19 June, 2012

Density, spatial distribution and biomass of Hoffmannihadrurus gertschi

Ana Quijano-Ravell and co-workers have recently published an article on the density, spatial distribution and biomass of Hoffmannihadrurus gertschi (Soleglad, 1976) (Caraboctonidae)* in an area in Mexico.

The paper is written in Spanish so I have only read the English abstract.

[*The authors have placed this species in Hadrurus, but it was transfered to Hoffmannihadrurus by Fet & Soleglad i 2008 and this species is listed as Hoffmannihadrurus gertschi (Soleglad, 1976) in The Scorpion Files. Some scientists disagree on the validity of Hoffmannihadurus, as this paper is an example of. Also, some scientists choose to put Hadrurus in Iuridae and reject the validity of Caraboctonidae. See details here.]

Density, spatial dispersion and biomass of Hadrurus gertschi Soleglad 1976 were estimated from field data obtained during a year of observations at “La Coronilla” hill in the municipality of Tepecoacuilco de Trujano, Guerrero, Mexico. Five quadrants of 400 m2 with differing slope exposures were used. The highest density was recorded in the quadrant without slope or “flat quadrant” with 0.3450 burrows per m2 and the southern exposure quadrant (0.2300 burrows per m2). The lowest densities occurred in the quadrants with northern and western exposures (0.1325 and 0.0825 burrows per m2 respectively). The highest values of the year were recorded in the months of May to July. The spatial dispersion of burrows in all exposures studied corresponds with a clumped distribution according to the Morisita Index. Average dry weight of adults was 2.22 ± 0.73 g and 6.4 ± 0.89 g in fresh weight. The juveniles weighted 0.08 ± 0.05 g in dry weight and 0.2 of fresh weight instar II and 1.10 ± 0.41 g dry weight and 3.63 ±1.95 g in fresh weight in the preadult stage. The biomass per ha was estimated in 2471.26 g of dry weight and 6190.02 g of fresh weight.

Quijano-Ravell AF, Ponce-Saavedra J, Francke OF. Densidad, distribucion espacial y biomasa de Hadrurus gertschi Soleglad (Scorpiones, Iuridae) en una localidad de Guerro, Mexico. Revista Iberica de Arachnologia. 2012;20:35-43.

Thanks to Dr. Francke for sending me this paper!

Family Caraboctonidae

18 June, 2012

Tityus pachyurus sting in Colombia - a case report

The genus Tityus C. L. Koch, 1836 is the most medical genus in South America and several species are known to cause death and serious morbidity, especially in children. In Colombia, Tityus pachyurus Pocock, 1897 is known to cause life threatening symptoms in children. This species pose a special threat because its normal habitat is inside and outside homes in some areas. 

Ledys Izquierdo & Javier Buitrago have recently published a paper presenting a case where a 12 year old boy was stung during sleep in his home. The boy developed serious symptoms, but survived after medical treatment.

The scorpion envenomation is considered the second event by poisonous animals in importance around the world according to the World Health Organization. In Colombia there are 35 species of clinical significance, among them, the genus Tityus, which contains the most deadly scorpions in South America and is represented by 29 species of wide distribution in Colombia, which include Tityus pachyurus causing life-threatening events, especially in children. The present work shows the case of a 12 years old boy, from Tolemaida to 2 h of Bogotá D.C., who was stung by a scorpion on his right thigh, with the onset of intense signs and symptoms of local effect rapidly progressing to severe systemic involvement causing myocardial dysfunction, cardiovascular collapse and heart arrest, and his favorable response to adequate basic and advanced life support and use of scorpionspecific F(ab0)2 antivenom.

Izquierdo LM, Rodriguez Buitrago JR. Cardiovascular dysfunction and pulmonary edema secondary to severe envenoming by Tityus pachyurus sting. Case report. Toxicon. 2012. Epub 2012/06/12. [Subscription required for full text]

06 June, 2012

Burrows and burrowing in Hadrurus arizonensis

Daniel Hembree and co-workers have recently published a paper describing the forms and shapes of Hadrurus arizonensis Ewing, 1928 (Caraboctonidae) burrows. The authors are geologists (and/or palaentologists), and the angle and terminology of this papers is somewhat different from what I'm used to from the traditional scorpion literature. I must admit there are quite a few terms in the paper that unknown to me (but praise Google for being a helpful friend ;)

The goal of the paper is both to learn more about scorpion burrows, but also to aid in the recognition of scorpion burrows in the fossil record and to determine if aspects of palaeoenvironment can be ascertained by variations in scorpion burrow morphology.

The paper also has a nice mini-review of scorpion burrowing behavior and several pictures of burrow castings showing the form and shape of Hadrurus burrows.

