Polinização e sua influência na produção de culturas de Cucurbitaceae

Abstract

The production of many agricultural crops depends on pollinators, especially bees, considered primarily responsible for crop yields, influencing the size, weight, and chemical composition of fruits and seeds. However, although its importance is known, the presence of pollinating insects in crops has been decreasing, threatening global nutritional security. As a result, agricultural crops that are more dependent on pollinators are consequently the most affected, among those in the Cucurbitaceae family, such as pumpkin (Cucurbita moschata), due to their monoecy. Despite the importance of the family in global agricultural production, there are no studies that statistically integrate data on the interaction of Cucurbitaceae crops and their pollinators, nor indicate gaps in knowledge. Furthermore, given the importance of pollinators in pumpkin production, investigations into the influence of pollination on production are essential to assist with pollinator management and conservation actions. The objective of this work was to understand the trend of studies and plant-pollinator interactions of cucurbits of economic importance on a global scale, integrate global data on the pollination of zucchini (Cucurbita pepo) and evaluate the relationship between floral display, frequency of visits, quantity and quality of agricultural production, including analysis of fruit antioxidants, using pumpkin cultivation (Cucurbita moschata) as a model. The doctoral thesis is structured into three chapters. In the first chapter, a systematic review of the literature was carried out and, based on data from floral visitors, a meta-network was constructed. The meta-network was highly modular, with most species being peripheral, the module hub was Xenoglossa kansensis and the network hubs were Apis florea and A. mellifera. The formation of modules cannot be explained exclusively by functional characteristics of the species, because although the flowers are similar in color, they differ in other attributes, explaining the great diversity of insects observed. Our data reinforces the need to support native pollinators, contributing to mitigating the global pollinator crisis. In the second chapter, through a systematic review, we analyze the distribution of studies, build a network of countries and pollinators and compare data on the efficiency of specific pollinators. Studies have been carried out on almost every continent, where most studies have investigated the frequency and diversity of floral visitors. Zucchini flowers fed 116 species of pollinators, mainly bees. Many countries had almost exclusive groups of native pollinators, among which it is possible to find efficient and manageable species, capable of replacing exotic pollinators. The data compiled here will help in the development and improvement of strategies for the management and conservation of pollinators. Furthermore, future studies on the influence of pollinators on the chemical aspects of fruits and seed germination are necessary. In the third chapter, we verify floral biology, carry out focal observations and conduct pollination treatments (natural and cross). Seven species of visitors were recorded, with A. mellifera and T. spinipes being the most frequent. The fruit set resulting from natural pollination was greater than that from cross pollination and presented greater antioxidant activity of the fruits. Furthermore, the number of seeds was positively related to fruit weight. Thus, bees were the main pollinators of pumpkin produced in the semi-arid region of Northeast Brazil, with emphasis on T. spinipes and A. mellifera, which positively influenced the weight of the fruits. Furthermore, pollinators favored the antioxidant potential of the fruits.