Dasymutilla occidentalis

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Dasymutilla occidentalis
Female
Male
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Mutillidae
Genus: Dasymutilla
Species:
D. occidentalis
Binomial name
Dasymutilla occidentalis
Synonyms[1]

Mutilla occidentalis Linnaeus, 1758

Dasymutilla occidentalis (red velvet ant, eastern velvet ant, cow ant or cow killer)[2][3][4] is a species of parasitoid wasp native to the eastern United States. It is commonly mistaken for a member of the true ant family, as the female is wingless. The species ranges from Connecticut to Kansas in the north and Florida to Texas in the south.

The eastern velvet ant is the largest of the velvet ant species in the eastern United States, attaining an approximate length of 0.75 in (1.9 cm). Adults display aposematic coloration, consisting of black overall coloring with an orange-red pattern on the dorsal surface of the thorax and abdomen. They are covered in dense, velvet-like hair.[3][4]

Characteristics and Description[edit]

Commonly mistaken for an ant, because of its appearance and its common name, it is a parasitoid wasp species in which the females are wingless, as is true for all females of Mutillidae. It can be recognized by its distinctive red coloring, with a black stripe that goes across the abdomen.[4] They are quick-moving and often take a defensive posture when threatened. Instead of creating nests, the females seek out the brood cells of Eastern cicada killers and horse guard wasps as well as other large ground-nesting members of Crabronidae, where they deposit an egg onto a host larva. The egg quickly hatches into a white, legless grub, which consumes the host and goes through several larval stages prior to pupation. Unlike the females, males have dark, translucent wings and do not possess a sting.[5][2][3] Males fly low over grass in search of mates. Both sexes make a squeaking noise (stridulation) to warn potential predators (another form of aposematism in females, and automimicry in males).[6]

Ecology[edit]

Dasymutilla occidentalis plays an ecological role as pollinators, parasites, and prey. Velvet ants may fall prey to insectivores like some toads and lizards, as well as some birds and small rodents.[7] The insect may evade predators' by previously stated defense mechanisms, as well as their aposematic coloration. In defense, they may sting, the female velvet ants have a stronger sting than the males. Velvet ants are not known to predate on other animals as their diet primarily consists of nectar as adults.[8] However, they do play a role as parasites, velvet ants will lay their eggs on larvae of other insects, once the egg hatches the velvet ant larvae will feed on the host larvae.[9]

Defense[edit]

The velvet ant has multiple defensive strategies, but is best known for its extremely painful sting, ranked 3 out of 4 on the Schmidt's sting pain index, earning it the nickname of "cow killer".[5][10] Its defenses include a thickened exoskeleton, the ability to run fast and evasively, warning coloration, stridulatory warning sounds, a chemical secretion, and venom.[6] When stridulating, velvet ants rub their abdominal segments together in a rapid fashion. This is different than stridulation seen in insects such as crickets, in which the leg structures are rubbed against the abdomen. [11]

D. occidentalis and related species are well known for their high levels of Mullerian mimicry. Mullerian mimicry occurs when species with pre-existing defenses adopt similar colorations and patterns to increase the fitness of both all species involved. North American velvet ant species comprise one of the most intricate Mullerian mimicry rings in the natural world, being divided into eight separate rings of mimicry.[11] These complex rings of Mullerian mimicry allow predators to quickly learn to avoid any prey that resembles a velvet ant. Velvet ants occupying southern Texas and northern Mexico possess a characteristic orange "fur" on their most dorsal abdominal segment. Of the 351 species of velvet ants in North America, only 15 species do not easily fit into a Mullerian mimicry ring. [11]

Reproduction[edit]

Unlike most wasp species, velvet ants live solitary lives. Male velvet ants take to the air to detect pheromones released by female velvet ants. Males will fly towards female stridulation sounds as well.[12] Once a receptive female is located, the male will carry the female in his mandibles and move her to place he deems "safe" to mate. These mating spaces are often shaded and away from potential mating competitors.[12] Both males and females stridulate during the mating process. Once the mating process is finished, the female begins looking for eggs and larvae of host species.[12]

The female will enter the ground nest of a host species, typically a wasp or bee species, and lay her eggs near the host's larvae. As D. occidentalis' larvae develop, the species' true parasitoid nature is shown. The larvae grow and develop by feeding on and killing the larvae of the host species. [10] Velvet ant larvae will continue to feed until they enter the pupal stage. In this stage, larvae continue to grow into adults. Pupation typically takes 23 days, and most velvet ants are mature and ready to reproduce themselves after this. [12] Velvet ants have an interesting mating style compared to other Hymenopteran species. The male has no parental care responsibilities and the female leaves as soon as she lays her eggs. This is not out of the ordinary for a Hymenopteran species, but velvet ants are though to be monogamous and semelparous. [12] This means females mate just once in their lifetime with only one male. Many entomological organizations suspect velvet ants to mate only once in their lifetime.[13]

Economic Importance[edit]

D. occidentalis poses no real positive or negative economic effects on humans. However, their behavior and coloring has been used to study how aposematic coloration works in the wild. Additionally, the species high levels of Mullerian mimicry are of great interest to evolutionary biologists.[14] The sting of this species is extremely painful, but is not lethal to humans. Pest control efforts could be inhibited by the life cycle of velvet ants. Since velvet ants parasitize the larvae of predatory species, prey species could grow to unsustainable numbers if velvet ants become too reproductively successful.[15] However, there is no record of this occurring.

