Oceanic islands have reduced resources and natural enemies and potentially affect life history traits of arriving organisms. Among the most spectacular invasions in the Western hemisphere is that of the Africanized honeybee. We hypothesized that in the oceanic island Puerto Rico, Africanized bees will exhibit differences from the mainland population such as for defensiveness and other linked traits. We evaluated the extent of Africanization through three typical Africanized traits: wing size, defensive behavior, and resistance to Varroa destructor mites. All sampled colonies were Africanized by maternal descent, with over 65% presence of European alleles at the S-3 nuclear locus. In two assays evaluating defense, Puerto Rican bees showed low defensiveness similar to European bees. In morphology and resistance to mites, Africanized bees from Puerto Rico are similar to other Africanized bees. In behavioral assays on mechanisms of resistance to Varroa, we directly observed that Puerto Rican Africanized bees groomed-off and bit the mites as been observed in other studies. In no other location, Africanized bees have reduced defensiveness while retaining typical traits such as wing size and mite resistance. This mosaic of traits that has resulted during the invasion of an oceanic island has implications for behavior, evolution, and agriculture.

Generalized pollination systems may be advantageous on island systems or regions of substantial disturbance. We examined whether or not specialization breakdown has occurred in a presumably bat‐pollinated columnar cactus, Pilosocereus royenii, on Puerto Rico, an island subjected to periodic hurricanes. The flowers show characteristics related to bat pollination including nocturnal anthesis, morphology, and amount and quality of nectar reward. The cactus produces flowers whose styles are temporally and mechanically separated from its anthers and do not self‐pollinate. Hand manipulations indicated that it is partially self‐incompatible or suffers some inbreeding depression. In 217 h of observations conducted biweekly over the course of 1 yr, P. royenii received visits from bats, moths, bees, and birds, but the only effective pollinator was the carpenter bee, Xylocopa mordax. Only four bat visits were recorded, all prior to stigma receptiveness. Floral morphology of P. royenii was significantly more variable than that of other bat‐pollinated species of the genus. We propose that infrequent bat visits are a consequence of a population crash and that floral variability is due to either relaxed selection for bat pollination or a transitional stage from bat pollination to bee pollination.

Defense is one of the most important factors affecting life history. The relationship of defense to life history traits as well as its possible costs has been reviewed extensively for many groups, including plants. However, defense in social insects, such as honey bees, has never been examined from a trade-off perspective, although defense in honey bees, Apis mellifera L. (Hymenoptera: Apidae), has been widely studied. In this review, we discuss the life history traits of honey bees, particularly traits related to defense. We then examine trade-offs in the context of resource availability. Lastly, we offer suggestions for future research on trade-offs in honey bees and other social insects.

BackgroundThe Africanized honey bee is one of the most spectacular invasions in the Americas. African bees escaped from apiaries in Brazil in 1956, spread over Americas and by 1994 they were reported in Puerto Rico. In contrast to other places, the oceanic island conditions in Puerto Rico may mean a single introduction and different dynamics of the resident European and new-coming Africanized bees.To examine the genetic variation of honey bee feral populations and colonies from different locations in Puerto Rico, we used eight known polymorphic microsatellite loci.ResultsIn Puerto Rico, gAHB population does not show any genetic structure (Fst = 0.0783), and is best described as one honey bee population, product of hybridization of AHB and EHB. The genetic variability in this Africanized population was similar to that reported in studies from Texas. We observed that European private allele frequencies are high in all but one locus. This contrasts with mainland Africanized populations, where European allele frequencies are diminished. Two loci with European private alleles, one on Linkage Group 7, known to carry two known defensiveness Quantitative Trait Loci (QTLs), and the other on Linkage Group 1, known to carry three functionally studied genes and 11 candidate genes associated with Varroa resistance mechanisms were respectively, significantly greater or lower in European allele frequency than the other loci with European private alleles.ConclusionsGenetic structure of Puerto Rico gAHB differs from mainland AHB populations, probably representing evolutionary processes on the island.