Bioturbation by terrestrial animals is common in arid and semi-arid continental environments. Scorpions have comprised a significant portion of the diversity of predatory arthropods in these environments from the Late Paleozoic to the Recent. Many scorpions are active burrowers and likely have a substantial, if rarely recognized, ichnofossil record. This project involved the study of the burrowing behaviors and trace morphologies of the scorpion Hadrurus arizonensis (Scorpiones: Caraboctonidae). Individual animals were placed into sediment-filled terrariums for two- to three-week periods after which burrows were cast, excavated, and described. Descriptions of the subsurface structures included architecture, dimensions, bioglyphs, complexity, and tortuosity. Additional experiments were run with differing sediment composition, density, and moisture to evaluate the animal’s behavioral response to altering environmental conditions. Specimens of H. arizonensis burrowed by scratching and kicking loose sediment from the subsurface with the first two to three pairs of walking legs. The subsurface biogenic structures produced consisted of subvertical ramps, U-shaped burrows, helical burrows, and mazeworks. In the process of excavating the burrows, the desert scorpions also produced a hummocky surface topography as well as structures in dry, sandy sediment that resembled lamination and ripple cross-lamination. Increasing clay content and sediment density increased the complexity of burrow architectures produced. Reducing these variables limited the complexity of the burrows, reduced their likelihood of preservation, and increased the abundance of biogenic cross-lamination. Data collected from these and similar experimental studies can be applied to terrestrial ichnofossil assemblages in order to better interpret the paleoecology of ancient soil ecosystems.

Hembree DI, Johnson LM, Tenwalde RW. Neoichnology of the desert scorpion Hadrurus arizonensis: burrows to biogenic cross lamination. Palaeontologia Electronica. 2012;15(1):1-34. [ Free full text]

Thanks to Jahn Hornung for informing me about this paper!

05 June, 2012

Clinical course of Centruroides sculpturatus envenomations managed without antivenom

In 2004, most supplies of the antivenom used to treat serious cases of Centruroides sculpturatus sting in the southwestern USA was exhausted, and supportive care and interventions became the only option available. Ayrn O'Connor and Anne-Michelle Ruha have now published a study showing the clinical course of Bark scorpion envenomations managed without antivenom.

The results show that treatment without antivenom are effective without antivenom, but 24 % of 88 patients (mainly children between 2 and 9 years) experienced respiratory failure and needed intubation. No mortality occurred, but this study show that C. sculpturatus is a dangerous scorpion for young children (and not only infants and toddlers).

In August 2011, a new antivenom for Centruroides was approved by FDA after studies showing it being effective in the treatment for serious cases. Unfortunately, this treatment is very expensive, and may force doctors and/or patients to limit the use. O'Connor & Ruha therefor highlight the importance of supportive treatment of severe scorpions stings.

Bark scorpion envenomation is potentially life threatening in children and traditionally treated with antivenom (AV). We sought to describe the clinical course, management, complications and outcome of children with severe scorpion envenomation treated with supportive care during a period when AV was unavailable. A retrospective chart review was performed, all children presenting to a referral hospital between September 1, 2004 and July 31, 2006 with severe scorpion envenomation not receiving AV, were included. A standardized data abstraction form was used to record time of symptom onset, time to healthcare facility (HCF), clinical findings, treatment, complications, and length of stay. Eighty-eight patients were included with mean age of 3.7 years (0.33–12). Mean time to symptom onset was 20 min (0–130) and mean time to HCF was 79 min (10–240). Incidence of clinical manifestations include: neuromuscular agitation, 100 %; opsoclonus, 97 %; hypersalivation, 81 %; tachycardia, 82 %; hypertension, 49 %; vomiting, 38 %; fever, 28 %; respiratory distress, 33 %; and hypoxia, 18 %. Complications included rhabdomyolysis in 18 (20 %) and aspiration in 12 (13 %) patients. Intubation was required in 24 % of patients. The most frequently used agents to control symptoms were benzodiazepines (98 %) followed by opioids (69 %). Intravenous fluids were given to 84 %. Mean length of stay was 29 h (range, 6–73 h). There were no deaths. In addition to the classic findings of neuromuscular hyperactivity, opsoclonus, and hypersalivation, a high incidence of hyperadrenergic findings and respiratory compromise are noted in this series. A significant number of patients required mechanical ventilation. Benzodiazpines and opioids were the most common medications used to control symptoms.

O'Connor A, Ruha AM. Clinical Course of Bark Scorpion Envenomation Managed Without Antivenom. Journal of Medical Toxicology. 2012. Epub 2012/05/09. [Subscription required for full text]