How to kill the most dangerous scorpion in Brazil

 As I discussed last time, the Brazilian Yellow Scorpion (BYS) has an incredibly powerful sting, fatal to humans in hours. And it’s numbers are increasing in cities in Brazil, for various reasons, but mainly because it feeds on cockroaches and flies, more rubbish means more food, so more scorpions. And also the absence of natural enemies (see below).

So how do you control it? Well they are quite small, but I strongly warn against treading on one! Insecticides can work, Bifentol for example can kill them, but BSYs can survive for up to 400 days without food, as long as they stay wet, and it’s hard to spray everywhere. When they do reproduce, which they can do at any time in the year, they are quite fertile.

Surprisingly, there are natural enemies. Hens will voraciously feed on BYS’s though they are well aware of the sting, and apparently survive. They even prefer them to corn (“hmm, spicy”). In 1922 the mayor of Aparecida in Brazil distributed chickens as a way of attempting to control a scorpion outbreak.

But the true Nemesis of the Brazilian Yellow Scorpion is a toad, Rhinella icterica. Quite a common toad in southern Brazil, living in forests and Cerrado savanna, in the wild R. icterica tends to live in the same environments as BYSs, and both are active at night. They appear to be more or less immune to the scorpion sting and will happily hunt and kill scorpions. 

Photo conveniently showing the different coloration of male and female Rhinella icterica. Wikimedia Commons - Caio Biasoli

None of this however helps in the city. At a domestic level advice is remove any food sources which might attract cockroaches and seal any cracks in walls, especially in damp areas. Put down insecticides or sticky traps. And, anecdotally, tip out shoes before you put them on - and run a shower for a few minutes before entering, scorpions like damp, dark places and are quite capable of crawling up the drains!
 

Jared C, Alexandre C, Mailho-Fontana PL, Pimenta DC, Brodie ED Jr, Antoniazzi MM. (2020). Toads prey upon scorpions and are resistant to their venom: A biological and ecological approach to scorpionism. Toxicon., 178:4-7.

Murayama GP, Pagoti GF, Guadanucci JPL, Willemart RH. (2020). Voracity, reaction to stings, and survival of domestic hens when feeding on the yellow scorpion (Tityus serrulatus). J Venom Anim Toxins Incl Trop Dis., 28:e20210050

Murayama GP, Barbosa B, Willemart RH (2023). Experimental approach to the dislodging effect and the mortality of a pesticide in the yellow scorpion Tityus serrulatus. PLoS ONE 18(7): e0289104.

The Most Dangerous Scorpion in Brazil

 So imagine you are in the Brazilian holiday resort of Buzios, lazing on the beach or sipping a caipirinha, and a yellow scorpion appears. Not only that, it is the MOST DANGEROUS SCORPION IN BRAZIL!

Wikimedia Commons, Fernanda Moreira

It’s Tityus serrulatus, the Brazilian Yellow Scorpion ("escorpião-amarelo") (who makes up these names?). Anyway, they are quite small, 5-7cm, but manage to cause the highest number of poisonings from animal bites in Brazil, facing some strong competition! A cocktail of toxins cause a whole raft of symptoms and can kill you in an hour. The Instituto Vital Brazil has reportedly captured 200 of these little monsters in Buzios, and taken them to the institute for anti-venom research.

This scorpion loves to feed on flies and cockroaches, and so is drawn to the same refuse that they are. An absence of natural enemies in cities (not surprisingly) makes them well adapted to urban life, and their numbers are increasing. Make sure you clean up your rubbish!

https://revistaforum.com.br/brasil/2024/2/21/paraiso-turistico-brasileiro-invadido-por-escorpies-venenosos-154375.html

Pimenta RJG, Brandão-Dias PFP, Leal HG, Carmo AOD, Oliveira-Mendes BBR, Chávez-Olórtegui C, Kalapothakis E. (2019). Selected to survive and kill: Tityus serrulatus, the Brazilian yellow scorpion. PLoS One, 14(4),e0214075.

