Microstigmus

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Microstigmus
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Pemphredonidae
Subtribe: Spilomenina
Genus: Microstigmus
Ducke, 1907

Microstigmus, or the thin-waisted social wasps, is a small genus wasp in the family Pemphredonidae. [1] This genus is found in the Neotropical realm from Central to South America. They build nests and live in colonies ranging in size from 1 to 18 members. [2] Microstigmus is widely considered to be the only true eusocial species of apoid wasp. [3]

Contents

Biology

The species of Microstigmus ranges in length from 2.5 to 5.5 millimetres (0.098 to 0.217 in). [4] Unlike other Hymenoptera, the head and thorax lack branched or plumose hairs. [5] The wasps also have their posterior metatarsus modified into a cleaning mechanism. [6]

Apoid wasps also have a silk gland in the abdomen, which in the Pemphredonidae is used for nest building. In Microstigmus, the gland cells each have a singular nucleus and form a conducting canal. Bristles at the end function as spinnerets. This epidermal gland evolved independently for most species under the Pemphredoninae subfamily. [7]

Diet

As with most wasp species, those in the genus Microstigmus are predators. Prey for the wasps can vary from flies to aphids. Most of the time, the kill is performed with the powerful mandibles literally biting through the head of the prey causing either death or immobilization. [8] Social wasps will kill the prey and then return to the nest to provide for the young. This can be done in several ways. One is for the wasp to suck out the inner bodily fluids of the prey and carry the hemolymph back to the nest where the adults will regurgitate some of the fluids to the larva wherein the adult retains some of the hemolymph. [9] This trophallaxis between adults and larva may have played a role in social wasp evolution in three primary ways. Adults who provide nourishment for larva and get food in return may reduce the need to forage for food for themselves. Therefore, flights from the nests may be more efficient where flights are only performed for larval food foraging and nest construction materials over species that do not practice trophallaxis. [9] The larval-adult saliva exchange may also increase reproductive fitness in females. An example would be a period of inclement weather where food is hard to come by. The reproducing females would still have a source of nutrition and be able to continue reproductive cycles which are crucial in eusocial colonies. There might also be a situation where the trophallaxis benefits the adults but also hinders the larva in form of nutritional castration where the lack of food results in underdeveloped reproductive organs thus leading to the creation of a worker class. [9]

Nesting

Nests generally have a rough external appearance with a brownish-gray hue although some species have a whitish appearance with smooth texture. Species usually form communal nests that hang from a strong support such as a tree branch, vine, or overhanging rock formation via a petiole which is produced from a root tip rather than silk. The nests are typically built with substrate surface material such as bark, lichens, and sand grains interlaced with silky secretion produced by the female wasps. [10] The nests are developed into conical structures approximately 12 mm in length. Most of the infant holding cells are the near the bottom and the adults reside in the upper hollow section of the next close to the entrance. The interior of the entrance is covered by a translucent coating. [11] In most instances the beginnings of the nest are created all by a single queen wasp that decides to spawn more workers once the nest has reached a certain size (generally the size of a walnut). While most social insects build their nests over time gradually increasing in size, the Microstigmus construct the entire confines of the nest in one effort and thus the workers and queen are confined to the nest until it is fully completed. [12] As such all of the construction materials are gathered prior to the building of the nest as seen with Microstigmus comes. [10]

Behavior

Larva interaction

As Microstigmus is a social genus that lives together in a colony, larval care is provided by adults. In Microstigmus thysanoptera, the adults form a compact mass of prey provisions and silk fibers which, upon hatching, the larva consumes. [10] The fecal matter produced by the larva that have molted is removed from the nest along with other trash by the adults performing housekeeping duties. [10] Larval incubation habits indicate the sociality among wasps, as females will routinely bring food to the same incubation cell in a cooperative effort. [11] Social divisions also reveal the specialization of roles and thus how each individual contributes to the overall colony. No two eggs are at the same stage of development and only one egg is available for care at any given time. This is supported by the fact that there is only one female with significantly larger ovaries over the other females at any given time and this select female is considered the primary egg layer. [12]

The anatomy of Microstigmus larvae has unique evolutionary characteristics. One is the conical supranal process which is potentially an adaptation for obtaining the prey provisions stuck on the walls of a nursery cell. During the larval stage, there also is a complete lack of spinnerets which indicate that a pupal stage with a cocoon is not present in some species of Microstigmus (M. xylicola nests have been found with pupa present). [4] The spinulose lobe of the mandible is not like most and is a possible modification for ingestion of collembolans. [13] Other aspects of Microstigmus biology are shared with other genera in the family Pemphredonidae such as antennal papillae, lack of galeae, and tridentate mandibles which indicate close relation to Spilomena and distant from Ammoplanus. [13]

Adult/nest interaction

A typical worker female exhibits repetition of select behaviors, mainly with a purpose of sustaining the colony. They would forage for food for the young which can range from decaying dead insects and bodily fluids of paralyzed insects to decaying fruit. Adults usually feed off nectar as their primary source of nourishment but in some colonies such as M. nigrophthalmus the adults feed off the secretion of the larva (a form of defecation). Adults deliver the food to the young through a process called trophallaxis. Adults also inspect the nest, clean by ejecting excess material, and silk which is reinforcement of the nest structure through adding silk to the petiole. More rarely, individuals would partake in nest defense, usually from small arthropods, and mate where a female and a male would exit the nest joined at the genitalia. [8]

Before leaving the nest, the adults generally make an inspection walk around the nest and will also perform the same task upon returning, generally to make sure the nest is in good order and not damaged in any way. [10] Another potential reason for the inspection routine could be to check for parasites around the nest. Along with the inspections, adults also perform the maintenance routes where the wasps remove particles and waste and check the integrity of the nest. Females occasionally will apply silk to reinforce the nest surface, pedicel and attachment point between the leaf and pedicel. [10]

Eusociality

In some species, social altruism is visible; however, studies on these topics have been limited. The small size and enclosed nest structure makes it difficult to obtain significant data.[ citation needed ] In colonies of wasps with more than one adult, one adult would almost always remain at the nest site while the others would go out and forage for food or construction materials. [11] Nest defense are also done together with most of the females congregating around the nest during an attack. [11]

Eusocial insects typically discriminate against non-nest members. However, in M. thripoctenus, tolerance of non-related individuals was observed, and may have some social benefit. One hypothesis and is that in a solitary nest where more members can provide more work, the additional help is kept around in order to benefit the overall fitness of the colony. A second hypothesis is that additional members would increase the longevity of the nest as it is theorized that each wasp is only capable of so much silk production which is the key building block in nest construction. [10]

Kin selection based on Hamiliton’s Rule provides an explanation to the population genetics framework and specifies the patterns of local and family genetic makeup that results in the most favorable outcome. The key to this is that the genetic structure spawns nonrandom genotypes which coupled with differential reproduction makes kin selection possible. [14] Inter-nest relatedness was high resulting in few independent haploid genomes which makes possible the development of a social hierarchy. [14]

Relatedness

Between the females within a nest, relatedness was very high and contributes to altruistic behavior in an effort to support the survivability of the brood regardless of whether the brood is one’s own offspring or not. Additionally, the nest has a group effort toward raising brood members due to the high cost of constructing where females have to invest, time, effort, and energy in order to produce and maintain a nest. Relatedness between individuals drastically decreases over a few generations and as such, mating in Microstigmus colonies tend to be low to the point where it is not uncommon to see a nest with only one female with fully functioning ovaries. Reproduction within Microstigmus nests from various subspecies where some has a queen-worker divide and the queen's sole purpose is to reproduce, while others have specific females rear the offspring. [8]

Related Research Articles

<span class="mw-page-title-main">Trophallaxis</span> Transfer of food between members of a community through stomodeal or proctodeal means

Trophallaxis is the transfer of food or other fluids among members of a community through mouth-to-mouth (stomodeal) or anus-to-mouth (proctodeal) feeding. Along with nutrients, trophallaxis can involve the transfer of molecules such as pheromones, organisms such as symbionts, and information to serve as a form of communication. Trophallaxis is used by some birds, gray wolves, vampire bats, and is most highly developed in eusocial insects such as ants, wasps, bees, and termites.

<span class="mw-page-title-main">Vespidae</span> Family of insects

The Vespidae are a large, diverse, cosmopolitan family of wasps, including nearly all the known eusocial wasps and many solitary wasps. Each social wasp colony includes a queen and a number of female workers with varying degrees of sterility relative to the queen. In temperate social species, colonies usually last only one year, dying at the onset of winter. New queens and males (drones) are produced towards the end of the summer, and after mating, the queens hibernate over winter in cracks or other sheltered locations. The nests of most species are constructed out of mud, but polistines and vespines use plant fibers, chewed to form a sort of paper. Many species are pollen vectors contributing to the pollination of several plants, being potential or even effective pollinators, while others are notable predators of pest insect species, and a few species are invasive pests.

<i>Sceliphron caementarium</i> Species of wasp

Sceliphron caementarium, also known as the yellow-legged mud-dauber wasp, black-and-yellow mud dauber, or black-waisted mud-dauber, is a species of sphecid wasp. There are some 30 other species of Sceliphron that occur throughout the world, though in appearance and habits they are quite similar to S. caementarium.

<span class="mw-page-title-main">Philanthidae</span> Family of wasps

Philanthidae is one of the largest families of wasp in the superfamily Apoidea, with 1167 species in 8 genera, most of which are Cerceris.

<span class="mw-page-title-main">Stenogastrinae</span> Subfamily of wasps

The Stenogastrinae are a subfamily of social wasps included in the family Vespidae. They are sometimes called hover wasps owing to the particular hovering flight of some species. Their morphology and biology present interesting peculiarities.

<span class="mw-page-title-main">Mass provisioning</span>

Mass provisioning is a form of parental investment in which an adult insect, most commonly a hymenopteran such as a bee or wasp, stocks all the food for each of her offspring in a small chamber before she lays the egg. This behavior is common in both solitary and eusocial bees, though essentially absent in eusocial wasps.

