Avelino José Bittencourt

Virulence of Metarhizium anisopliae to eggs and immature stages of Stomoxys calcitrans.

Stomoxys calcitrans control is primarily based on the use of chemical products; however, new methods for control have been investigated. Biological control has been proposed as a promising alternative to traditional chemicals. The current study evaluated three methods in vitro to treat S. calcitrans eggs with the fungus Metarhizium anisopliae and assessed the virulence of this fungus to immature stages of this fly. In the first method of egg exposure, eggs were immersed in conidial suspensions and transferred to Petri plates with high humidity. A high mortality was observed in both treated and control groups. In the second method, the eggs were transferred to rearing medium right after immersion in conidial suspensions; the suspensions with highest conidial concentrations, 107 and 108 conidia mL−1, caused 96.25% and 100% mortality, respectively. In the third method, the eggs were sprayed with conidial suspensions on the rearing medium. A high mortality was observed at 107 and 108 conidia mL−1, 78.3% and 100%, respectively. The second method had the lowest mortality in the control group and was considered the most useful method for evaluating the effect of entomopathogenic fungi on S. calcitrans eggs. While eggs were very susceptible to M. anisopliae infection, larvae and pupae were not.

Aerobic bacterial microbiota in stomoxys calcitrans: preliminary studies in Brazil

The stable fly, Stomoxys calcitrans, has a great importance in medical and veterinary health due to its feeding and reproductive habits, which can disseminate some pathogenic agents among hosts even at long distances. This study aimed to describe, for the first time in Brazil, the bacterial microbiota in segments of the stable fly. Bacterial species were isolated from three different segments (cuticle, mouth parts and abdominal alimentary tract) of the stable fly. Twenty dairy farms were visited in four municipalities: Barra Mansa, Quatis, Resende and Rio Claro in the State of Rio de Janeiro in order to collect 20 flies in each site. Dissection of the flies and procedures of isolation and identification of bacterial species were performed. A total of 161 colonies of 33 distinct species were isolated, such as Escherichia coli, Staphylococcus aureus, and S. intermedius. Stomoxys calcitrans may harbor bacterial agents on their cuticle, mouth parts and abdominal alimentary tract and these bacteria may be pathogenic to their hosts.

Occurrence of Shiga-toxigenic Escherichia coli in Stomoxys calcitrans (Diptera: Muscidae)

This study aimed to verify the occurrence of Shiga toxin-producing Escherichia coli (STEC) strains in three distinct anatomic parts of the stable fly Stomoxys calcitrans by multiplex polymerase chain reaction (PCR Multiplex). According to the results obtained, E. coli was identified in 19.5% of the stable flies. Shiga toxin genes were detected in 13% of the E. coli isolated, most frequently from the surface, followed by abdominal digestive tract and mouth apparatus of insects, respectively. This is the first study to detect presence of STEC in Stomoxys calcitrans in Brazil; it has also revealed the potential role of stable flies as carriers of pathogenic bacterial agents.

Influência do vinhoto no desenvolvimento de Stomoxys calcitrans

Stomoxys calcitrans is known for its painful sting that causes stress in animals and also by transmitting several diseases, and attack man. Due to the outbreaks in sugarcane fields in Brazil, where the vinasse is used in fertigation of the sugarcane fields, this study was conducted, aiming to verify if the vinasse would improve posture and development of the immature stages of this insect. For this, eggs were deposited into diet of larval growth of Bailey (control), and also in diets with replacement of 5, 10, 20 and 30% of this water volume per vinasse. Part of the results was submitted to analysis of variance and means were compared by Tuket test, and the other, was assessed by Chi-square. The eggs viability was of 66%, 64%, 69%, 80% e 20%, the larvae was of 96.4%, 96.,9%, 95.1%, 99.3% e 97.2% and the pupae was of 90.2%, 94.7%, 93.5%, 91.5% and 86.1%, respectively to the control, 5, 10, 20, e 30%. The weight of the third stage larvae was 16.4; 16.9; 19.7; 15.8 and 18mg, and pupae was of 12.9; 13.9; 17.4; 14.5 e 21.9mg. The larval period was of 10.38, 11.81, 10.00, 10.86, 9.5 days, and the pupal was of 6.57, 6.19, 7.05, 7.00 and 6.00 days, respectively. The viability of the immature stages was higher in diet with replacement of vinasse. Some of vinasse concentrations used in diets affected the biology of immature stages of S. calcitrans.

