Schmidt Sting Pain Index

The Schmidt sting pain index is a pain scale rating the relative pain caused by different hymenopteran stings. It is mainly the work of Justin O. Schmidt, who was an entomologist at the Carl Hayden Bee Research Center in Arizona.

Schmidt's original 1983 paper was a way to systematize and compare the hemolytic properties of insect venoms. A table in the paper included a column that rated sting pain, starting from 0 for stings that are completely ineffective against humans, progressing through 2 for familiar pains such as those caused by common bee or wasp stings, and finishing at 4 for the most painful stings. Only the bullet ant, ''Paraponera clavata'', was given a rating of 4, although later versions of the index added two more species.

Schmidt repeatedly refined his scale, including a paper published in 1990, which classifies the stings of 78 species and 41 genera of Hymenoptera, and culminating in a book published in 2016.

Motivation

The Schmidt sting pain index arose from the pursuit of a larger hypothesis: that the evolution of sociality in Hymenoptera was dependent on the evolution of venom that was both painful and toxic.

Pain is a signal of damage in the body, but molecules that produce pain are not the same as toxic molecules, which actually cause damage. Although the painful signal acts as a deterrent, intelligent predators learn the dishonesty of this signal with repeated exposure.

For the early Hymenoptera that were primarily solitary, the pain alone would allow them the chance to escape. Moreover, solitary insects do not provide a high energy reward for predators, and therefore predators do not expend significant effort to hunt them.

However, colonies of Hymenoptera are a nutritionally rich target. If there were no defenses, predators would devour the defenseless society, leaving few surviving individuals. Therefore it was theorized that the development of toxicity in Hymenoptera facilitated the development of sociality, which brings various benefits, including the shared raising of youth, individual task specialization, inter-colony communication, and food storage.

Assays for toxicity were already well characterized, so the evolutionary connection between toxicity and sociality could be studied. Schmidt developed his pain index to relate the amount of sociality to the level of pain.

Scale

Schmidt's pain scale of Hymenopteran stings is organized into levels, ranging between 1 and 4, with 4 being the most painful. However, insect stings that feel very different can be put into the same level. Thus, later versions of the scale always include a brief description of his experience being stung by each type of insect.

Level 1

Some of the insect stings Schmidt considered to be at a pain level of 1 include the Southern fire ant, the graceful twig ant, the Western paper wasp, the urban digger bee, and most small bees. The duration of the pain of insect stings categorized into Pain Level 1 generally is five minutes or less.

Many small bees are categorized into a pain level of 1, with their venom containing polypeptides such as melittin, apamin, and MCD peptide. Melittin is the main toxin of bee venom, and it damages red blood cells and white blood cells. Apamin is a neurotoxin that augments polysynaptic reflexes. MCD peptide destroys mast cells.

Feeling only slight pain, Schmidt described the sting of an urban digger bee, categorized into pain level 1, as "almost pleasant, a lover just bit your earlobe a little too hard." Also rated into pain level 1, Schmidt has described the sting of a sweat bee as "light, ephemeral, almost fruity. A tiny spark has singed a single hair on your arm."

Level 2

Schmidt set the sting of the Western honey bee at a pain level of 2 to be the anchoring value, basing his categorization of all other stings on it. He has categorized a variety of wasps, bees, and ants into pain level 2, including yellowjackets, the Asiatic honey bee, the trap-jaw ant, and the bald-faced hornet. The duration of the pain of the stings in this level is generally between five and ten minutes long. Schmidt categorized the majority of Hymenopteran stings as having a pain level of 2.

The sting of a termite-raiding ant, categorized as a pain level of 2, has a similar feeling as "the debilitating pain of a migraine contained in the tip of your finger," according to Schmidt. On the contrary, a yellowjacket's sting was described as being "hot and smoky, almost irreverent. Imagine W. C. Fields extinguishing a cigar on your tongue." He also described the sting of the honeybee as a similar feeling to “The oven mitt had a hole in it when you pulled the cookies out of the oven.”

Level 3

Most insects that are characterized as having a pain level of 3 are wasps, including the neotropical red paper wasp, the red-headed paper wasp, and Klug's velvet ant (a wingless wasp and not a true ant). The duration of the sting pain can range anywhere from one minute (such as the sting of the red paper wasp) to half an hour (such as the sting of the velvet ant). Wasp venom uniquely contains kinin. One of the kinins found in wasp venom, "polistes kinin 3", is found to lead to similar effects on smooth musculature and circulation as bradykinin.

Some ants are also rated at a pain level 3, including the giant bull ant and the Maricopa harvester ant. Schmidt considered the sting of the Maricopa harvester ant as having a pain level of 3, describing it as such: "After eight unrelenting hours of drilling into that ingrown toenail, you find the drill wedged into the toe."

Level 4

Pain level 4 is the highest level in the Schmidt sting pain index. Schmidt's original index rated only one such example, the sting of the bullet ant ''Paraponera clavata'', as a 4. He wrote, "''Paraponera clavata'' stings induced immediate, excruciating pain and numbness to pencil-point pressure, as well as trembling in the form of a totally uncontrollable urge to shake the affected part." In a later work, he described the sting as "pure, intense, brilliant pain...like walking over flaming charcoal with a three-inch nail embedded in your heel." The bullet ant's venom primarily contains poneratoxin, a paralyzing neurotoxic peptide.

Schmidt later gave the sting of a tarantula hawk species, '' Pepsis grossa'', a rating of a 4, which he described as "blinding, fierce ndshockingly electric", though the duration of pain from the sting is short-lived, lasting only approximately five minutes. The composition of tarantula hawk venom is unknown.

Schmidt also later rated the sting of '' Synoeca septentrionalis'' as a 4, describing it as "Torture. You are chained in the flow of an active volcano. Why did I start this list?", saying the pain lasts up to two hours.

Legacy

While Schmidt's published scientific papers use a 1 through 4 number scale, an entry in ''The Straight Dope'' reported that "implausibly exact numbers" such as "bullhorn acacia ant at 1.8" were "wheedled out of him" by ''Outside'' magazine for an article it published in 1996.

In September 2015, Schmidt and Michael L. Smith were co-awarded the Ig Nobel Physiology and Entomology prize for their Hymenoptera research.

The Starr sting pain scale is based on the Schmidt index.

See also

* Dol scale to measure pain
* '' Kings of Pain'', a TV series with another pain index

Notes

References

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Further reading

* Berenbaum, May
"A Stinging Commentary"
in '' American Entomologist'', (Summer 2003).
* Conniff, Richard. "The King of Sting", in '' Outside,'' v. 21 n. 4 (April 1996), pp. 82–84, 147.
* Conniff, Richard.
Stung: How tiny little insects get us to do exactly as they wish
, '' Discover'', June 2003.

External links

The Chemical Compositions of Insect Venoms
- Includes the graphic below

A Partial Schmidt Insect Sting Pain Index

Insect bites and stings
Pain scales
1983 introductions