Misplaced Pages

#130869

67-516: Schwarziana bocainensis Schwarziana chapadensis Schwarziana mourei Schwarziana quadripunctata Schwarziana is a relatively small genus of South American stingless bees . Like other stingless bees, Schwarziana are eusocial , with large colonies primarily composed of workers and one queen. Unusually for stingless bees, colonies are formed in underground chambers rather than in tree cavities. Workers are approximately 6.5mm long The type species for this genus, S. quadripunctata ,

134-425: A paramagnetic one (inducing a magnetic field in the same direction as the applied field). The antennae of the stingless bee, therefore, exist as a complex sensory organ used for orientation and navigation through the combined use of thousands of hair-shaped sensilla . Like most eusocial insects, S. quadripunctata reproduction relies heavily on the established hierarchy and level of environmental quality. Usually,

201-439: A 2005 study conducted by Esquivel et al. on a S. quadripunctata nest near Rio de Janeiro, Brazil. The study applied various levels of applied magnetic fields across the entrance of the nest. The exiting angles (both vertical and horizontal) of the individual bees were then measured as they emerged from the nest. The primary control experiment confirmed that the majority of the nest had a preferential exiting angle in accordance with

268-424: A body area of 2.1 square millimetres ( 1 ⁄ 256  sq in), this gives a ratio of 6.8 opening to bee. This smaller entrance provides more than enough space for the relatively low enter and exit traffic of 17.4 individuals per minute. Schwarziana quadripunctata appears to rely heavily on the small entryway size as their main source of defense. Although three to five guards are typically seen guarding

335-534: A diverse array of these chemicals were present in each member. They then charted these hydrocarbon differences and found a distinct separation according to colony location, age, sex, and hierarchal position. In particular, older workers, which are in charge of colony protection, had higher concentrations of the alkenes heptacosene and hentriacontene. It was thus deduced that these alkenes were vital parts of kin recognition. Some of these essential hydrocarbons were also found to be lacking in younger individuals, alluding to

402-554: A dwarf queen can be beneficial. Dwarf queens have a lower fecundity and reproduction rate than normal queens. This appears to be the consequence of a reduced egg-laying rate and a lower average ovary weight. A queen’s ovary is nearly four times larger than a dwarf queen’s. In some aspects, however, workers occasionally have a slight advantage over queens and dwarf queens. Worker bees are in charge of delivering food supplies to developing larvae. Thus, workers can force underdeveloped dwarf queen larvae and queen larvae to be converted into

469-507: A few hairs. Glands are present on the head and thorax. The glands are larger in the heads of general worker bees and larger in the thorax for nursing worker bees. Nests are entirely underground on the subtropical floor and consist of vast and expansive cavities. Each nest is occupied by a single colony consisting of an individual queen and several thousand workers. Brood cells are arranged in spiral combs, each cell housing only one individual. Cells housing queens are typically much larger than

536-475: A genus, while Plebeia appears to be paraphyletic. This Apinae article is a stub . You can help Misplaced Pages by expanding it . Schwarziana quadripunctata Schwarziana quadripunctata is a small, stingless bee found in a stretch of the South American Amazon from Goiás , Brazil , through Paraguay , to Misiones , Argentina . This highly eusocial insect constructs earthen nests in

603-432: A larger clutch size to compensate for the reduced reproduction frequency, thus increasing those species' fecundity. Fecundity is a significant component of fitness . Fecundity selection builds on that idea. This idea claims that the genetic selection of traits that increase an organism's fecundity is, in turn, advantageous to an organism's fitness. Fecundity Schedule Fecundity Schedules are data tables that display

670-405: A larger queen with greater fecundity than dwarf queens, causing the size discrepancy between the two. Unusual for most other eusocial insects, worker bees and dwarf queen bees tend to be similar in weight and size. The bees have a pale coloration of brown or reddish-brown with occasional yellow markings on the head. They maintain a punctate thorax and abdomen and a dorsal thoracic area sporting

