Introduced Honeybee Apis Mellifera Research Articles

Effectiveness of native nectar-feeding birds and the introduced Apis mellifera as pollinators of the kangaroo paw, Anigozanthos manglesii (Haemodoraceae)

Plants pollinated by vertebrates are often visited by native and exotic insects foraging for pollen and nectar. We compared flower visitation rates, foraging behaviour, and the contribution to reproduction of nectar-feeding birds and the introduced honeybee Apis mellifera in four populations of the bird-pollinated Anigozanthos manglesii (Haemodoraceae). The behaviour of floral visitors was quantified with direct observations and motion-triggered and hand-held cameras. Pollinator access to flowers was manipulated by enclosure in netting to either exclude all visitors or to exclude vertebrate visitors only. Apis mellifera was the only insect observed visiting flowers, and the most frequent flower visitor, but primarily acted as a pollen thief. Although birds visited A. manglesii plants only once per week on average, they were 3.5 times more likely to contact the anther or stigma as foraging honeybees. Exclusion of birds resulted in 67% fewer fruits and 81% fewer seeds than flowers left open and unmanipulated. Unnetted flowers that were open to bird and insect pollinators showed pollen-limitation and a large variation in reproductive output within and between sites. Although honeybees have been shown to pollinate other Australian plants, compared to birds, they are highly inefficient pollinators of A. manglesii.

Conspecific Pollen on Honey Bees and a Chrysomelid Beetle Species Visiting Female Flowers onNolina microcarpa(Asparagaceae)

Nolina microcarpa (Asparagaceae) is a dioecious monocot shrub found in Arizona, New Mexico, and northern and central Mexico. Leaf rosettes of the species grow in colonies that produce tall inflorescences of small male or female flowers during spring. Dioecious flowering requires pollinating insects to carry pollen from flowers on male colonies to flowers on female colonies. I investigated pollination of female flowers at 12 colonies of N. microcarpa in the Cerbat Mountains in northwestern Arizona during May–June 2017. I examined pollen from male flowers, aspirated insects on female flowers, counted conspecific pollen grains carried by insects, and estimated floral constancies from proportions of conspecific pollen. Pollen on N. microcarpa was prolate and monosulcate with a deep furrow and reticulate sculpturing. The most abundant insect on female flowers was the native beetle Triarius trivittatus (Chrysomelidae), followed by the introduced honey bee Apis mellifera (Apidae). Activities of honey bees, but not beetles, were limited to flowers. Two species of native bees in Halictidae and Megachilidae were also found in low numbers on flowers. Nearly all insects carried N. microcarpa pollen, and conspecific pollen comprised most of the pollen load on most insects. Conspecific pollen loads were highest on A. mellifera, followed by the native bees and T. trivittatus. Amounts of conspecific pollen on A. mellifera and on T. trivittatus males, but not females, were dependent on the distance to the nearest male inflorescence and decreased exponentially as the distance increased. Nolina microcarpa appears to be pollinated primarily by bees and beetles. Pollination by these insects is consistent with pollination of other plants, such as palms (Arecaceae), that similarly produce open inflorescences and small, unisexual, diurnal flowers with nectar.

Observations on the foraging behaviour of the introduced honeybee Apis mellifera L. (Hymenoptera: Apidae) on the saltmarsh plantSarcocornia quinquefloraat Sydney Olympic Park

The foraging behaviour of the introduced honey bee Apis mellifera on the saltmarsh plant Sarcocornia quinqueflora was observed over three days at Sydney Olympic Park in February 2007. Within an observation area of approximately 3m × 3m, the number of flowering and non-flowering branches of S. quinqueflora visited by bees and an estimated duration of each visit was recorded. The foraging behaviour of 63 bees was observed on branches within the observation area with a significantly greater mean number of flowering branches (3.68±1.86) visited compared to non-flowering branches (1.58±1.72) per bee. The mean visitation time to flowering branches by each bee (2.1 1 ±0.58 sec per branch) was significantly greater than that of non-flowering branches (1.29±0.41 sec). The majority of bees collected had pollen from S. quinqueflora on all parts of their body, as well as within the corbicula. Combined with the disturbance of pollen, that may assist wind dispersal, the transfer of pollen between the saltmarsh plants b...

