Megalopta genalis

Megalopta genalis
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Hexapoda
Class: Insecta
Order: Hymenoptera
Family: Halictidae
Subfamily: Halictinae
Genus: Megalopta
Species: M. genalis
Binomial name
Megalopta genalis
Meade-Waldo, 1916
Museum specimen

Megalopta genalis is a species of bee in the family Halictidae, the sweat bees. It is native to Central and South America.[1] This species has served as a model organism in studies of social behavior and night vision in bees.

Description

This bee is variable in size, especially among females. The average female has an intertegular distance (the width of the body measured between the wing bases) of 3 millimeters, and the average male is more slender, with an intertegular distance of about 2.4 millimeters.[2] Gynandromorphy occurs in this species, where an individual of one sex can have some body parts of the opposite sex.[2]

Upon emerging from the egg it takes the bee about 35 days to reach adulthood.[3]

Ecology

Like other bees of its genus, this species nests in dead wood. It typically uses fallen branches and vines that lie in tangles in the understory. The sticks used for nesting are 1 to 10 centimeters wide. It creates a tunnel with an opening surrounded by a collar of crumbled wood. The cells inside the nest are made of wood fibers. The adult female bee places a loaf of pollen in each cell and lays an egg on top.[4]

This bee collects pollen from tropical plants in its habitat, including kapok (Ceiba pentandra), pochote (Pachira quinata), hog plums (Spondias spp.), and acacias, as well as Vismia baccifera and Pseudobombax septenatum.[4]

Nocturnal adaptations

Most bees are diurnal, active during the day. This species and its closest relatives are nocturnal, leaving the nest to forage in the evening. Its adaptations to dim light have been well studied. Like other bees it has apposition compound eyes, an eye type which is effective in bright light.[1] Specialized anatomical differences in the eyes, such as larger facets, make them 27 times more sensitive to light than those of diurnal bees.[5] Cells in the eyes are especially sensitive to the polarization of light that occurs during twilight hours, the time when the bee is active.[6] The brain also has specialized neurons that help it process low light.[1]

Social behavior

This species is facultatively social; individuals may be solitary nesters or live communally when it is advantageous to do so. They mass provision their nests, stocking them with all the pollen that the larvae will need to grow to maturity. The group size and frequency of social nesting change across the seasons. At the start of the dry season most bees are solitary, but later in the season up to half of the nests have multiple females. Nests can have up to 11 females,[7] but usually no more than 4.[8]

There is a division of labor in communal nests. The dominant female is usually the largest and oldest individual and is sometimes the only reproductive individual in the group. The other females are foragers, bringing food back to the reproductive female.[8] They engage in trophallaxis, feeding nectar to the reproductive female.[7] Most communal nests are simply pairs: one queen that stays in the nest and lays eggs and one worker that leaves the nest to obtain food for herself and the queen.[9] Most females are capable of producing eggs but they are suppressed by the presence of a dominant queen in their group; if the queen dies, a foraging worker can take her place and lay eggs.[10]

References

  1. ↑ 1.0 1.1 1.2 Greiner, B., et al. (2004). Neural organisation in the first optic ganglion of the nocturnal bee Megalopta genalis. Cell and Tissue Research 318(2), 429-37.
  2. ↑ 2.0 2.1 Wcislo, W. T., et al. (2004). A review of deviant phenotypes in bees in relation to brood parasitism, and a gynandromorph of Megalopta genalis (Hymenoptera: Halictidae). Journal of Natural History 38(11), 1443-57.
  3. ↑ Tierney, S. M., et al. (2013). Frequency of social nesting in the sweat bee Megalopta genalis (Halictidae) does not vary across a rainfall gradient, despite disparity in brood production and body size. Insectes Sociaux 60(2), 163-72.
  4. ↑ 4.0 4.1 Wcislo, W. T., et al. (2004). The evolution of nocturnal behaviour in sweat bees, Megalopta genalis and M. ecuadoria (Hymenoptera: Halictidae): an escape from competitors and enemies? Biological Journal of the Linnean Society 83(3), 377-87.
  5. ↑ Greiner, B., et al. (2004). Retinal and optical adaptations for nocturnal vision in the halictid bee Megalopta genalis. Cell and Tissue Research 316(3), 377-90.
  6. ↑ Greiner, B., et al. (2007). Anatomical and physiological evidence for polarisation vision in the nocturnal bee Megalopta genalis. Journal of Comparative Physiology A 193(6), 591-600.
  7. ↑ 7.0 7.1 Wcislo, W. T. and V. H. Gonzalez. (2006). Social and ecological contexts of trophallaxis in facultatively social sweat bees, Megalopta genalis and M. ecuadoria (Hymenoptera, Halictidae). Insectes Sociaux 53(2), 220-25.
  8. ↑ 8.0 8.1 Smith, A. R., et al. (2003). Assured fitness returns favor sociality in a mass-provisioning sweat bee, Megalopta genalis (Hymenoptera: Halictidae). Behavioral Ecology and Sociobiology 54(1), 14-21.
  9. ↑ Smith, A. R., et al. (2010). Socially induced brain development in a facultatively eusocial sweat bee Megalopta genalis (Halictidae). Proceedings of the Royal Society B: Biological Sciences 277(1691), 2157-63.
  10. ↑ Smith, A. R., et al. (2009). Social competition but not subfertility leads to a division of labour in the facultatively social sweat bee Megalopta genalis(Hymenoptera: Halictidae). Animal Behaviour 78(5), 1043-50.

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