Nocturnal and Diurnal Floral Visitors Complement Pollination Services to Pitahaya (Selenicereus undatus) in the Yucatan Peninsula of Mexico

Abstract

The pitahaya (Selenicereus undatus), a night-blooming cactus with edible fruit, has been cultivated for centuries in the Yucatan Peninsula, one of the main regions of production in Mexico and globally. Although pitahaya flowers are mostly receptive at night, stigma receptivity extends into the morning, attracting numerous insect visitors. This study compared the overall contributions of nocturnal (N) and diurnal (D) floral visitors to pitahaya pollination. We quantified the abundance of both groups over one plantation and conducted controlled floral access experiments to compare their effects on fruit quantity and quality, to estimate the overall pollination service provision (PSP) to the crop. D visitors were significantly more abundant than N ones. The beetle Carpophilus sp. was the predominant visitor recorded throughout the study period, followed by Africanised Apis mellifera, which predominated among D visitors. Controlled experiments showed that D visitors significantly improved fruit set (95.6%), seed number (3543 ± 219), and fruit weight (309 ± 14 g) compared to N visitors (75.6%; 2373 ± 297 seeds; 228 ± 17 g). D visitors provided substantially higher pollination service (Spear's index = 0.90) than N ones (0.22). The overall PSP was 0.56, confirming a pollination deficit due to insufficient N pollination. Our results show that the diurnal insect community, particularly Africanised honey bees, play an important role in providing complementary pollination services to pitahaya crops. These findings should be considered to implement management strategies to improve pollination and productivity of this economically important crop in Mexico.