The tolerance of island plant–pollinator networks to alien plants

Summary1.Invasive alien plant species pose a severe threat to native plant communities world‐wide, especially on islands. While many studies focus on the direct impact of alien plants on native systems, indirect effects of plant invaders on co‐flowering natives, for example through competition for pollination services, are less well studied and the results are variable.2.We used six temporally and taxonomically highly resolved plant–pollinator networks from the island of Mahé, Seychelles, to investigate the indirect impact of invasive alien plant species on remnant native plant communities mediated by shared pollinators. We employed fully quantitative network parameters and information on plant reproductive success, and pollinator diversity and behaviour, to detect changes in plant–pollinator networks along an invasion gradient.3.The number of visits to and fruit set of native plants did not change with invasion intensity. Weighted plant linkage and interaction evenness, however, was lower at invaded sites than at less invaded sites. These patterns were primarily driven by shifts in interactions of the most common pollinator, the introduced honey beeApis mellifera, while weak interactions and strong native interactions remained unchanged.4.Synthesis.The implications of these findings are twofold: first, quantitative network parameters are important tools for detecting underlying biological patterns. Secondly, alien plants and pollinators may play a greater role in shaping network structure at high than low levels of invasion. We could not show, however, whether the presence of invasive plants result in a simplification of plant–pollinator networks that is detrimental to native plants and pollinators alike.

Floral Visitors and Pollination of Psychotria tenuinervis (Rubiaceae): Distance from the Anthropogenic and Natural Edges of an Atlantic Forest Fragment1

ABSTRACTPollinators, especially insects, could be influenced by forest fragmentation. The aim of this paper was to examine whether there were differences in 1) the communities of floral visitors; 2) the frequency of visits; and 3) the fruit and seed sets of individuals of Psychotria tenuinervis occurring at anthropogenic edges (AEs), natural edges (NEs), and in the forest interior (FI) in 2 yr of study. In 2002, the total number of flower visits was greater in NE and lower in AE, while no difference among habitats was found in 2003. There were differences among sample plots, within habitats, in both years. Bees were the most frequent visitors of P. tenuinervis flowers, and the introduced honeybee Apis mellifera was the most common species observed. There were no differences in the fruit and seed sets, or in the density of reproductive individuals of P. tenuinervis among habitats. However, in 2002, NE showed the greatest proportion of fruits per flower and AE the smallest. The similarity among the habitats was probably due to the marked variation or heterogeneity among the sample plots and among the plants within the habitats, which may have masked any interhabitat differences. The observed heterogeneity and the likely importance of other factors, such as gaps and the age of the edge, on the fragment studied, could be viewed as important issues for conservation programs.

Pollination services provided by various size classes of flower visitors to Eucalyptus globulus ssp. globulus (Myrtaceae)

Flowers of the commercially important tree Eucalyptus globulus Labill. ssp. globulus were visited by a wide variety of insects and birds within its natural distribution. Flowers were visited so frequently that most available nectar was consumed, but seed production within 5 m of the ground was consistently far less than the maximum possible, indicating the presence of large numbers of inefficient pollinators and few efficient pollinators. Pollen limitation was more severe on fully self-incompatible trees than on partially self-compatible trees, demonstrating that pollinator inefficiency resulted from infrequent outcrossing rather than inability to deposit pollen on stigmas. The flower visitors that were responsible for almost all nectar consumption from flowers within 5 m of the ground were insects that were able to permeate cages with 5-mm apertures but not cages with 1-mm apertures, the most abundant of which was the introduced honeybee Apis mellifera L. These insects contributed less than 20% of the maximum possible seed set, indicating that they were inefficient pollinators. Birds and smaller insects made lesser contributions to seed production, but consumed little nectar within 5 m of the ground. However, anthophilous birds appeared to mostly forage higher in the trees and probably consumed more nectar from, and provided more pollination services to, flowers higher in the trees.