Velvet ants are extremely successful at keeping yellow jackets and other Hymenopteran species at bay. Females search for the larva of ground nesting species to lay her eggs on. Once the host's larvae is killed, the velvet ants are fully developed. Velvet ants keep ant populations in check as well. Multiple studies have shown the alert pheromones released from the mandibles of velvet ants contain ketones that act as allomones.[16] These allomones are used to "control" ant species to perform actions that benefit the velvet ant. Velvet ant allomones are commonly used in research to better understand the use of allomones in other species.

Dasymutilla occidentalis have both negative and positive effects on humans and economics as a whole. Negatively, their is an injury to humans as the sting is painful. Positively, they are a topic of research. Their behaviors and adaptations are being studied. They also provide insight into parasitism and aposematic coloration.[12] The larvae of dasymutilla occidentalis are parasitic to bumblebees, bees are the worlds biggest source of pollination, this can be a concern if the parasitic velvet ant larvae take over a large portion of bees.[17] However, dasymutilla occidentalis are not aggressive and their venom is not very toxic, overall this species poses no real threat to humans, animals, or our world beside a harmful sting and larvae affecting bees.[18]

References[edit]

  1. ^ "Dasymutilla occidentalis (Linnaeus)". Global Biodiversity Information Facility. Retrieved 11 May 2023.
  2. ^ a b "Species Dasymutilla occidentalis". Bugguide. Iowa State University. Retrieved September 12, 2011.
  3. ^ a b c "Red Velvet Ant or "Cow Killer"". Texas AgriLife Extension Service: A Field Guide To Common Texas Insects. Texas A&M University. Archived from the original on September 2, 2011. Retrieved September 12, 2011.
  4. ^ a b c "Red velvet ant; cow killer". Arthropod Museum. University of Arkansas: Division of Agriculture. Archived from the original on May 26, 2012. Retrieved September 12, 2011.
  5. ^ a b Jackman, John. "Venomous Terrestrial Animals of Texas" (PDF). Texas A&M University System. {{cite journal}}: Cite journal requires |journal= (help)
  6. ^ a b Schmidt, Justin O.; Blum, Murray S. (1977). "Adaptations and responses of Dasymutilla occidentalis (Hymenoptera: Mutillidae) to predators". Entomologia Experimentalis et Applicata. 21 (2): 99–111. doi:10.1111/j.1570-7458.1977.tb02663.x. ISSN 1570-7458. S2CID 83847876.
  7. ^ Gall, B. G.; Spivey, K. L.; Chapman, T. L.; Delph, R. J.; Brodie Jr, E. D.; Wilson, J. S. (2018). "The indestructible insect: Velvet ants from across the United States avoid predation by representatives from all major tetrapod clades". Ecology and Evolution. 8 (11): 5852–5862. doi:10.1002/ece3.4123. PMC 6010712. PMID 29938098.
  8. ^ "Velvet Ants".
  9. ^ "Dasymutilla occidentalis, Eastern Velvet Ant (Hymenoptera: Mutillidae)". 28 March 2023.
  10. ^ a b "Velvet Ant (Cow Killer Ant) | Nebraska Extension in Lancaster County". lancaster.unl.edu. Retrieved 2023-09-27.
  11. ^ a b c "Velvet ants: flamboyant and fuzzy with extreme PPE". www.nhm.ac.uk. Retrieved 2024-02-21.
  12. ^ a b c d e f Smith, Caleb. "Dasymutilla occidentalis". Animal Diversity Web. Retrieved 2024-02-21.
  13. ^ Deyrup, Mark (2017-11-13). "Review of Adaptations of Velvet Ants (Hymenoptera: Mutillidae)". The Great Lakes Entomologist. 21 (1). doi:10.22543/0090-0222.1623. ISSN 0090-0222.
  14. ^ Wilson, Joseph S.; Williams, Kevin A.; Pitts, James P. (2010). "Preliminary Assessment of Velvet Ant (hymenoptera: Mutillidae) Diversity in the Deserts of Southern California". Western North American Naturalist. 70 (2): 224–232. doi:10.3398/064.070.0209. ISSN 1527-0904. JSTOR 41717897.
  15. ^ "Velvet Ant". entomology.ces.ncsu.edu. Retrieved 2024-03-20.
  16. ^ Fales, H. M.; Jaouni, T. M.; Schmidt, J. O.; Blum, M. S. (1980-09-01). "Mandibular gland allomones ofDasymutilla occidentalis and other mutillid wasps". Journal of Chemical Ecology. 6 (5): 895–903. doi:10.1007/BF00990473. ISSN 1573-1561.
  17. ^ "Red Velvet Ant or "Cow Killer"". texasinsects.tamu.edu. Retrieved 2024-04-17.
  18. ^ "Mutillidae - velvet ants". entnemdept.ufl.edu. Retrieved 2024-04-17.

External links[edit]

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