Differences in the Chemical Composition of Melon (Cucumis melo L.) NectarExplain Flower Gender Preference by Its Pollinator, Apis mellifera

Melon is a pollinator-dependent crop that relies mainly on bees to set fruits. However, manselected varieties vary in their attractiveness to flower visitors, and some flower genders and
melon types may be less visited than others, harming pollination. We investigated the nectar
composition of male, female and hermaphrodite flowers of 270 individuals of five commercial
melons Cucumis melo (Cantaloupe, Charentais, Galia, Piel de Sapo, and Yellow), and its role
in flower visit by Apis mellifera foragers. We found that melon nectar is composed mainly of
sugars and amino acids such as tyrosine, phenylalanine, tryptophan, and flavonoids kaempferol3-O-neohesperidoside, luteolin hexoside, and kaempferol rhamnoside. But the amount of these
chemical compounds varies among the flower genders. We also developed an accurate regression
model to predict the number of bee visits to melon flowers based on the nectar composition. Our
results indicate that nectar composition plays little role in bee discrimination among flowers of
different melon types but is essential to the honeybee choice between flower gender. The amounts
of phenylalanine (49.40%) and tryptophan (12.05%) in the nectar are related to bee preference for
hermaphrodite flowers. More visits to hermaphrodite flowers contribute to setting and developing
well-formed fruits, increasing productivity