Bee pollination effects on yield and chemical composition of West Indian gherkin fruits (Cucumis anguria L., Cucurbitaceae) in the Brazilian semi-arid region.

Animal pollination plays a key role in global agricultural production and especially of monoecious crops, which are essentially dependent on pollinators. The West Indian gherkin fruit (Cucumis anguria L., Cucurbitaceae) is a monoecious vegetable adaptable to adverse abiotic conditions, resistant to diseases, and rich in minerals and vitamins, thus being a relevant alternative for improving nutritional security of socioeconomically vulnerable populations. The knowledge on the influence of pollination and of specific pollinators on chemical characteristics of fruits would help pollinators' management, but it is still poorly understood. In this study we investigated the influence of pollination on quantitative and qualitative aspects of fruits fruits of West Indian gherkin fruits (Cucumis anguria L., Cucurbitaceae) in the Brazilian semi-arid region. Data on pollination biology and on fruits resulted from controlled crosses (open-OP, cross-CP and Apis mellifera Linnaeus, 1758 pollinations) were compared among crosses: number, length, weight, number of seeds, firmness and chemical traits related to flavor and shelf life. Flowers were pollinated by four bee species, and Apis mellifera was the most frequent. followed by two native bee species. OP and A. mellifera resulted in more fruits than CP. Fruits resulting from OP were heavier than CP and had similar weight when compared to A. mellifera. The other variables did not differ between treatments. The better performance of OP and A. mellifera when compared to CP is probably related to the xenia, i.e., the influence of tissues bearing paternal genes (pollen and pollen tube) in maternal tissues. OP and A. mellifera experiments apparently resulted in the deposition of a greater genotypic diversity of the pollen loads when compared to CP. This result is also explained by the higher functional diversity of pollinators related to OP when compared to CP. This study not only elucidates immediate impacts on yield but also emphasizes the deeper connections between floral biology, pollinator diversity, and sustainable crop production, once West Indian gherkin profit was enhanced by bee pollination.

Different visitation frequencies of native and non-native bees to vines: how much vegetation is necessary to improve fruit production?

Pollination is provided by biodiversity and maintains global food production. We investigated the effects of vegetation cover on the abundance of floral visitor and vine (Vitis labrusca Raf.) production. We expected an increase in both floral visitor frequencies and vineyard yields with an increase in native vegetation cover in the landscape. We also investigated different scenarios of visitor abundance with and without honeybees (Apis mellifera L.). We surveyed floral visitors from ten vineyard plots with different native cover surrounding them and related both visitors and native vegetation to fruit set. Considering some of these vineyards, we compared physical and chemical traits of berries to understand how they vary according to native vegetation. Floral visitor abundance was positively related to native vegetation cover. However, considering only native bee abundance, we found a dual (hyperbolic) response. Apis mellifera (L.) Africanized was the most abundant species and had the highest number of interactions; however, when removed from the network analysis, the relationship between vineyards and native bees became more specialized. The fruit size and mass of berries differed among vineyards, as did some chemical traits related to commercial quality of fruits, such as soluble solids, pH and flavonoids. Vineyards surrounded by intermediate areas of native vegetation present a balance between resource availability from vineyards and native vegetation. Apis and non-Apis (such as flies and small bees) floral visitors, known to have different effects on vine pollination, could hypothetically provide variation in vine production and quality. Considering a near 20% native vegetation increment, there was an enhancement, on average, of ten-fold more berries per bunch, the changing physical and chemical fruit traits by vegetation increment could also increase the aggregate value of vines and the value of pollination services in the economy.

Extranuptial nectaries in flowers: ants increase the reproductive success of the ant-plant Miconia tococa (Melastomataceae).

Although the production of extranuptial nectar is a common strategy of indirect defence against herbivores among tropical plants, the presence of extranuptial nectaries in reproductive structures is rare, especially in ant-plants. This is because the presence of ants in reproductive organs can generate conflicts between the partners, as ants can inhibit the activity of pollinators or even castrate their host plants. Here we evaluate the hypothesis that the ant-plant Miconia tococa produces nectar in its petals which attracts ants and affects fruit set. Floral buds were analysed using anatomical and histochemical techniques. The frequency and behaviour of floral visitors were recorded in field observations. Finally, an ant exclusion experiment was conducted to evaluate the effect of ant presence on fruit production. The petals of M. tococa have a secretory epidermis that produces sugary compounds. Nectar production occurred during the floral bud stage and attracted 17 species of non-obligate ants (i.e. have a facultative association with ant-plants). Ants foraged only on floral buds, and thus did not affect the activity of pollinators in the neighbouring open flowers. The presence of ants in the inflorescences increased fruit production by 15%. To our knowledge, the production of extranuptial nectar in the reproductive structures of a myrmecophyte is very rare, with few records in the literature. Although studies show conflicts between the partners in the ant-plant interaction, ants that forage on M. tococa floral buds protect the plant against floral herbivores without affecting bee pollination.