Prolasius advenus

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Prolasius advenus
Prolasius advenus worker
Scientific classification Edit this classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Formicinae
Genus: Prolasius
Species:
P. advenus
Binomial name
Prolasius advenus
(Smith, 1862)
Synonyms
Synonymy
  • Formica advena Smith, 1862
  • Formica zealandica Smith, 1878
  • Prenolepis advena Mayr, 1886
  • Lasius (Prolasius) advena Suter, 1892
  • Lasius advena Dalla Torre, 1893
  • Melophorus advena Forel, 1905
  • Lasius zealandica Dalla Torre, 1893
  • Melophorus (Prolasius) advena Emery, 1925
  • Colobopsis zealandica Wheeler, 1927
  • Prolasius zealandica McAreavey, 1947

Prolasius advenus is a species of ant in the genus Prolasius. It is endemic to New Zealand where it is widespread across the North and South Islands, including offshore islands. P. advenus typically occurs in forest habitat, but can also sometimes be found in open habitat such as tussock. It was first formally described in 1862 by Frederick Smith from a specimen collected in Lyttleton. It is commonly referred to as the "small brown bush ant". The ant is small and coloured brown, with workers being 2.9-3.5mm (0.11-0.14 in) in length. Colonies typically have hundreds of workers and several queens. They are generalist foragers that scavenge for food. When starved of food, they become more aggressive towards other ant species. Unlike some other ant species, the worker ants are not sterile and can produce male offspring if the queen is absent. Several species of beetle such as Holloceratognathus passaliformis and Neosampa granulata live in their nests. P. advenus are impacted by high densities of Vespula wasps, which cause genetic bottlenecks and for workers to have smaller body sizes.

Taxonomy and etymology

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This species was first described as Formica advena by Frederick Smith in 1862 from a specimen collected in Lyttleton.[1] In 1878, Smith described a synonym of this species, Formica zealandica.[2] Both Formica advena and Formica zealandica were transferred to other genera numerous times.[3] In 1892, Formica advena was placed in the genus (then subgenus) Prolasius, of which it is the type species.[4] In 1958, Formica zealandica was later recognised as a synonym of P. advenus.[5] The holotype specimen is stored in the Natural History Museum of London under registration number BMNH(E)1016251.[6] The species is commonly referred to as the "small brown bush ant".[7]

Description

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The female workers are 2.9-3.5mm (0.11-0.14 in) in length. They are brown in colour, with the abdomen being somewhat darker and the legs lighter. The antennae is 12 segmented, with a long scape. Each mandible has 6 teeth. The clypeus is roundish and has a ridge. On the metanotum, there is a well defined groove. The petiole is shaped like a wedge. At the apex of the abdomen there is a ring of hairs.[8] The non-worker (reproductive) females are similar to workers but larger, being around 4.6-6mm (0.18-0.23 in) in length and are more darkly coloured than the workers. Before mating for the first time, the females possess wings. Males are similar to workers, but are more slender and somewhat smaller. They are yellow brown in colour and have a small head with large eyes.[5] The pupa are wrapped in cocoons that are creamy in colour.[8]

Distribution and habitat

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Prolasius advenus are endemic to New Zealand, where they are widespread and very common throughout the North Island, the South Island and Stewart Island.[8] They are also known to occur on offshore islands including Three Kings Islands.[9][8]

They are known to occur in habitats such as beech, mixed podocarp and podocarp forests, but can also sometimes be found in open habitat such as tussock (but usually in the vicinity of forest edges). They are known to occur from sea level up to at least 1200m in altitude.[8]

Biology

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Colonies can include hundreds of workers and multiple queens. One study reported that a colony had roughly 500 workers, twelve queens and about 90 males. The nests are rather complex with numerous connected galleries. The queens and males are typically found deeper in the nest, but will occasionally come to the surface.[8]

They are generalist foragers, preying upon and scavenging small arthropods, as well as tending mealy-bugs and scale insects for honeydew.[8] When struggling to gather sufficient carbohydrates or proteins, the workers will focus on gathering the nutrient they are more lacking. Because of this, more workers will leave the colony to perform foraging behaviour. During this period of starvation, they behave more aggressively towards other ants. This may indicate that P. advenus will be able to at least partly adapt to food competition due to the presence of exotic species.[10] P. advenus will also become more aggressive and forage more when temperatures increase.[11] It has been suggested that the workers lay pheromone trails to guide other workers to food sources.[8]

Although ant workers are often sterile, the workers of P. advenus still possess functional ovaries and can produce eggs. In one study, the workers produced eggs in colonies that had no queen, indicating that in nature they can produce males if the queen dies or is otherwise absent.[12]