Looking in, looking out

 A treehopper (Membracis sp.) on the window pane. 

Chrysanthemum world

 Chrysanthemums (Chrysanthemum sp.) are native to east Asia, but have been cultivated in China for millennia, apparently since the 15th century BC, or even earlier. Later they became very popular in Japan, and the monarchy there is known still as the Chrysanthemum Throne.

Although most chrysanthemums are grown for their beauty, some species can be drunk as a tea, or boiled and eaten in dishes such as Chinese hotpot. Conversely, the seed pots of some species have been used for centuries to make permethrin, an effective insecticide and the ancestor of modern synthetic pyrethroids.  

So why am I talking about chrysanthemum's in a blog about Brazilian nature? Because they are part of it, being grown mainly in the state of Sao Paulo. Especially around Holambra, where Dutch immigrants established a flourishing horticultural industry and today there is an important flower auction system, the Veiling Holambra. The ornamental flower industry has grown rapidly in Brazil, with Ibraflor (the Brazilian Institute of Floriculture) reporting in 2021 an annual average growth rate of 10-12 per cent over the previous 10 years. Roses are the most popular, followed by chrysanthemums, alstroemerias, lilies and lisianthus, and orchids. 97% of domestic demand for chrysanthemums is supplied by domestic production (Gobatto et al 2019).

A survey of virus infections in chrysanthemum greenhouses and the weeds present in and around those greenhouses gives a snapshot of an ecosystem in Sao Paulo (and Colombia, but I'll just talk about Brazil) (Gobatto et al 2019).

 The chrysanthemums are grown in greenhouses, but they can interact with the environment outside. A survey of weeds in and around greenhouses in Sao Paulo found 51 different species, which were consequently tested for the commercially important RNA viroid, Chrysanthemum stunt disease (CSVd). The only one found to have a natural infection was Oxalis latifolia (in Brazil "trevo"), which not only contained virus particles but also showed symptoms. Originally from Central America, O. latifolia is a very common weed, and in fact has been introduced around the world as a garden flower, and even, in India, as rabbit food.

Oxalis latifolia (Wikimedia Commons)

 Of the other species of weeds tested, 17 were found to be possible hosts of CSVd. ie. they didn't have virus infections, but could be infected in lab conditions. The most widespread in and around greenhouses was Cardamine bonariensis ("griãozinho") a kind of cress. C. bonariensis seems to have originated in Europe, probably entering Brazil with imported plants. Although no natural infections were found, or have been reported, evidence that it can support CSVd is worrying.

 And of course there are insects. The most important pests of chrysanthemums in Brazil are aphids and thrips (Bueno et al, 2003). One of the commonest thrips is Frankliniella occidentalis, a very polyphagous species that has spread from the southern USA around the world, and can feed on practically everything (well, at least 500 species). F. occidentalis has been shown to transmit another chrysanthemum virus Chrysanthemum stem necrosis virus (Goretti & Lima 2019).

Frankliniella occidentalis (author's collection)

So there we have it. An ecosystem, a world, of mainly expats in the same place and time. An artificial ecosystem for sure, but how many ecosystems are completely "natural" these days?

 Bueno, V.H.P.; Lenteren, J.C. van; Silveira, L.C.P.; Rodrigues, S.M.M. (2003). An overview of biological control in greenhouse chrysanthemums in Brazil. Bulletin OILB/SROP 26(10), 1-5.

 Gobatto, D., de Oliveira, L.A., de Siqueira Franco, D.A., Velásquez, N., Daròs, J.A., Eiras, M. (2019). Surveys in the chrysanthemum production areas of Brazil and Colombia reveal that weeds are potential reservoirs of Chrysanthemum Stunt Viroid. Viruses. 2019 Apr 17;11(4):355.

 Goretti, Maria & Lima, Élison (2019). Tripes - ornamentais. Pragas e doenças associados aos cultivos na Serra de Baturité, CE (pp.123-130). Publisher: Liceu.