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Polistes humilis is a species of Vespidae that occurs throughout Australia. Also known as a common paper wasp, this species can be identified by their long thin legs and banded yellow and black coloring. This species is particularly known for it's sting when a nest is disturbed.
- 1 Taxonomy and phylogeny
- 2 Description and identification
- 3 Distribution and habitat
- 4 Colony Cycle
- 5 Behavior
- 6 Kin Selection
- 7 Interactions with other species
- 8 Human importance
- 9 References
Taxonomy and phylogeny
Polistes humilis is in the genus Polistini, which consists of 150 species that can be found in all regions of the world except the colder climates. Polistes humilis is the only species of Polistini found in New Zealand after it was accidentally introduced from Australia. There are 11 different Polistes species found in Australia. Historically,the species Polistes variabilis has been misidentified as a sub-species of Polistes humilis but recent photogenic analysis has indicated that these are two separate species. The species can be divided into two sub-classes, P. humilis humilis which is found in northern Australia and P.humilis synoeus which can be found in the south.
Description and identification
This species of wasp can be identified by their slender body structure and banded coloring  Adults are are about 10-15mm long with a tanish-red coloration and yellow faces. Males can be distinguished from females by a yellow marking on the mesosternal area.< ref name = mating></ref> In addition, Polistes humilis are generally bigger than most other paper wasps. Nests of this species can be identified by their cone shaped appearance with multiple hexagonal cells. The species builds its nest out of grey wood fiber material, which is a mixture of their own saliva and wood. Unlike most species of wasp, Polistes humilis colonies have been know to re-utilize old nests from year to year. Some colonies over winter and shelter above the comb in colder months.
Distribution and habitat
Polistes humilis is mostly found in Australia, particularly in southern Queensland, New South Wales, Victoria, and South Australia. The species was spread to New Zealand in the 1880s and has a established a sable population on the island. In New Zealand, the species is largely confined to the area north of Tauranga and west of Te Kuiti. The highest abundance of P. humilis can be found in shrublands. However, the species can also be found in flax swamps and forest sites.
The colony cycle of Polistes humilis starts in the Spring and can begin in three ways. First, the colony cycle can begin with the founding of a new nest, typically by several foundresses. Next, the cycle can start with the re-utilization of an old nest, which can be several years old. Third, the cycle can also begin with the continued use of an old nest as this species can over winter. In situations where old nests are used, new eggs are typically laid around the old cells.
Throughout the year, production of polistes humilis nests typically follow a distinctive cycle. In spring, nests are founded by females that overwintered and have been previously inseminated. After founding, worker females are produced in the late spring and early summer. Males and queen females are produced in the late summer and early fall. This overwintering system likely evolved due to the temperate Australian winter.
In Polistes humilis nests, there is an observable hierarchy between reproducing queens and sterile workers. There are no outward physical differences between females, even small females have been known to produce eggs  Dominant females can only determined by behavioral characteristics as there are no morphological differences between females. These females often receive solid food, honey, and water from worker females returning from foraging. Besides the "tail waging" display of dominance, Polistes humilis appear to have lower than average aggressive behavior within the species. This is likely caused by a high degree of relatedness between individuals.
Polistes humilis queens are singly mated, meaning that the eggs of the queen are fertilized by a single male and only one fertilization event occurs per female. Within each colony, there are an average of two queen females. Due to this, different males can fertilize each female in the nest, resulting in increased genetic diversity within the nest. A distinctive characteristic of this species is that there is no inbreeding within P. humilis colonies. This suggests that dispersal is primarily male based. This suggests that males do not reproduce in their native colony and that dispersal likely happens before mating.
Polistes humilis are a haplodiploid species, with females developing from a fertilized egg and males developing from an unfertilized egg. In this system, queens are singly mated with full sisters sharing the paternal genetic information and either one of the maternal alleles. This results in the 75% relatedness between females in the nest, making sisters more related to each other parents and offspring in diploid species. However, this ratio is skewed by the fact that there are typically multiple queens in a nest. Therefore, within a nest some groups of females are more related to each other than other. This should result in unique eusocial behavior within the nest.