Interactions with other species

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The stag beetle Holloceratognathus passaliformis has only ever been found living in the nests of Prolasius advenus. The beetle is only known from a few localities near Wellington.[13] The rove beetles Neosampa granulata and Zeasampa nunni are known to live in the nests of P. advenus.[14] Other beetles such as featherwing beetles and Ecomorypora granulata have also been recorded in nests.[8] A species of nematode, Diploscapter formicidae, is known to parasitise P. advenus. The juveniles occupy the heads of workers. Because of the wide distribution of P. advenus, it is likely that D. formicidae is widespread in New Zealand as well.[15] There is very little overlap in distribution between P. advenus and Chelaner antarcticus, another species of endemic ant. Is is thought that this negative co-occurrence is due to environmental effects.[11]

The wasps Vespula germanica and Vespula vulgaris are an exotic species in New Zealand and have impacted P. advenus. Genetic bottlenecks in P. advenus populations have been recorded in areas where Vespula populations are high. It was hypothesized that this was because of Vespula preying upon the winged queens.[16] Similarly, in areas of high wasp density, workers of P. advenus had smaller body sizes. This was hypothesized to be due to competition for food with the Vespula.[17]

References

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  1. ^ Smith, F (1862). "Descriptions of new species of Australian Hymenoptera, and of a species of Formica from New Zealand". Transactions of the Entomological Society of London. 1: 53.
  2. ^ Smith, F (1878). "Descriptions of new species of Hymenopterous insects from New Zealand, collected by Prof. Hutton, at Otago". Transactions of the Entomological Society of London. 1878: 6.
  3. ^ Valentine, E W; Walker, A K (1991). "Annotated catalogue of New Zealand Hymenoptera". DSIR Plant Protection Report. 4: 38.
  4. ^ Forel, A H (1892). "The ants of New Zealand". Transactions and Proceedings of the New Zealand Institute. 25: 153–155.
  5. ^ a b Brown, W L (1958). "A review of the ants of New Zealand (Hymenoptera)" (PDF). Acta Hymenopterologica. 1 (1): 43–44.
  6. ^ "Collection specimens - Specimens - BMNH(E)1016251 - Data Portal". data.nhm.ac.uk. Retrieved 2025-08-22.
  7. ^ Ferro, D N; Lowe, A D; Ordish, R G; Somerfield, K G; Watt, J C (1977). "Standard names for common insects of New Zealand". Entomological Society of New Zealand Bulletin. 4: 17.
  8. ^ a b c d e f g h i Don, W (2007). Ants of New Zealand. Otago University Press. pp. 180–184. ISBN 9781877372476.
  9. ^ Taylor, R W (1962). "The ants of the Three Kings Islands". Records of the Auckland Institute and Museum. 5: 253.
  10. ^ Grangier, J; Lester, P J (2014). "Carbohydrate scarcity increases foraging activities and aggressiveness in the ant Prolasius advenus (Hymenoptera: Formicidae)". Ecological Entomology. 39 (6): 684–692. doi:10.1111/een.12146. ISSN 1365-2311.
  11. ^ a b Barbieri, R F; Grangier, J; Lester, P J (2015). "Synergistic effects of temperature, diet and colony size on the competitive ability of two ant species". Austral Ecology. 40 (1): 90–99. doi:10.1111/aec.12176. ISSN 1442-9985.
  12. ^ Grangier, J; Avril, A; Lester, P J (2013). "Male production by workers in the polygynous ant Prolasius advenus". Insectes Sociaux. 60 (3): 303–308. doi:10.1007/s00040-013-0294-6. ISSN 0020-1812.
  13. ^ Holloway, B A (2007). "Lucanidae (Insecta: Coleoptera)". Fauna of New Zealand. 61: 33–35. doi:10.7931/J2/FNZ.61. ISSN 1179-7193.
  14. ^ Nomura, S; Leschen, R A B (2015). "Myrmecophilous Pselaphinae (Coleoptera: Staphylinidae) from New Zealand". The Coleopterists Bulletin. 69 (1): 121–152. doi:10.1649/0010-065X-69.1.121. ISSN 0010-065X.
  15. ^ Zhao, Z Q; Davies, K A; Brenton-Rule, E C; Grangier, J; Gruber, M A M; Giblin-Davis, R M; Lester, P J (2013). "Diploscapter formicidae sp. n. (Rhabditida: Diploscapteridae), from the ant Prolasius advenus (Hymenoptera: Formicidae) in New Zealand". Nematology. 15 (1): 109–123. doi:10.1163/156854112X649828. ISSN 1388-5545.
  16. ^ Burne, A R; Ritchie, P A; Gruber, M A M; Lester, P J (2017). "A genetic bottleneck in populations of a New Zealand endemic ant associated with density of an invasive predatory wasp". Insectes Sociaux. 64 (1): 65–74. doi:10.1007/s00040-016-0512-0. ISSN 0020-1812.
  17. ^ Burne, A R; Haywood, J; Lester, P J (2015). "Density-dependent effects of an invasive wasp on the morphology of an endemic New Zealand ant". Biological Invasions. 17 (1): 327–335. doi:10.1007/s10530-014-0731-0. ISSN 1573-1464.
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  • Media related to Prolasius advenus at Wikimedia Commons
  • AntWiki lists the species under the synonym Prolasius advena
  • Lessons from Little Creatures: article on New Zealand ants from NZ National Geographic.