Halictus sexcinctus

Last updated

Halictus sexcinctus
Halictus fg02.jpg
Female Halictus sexcinctus
Halictidae - Halictus sexcinctus (male).JPG
Male
Scientific classification OOjs UI icon edit-ltr.svg
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Halictidae
Tribe: Halictini
Genus: Halictus
Subgenus: Halictus (Hexataenites)
Species:
H. sexcinctus
Binomial name
Halictus sexcinctus
Fabricius, 1775
Halictus sexcintus distribution.jpg
Halictus sexcintus distribution

Halictus sexcinctus, commonly referred to as the six-banded furrow bee, is a species of sweat bee found throughout Europe and as far east as Asian Turkey and Iraq.The H. sexcinctus can be easily confused with the closely related species, Halictus scabiosae , due to very similar morphological features. H. sexcinctus show a social polymorphism in which different colonies can exhibit solitary, communal, or eusocial structure. Due to this large variance in social organization, it was suspected that it was not one species at all, but rather multiple, cryptic species. However, genetic analysis was able to confirm these varying populations as one species. H. sexcinctus will forage from multiple flower species, but prefers plant species with wide-open flowers. Their nests can be found dug into the ground in loamy or sandy soil.

Contents

Taxonomy and phylogenetics

Halictus sexcinctus is part of the family Halictidae, which are commonly referred to as the sweat bees. Species in the genus Halictus are the most recently evolved in the Halictid family, and H. sexcinctus falls into the most recently evolved clade of the family, which is a eusocial taxa. [1] The family Halictidae has the most eusocial species of any bee family. [1] Study of the sociality of this family has been held back by a lack of understanding of how the species are phylogenetically related, and how closely related species within the family show very different levels of sociality. [1] Due to the different levels of sociality seen with the species, it was first thought possible that H. sexcinctus was actually a cryptic species. A genetic study of their mitochondrial DNA showed H. sexcinctus is in fact one species. However, that study was not definitive, and further studies of their nuclear genes are needed to be sure. [2] H. sexcinctus has been observed to be both solitary and eusocial. Because it belongs to a eusocial clade, its solitary behavior is an evolutionary reversion. However, H. sexcinctus is not alone in this, as there have been multiple losses of eusociality within the genus, such as in the species Halictus rubicundus . [1]

Description and identification

Halictus sexcinctus is a species of ground-nesting bees, previously thought to only exhibit solitary behavior. [3] They are relatively large compared to other sweat bees. [4] They are 14–16 mm in length, and have white felt bands on their abdomens. [5] Workers are typically smaller than foundresses, while foundresses will usually be the largest and most worn individuals in the nest. [4] Sterile and reproductive workers do not differ in size. [6]

Sexual dimorphism

As is typical among sweat bees, females are larger than males. [4] Males also have slimmer bodies than females and their antennae are longer with a slightly different coloration. [7] H. sexcinctus looks very similar to Halictus scabiosae , so the two are easily confused. Both have ring-like bands on their tergites, with females having anterior and posterior buff-colored bands on tergites 2-4, while males have whitish posterior bands on tergites 2-6. H. sexcinctus differs from H. scabiosae in that males have longer, reddish antennae, and females lack the basal hair bands on tergites 2-4. [8]

Social description

In eusocial nests, queens show aggressive behavior, and a fight to the death can occur if another female tries to usurp the foundress. However, in communal nests, aggression between females is little to non-existent, and foundresses will continuously join the colony during the founding period from late May to early June. Depending upon the social organization of a particular nest, female workers show a range of behavior, from complete selfishness to eusocial helping. H. sexcinctus has been very important in the understanding of the evolution of eusociality. Phylogenetic analysis suggests that H. sexcinctus has a social ancestor, and that solitary populations are an example of evolutionary reversal.