737-800: A multitude of factors that potentially affect the rates of fecundity. For example: ontogeny , population density and latitude . Ontogeny Fecundity in iteroparous organisms often increases with age but can decline at older ages. Several hypotheses have been proposed to explain this relationship. For species with declining growth rates after maturity, the suggestion is that as the organism's growth rate decreases, more resources can be allocated to reproduction. Other possible explanations exist for this pattern for organisms that do not grow after maturity. These explanations include: increased competence of older individuals; less fit individuals have already died off; or since life expectancy decreases with age, older individuals may allocate more resources to reproduction at

SECTION 10

#1733106069131

804-465: A past evolutionary benefit. More distinctive to the intra-communal dynamics of the Schwarziana quadripunctata nest is the existence of multiple statuses of queen – the physogastric queen (those that are larger in size and more involved in reproduction) and multiple dwarf queens. The number of these dwarf queens varies in accordance to resource availability, colony conditions, and the physical state of

871-408: A population. Fecundity may be defined differently for different ecological studies to explain the specific data the study examined. For example, some studies use apparent fecundity to describe that their data looks at a particular moment in time rather than the species' entire life span. In other studies, these definitions are changed to better quantify fecundity for the organism in question. This need

938-484: A potential advantage when it comes to fecundity, as they are producing more offspring. Iteroparity is when a species reproduces multiple times over its lifetime. This species' strategy is to protect against the unpredictable survivability of their offspring, in which if their first litter of offspring dies, they can reproduce again and replace the dead offspring. It also allows the organism to care for its offspring, as they will be alive during their development. There are

1005-412: A single menstrual cycle , and fecundity is the probability of achieving a live birth within a single cycle. In ecology , fecundity is a measure of the reproductive capacity of an individual or population, typically restricted to the reproductive individuals. It can be equally applied to sexual and asexual reproduction, as the purpose of fecundity is to measure how many new individuals are being added to

1072-401: A specialized cell in groups of one to five along with one or two worker bees. This is done in order to limit interference to the cell provisioning and oviposition processes of the physogastric queen. Future queen eggs are positioned near the periphery of the comb in larger, specialized cells while workers and dwarf queens (in a ratio of about 1000 to 6, respectively) are randomly placed about

1139-452: A tube network, several layers, or multiple openings. S. quadripunctata nest entrances in São Paulo , Brazil consisted of an average entrance area of 14.5 square millimetres ( 3 ⁄ 128  sq in), relatively small compared to the 2.1 square millimetres ( 1 ⁄ 256  sq in) body of the bee. This may account for the lower traffic levels of the stingless bee through

1206-404: A worker bee, or to be eradicated completely, through extreme limitations of their food rations. The division of labor often, in some way or another, reflects the evolutionary sex ratio of a species. This is especially true in S. quadripunctata , where worker bees can outnumber queens by about one thousand to one (1000:1). The main purpose of the colonial queen, or gyne , is to lay eggs within

1273-413: Is a distinct comparison to the complex entryways consisting of layered entrances or closable doorways observed in some other related species. Through the observation and measurement of several S. quadripunctata nests near São Paulo , Brazil , entrances were discovered to have an average area of 14.5 square millimetres ( 3 ⁄ 128  sq in). In comparison to the average stingless bee having

1340-688: Is also responsible for the ability of worker bees to determine the location of their home nest. Many stingless bee colonies, those of S. quadripunctata included, are repopulated by a single queen who mates. This should, in theory, create a conflicting rift between queens and the worker bees due to variations in genetic relatedness. Queens produce haploid males that are genetically identical to them. In contrast, workers only share fifty percent (50%) of their genes with males, leading to an evolutionary conflict of interest. However, worker bees were not observed to increase their aggressive behaviors towards newly reproduced males. A few possible explanations arose from

1407-430: Is believed that dwarf queens are evolutionarily advantageous in that they develop in order to avoid becoming a worker bee. Their role was found to become the head of a colony in the absence of viable, full-sized queens. The roles of the worker bee in S. quadripunctata include the maintenance and protection of larvae (queen, dwarf, or worker) placed within the brood cells. They are responsible for delivering nutrients to

SECTION 20

#1733106069131

1474-466: Is low. Occasionally high density can stimulate the production of offspring, particularly in plant species, because if there are more plants, there is food to lure pollinators, who will then spread that plant's pollen and allow for more reproduction. There are many different hypotheses to explain the relationship between latitude and fecundity. One claimed that fecundity increases predictably with increasing latitude. Reginald Morean proposed this hypothesis,

