Early Cretaceous trypanosomatids associated with fossil sand fly larvae in Burmese amber

Early Cretaceous flagellates with characters typical of trypanosomatids were found in the gut of sand fly larvae, as well as in surrounding debris, in Burmese amber. This discovery supports a hypothesis in which free-living trypanosomatids could have been acquired by sand fly larvae in their feeding environment and then carried transtadially into the adult stage. At some point in time, specific genera were introduced into vertebrates, thus establishing a dixenous life cycle.

Stochastic modelling of the invasion process of nematodes in fly larvae

Stochastic models based on Markov birth processes are constructed to describe the process of invasion of a fly larva by entomopathogenic nematodes. Various forms for the birth (invasion) rates are proposed. These models are then fitted to data sets describing the observed numbers of nematodes that have invaded a fly larval after a fixed period of time. Non-linear birthrates are required to achieve good fits to these data, with their precise form leading to different patterns of invasion being identified for three populations of nematodes considered. One of these (Nemasys) showed the greatest propensity for invasion. This form of modelling may be useful more generally for analysing data that show variation which is different from that expected from a binomial distribution.

Some ultrastructural superficial changes in house fly (Diptera: Muscidae) and blow fly (Diptera: Calliphoridae) larvae induced by eucalyptol oil

The ultrastructural superficial changes in third instar house fly (Musca domestica) and blow fly (Chrysomya megacephala) induced by eucalyptol oil were observed using scanning electron microscopy. Dipped in 0.902 g/ml eucalyptol for 30 sec, the larvae integument of both species showed significant aberrant appearance of the body surface, particularly swelling integument, bleb formation, partial breach and deformation of spines.

Posterior spiracles of fourth instar larvae of four species of phlebotomine sand flies (Diptera: Psychodidae) under scanning electron microscopy

In the present study, posterior spiracles of laboratory-reared fourth instar larvae of Lutzomyia longipalpis, L. migonei, L. lenti, and L. whitmani (Diptera: Psychodidae) of the State of Ceará, Brazil, were examined under scanning electron microscopy. The number of papillae of spiracles examined varied according to the species examined, but no intraspecific differences were found. The importance of this structure to sand fly larva identification and phylogeny is commented.

External morphology of sensory structures of fourth instar larvae of neotropical species of phlebotomine sand flies (Diptera: Psychodidae) under scanning electron microscopy

In the present study, some morphological structures of antennae, maxillary palps and caudal setae of fourth instar larvae of laboratory-reared phlebotomine sand flies (Lutzomyia longipalpis, L. migonei, L. evandroi, L. lenti, L. sericea, L. whitmani and L. intermedia) of the State of Ceará, Brazil, were examined under scanning electron microscopy. The antennal structures exhibited considerable variation in the morphology and position. A prominent digitiform distal segment has been observed only on the antenna of species of the subgenus Nyssomyia. The taxonomic relevance of this and other antennal structure is discussed. The papiliform structures found in the maxillae and the porous structures of the caudal setae of all species examined may have chemosensory function. Further studies with transmission electron microscopy are needed to better understand the physiological function of these external structures.

Trichomycete Fungi (Zygomycota) Associated with the Digestive Tract of Simulium goeldii Cerqueira & Nunes de Mello and Simulium ulyssesi (Py-Daniel & Coscarón) (Diptera: Simuliidae) Larvae, in Central Amazônia, Brazil

Trichomycete fungi are associated with digestive tract of black fly larvae. These fungi have not been studied in Brazil, knowing them and their relationship with black flies could be an alternative to control vector populations. The objectives of this study were to survey the Trichomycete fungi associated with larvae of Simulium goeldii and S. ulyssesi, and to determine if there is specificity and/or difference in the infection rates in these species. Black flies were collected in Central Amazônia, Brazil. Three genera of Trichomycetes were found: Harpella, Genistellospora and Smittium. All these fungi were common to both black fly species.

Histopathological and ultrastructural effects of delta-endotoxins of Bacillus thuringiensis serovar israelensis in the midgut of Simulium pertinax larvae (Diptera, Simuliidae)

The bacterium Bacillus thuringiensis (Bt) produces parasporal crystals containing delta-endotoxins responsible for selective insecticidal activity on larvae. Upon ingestion, these crystals are solubilized in the midgut lumen and converted into active toxins that bind to receptors present on the microvilli causing serious damage to the epithelial columnar cells. We investigated the effect of these endotoxins on larvae of the Simulium pertinax, a common black fly in Brazil, using several concentrations during 4 h of the serovar israelensis strain IPS-82 (LFB-FIOCRUZ 584), serotype H-14 type strain of the Institute Pasteur, Paris. Light and electron microscope observations revealed, by time and endotoxin concentration, increasing damages of the larvae midgut epithelium. The most characteristic effects were midgut columnar cell vacuolization, microvilli damages, epithelium cell contents passing into the midgut lumen and finally the cell death. This article is the first report of the histopathological effects of the Bti endotoxins in the midgut of S. pertinax larvae and the data obtained may contribute to a better understanding of the mode of action of this bacterial strain used as bioinsecticide against black fly larvae.

Diversity and microdistribution of black fly (Diptera: Simuliidae) assemblages in the tropical savanna streams of the Brazilian cerrado

We describe the abiotic factors affecting the distribution of black flies at a microhabitat scale, rather than at the regional scale usually present in the literature on the Neotropics. Black fly larvae were sampled from the Tocantins River and three tributaries, located in the Brazilian savanna (state of Tocantins, Brazil) during six bi-monthly sampling periods from October 2004-August 2005. At each sampling site, 15 random quadrats (30 x 30 cm) were sampled each period and for each quadrat were determined mean water velocity, predominant substrate type (rocks, riffle litter or riparian vegetation) and depth detrended correspondence analysis (DCA) was used to determine associations with current velocity, whereas correspondence analysis (CA) was used to estimate site specific current velocity associations. