Mutillidae
Mutillidae | |
---|---|
Dasymutilla sp. | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Arthropoda |
Class: | Insecta |
Order: | Hymenoptera |
Superfamily: | Pompiloidea |
Family: | Mutillidae Latreille, 1802 |
Subfamilies | |
Mutillinae |
The Mutillidae are a
Distribution
Mutillidae can be found worldwide with about 230 genera or subgenera and around 8,000 species worldwide. Over 400 species occur in the North American Southwest.[5]
North American Mutillidae have eight phenotypically distinct and geographically limited Müllerian mimicry rings (Desert, Eastern, Madrean, Texan, Red-headed Timulla, Black-headed Timulla, Tropical, and Western) making up one of the largest Müllerian mimicry complexes on the planet.[6] These mimicry rings are the result of repeated convergent evolution of aposematic traits between co-occurring velvet ant species, rather than shared phylogenetic history.[7] Through the evolution of aposematic traits in velvet ant species in the same ring, local predators have learned to avoid these well-defended wasps.
Description
The exoskeleton of all velvet ants is unusually tough (to the point that some entomologists have reported difficulty piercing them with steel pins when attempting to mount them for display in cabinets).[citation needed] This characteristic allows them to successfully invade the nests of their prey and also helps them retain moisture. Mutillids exhibit extreme sexual dimorphism. As in some related families in the Vespoidea, males have wings, but females are wingless. The males and females are so distinct in their morphology that entomologists often find it very hard to determine whether a given male and female belong to the same species, unless they are captured while mating.[8] In some species, the male carries the smaller female aloft while mating, which is also seen in the related family Thynnidae.
As is the case for all
Behavior
Adult mutillids feed on
Defense mechanisms
Predation is one of the strongest forces natural selection uses to drive the evolution of an organism's morphology, physiology, and behavior.
The venom that velvet ants inject through their stinger has an unknown composition. According to one researcher, the painfulness of the sting of Dasymutilla klugii outscored 58 other species of stinging insects tested; the only species this researcher rated as having a more painful sting were the Paraponera clavata (bullet ant), Synoeca septentrionalis (warrior wasp), and Pepsis spp. and Hemipepsis spp. (tarantula hawks).[13] In an experimental setting, only two lizard species (one whiptail and one side-blotched lizard) attacked a velvet ant it was exposed to.[12] In both cases the velvet ants were exhibiting rapid lateral and vertical movements to ward off an attack. Once the attack occurred the velvet ants would immediately sting the lizards. This sting resulted in the dropping of the ants in both cases and avoidance for the remainder of the trial.[14] The side-blotched lizard was found dead in its tank 24 hours later.[12] The side-blotched lizard is a natural predator of velvet ants, while the whiptail is not.[12]
The aposematic coloration of velvet ants often corresponds to a specific Müllerian mimicry ring consisting of dozens of species. This offers protection because many local predators have learned to avoid prey with this same coloration.[6] To test the aposematic coloration on birds, mealworms were painted to resemble a velvet ant. During these trials, none of the painted mealworms were consumed, while all the control mealworms were consumed immediately.[12] However, the painted mealworms were attacked by the birds, but the birds immediately ceased the attack.[12] These experiments provide evidence that the aposematic coloration of velvet ants causes their predators to hesitate, acting as a visual defense mechanism.
The stridulatory organ that velvet ants possess produces an audible squeaking when the abdomen is contracted.[15] This mechanism is an auditory cue warning predators that are about to attack to stay away. In one experiment, every time a shrew got within 1 meter of a velvet ant, the velvet ant would begin stridulating.[14] Stridulations became more frequent as the predator moved closer to the velvet ant, and the shrew never attempted to attack the velvet ant. However, different scenarios with shrews have shown that the velvet ant would also stridulate after the shrew attacked it. Every time this occurred the shrew dropped the wasp.[14]
The exoskeleton of the velvet ant is remarkably strong. It required 11 times more force to crush than that of the honeybee.[15] As well as being durable, the exoskeleton is also round, making it more difficult for predators to pierce it with attempted stings or bites. During all the trials that led to the fracture of a velvet ant's exoskeleton, a total of 4 times resulted in the death of that velvet ant within 24 hours. Aside from protection from predators, the exoskeleton also helps control moisture.[15]
Due to these strong defense mechanisms, local predators generally avoid the velvet ants, so it has been difficult to determine their predators.[12] One study found tropical and subtropical iguanian lizards (Dactyloidae) to be a local predator of velvet ants in the Black-headed Timulla and Tropical mimicry rings.[16]
Life cycle
Male mutillids fly in search of females; after mating, the female enters a host insect nest, typically a ground-nesting bee or wasp burrow, and deposits one egg near each
Taxonomy
Recent classifications of Vespoidea sensu lato (beginning in 2008) concluded that the family Mutillidae contained one subfamily that was unrelated to the remainder, and this subfamily was removed to form a separate family Myrmosidae.[18][19]
See also
References
- ISBN 978-0-88706-896-6.
- ^ "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.
- ^ Meyer, W.L. (1996). "Most Toxic Insect Venom". Book of Insect Records. University of Florida.
- S2CID 205781311.
- ^ "Mutillidae — velvet ants". Featured Creatures. University of Florida/IFAS.
- ^ PMID 26294178.
- PMID 23232402.
- OCLC 28024976.
- doi:10.1139/z90-092.
- ISBN 978-5-8044-0280-9.
- OCLC 889162931.
- ^ PMID 29938098.
- .
- ^ PMID 29938098.
- ^ S2CID 83847876.
- ISSN 0024-4066.
- ^ Brothers, Denis J., "Phylogeny and classification of the aculeate Hymenoptera, with special reference to Mutillidae" (1975) University of Kansas Science Bulletin 50(11):483-648.
- S2CID 85905070.
- PMID 24094856.
- .
Sources
- Brodie, E.D. Jr. (1968). "Investigations on the skin toxin of the adult rough-skinned newt, Taricha granulosa". Copeia. 1968 (2): 307–313. JSTOR 1441757.
- Brodie, E.D. Jr.; Formanowicz, D.R. Jr.; Brodie, E.D. III (1991). "Predator avoidance and antipredator mechanisms: Distinct pathways to survival". Ethology Ecology & Evolution. 3 (1): 73–77. .
- Endler, J.A. (1986). Natural selection in the wild. Princeton University Press.
- Mickel, C.E. (1928). "Biological and taxonomic investigations on the mutillid wasps". United States National Museum Bulletin. 143 (143): 1–351. .
- Milne, Lorus J. (1980). National Audubon Society Field Guide to North American Insects and Spiders. Audubon Society Field Guide (Turtleback). Knopf. ISBN 978-0-394-50763-7.
External links
- Media related to Mutillidae at Wikimedia Commons
- Cow Killer at the University of Nebraska-Lincoln Extension in Lancaster County, Nebraska
- Mutillidae at the University of Florida Institute of Food and Agricultural Sciences
- Red Velvet Ant or "Cow Killer", Texas A&M Field Guide to Common Texas Insects