Pollination of ‘criollo’ avocados (Persea americana) and the behaviour of associated bees in subtropical Mexico
Cesar Can-Alonzo, Jose Javier G Quezada-Euan, Patricia Xiu-Ancona, Humberto Moo-Valle, Gustavo Rafael Valdovinos-Nunez and Salvador Medina-Peralta
The flowering characteristics, contribution of self versus cross pollination and bee visitation were studied in ‘criollo’ avocado cultivars in Yucatan, Mexico. The pattern of pistillate and staminate stages (I and II, respectively), stigma receptiveness and the production of fruit in bagged and open panicles was followed in two commercial orchards. The number of bee visits across the day and the number of pollen grains on the body of workers of honey bees and two native stingless bee species were compared. Environmental variables were also recorded to determine their influence on bee visit rates. Few stigmas were morphologically receptive during the second day of opening of individual flowers (stage II). There was no overlapping between stages I and II. Open panicles produced significantly more fruit (60% on average) than bagged ones. Bee visits to flowers of both type A and B cultivars were significantly more frequent during the pistillate stage than during the staminate stage. Apis mellifera had an overall higher frequency of visits compared with the other two species. The number of pollen grains on the bees was not statistically different between A. mellifera (1644 ± 90.1 [s.d.]) and Trigona nigra (1356 ± 71.3) but it was significantly less in Nannotrigona perilampoides (781 ± 16.1). Environmental humidity had an influence on the visits of A. mellifera (r = -0.88) and N. perilampoides (r = 0.92) but not on T. nigra. It is concluded that self pollination is of limited influence in fruit production in avocado cultivars in subtropical Mexico and that both native stingless bees and honey bees potentially are efficient pollinators of this crop.