Distribution and habitat

Halictus sexcinctus are commonly found across Europe, and can be found as far north as southern Sweden [5] and as far east as Turkey and Iraq. They are solitary in the northern part of the range and social in their southern range. [4] They live in very large aggregations in central Europe, despite being solitary in this part of their range. [4] H. sexcinctus prefers to nest in sandy or loamy soil. [5] They use their mandibles to dig nests in the ground or even on vertical substrates if it is made of earth. Their nests consist of a main tunnel dug diagonally into the ground, with several short side chambers off of it leading to brood cells. One egg is laid per cell on top of a nectar-pollen mixture. [7] Females primarily collect pollen from plants of the family Asteraceae, and tend to forage in plant species with wide-open flowers. [5] Examples of plants they forage pollen and nectar from are asters, daisies, and sunflowers. [7]

Colony cycle

It takes about 4.5–5 weeks for a newly laid H. sexcinctus egg to develop into an adult. Foundresses will on average lay 9.6 eggs in their first brood. The colony cycle lasts around 10–12 weeks, constrained on either side by a winter hibernation. [4]

Colony initiation

Females hibernate inside their nests in the winter after mating. From the end of May to the beginning of June, they will begin to build new nests, in which they store foraged pollen and nectar. These food reserves in the new nest are used to feed the larvae. The next generation emerges from their pupae (eclose) from July to August, and the females of the previous generation typically die at this time. The newly eclosed females remain in the nest, while the males leave in order to mate with unrelated females in other nests. The males then die in Autumn after mating, while the females enter hibernation, meaning males have a comparatively short lifespan. [3]

Colony growth

Females from the first brood are called workers, while females of the second brood are called gynes. [4] The workers can be either reproductive or sterile. [6] As soon as the workers emerge, provisioning for the second brood begins. There is overlap between foundress and daughter generations during production of the second brood, and because both daughters and foundresses lay eggs in the second brood, this type of colony cycle is called “partially bivoltine”. [4] Some workers will leave their maternal nest before overwintering so that they can become foundresses in the spring. In one southern Greek population, up to three quarters of females were observed to disappear from their colonies by spring. While some will die, many likely will become foundresses of eusocial colonies. In this Greek population, only about 50% of foundresses survived to the eclosion of the first brood, so it is probably necessary that workers lay many of the second-brood eggs. [6]

Social polymorphism

There is a difference between communal and eusocial organization in halictine bees. Communal colonies do not have castes, but rather multiple females of the same generation work together with relatively little reproductive skew and aggression. These females may or may not be related. Eusocial colonies have a queen (the foundress) and reproductive castes with high reproductive skew and aggression, typically directed from the queen to workers. This type of society is formed when the queen’s progeny become workers. [9] H. sexcinctus has the strongest polymorphic social behavior discovered in sweat bees so far. [6] The social polymorphism they exhibit is one where either a solitary female founds a nest, and sociality emerges in the next generation of females, or several females from the same generation will cofound a new colony. [2] Solitary and communal behavior is seen in the northern range, while populations in the southern range exhibit communal and eusocial structure. [6] It is fairly unusual to find both communal and eusocial behavior exhibited by the same species outside of the halictine bees. [2] H. sexcinctus was the first example of a definite eusocial/communal polymorphism in halictine bees, and may possibly be the most extreme example of intraspecific social polymorphism among insects. [9]

Morphological differences due to sociality

Communal females range in size from that of a worker to a eusocial queen, but all of them have proportionally shorter wings than those of solitary and eusocial females, indicating that they follow a different developmental pathway. [2] The morphological differences between communal and eusocial individuals represents a novel preimaginal developmental difference, implying that their behavioral differences also have a preimaginal origin. This difference might be brought on by environmental factors during the larval period, such as differential feeding by queens. [9] It has not yet been determined whether the different social organizations arise from phenotypic plasticity brought on by an environmental switch (a trait commonly seen in halictine bees), [9] or based upon genetic differences. Genetic differences could not cause relative sterility because genes for such a trait would not be passed on. We do not fully understand the mechanism behind the morphological differences seen between the social strategies. [2]