In this species there does appear to be benefits to having larger nest sizes. As nest size increases, the number of females directly increases. This decreases the genetic relatedness of individuals and could cause a breakdown of the dominance hierarchy of the nest. However, this likely evolved as a defense against disease transmission. Increased genetic variability has been shown to reduce disease transmission within a nests and could prevent a nest from dying out.
Since queen females have few morphological differences from worker females, they must use behavioral means to prevent them from laying eggs. As each queen selfishly wants to have as much offspring as possible, it is likely that oophagy occurs in Polistes humilis. This practice limits the eggs that weaker females can produce and reduces the genetic variability of the nest. Dominance of females can also be through behavioral displays. Dominant females display their dominance by horizontal vibrations of the gaster and demonstrate it by mounting and wrestling with other females. These behaviors help the queens maximize their offspring's ability to survive and increases the genetic relatedness within the nest.
Interactions with other species
Polistes humilis are observed to subsist on food brought back to the nest by worker wasps. Once food is brought back to the nest, workers distribute food to the queen and larvae. The species consumes primary water, pulp, carbohydrate and protein prey. In southern Australia, Polistes humilis appears to specialize consuming lepidopteran larvae for protein as well as small spiders. Polistes humilis has to compete with other species for food, particularly the newly introduced, invasive species Vespula germanica. While Polistes humilis is very common now, competition for food could reduce its population in the future.
As a stinging wasp, Polistes humilis has a very powerful defense mechanism. The venom in the sting of the species helps with prey capture and nest defense from predators. The venom comes from the two tubular glands and are secreted by powerful muscles that coat the reservoir and squeeze out the venom. The venom is known to be used in fights between species and is often used in limited amounts. The venom is largely made of serotonine, histamine, tyramine, dopamine, and 5-hydroxytryptoamine which are all considered major pain producing components of the venom.
Nest location and stings
As with most Polistes, Polistes humilis are often seen as a pest to humans. Most nests are found in "modified habitats" where there is a mix of human structures and vegetation. Therefore nests are typically found in walls, eaves of buildings, and fences. However, beyond a sometimes painful sting there is no danger from a sting, unless one is known to be allergic. The best way to avoid a sting is to simply stay away from a nest if possible, trying not to antagonize a nest if there is no need.
- "Common Paper Wasp (Polistes humilis)". Retrieved October 7, 2014.
- "Biology and Pest Status of Venomous Wasps". 1978. Retrieved October 9, 2014.
- "A Taxonomic Note and Nest Description of an Australian Paper Wasp, Polistes variabilis (FABRICIUS)(Hymenoptera, Vespidae, Polistinae)". November 15, 1997. Retrieved October 10, 2014.
- "Spring Behaviour of an Australian Paper Wasp, Polistes humilis synoecus : Colony Founding by Haplometrosis and Utilization of Old Nests". June 25, 1986. Retrieved October 9, 2014.
- "Common paper wasps". October 11, 2011. Retrieved October 8, 2014.
- "Distribution and abundance of the Asian paper wasp Polisteschinensis antennalis Perez and the Australian paper wasp P. humilis (Fab.)(Hymenoptera: Vespidae) in New Zealand". March 30, 2010. Retrieved October 9, 2014.
- "Nesting biology of Asian paper wasps Polistes chinensis antennalis Pérez, and Australian paper wasps P. humilis(Fab.) (Hymenoptera: Vespidae) in northern New Zealand". April 2005. Retrieved October 10, 2014.
- "Mating system and genetic structure in the paper wasp (Polistes humilis)". July 10, 2009. Retrieved October 10, 2014.
- "Assessment of prey overlap between a native (Polistes humilis) and an introduced (Vespula germanica) social wasp using morphology and phylogenetic analyses of 16S rDNA". April 22, 2004. Retrieved October 10, 2014.
- "Polistes venom: a multifunctional secretion". December 29, 2006. Retrieved October 11, 2014.
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