1541-418: Is often adverse weather conditions, rather than complete depletion of pollen and nectar from the resource, that terminate the length of harvesting by the stingless bees. In total, S. quadripunctata utilizes over 35 different species of flowering plants. Many of these produce a large quantity of flower material, limiting interspecies and intraspecies competition. Over ten percent (10%) of their diet comes from

1608-436: Is often used to describe the rate of offspring production after one time step (often annual). In this sense, fecundity may include both birth rates and survival of young to that time step. While levels of fecundity vary geographically, it is generally a consistent feature of each culture. Fecundation is another term for fertilization . In obstetrics and gynecology , fecund-ability is the probability of being pregnant in

1675-504: Is particularly true for modular organisms , as their modular organization differs from the more typical unitary organism, in which fecundity is best defined through a count of offspring. Parity is the organization of fecundity into two distinct types, semelparity, and iteroparity. Semelparity occurs when an organism reproduces only once in its lifetime, with death being a part of its reproductive strategy. These species produce many offspring during their one reproductive event, giving them

1742-438: Is projected to continue into the future. Colonies are founded by the swarming of individuals consisting of a single queen followed by several thousand worker bees. This can only be achieved if both the queen and her workers “align” themselves towards the same goal in production of fertile females. Once a colony has been established, housing combs are produced by the workers, with larger ones allocated to potential queen larvae and

1809-411: The physogastric queen lays the majority of the eggs. However, the miniature (or dwarf) queens may also lay fertile eggs, although they tend to be fewer in number and smaller in size. As multiple virgin queens approach the age of reproductive success, they begin to accumulate the reddish-brown pigmentation associated with adult members. At this time, male workers will begin individually courting them on

1876-684: The Fx is 16, and the mx is 1.336. Infecundity is a term meaning "inability to conceive after several years of exposure to the risk of pregnancy." This usage is prevalent in medicine, especially reproductive medicine , and in demographics . Infecundity would be synonymous with infertility , but in demographic and medical use fertility (and thus its antonym infertility ) may refer to quantity and rates of offspring produced, rather than any physiological or other limitations on reproduction. Additionally, social trends and societal norms may influence fecundity, though this influence tends to be temporary. Indeed, it

1943-420: The brood cells housed in the combs. They also play a vital role in the establishment of new colonies. Using their attractive senses, queen bees are able to lead a swarm of workers and the occasional dwarf queen to new locations. Until fairly recently, it was hypothesized that these dwarf, or miniature, queens were the result of developmental mistakes. However, through Tom Wenseleers' "Caste Conflict Hypothesis," it

2010-444: The case of an encounter between the physogastric queen and the newborn “virgin” queens, the larger queen may initiate buccal contact with the smaller queen. A rapidly growing virgin queen may incite her own imprisonment in specialized prison chambers. In one case, an abnormally large and pigmented virgin queen became overly agitated in her prison cell. The release of this queen prompted the interruption of brood cell construction, though

2077-525: The colony, ensuring that, should one queen unexpectedly succumb to injury or illness, another one is readily available to take its place in maintaining the nest. The subtropical environment of the South American Amazon provides a vast array of dietary options for a stingless bee such as S. quadripunctata . With such a densely populated niche of pollinating insects, it remains of utmost importance to balance competition and resource acquisition. It

Schwarziana - Misplaced Pages Continue

2144-431: The current physogastric queen. However, the dwarf queens are typically produced year round, with several hatching simultaneously. Mate attractiveness to the newly born queens coincides with pigmentation. The more brightly colored queens were more likely to lay more eggs than their paler counterparts. As the newborn queens begin to age, pigmentation increased as well as the number of courtships from male stingless bees. In

2211-414: The developing larvae until they hatch. Worker bees are also responsible for accompanying the establishments of new colonies by a queen. Unlike typical honeybees , which practice multiple mating, stingless bees have been suspected of single mating between drones and queen bees. This, along with the consequential pairing of the high relatedness rates within colonies of S. quadripunctata , serves to explain