Reproductive skew

Reproduction between foundresses is shared fairly equally in communal nests, and there is almost no aggression between the females. [2] In all socialites, foundresses tend to show higher levels of ovarian development than workers and are also more likely to mate. Sometimes, workers will actually have more developed ovaries than foundresses. Compared to other Halictus species, H. sexcinctus has a high rate of worker ovarian development. In eusocial colonies there is a reproductive skew favoring queens, but workers still have quite a lot of opportunity for mated reproduction. Unlike many bees, insemination status does not determine which females are queens and which females are workers, though of course only mated females can produce daughters, a necessary requirement of being a queen. [4]

Sex ratio

The majority of offspring produced in the first brood are female, ranging from 74-81% of the offspring. Only about 50% of foundresses survive to the production of the second brood. This means that some unmated workers will produce offspring, which leads to more male offspring being produced in the second brood than in the first. Therefore, the ratio of males produced in the second brood most likely depends upon whether the foundress does or does not survive. Very rarely, foundresses will not mate and thus produce an all-male brood, which therefore means they will not produce a second brood. Less pollen is needed in order to produce males, because they are smaller than gynes. When resources are scarce, the sex ratio may be shifted towards males. [4]

Division of labor

Foundresses tend to show more wear than workers do on their mandibles and wings, suggesting they participate in more work, such as constructing brood cells, maintaining the nest, and provisioning the brood. Workers show “reproductive opportunism,” where their level of altruism can range from entirely altruistic to entirely selfish. It is unclear how exactly this flexibility is possible or how this individual behavior leads to spreads throughout the population. [4] Sterile workers typically show more wear on their wings and mandibles than reproductive workers. This is most likely due to sterile workers performing more work than reproductive workers. This suggests that infertile workers are more altruistic in order to gain inclusive fitness through kin selection, due to the fact that they are unable to produce their own offspring. Some reproductive workers are somewhat altruistic and will help to raise the broods of their sisters and mother. Some, however, are not altruistic and seem only to take care of their own brood, essentially making them parasites to the colony. [6] One reason that communal/eusocial polymorphisms are so rare could be because communal strategies are unstable due to their vulnerability to cheating. [9]

Parasites

A new species of mites, Histiostoma halicticola, was discovered to parasitize H. sexcinctus in a study by Fain et al. In this study, the new species of mite was observed only in the deutonymphal stage. The bees harboring these mites were found in the Döberitzer Heide nature reserve, nearby Berlin, Germany. The mites were found on both males and females. On females, the mites are found in a deep, bristly furrow on the second tergite. This site protects the mites and makes them hard to remove. When a female H. sexcinctus had more than thirty mites on its body, the mites were then found in other areas lacking specific shelter. This shows that the furrow is the preferred spot, and the mites will only settle elsewhere if the furrow is already full. Males lack this particular furrow, so the mites are found on the smooth, concave ventral surface of the thorax between the coxae. H. sexcinctus was also found to harbor mites of the families Pygmephoridae and Scutacaridae. [3]

Human importance

Antimicrobial properties of proteins in the venom

With the rise of antibiotic resistant bacteria, the need to find antimicrobial substances that function differently than current antibiotics is incredibly important. Antimicrobial peptides (AMPs) are commonly found in the venom of arthropods, and these proteins function by breaking up bacterial cell membranes. However, these AMPs will often also damage eukaryotic cells, typically red blood cells. A substance that damages human red blood cells will be less valuable as an antibiotic for obvious reasons. AMPs that damaged red blood cells at low rates were found in the venom of several species of bees, leading to a study of the venom of H. sexcinctus. Two newly isolated peptides from the venom were found to be significantly different in structure to any other AMPs in the antimicrobial peptide database. These new proteins showed effective antimicrobial activity against four strains of bacteria ( B. subtilis , S. aureus , E. coli , and P. aeruginosa ) and a yeast pathogen ( C. albicans ). While these proteins isolated from H. sexcinctus venom show good antimicrobial properties, they also show found to damage red blood cells (hemolysis), reducing their therapeutic potential. However, when their structures were modified a few analogs with slightly lower hemolytic activity were discovered, meriting further study. [5]

