Floral visitors in the crop Phaseolus coccineus (Fabaceae) on the Altiplano of Puebla, Mexico: importance of agricultural management and flower color

Abstract

Background and Aims: Phaseolus coccineus is an allogamous plant, with variation in flower color, and reproduction that depends on pollinators. The species is cultivated under two approaches: one in which agrochemicals are not used to control weeds and pests (traditional management) and another in which they are (technified management). No studies have evaluated the influence of agricultural management system and flower color on the floral visitors of this species; our objective was therefore to analyze how these factors affect the diversity and frequency of the floral visitors of P. coccineus. Methods: A study was conducted with two landraces of P. coccineus (white-flowered and red-flowered), cultivated under two different management systems. Simultaneous observations were conducted for a period of eight days during the peak of flowering, quantifying the number of floral visitors and visits. Species richness and the effective number of species were calculated, the latter was used as a measure of diversity. Chi-square tests were applied, a correspondence analysis performed, and rank abundance curves constructed. Key results: Forty-two morphospecies were recorded, grouped into six orders. Apis mellifera and Hylocharis leucotis were the predominant species. The numbers of visits recorded under traditional management were 1613 and 1105 in white and red flowers, respectively. Under the technified management, these values were 1427 and 815, respectively. There were consistent statistical differences between management systems, but not for flower color. In the white flowers, the traditional management was twice more diverse than the technified management. In the red flowers, this difference was 1.26 times. Conclusions: The diversity and frequency of floral visitors of P. coccineus are favored by the traditional agricultural management, demonstrating the desirability of promoting this type of cultivation. Under the conditions studied, flower color did not influence the species richness or demonstrate any defined tendencies on the frequency of visits.