2278-425: The entryway, an average of 17.4 bees per minute per nest. Members of this species are fairly common in their large South American region, with nests containing over several thousand members each. However, their population is believed to have declined by nearly sixty-five percent (65%) over the past few decades due to competition with the introduced Africanized honeybees along with human deforestation . This decline

2345-422: The entryway, they act in a fairly non-aggressive manner (dipping inside the inner entrance) when presented with an intruder. It is speculated they may act as an alarm for the rest of the nest rather than an attack force. Fecundity Human demography considers only human fecundity, at its culturally differing rates, while population biology studies all organisms . The term fecundity in population biology

2412-474: The expense of survival. In semelparous species, age is frequently a poor predictor of fecundity. In these cases, size is likely a better predictor. Population density is often observed to negatively affect fecundity, making fecundity density-dependent. The reasoning behind this observation is that once an area is overcrowded, fewer resources are available for each individual. Thus there may be insufficient energy to reproduce in high numbers when offspring survival

2479-429: The explanation being that there is higher mortality in seasonal environments. A different hypothesis by David Lack attributed the positive relationship to the change in daylight hours found with changing latitudes. These differing daylight hours, in turn, change the hours in which a parent can collect food. He also accounts for a drop in fecundity at the poles due to their extreme amounts of day lengths, which can exhaust

2546-404: The fertile topsoil of the subtropical rainforests. The niche breadth of S. quadripunctata includes a wide variety of flowering plants that overlaps with many other eusocial bees native to the area, including members of the tribes Meliponini and Trigoni , as well as Africanized honeybees . Each nest features a single, simple rounded entrance, as opposed to a triangular entrance or one with

2613-440: The form of chemical signals between members of the same colony. In particular, cuticular hydrocarbon levels are thought to be of great importance to S. quadripunctata communication and can vary greatly according to age, sex and caste. Hydrocarbons in the stingless bee can vary in length from nonadecane with nineteen carbons to tritriacontane with thirty-three carbons, as discovered in a study conducted by Nunes et al. (2009). It

2680-446: The genus Schwarziana in the world. However, two more species were discovered in the high altitude environment of South America – S. bocainensis in southeastern Brazil and S. chapadensis in central Brazil. The stingless bee S. quadripunctata varies in size from 6.0 to 7.5 millimetres ( 1 ⁄ 4 to 9 ⁄ 32  in). Worker bees and dwarf queens tend to be on the lower end of this spectrum while queens tend to lie on

2747-446: The growing larvae. With so much control, worker bees occasionally discriminate or display reproductive suppression tendencies against dwarf queens by either uncapping the cell before the dwarf hatches, halting the supply of nutrients, or killing the newly developed individual upon emergence of the cell. A major strength of any eusocial insect is the ability to communicate amongst one another. Often, this method of communication comes in

Schwarziana - Misplaced Pages Continue

2814-452: The high degree of kin selection among stingless bees. After a female queen mates and lays her brood, the worker bees package them into specifically designed cells – queens in larger “royal” cells and workers and dwarf queens in smaller ones. Each cell is then capped with a layer of wax-like substance. With the queen’s role in production complete, the combs are left to the tending of worker bees, which distribute nutrients and vital resources to

2881-428: The higher end. Dwarf queens and workers tend to have an average weight of about 30 mg, but have been known to weigh as much as 40 mg or as little as 22 mg. Mated queens (those in charge of the nest) are, in comparison, much larger. The average queen bee weighs in at about 130 mg. However, some have been measured at over 160 mg, about a quarter of the weight of an average paperclip. Colonies contain

2948-550: The idea that the chemicals are acquired as the exposure to the waxy comb, specific to each colony, increases. One case sought to further test the importance of hydrocarbon concentration. In a group of related worker bees, half were injected with an alien alkene . Aggressive behaviors towards these individuals by the non-injected worker bees increased significantly. They were unable to be recognized by their unique odor and were subsequently treated as intruders. The recognition of various odors associated with hydrocarbon concentrations