Understanding the evolution of eusociality

Sweat bees are important model organisms for studying the evolution of social behavior, because they show a wide variety of social strategies. [2] H. sexcinctus behavior is important in understanding the evolution of eusociality because it was previously thought that a communal social organization was a transitional step to eusociality. However, because these communal and eusocial strategies exist separately without transition in this species, the data do not support that theory. [2] As shown by phylogenetics, communal behavior may actually be a transition step between eusocial behavior and the reversion to solitary behavior. [6]

Related Research Articles

<span class="mw-page-title-main">Bee</span> Clade of insects

Bees are winged insects closely related to wasps and ants, known for their roles in pollination and, in the case of the best-known bee species, the western honey bee, for producing honey. Bees are a monophyletic lineage within the superfamily Apoidea. They are presently considered a clade, called Anthophila. There are over 16,000 known species of bees in seven recognized biological families. Some species – including honey bees, bumblebees, and stingless bees – live socially in colonies while most species (>90%) – including mason bees, carpenter bees, leafcutter bees, and sweat bees – are solitary.

<span class="mw-page-title-main">Colony (biology)</span> Living things grouping together, usually for common benefit

In biology, a colony is composed of two or more conspecific individuals living in close association with, or connected to, one another. This association is usually for mutual benefit such as stronger defense or the ability to attack bigger prey.

<span class="mw-page-title-main">Halictidae</span> Family of bees

Halictidae is the second-largest family of bees with nearly 4,500 species. They are commonly called sweat bees, as they are often attracted to perspiration. Halictid species are an extremely diverse group that can vary greatly in appearance. These bees occur all over the world and are found on every continent except Antarctica. Usually dark-colored and often metallic, halictids are found in various sizes, colors and patterns. Several species are all or partly green and a few are red, purple, or blue. A number of them have yellow markings, especially the males, which commonly have yellow faces, a pattern widespread among the various families of bees. The family is one of many with short tongues and is best distinguished by the arcuate basal vein found on the wing. Females in this family tend to be larger than the males.

<i>Halictus rubicundus</i> Species of bee

Halictus rubicundus, the orange-legged furrow bee, is a species of sweat bee found throughout the Northern Hemisphere. H. rubicundus was introduced into North America from the Old World during one of two main invasions of Halictus subgenera. These invasions likely occurred via the Bering land bridge at times of low sea level during the Pleistocene epoch.

<i>Lasioglossum malachurum</i> Species of bee

Lasioglossum malachurum, the sharp-collared furrow bee, is a small European halictid bee. This species is obligately eusocial, with queens and workers, though the differences between the castes are not nearly as extreme as in honey bees. Early taxonomists mistakenly assigned the worker females to a different species from the queens. They are small, shiny, mostly black bees with off-white hair bands at the bases of the abdominal segments. L. malachurum is one of the more extensively studied species in the genus Lasioglossum, also known as sweat bees. Researchers have discovered that the eusocial behavior in colonies of L. malachurum varies significantly dependent upon the region of Europe in which each colony is located.

<i>Lasioglossum</i> Genus of insects

The sweat bee genus Lasioglossum is the largest of all bee genera, containing over 1800 species in numerous subgenera worldwide. They are highly variable in size, coloration, and sculpture; among the more unusual variants, some are cleptoparasites, some are nocturnal, and some are oligolectic. Most Lasioglossum species nest in the ground, but some nest in rotten logs.

<span class="mw-page-title-main">Eusociality</span> Highest level of animal sociality a species can attain

Eusociality, the highest level of organization of sociality, is defined by the following characteristics: cooperative brood care, overlapping generations within a colony of adults, and a division of labor into reproductive and non-reproductive groups. The division of labor creates specialized behavioral groups within an animal society which are sometimes referred to as 'castes'. Eusociality is distinguished from all other social systems because individuals of at least one caste usually lose the ability to perform at least one behavior characteristic of individuals in another caste. Eusocial colonies can be viewed as superorganisms.

