The relative success of Africanized and European honey-bees over a range of life-zones in Costa Rica.
Abstract
The reproductive success and biology of Africanized (A) and European (E) honeybees (Apis mellifera) were compared for a year (1984-86) over 3 life-zones from 900 to 2800 m in Costa Rica, with the aim of identifying the factors which might limit the distribution of both bee types in tropical highlands. There was a significant difference in the rainy season between E colonies given supplemental feedings and those not so fed; however, there were no significant differences in survivorship between the fed and unfed A colonies. More E than A colonies died from gradual weakening, and only A colonies absconded. However, colony deaths and absconding occurred with approximately equal frequency over all elevations during the year. Almost 3 times as many A as E colonies swarmed over the year. Although the majority of swarms occurred in the dry season at the lowest apiary, both bee types issued swarms at the highest elevation. A colonies weighed significantly more and maintained significantly larger worker brood areas than E colonies across all elevations from most months of the year, except at 2800 m from March to June. A colonies reared more drones than E colonies, except during the dry season at the highest elevation. There were no significant differences in pollen storage between bee types across all elevations for 10 months of the year, and there were no significant differences in nectar storage throughout the year. The most pronounced differences between the bee types were observed in the lowlands, which accounts for the rapid population growth and range expansion of A bees, and their displacement of E bees in these areas. The differences between the bee types in the highlands (2200 m and 2800 m) were not as pronounced for any of the determinations, indicating that neither was better adapted than the other to the climatic and resource conditions of tropical highlands.<new para>ADDITIONAL ABSTRACT:<new para>The reproductive success, biology and survival of Africanized (A) and European (E) honey bee colonies were recorded for a year at 4 altitudes (900, 1800, 2200 and 2800 m) belonging to 3 life-zones. During the rainy season, E that were fed survived better than those that were not, but feeding did not affect survival in A. More E. than A died from gradual weakening; only A absconded. Deaths and absconding did not vary much with season or altitude. Swarming by A was recorded 3 times more than by E; most swarming occurred in the dry season and at the lowest altitude. In general, A weighed more than E and had more brood (however, this was not so at 2800 m during the period from March to June). Other differences are reported, as well as some similarities. Differences between A and E were most marked in the lowlands, which is the type of area where A has rapid population growth and displaces E. Differences were less pronounced at 2200 m and 2800 m. The results are discussed in relation to the potential distribution of A.
Key words
- altitude
- behaviour
- beneficial arthropods
- beneficial insects
- beneficial organisms
- brood rearing
- death
- development
- Ecology
- effects
- Geographical distribution
- honey bee colonies
- honey bees
- Introduced species
- Life history
- population dynamics
- races
- Reproduction
- seasonal variation
- Social insects
- swarming
- tropical Africa
- tropics