Stomoxys calcitrans Parasitism Associated with Cattle Diseases in Espírito Santo do Pinhal, São Paulo, Brazil

Abstract: The stable fly has been of great significance to livestock production in the county of Espirito Santo do Pinhal; it has a painful bite, sucks blood, and carries many diseases. The aim of this study was to establish a relationship between the parasitism of Stomoxys calcitrans, manure management, cattle diseases, and technical support. According to the farmers the stable fly reaches its highest level in the rainy season, the same period in which diseases were detected. Most of the farmers said that they did not receive technical assistance. The association of inappropriate manure management, verified in this survey, with the low frequency of technical visits, resulted in a low level of technology utilization. Better technological assistance could moderate the stable fly infestation and help manage serious cattle diseases.

Patogenicidade de Beauveria bassiana sobre estágios imaturos de Stomoxys calcitrans

Because it is a hemathofagic diptera, the Stomoxys calcitrans (Linnaeus, 1758) inflicts great losses in the Brazilian cattle. Nowadays, researches have been directed to the control methods that reduce the use of chemical insecticides and preserve the environment. This study evaluated the entomopathogenic potential of the isolated CG 138 and CG 228 of Beauveria bassiana on eggs, larvae and pupae of S. calcitrans in environmental conditions and the isolated ESALQ 986 of B. bassiana in eggs. For each fungal isolated were used concentrations of 2x106, 2x107 and 2x108 conidia ml-1. The results suggest that the isolated CG 138, CG 228, ESALQ 986 present a saprophytic effect, because they did not affect significantly the development of immature stages of the stable flies, affecting this way its use as entomopathogenic agent.

Antifungal activity of Stenotrophomonas maltophilia in Stomoxys calcitrans larvae.

The microbiota present in Stomoxys calcitrans larvae may assist their survival in contaminated environments through production of inhibitory substances. Bacteriological identification methods, the polymerase chain reaction (PCR) and scanning electron microscopy (SEM) were used to detect a bacterium naturally present in mucus and macerated S. calcitrans larvae. The antifungal activity was determined based on the results from disk diffusion tests on an artificial solid medium. The bacterium was identified as Stenotrophomonas maltophilia and presented antifungal activity against Beauveria bassiana sensu lato isolates CG 138, CG 228 and ESALQ 986. This result suggests that the larval microbiota is a factor that can compromise the use of B. bassiana s.l. fungus for biological control of S. calcitrans larvae.

Enterobacterial Microbiota on Stomoxys calcitrans External Surface

The current study evaluated the prevalence of enterobacterial agents on the external surface of the stable fly, Stomoxys calcitrans. In addition, this study investigated the presence of virulence genes of enterobacteria. Twenty different species were isolated and identified, Escherichia coli was the most frequent species isolated. The genes stx1, stx2 and/or eae for production of Shiga toxin were present in 13.04% of the E. coli samples.

Isolamento de espécies enterobacterianas em Stomoxys calcitrans

This study aimed to report enterobacterial species recovered from body segments of Stomoxys calcitrans collected in dairy farms from counties of Rio de Janeiro State, Brazil. Nine of the isolated and identified species were not yet described in stable flies, according to the worldwide literature. Some of them are known to present pathogenical potential to man and other animals, while others were not described causing diseases of medical or veterinary importance.

Caracterização genotípica de Escherichia coli isolados de leite com mastite e da mosca dos estábulos Stomoxys calcitrans

The stable fly Stomoxys calcitrans (Linnaeus, 1758) has been described as a potential spreader of infectious agents to cattle herds. Among the agents transmitted by this fly, Escherichia coli has attracted attention due to its potential to cause gastrointestinal disorders as well as environmental mastitis in dairy cows. Therefore, the aim of this study was to isolate and to assess the genetic diversity and the clonal relatedness among E. coli isolates from the milk of dairy mastitis and from stable flies anatomical sites by the Random Amplification of Polymorphic DNA (RAPD-PCR) technique. The molecular typing revealed a high degree of genetic polymorphism suggesting that these microorganisms have a non-clonal origin. Identical electrophoretic profiles were observed between E. coli isolates from different flies, different mammary quarters of the same cow and from cows on a single farm. These results reveal the circulation of the same bacterial lineages and suggest the role of the stable fly in bacterial dispersion. Considering the high pathogenic potential of this bacterial species, our findings alert to a more effective health surveillance.