<i>Halictus scabiosae</i> Species of bee

Halictus scabiosae, the great banded furrow-bee, is a species of bee in the family Halictidae, the sweat bees.

<span class="mw-page-title-main">Halictinae</span> Subfamily of bees

Within the insect order Hymenoptera, the Halictinae are the largest, most diverse, and most recently diverged of the four halictid subfamilies. They comprise over 2400 bee species belonging to the five taxonomic tribes Augochlorini, Thrinchostomini, Caenohalictini, Sphecodini, and Halictini, which some entomologists alternatively organize into the two tribes Augochlorini and Halictini.

<i>Lasioglossum zephyrus</i> Species of bee

Lasioglossum zephyrus is a sweat bee of the family Halictidae, found in the U.S. and Canada. It appears in the literature primarily under the misspelling "zephyrum". It is considered a primitively eusocial bee, although it may be facultatively solitary. The species nests in burrows in the soil.

<i>Halictus ligatus</i> Species of bee

Halictus ligatus is a species of sweat bee from the family Halictidae, among the species that mine or burrow into the ground to create their nests. H. ligatus, like Lasioglossum zephyrus, is a primitively eusocial bee species, in which aggression is one of the most influential behaviors for establishing hierarchy within the colony, and H. ligatus exhibits both reproductive division of labor and overlapping generations.

<i>Polistes dorsalis</i> Species of wasp

Polistes dorsalis is a species of social wasps that can be found throughout various parts of North America. It is classified under the Vespidae within the genus of Polistes. Male Polistes dorsalis wasps can be distinguished from other Polistes species by their distinctly prominent median tubercle of sternum 7. Both sexes can also be recognized due to their v- shaped yellow markings on their head. They are distributed widely across North America and can be found in sheltered nests, typically closer to the ground. These wasps live in a dominance hierarchy in which the queen's role differs from that of ordinary workers. When threatened, these wasps can deliver moderately painful stings. Their venom might also be of human interest for their antimicrobial uses.

<i>Megalopta genalis</i> Species of bee

Megalopta genalis is a species of the family Halictidae, otherwise known as the sweat bees. The bee is native to Central and South America. Its eyes have anatomical adaptations that make them 27 times more sensitive to light than diurnal bees, giving it the ability to be nocturnal. However, its eyes are not completely different from other diurnal bees, but are still apposition compound eyes. The difference therefore lies purely in adaptations to become nocturnal, increasing the success of foraging and minimizing the danger of doing so from predation. This species has served as a model organism in studies of social behavior and night vision in bees.

<i>Lasioglossum cressonii</i> Species of insect

Lasioglossum cressonii is a species in the sweat bee genus Lasioglossum, family Halictidae. Halictidae exhibit eusocial hierarchy behavior which is interesting given that eusociality in this group is hard to evolve and easy to lose. L. cressonii is found throughout North America. L. cressonii have been shown to be important pollinators for apple trees and many other North American native plants.

<i>Lasioglossum hemichalceum</i> Species of bee

Lasioglossum hemichalceum, which has sometimes been confused with L. erythrurum, is a sweat bee endemic to Australia. Large numbers of unrelated females will typically share a single nest, a behavior referred to as "communal". Nests are constructed underground by the independent efforts of the females. L. hemichalceum will typically begin creating new colonies during the summer, with brood production from late November through the first few months of spring. Members of this species do not demonstrate aggressive behavior towards one another. As the size of the colony increases, the reproductive potential of each female does not change, unlike many species of bees.