<span class="mw-page-title-main">Wasp</span> Group of insects

A wasp is any insect of the narrow-waisted suborder Apocrita of the order Hymenoptera which is neither a bee nor an ant; this excludes the broad-waisted sawflies (Symphyta), which look somewhat like wasps, but are in a separate suborder. The wasps do not constitute a clade, a complete natural group with a single ancestor, as bees and ants are deeply nested within the wasps, having evolved from wasp ancestors. Wasps that are members of the clade Aculeata can sting their prey.

<i>Ropalidia marginata</i> Species of insect

Ropalidia marginata is an Old World species of paper wasp. It is primitively eusocial, not showing the same bias in brood care seen in other social insects with greater asymmetry in relatedness. The species employs a variety of colony founding strategies, sometimes with single founders and sometimes in groups of variable number. The queen does not use physical dominance to control workers; there is evidence of pheromones being used to suppress other female workers from overtaking queenship.

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

Polistes chinensis is a polistine vespid wasp in the cosmopolitan genus Polistes, and is commonly known as the Asian, Chinese or Japanese paper wasp. It is found in East Asia, in particular China and Japan. The subspecies P. chinensis antennalis is an invasive species in New Zealand, having arrived in 1979.

<i>Sphex pensylvanicus</i> Species of wasp

Sphex pensylvanicus, the great black wasp, is a species of digger wasp. It lives across most of North America and grows to a size of 20–35 mm (0.8–1.4 in). The larvae feed on living insects that the females paralyze and carry to the underground nest.

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

Polistes metricus is a wasp native to North America. In the United States, it ranges throughout the southern Midwest, the South, and as far northeast as New York, but has recently been spotted in southwest Ontario. A single female specimen has also been reported from Dryden, Maine. P. metricus is dark colored, with yellow tarsi and black tibia. Nests of P. metricus can be found attached to the sides of buildings, trees, and shrubbery.

<i>Ammophila sabulosa</i> Species of wasp

Ammophila sabulosa, the red-banded sand wasp, is a species of the subfamily Ammophilinae of the solitary hunting wasp family Sphecidae, also called digger wasps. Found across Eurasia, the parasitoid wasp is notable for the mass provisioning behaviour of the females, hunting caterpillars mainly on sunny days, paralysing them with a sting, and burying them in a burrow with a single egg. The species is also remarkable for the extent to which females parasitise their own species, either stealing prey from nests of other females to provision their own nests, or in brood parasitism, removing the other female's egg and laying one of her own instead.

<i>Dolichovespula adulterina</i> Species of wasp

Dolichovespula adulterina is a species of parasitic social wasp found in the Palearctic region. D. adulterina feeds on a variety of foods, including insects, spiders, arthropods, meat, molluscs, fruit, nectar, and larval secretions. D. adulterina was formerly considered to be synonymous with D. arctica from the Holarctic region, but more recent research indicates that D. arctica is a separate species.

<i>Apoica pallens</i> Species of wasp

The Central American paper wasp is a nocturnal eusocial wasp. It is famous for its swarm based emigration behavior, and is native to the lowlands of Central and northern South America. This species has developed special night vision adaptations to facilitate their night-time swarming and foraging behavior and has important medicinal properties for the Pankararú people of Brazil.

Belonogaster juncea juncea is a subspecies of Belonogaster juncea and is classified as a primitively eusocial wasp, meaning that the species is social while exhibiting a morphology that is indistinguishable from that of other castes. It is also classified as a type of African Paper Wasp. Many of the studies relating specifically to B. j. juncea take place at the University of Yaoundé in Cameroon.

<i>Belonogaster petiolata</i> Species of wasp

Belonogaster petiolata is a species of primitively eusocial wasp that dwells in southern Africa, in temperate or subhumid climate zones. This wasp species has a strong presence in South Africa and has also been seen in northern Johannesburg. Many colonies can be found in caves. The Sterkfontein Caves in South Africa, for example, contain large populations of B. petiolata.

<i>Ropalidia revolutionalis</i> Species of wasp

Ropalidia revolutionalis, the stick-nest brown paper wasp, is a diurnal social wasp of the family Vespidae. They are known for the distinctive combs they make for their nests, and they have been found in Queensland, Australia in the areas of Brisbane and Townsville. They are an independent founding wasp species, and they build new nests each spring. They can be helpful because they control insect pests in gardens.

Parischnogaster nigricans serrei is a hover wasp subspecies in the family Vespidae, and it is predominantly found in the Java region of Indonesia. Its nest cells are of conical structure, linearly attached to a string-like substratum. The nests are typically found in places open to human interactions, such as gardens, trees, or forests around villages. There is a clear dominance hierarchy within colonies, which often affects the behavioral activities of its members. The wasp’s most common predators are Vespa tropica, also known as the great banded hornet. P. nigricans serrei defends itself by flying away or giving out alarm calls.

Protopolybia chartergoides, also known as Pseudochartergus chartergoides, is a species of wasp within the genus Protopolybia. It is a social wasp found in southern Central America and northern South America.

<i>Pison spinolae</i> Species of insect

Pison spinolae, commonly known as mason wasp, is a solitary wasp of the family Crabronidae, found throughout New Zealand.

References

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