Tag Archives: ants

The warmer the dangerouser, at least if you are a caterpillar

by Piter Kehoma Boll

Scientist all over the world agree that species diversity is higher at the tropics than at polar regions, i.e., the closer you get to the equator, more species you will find. But apart from making food webs more entangled, does it increase the overall number of interactions that species experience? Afterall, despite the increase in species richness, the population size usually decreases. For example, while there are hundreds of different tree species in the Amazon forest, the number of individuals of each species is much lower than the number of individuals of a species in a temperate forest in Europe.

In order to test whether an increase in species richness would also mean an increase in biotic interactions, a group of ecologists all over the world engaged in a worldwide experiment using nothing else but small fake caterpillars made of plasticine. The small models were placed in different areas from the polar regions to the equatorial regions and the number of attacks that they suffered were counted and grouped according to the type of predator, which was usually identifiable based on the marks left on the models.

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A fake caterpillar in Tai Po Kau, Hong Kong. Photo by Chung Yun Tak, extracted from ScienceDaily.

The results indicate that there is indeed an increase in predation rates towards the equator, as well as towards the sea level. Areas close to the poles or at high elevations have a smaller number of interactions. But even more interesting was the revelation that this change is really driven by small predators, especially arthropods such as ants. The rate of attacks by birds and mammals was fairly constant across the globe.

Such an evidence on the importance of arthropod predators at the tropics may make us reevaluate our ideas on the evolution of species in such places, as the main concern for small herbivores such as caterpillars in tropical forests may not be birds, but ants. And this means a completely different way to evolve defense strategies.

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ResearchBlogging.orgReference:

Roslin, T., Hardwick, B., Novotny, V., Petry, W., Andrew, N., Asmus, A., Barrio, I., Basset, Y., Boesing, A., Bonebrake, T., Cameron, E., Dáttilo, W., Donoso, D., Drozd, P., Gray, C., Hik, D., Hill, S., Hopkins, T., Huang, S., Koane, B., Laird-Hopkins, B., Laukkanen, L., Lewis, O., Milne, S., Mwesige, I., Nakamura, A., Nell, C., Nichols, E., Prokurat, A., Sam, K., Schmidt, N., Slade, A., Slade, V., Suchanková, A., Teder, T., van Nouhuys, S., Vandvik, V., Weissflog, A., Zhukovich, V., & Slade, E. (2017). Higher predation risk for insect prey at low latitudes and elevations Science, 356 (6339), 742-744 DOI: 10.1126/science.aaj1631

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New Species: September 11 to 20

by Piter Kehoma Boll

Here is a list of species described from September 11 to September 20. It certainly does not include all described species. Most information comes from the journals Mycokeys, Phytokeys, Zookeys, Phytotaxa, Zootaxa, International Journal of Systematic and Evolutionary Microbiology, and Systematic and Applied Microbiology, as well as journals restricted to certain taxa.

petrolisthes-paulayi

Petrolisthes paulayi is a new crab described in the past 10 days.

SARs

Plants

Amoebozoans

Fungi

Sponges

Cnidaria

Flatworms

Annelids

Nematodes

Arachnids

Myriapods

Crustaceans

Hexapods

Cartilaginous fishes

Ray-finned fishes

Lissamphibians

Reptiles

Mammals

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Filed under Systematics, taxonomy

Friday Fellow: Bullet ant

by Piter Kehoma Boll

The rainforests of Central and South America host this small but scary creature, the bullet ant Paraponera clavata. Feared by people living where it is found, the bullet ant is one of the most venomous ants in the world. The name “bullet ant” is a reference to the pain caused by being shot, which is said to be the closest analogy to the pain of a bullet ant sting. In Portuguese it is known as tocandira, a word derived from Tupi, meaning “hurting very much”. In Spanish it is sometimes called “hormiga 24 horas” because the pain is said to last a whole day.

A bullet ant worker. Photo by Geoff Gallice.*

A bullet ant worker. Photo by Geoff Gallice.*

The bullet ant is found in the Neotropical Ecozone from Honduras and Nicaragua to Paraguay. Their nests are built at the base of the trees, under the ground, and workers look for food mostly on the tree trunk and canopy directly above the nest and on nearby trees, sometimes exploring the forest floor. They are predatory ants, feeding mainly on arthropods, but also consuming nectar.

Considered a primitive ant, the bullet ant lacks polymorphism among the worker caste, i.e., all workers have the same general appearance. The queen is also not very different from the workers.

The horrible sting inflicted by these ants is used as a form of defence.  It contains a neurotoxin known as poneratoxin that causes paralysis by blocking synaptic transmission. It is effective against at least vertebrates and arthropods. Nevertheless, the Sateré-Mawé people from Brazil use the ants’ stings in a sadic ritual to become a “warrior”. For this purpose, a poor boy has to put his hand inside a glove filled with bullet ants and let it there for 10 minutes. As a result the boy’s arm becomes paralyzed for days and he may shake incontrollably due to the venom’s effect. And he has to repeat this ritual 20 times!

I can only think that humans… oh, never mind.

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References:

Piek, T.; Duval, A.; Hue, B.; Karst, H.; Lapied, B.; Mantel, P.; Nakajima, T.; Pelhate, M.; Schmidt, J. O. 1991. Poneratoxin, a novel peptide neurotoxin from the venom of the ant, Paraponera clavata. Comparative Biochemistry and Physiology Part C: Comparative Pharmacology, 99 (3): 487–495.

Wikipedia. Paraponera clavata. Availabe at: < https://en.wikipedia.org/wiki/Paraponera_clavata >. Access on May 25, 2016.

Young, A. M.; Herrmann, H. R. 1980. Notes on foraging of the Giant Tropical Ant Paraponera clavata (Hymenoptera: Formicidae: Ponerinae). Journal of the Kansas Entomological Society, 53 (1): 35–55.

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*Creative Commons License
This image is licensed under a Creative Commons Attribution 2.0 Generic License.

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Filed under Entomology, Friday Fellow