<i>Augochlora pura</i> Species of insect

Augochlora pura is a solitary sweat bee found primarily in the Eastern United States. It is known for its bright green color and its tendency to forage on a variety of plants. Inhabiting rotting logs, this bee can produce up to three generations per year. Both males and females have been observed licking sweat from human skin, most likely seeking salt

<span class="mw-page-title-main">Dialictus</span> Subgenus of insects

Dialictus is a subgenus of sweat bees belonging to the genus Lasioglossum. Most of the members of this subgenus have a metallic appearance, while some are non-metallic. There are over 630 species worldwide. They are commonly found in the Northern Hemisphere and are found in abundance in North America. Members of this subgenus also have very diverse forms of social structure making them model organisms for studying the social behavior of bees.

<i>Augochlorella</i> Genus of bees

Augochlorella is a genus in the bee family Halictidae, commonly called sweat bees. They display metallic coloration, ranging from reddish to gold to bluish green, as is typical for other genera in the tribe Augochlorini.

<i>Halictus confusus</i> Species of bee

Halictus confusus, the southern bronze furrow bee or confused sweat bee, is a species of sweat bee in the family Halictidae. It is a primitively eusocial bee species found in open habitats in Eurasia and North America.

<i>Augochlorella aurata</i> Species of insect

Augochlorella aurata is a species of sweat bee in the family Halictidae. It is found in North America east of the Rocky Mountains. The body is a brilliant green metallic color, diffused to varying extents with a copper, red, or yellow color. Its length is 5 to 7 mm. A common name is golden green sweat bee.

References

  1. 1 2 3 4 Danforth, B. N., Sauquet, H., & Packer, L. (1999). Phylogeny of the bee genus Halictus (Hymenoptera: Halictidae) based on parsimony and likelihood analyses of nuclear EF-1alpha sequence data. Mol Phylogenet Evol, 13(3), 605–618. doi : 10.1006/mpev.1999.0670
  2. 1 2 3 4 5 6 7 8 Keller, L. (2003). Behavioral plasticity: levels of sociality in bees. Current Biology, 13(16), R644–R645. doi : 10.1016/S0960-9822(03)00571-2
  3. 1 2 3 Fain, A., & Erteld, C. (1998). Description of a new species of Histiostoma Kramer, 1876 (Acari: Histiostomatidae) phoretic on the solitary bee Halictus sexcinctus (Fabricius, 1775) (Hymenoptera: Apidae: Halictinae). Bulletin & Annales de La Societe Royale D’Entomologie de Belgique, 134, 47–57.
  4. 1 2 3 4 5 6 7 8 9 10 11 Richards, M. H. (2001). Nesting biology and social organization of Halictus sexcinctus (Fabricius) in southern Greece. Canadian Journal of Zoology, 79(12), 2210–2220. doi : 10.1139/cjz-79-12-2210
  5. 1 2 3 4 5 Monincová, L., Buděšínský, M., Slaninová, J., Hovorka, O., Cvačka, J., Voburka, Z., … Čeřovský, V. (2010). Novel antimicrobial peptides from the venom of the eusocial bee Halictus sexcinctus (Hymenoptera: Halictidae) and their analogs. Amino Acids, 39(3), 763–775. doi : 10.1007/s00726-010-0519-1
  6. 1 2 3 4 5 6 7 Richards, M. H. (2003). Variable worker behaviour in the weakly eusocial sweat bee, Halictus sexcinctus Fabricius. Insectes Sociaux, 50(4), 361–364. doi : 10.1007/s00040-003-0691-3
  7. 1 2 3 "Halictus sexcinctus." Insectoid.info. N.p., n.d. Web. 14 Oct. 2015. <http://insectoid.info/bees/halictus-sexcinctus/>.
  8. ↑ Falk, Steven. "Halictus Scabiosae (Great Banded Furrow-bee)." Flickr. Yahoo!, n.d. Web. 14 Oct. 2015. https://www.flickr.com/photos/63075200@N07/sets/72157638771523696/>.
  9. 1 2 3 4 5 Richards, M. H., von Wettberg, E. J., & Rutgers, A. C. (2003). A novel social polymorphism in a primitively eusocial bee. Proceedings of the National Academy of Sciences of the United States of America, 100(12), 7175–7180. doi : 10.1073/pnas.1030738100
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.