Ecological impatt on native bees by the invasive africanized honey eee / Abejas cleptoparasitas, con énfasis en las abejas hospederas colectoras de aceites (Hymenoptera: Apoidea)

Very little effort has been made to investigate bee population dynamics among intact wilderness areas. The presence of newly-arrived feral Africanized honey bee (AHB), Apis mellifera (Apidae), populations was studied for 10-17 years in areas previously with few or no escaped European apiary honey bees. Here I describe and interpret the major results from studies in three neotropical forests: French Guiana, Panama and Yucatan, Mexico (5° to 19° N. latitude). The exotic Africanized honey bees did not produce a negative effect on native bees, including species that were solitary or highly eusocial. Major differences over time were found in honey bee abundance on flowers near habitat experiencing the greatest degree of disturbance, compared to deep forest areas. At the population level, sampled at nest blocks, or at flower patches, or at light traps, there was no sudden decline in bees after AHB arrival, and relatively steady or sinusoidal population dynamics. However, the native bees shifted their foraging time or floral species. A principal conclusion is that such competition is silent, in floristically rich habitats, because bees compensate behaviorally for competition. Other factors limit their populations.

Pocos estudios han considerado la dinámica de poblaciones de abejas en bosques o hábitats no alterados por el hombre. La presencia de abejas silvestres Africanizadas de Apis mellifera (Apidae) fue estudiado por 10-17 años en áreas previamente sin esta especie. Aquí presento e interpreto resultados de tres bosques neotropicales: Guyana Francesa, Panamá y Yucatán, México (5° a 19° N. latitud). La abeja Africanizada exótica no produjo efecto negativo en las abejas nativas, incluyendo especies altamente sociales y solitarias. Diferencias mayores a través del tiempo fueron encontradas en la abundancia de las abejas de miel en flores cerca de hábitat con mayor grado de disturbio, comparado con el bosque espeso. Al nivel poblacional, muestreado en bloques de nidos trampa, en flores o con trampas ultravioletas de insectos, no hubo disminución pronta de abejas, y sí hubo una población relativamente estable o sinusoidal. Sin embargo, las abejas nativas cambiaron su hora de buscar provisiones o su selección de especies florales. Una conclusión principal es que esta competencia por los recursos es ‘silenciosa';, en las áreas florísticamente ricas estudiadas, porque las mismas abejas compensan con su comportamiento. Otros factores rigen sus poblaciones.

Direct costs of forest reproduction, bee-cycling and the efficiency of pollination modes.

The bee guild represents direct primary costs of angiosperm reproduction. Tropical flower visitors take an amount comparable to herbivores, exceeding 3% of net primary production energy. Therefore herbivory and aboveground net primary production have been underestimated. Comparing pollinators to other herbivores, harvest in mature forest by tropical bees is greater than leafcutter ants, game animals, frugivores, vertebrate folivores, insect defoliators excluding ants, flower-feeding birds and bats, but not soil organisms. The ratio of total aboveground net primary production to investment in pollen, nectar and resin used by pollinators suggests wind pollination is several times more efficient in temperate forests than is animal pollination in neotropical moist forest. Animal pollination may be favoured by habitat mosaics and an unpredictable or sparse dispersion of conspecifics — consequences of fluctuating abiotic and biotic environments. Natural selection evidently favours diminished direct reproductive costs in forests, for example by wind pollination, regardless of latitude and disturbance regime. An example is "wind pollination by proxy" of dominant trees in seasonal southeast Asian forests. They flower only occasionally and their pollen is dispersed by tiny winged insects that are primarily carried by the wind — rather than the nectar-hungry bees, bats, birds and moths used by most tropical flora. Increasing evapotranspiration is associated with greater net primary production; I show its correlation with species richness of social tropical bees across the isthmus of Panama, which may indicate increasing forest reproductive effort devoted to flowering, and its monopolization by unspecialized flower visitors in wetter and less seasonal lowland forests.