3015-407: The interior in smaller brood cells. The eggs are cared for by the workers. Since S. quadripunctata reproduction typically relies on a single queen, genetic relatedness within individual colonies is expected to be relatively high. In an analyzation of the genetic relatedness within four separate colonies with an average of eight different worker genotypes per colony, an average relatedness of .792

3082-423: The layers of wax on the comb or on the comb itself. Courting occurs in the form of buccal contact between the males and females through a lateral hole in the thorax of the female. Some virgin queens will begin manipulating the cerumen (wax) layers in preparation for the construction of brood cells by the workers. If the physogastric queen deems a virgin queen is too much of a sexual threat, it may be imprisoned in

3149-436: The local geomagnetic field. Over the course of four months, the study group measured the two angles in comparison to various magnitudes of applied magnetic fields and compared them to observed angles in natural geomagnetic fields. A significant correlation was found between the two, definitively showing that the stingless bee relies on magnetoreception for navigational purposes. A similar 2005 study by Lucano et al. observed

3216-413: The more numerous, normal-sized cells produced for the worker bee eggs. Dwarf queens are also reared in worker cells. Queen cells are typically located near the edge or periphery of the comb while worker and dwarf queen cells are randomly aggregated towards the center. Although less than one percent (1%) of dwarf queens were seen to emerge from worker cells, they account for nearly eighty-six percent (86%) of

3283-399: The navigational system of Schwarziana quadripunctata had remained elusive until quite recently. It has been determined that S. quadripunctata navigates, like many other bees, through the use of magnetoreception – utilizing magnetic fields in the atmosphere to recognize differences in location, altitude and directionality. This notion of magnetic navigational skills was first observed in

3350-479: The older member. In the stingless bee S. quadripunctata , as in many social insects, queens reign at the top of the dominance hierarchy, followed by dwarf queens and finally workers. However, dwarf queens have been observed to lead nearly one in five colonies. Although, this accounts for only seventeen percent (17%) of dwarf queens and is significantly lower than the rate at which they were reared (constituting 86% of all females). This does show, however, that becoming

3417-603: The parent. Fecundity intensity due to seasonality is a hypothesis proposed by Phillip Ashmole. He suggests latitude affects fecundity due to seasonality increasing with increasing latitudes. This theory relies on the mortality concept proposed by Moreau but focuses on how seasonality affects mortality and, in turn, population densities. Thus in places with higher mortality, there is more food availability, leading to higher fecundity. Another hypothesis claims that seasonality affects fecundity due to varying lengths of breeding seasons. This idea suggests that shorter breeding seasons select

SECTION 50

#1733106069131

3484-424: The patterns of birth amongst individuals of different ages in a population. These are typically found in life tables under the columns Fx and mx. Fx lists the total number of young produced by each age class, and mx is the mean number of young produced, found by finding the number of young produced per surviving individual. For example, if you have 12 individuals in an age class and they produced 16 surviving young,

3551-405: The physogastric queen maintained her normal routine. Within a couple days, the virgin queen was found dead and was being carried off by workers. The defining aspect of queen-queen conflict appears to rely heavily on size differentiation. The dominant queen can reach sizes over three times larger than that of the dwarf queens. However, multiple queen production serves a vital role in the survival of

3618-407: The same nest of Schwarziana quadripunctata to determine the location of the bodily magnetoreceptors. After separating the head, thorax, abdomen and antennae of a dozen stingless bees, magnetic fields were applied to each body part. It was found that the head, thorax, and abdomen present a diamagnetic contribution (inducing a magnetic field opposite to the applied field), while the antennae displayed

3685-460: The species Casearia sylvestris (called guaçatonga) and Myrcia tomentosa (commonly referred to as goiaba-brava) alone. Other popular flowering plants comprising their diet include Mikania catharinensis , Piptocarpha oblonga (or braço-do-rei in Brazil), and Cordia trichoclada . The entrance to a stingless bee nest serves as a particularly vulnerable area. It serves as the threshold that separates

3752-437: The study in an attempt to explain this lack of aggression. One hypothesis couples the production of males in a stingless bee society with an increase in food reproduction. In this case, the benefit of a stable diet would overcome the workers’ desire to produce females. Another possibility is that aggression is beneficial no matter the sex being produced. The aggression between workers and queens may just be residual left over from

