Flower visitors and efficient pollinators of Opuntia joconostle F.A.C.Weber. ex Diguet in Jalisco, Mexico

Abstract

Summary: The animals that visit the flowers, pollinators and reproductive system of Opuntia joconostle were studied. The objectives of the work were to identify its floral visitors, to determine which are the most effective pollinators and to evaluate the importance of floral visitors in seed production. To determine the richness and frequency of the animal visitors, five study visits were made from May to June 2017, during which the animals that interacted with the flowers were recorded and collected for a period of thirty minutes for each hour between 10am and 16pm, after which the pollen grains were removed from the body of the collected specimens. For pollination efficiency, the pollen deposited by a specific pollinator in a single visit on the stigma and by self-pollination was counted and seed production from flowers where pollinator visits were avoided and another group with no restrictions were compared. A total of 2,261 floral visitors were recorded, belonging to four orders, eleven families, and twenty-seven species. Bees were the most abundant floral visitors with 98% of the records; the species with the highest number of visits was Apis mellifera with 90%, followed by Diadasia australis with 5%. A higher number of pollen grains per insect were recorded in D. australis than in A. mellifera, D. australis deposited more pollen per visit than A. mellifera and by self-pollination. Flowers that received pollinators produced significantly more seeds per fruit than flowers where visitors were prevented. O. joconostle flowers are used by many animals, however, the majority are bees, particularly two species: A. mellifera and D. australis, the former having a higher frequency of visitation. However, D. australis carries and deposits more pollen. Joconostle seems to have a mixed autogamy/ xenogamy crossing system, as self-pollination was recorded, although it negatively affected seed production. Thus, cross-pollination is important for the conservation of this species, increasing its chances of reproductive success by seed and preserving genetic diversity.