Natural occurrence of the Fusarium solani on Tityus stigmurus ( Thorell , 1876 ) ( Scorpiones : Buthidae

Members of the Fusarium solani species complex are agents of human mycoses, also affecting plants and other animals. Nevertheless, this fungus has not been reported on scorpions. Ten specimens of Tityus stigmurus collected in the field and showing their surface covered by white mycelia were used to assess fungus presence in the animal after its death. Identification of the fungi was based upon the cultural and morphological characteristics. The fungus was isolated from chelicerae and intersegmental regions. Infected individuals had their behaviour modified by reducing feeding and locomotion. None of the infected individuals survived. It is likely that this fungus may have a role in the regulation of field scorpion populations.


Introduction
Tityus stigmurus (Thorell, 1876) belongs to the Buthidae family which has approximately 550 of the 1,500 known scorpion species (Lourenço and Eickstedt, 2003).The genus Tityus (Koch, 1836) comprises the largest species number of the Scorpiones order, and has a wide geographic distribution in South America.In Brazil, almost 60 species of Tityus genus has been recorded, three of which, T serrulatus Lutz & Mello, 1922, T. bahiensis (Perty, 1833) and T. stigmurus are responsible for serious and fatal accidents to humans (Lira da Silva et al., 2000;Brasil, 2001;Soares et al., 2002).
Several parasites including bacteria, virus and fungus have been described as caustive agents of natural scorpion infection (Matthiesen, 1984).Fusarium spp are described as a group of saprophagic soil fungi and plant pathogen with a wide range of hosts, as well as being a causative agent of superficial and systemic infections in humans and animals (Romano et al. 1998;Godoy et al. 2004;Zhang et al. 2006).In arthropods, one of the most common Fusarium species, Fusarium solani (Martius) (Saccardo, 1881), has been isolated in crustaceans from gill lesions of cultured kuruma prawn Penaeus japonicus (Bate) (Bian et al., 1981) and from eggs of the triatomine bug Panstrongylus genicalatus (Latreille, 1811) causing reduction on egg hatching (Hartung and Lugo 1996).In addition, F. solani has also been described in a symbiotic relationship with the coleoptera Hypothenemus hampei (Ferrari, 1867), producing a significant increase in the progeny of females colonising coffee beans infested with F. solani (Morales-Ramos et al., 2000).However, despite the increasing knowledge of Fusarium spp.interaction with plants and animals, there is little information regarding this fungus relationship with scorpions.This work describes for the first time the invasive infection of the F. solani in T. stigmurus.

Material and Methods
In December 2005, 23 specimens of T. stigmurus collected in the field were donated to the Laboratory of Terrestrial Invertebrates (Laboratório de Invertebrados Terrestres), UFPE.Ten of these specimens were infected by fungus and died during the quarantine period.The external sign of fungus infection was observed as white mycelia covering the surface of the scorpion.The dead specimens were used to identify the species of fungus causing the animals' death.No individuals from the laboratory colony showed similar symptoms.During the quarantine period, animals were maintained under environmental conditions (temperature ranging from 25 to 29 °C, relative humidity between 70-80% and average of 12 hours light/dark cycle).Specimens were kept in a terrarium (30 × 20 × 20 cm) made of glass, for easy visual monitoring, with a substrate of sand and gravels.Water and food (Periplaneta americana Linnaeus, 1758) were provided weekly.Using a standard aseptic technique, dead scorpions were rinsed with shaking in alcohol (70%) and sodium hypoclorite (4%).The surface sterilisation solution was removed by rinsing the animals for 2 minutes, with fresh sterile distilled water (Alves et al. 1998).The scorpions were transferred to a Petri dish containing BDA medium (Potato-Dextrose-Ágar) with antibiotic (Cloranfenicol).Plates were incubated at 28 ± 1° C for 5 days.Pure fungal cultures were obtained by removing hyphal tips from actively growing mycelia emerging from the exoskeletons.

Results and Discussion
The fungal isolated from chelicerae and from the ventral part of the mesossoma (Figure 1) were analysed under lamina and identification was based on their morphological characteristics and colony colour.
Infected scorpions showed behavioural changes by reducing walking and feeding activities.While uninfected individuals were continually active, infected specimens were motionless, not responding to the stimulus of touch near death.Behavioural changes due to fungus infection in scorpions has not been previouly described, however, in response to parasitism by entomopathogenic nematodes, the bark scorpion Centruroides exilicauda (Wood, 1863) showed modified walking and grooming patterns (Gouge and Snyder, 2005).According to these authors, infected specimens would hold their body high off the substrate when walking around; clean chelicerae and walk; and scrape their legs against their body.Behavioural changes due to F. solani infection have also been described in sharks with alterations in swimming patterns.Slowed down swimming, with occasional rapid bursts, was registered in infected sharks as the disease progressed (Crow et al., 1995).
In the advanced stages, black spots on the ventral part of the mesossoma were observed in some of the infected scorpions suggesting the occurrence of melanazation.Similar symptoms were described for gill lesions of the kuruma prawn P. japonicus associated with F. moniliforme (Sheldon, 1904) infection, presenting in the early stages a slight change in colours from opaque white to brown, leading to black spots on the gills (Rhoobunjongde et al. 1991).
Fungus infection in scorpions has been previously registered in Androctonus australis Hector (Gysin and Le Corroiler, 1969) and T. bahiensis (Matthiesen, 1984).However, no further comments on behaviour changes were performed in these studies.In A. australis infected with Aspergillus, superficial lesions showing chitine darkness and surface deformation reducing its defense capacity were described (Gysin and Le Corroiler, 1969).
One of the fungi features is to produce conidia over the body surface and this characteristic may lead to the successful spread of the fungus through the scorpion population.This indicates that F. solani may play a role as a mortality factor in T. stigmurus; however, the fact that this fungus has been reported as causing infections in humans makes it unsafe for biocontrol applications.