Dependent on Insect Pollination?

Abstract

The importance of insects for global food crop production is starting to be well-known but the level of dependence on insects is less referenced, especially for some aromatic crops. Fennel ( Foeniculum vulgare ) is an aromatic mass-flowering crop cultivated in the southern of France for its essential oil that contains trans -anethole of food and economical particular interest since it is used to elaborate anise drinks. Here, we have characterized the dependence of fennel on insect pollination. We used four controlled pollination treatments to compare the reproductive success (fruit initiation rate, fruit weight), and the fennel yield (weight of the fruits and amount of trans -anethole at the crop level) between insect pollinated flowers and bagged flowers. We also checked the ability of reproduction by autogamy in this species, and the existence of a reproductive limitation linked to insect activity. We have shown that pollination without insect leads to reproductive failure in fennel which is not an autogamous plant species. At the crop level, insect pollination is fundamental to improve the fruit initiation rate, the weight of the fruits and the amount of trans -anethole leading to an 92% dependence of fennel on insect pollination. Finally, we showed no reproductive limitation with the current state of insect activity. We are thus providing interesting clues to managers and producers to support the production of fennel crops, showing once again that insects are essential to sustain global food production.