3819-420: The subterranean level of the subtropical environment, an unusual feature among other stingless bees. The species ranges in sizes from 6.0 to 7.5 millimetres ( 1 ⁄ 4 to 9 ⁄ 32  in) and feeds on a diverse diet of flowering plants found abundantly on the forest floor, including guacatonga ( Casearia sylvestris ) and the mistletoe species Struthanthus concinnus . Schwarziana quadripunctata

3886-471: The surrounding cells housing males and workers. The distribution of S. quadripunctata ranges from the central highlands of Brazil down towards the northern edge of Argentina on the eastern side of South America . Altitudes can reach up to fifteen hundred meters (1,500 metres (4,921 ft)) in some areas. Lying so near the equator, temperatures are fairly warm year-round, averaging twenty-five degrees Celsius (25 °C (77 °F)). Nests are built into

3953-407: The term Schwarziana as a subgenus rather than genus and instead incorrectly classify it under the closely related genus Plebeia . The closest relative of S. quadripunctata is the species Schwarziana mourei , determined through morphological and genetic evidence collected in the early twenty-first century. Until recently (2015) it was believed that these were the only two existing species under

4020-399: The total queen population. A colony will continue to grow in size until the queen bee dies or swarms to a new location to begin a new colony. In rare cases, two queens may swarm to the same location, due to balanced attractiveness, to begin a new colony. In these special cases, the younger queen typically produces more eggs than the older queen and begins to take over the colony, phasing out

4087-422: The viability of the species from the outside world. The size of the entryway is critical. It must remain large enough to allow the easy to-and-fro passage of the bee, yet small enough to dissuade potential predators (such as orb spiders ) from causing havoc inside the nest. Evolutionarily, a size compromise must be reached. The nest entrance of Schwarziana quadripunctata consists of a simple, round opening. This

SECTION 60

#1733106069131

4154-527: The wax present in the nest. The relative concentrations of hydrocarbons in members of a colony differed between unrelated sites, alluding to the hypothesis that the wax of each nest contains a unique chemical blend from which the developing larvae absorb. Along with, and often closely related to, communication, effective navigation within an environment is vital to the successful reproduction of eusocial insects. Although some organisms’ methods of navigation seem quite apparent (i.e. through modes of sight and scent)

4221-410: Was collected and calculated on the evaluation of seven polymorphic microsatellite loci , each with several attributable alleles . Kin recognition often goes hand in hand with communication. For instance, researchers compared the relative amounts of various hydrocarbon compounds present in the epicuticles , serving as a chemical odor to other individuals, of S. quadripunctata . The study showed that

4288-500: Was first described by the French entomologist Amédéé Louis Michel le Peletier in 1836. Although originally placed in the genus Trigona , more recent taxonomic evaluations have since placed it under its current genus, following the 1943 description of Schwarziana by Padre J.S. Moure . However, some still categorize Schwarziana as a subgenus under the closely related genus Plebeia . Recent morphological studies support Schwarziana as

4355-560: Was first described by the French entomologist and former president of the French Entomologist Society Amédéé Louis Michel le Peletier in 1836. Although originally placed in the genus Trigona , more recent taxonomic evaluations have since placed it under its current genus, following the 1943 work of Padre J.S. Moure, occasionally referred to as "the Father of Brazilian Bee Taxonomy". However, some still consider

4422-571: Was found among worker bees within each colony. This value has been replicated in several studies, including one conducted by Toth et al. (2001) among eighteen colonies in Brazil (relatedness value = 0.75 ± 0.04 among worker bees). In the same study, males (being haploid ) had a relatedness value of 1.0 to queens, while workers only shared approximately fifty percent (50%) of the queen’s genes (relatedness value = 0.48). Relatedness between workers and males were also about half (relatedness value = 0.51). The data

4489-403: Was found that cuticles of older worker bees contained higher concentrations of heptacosene (C27) and hentriacontene (C31) than younger workers and virgin queens, indicating that these hydrocarbons play an important role in nest mate recognition. It was also found that younger stingless bees lacked some of the major hydrocarbons found in older individuals, most likely due a result of less exposure to

#130869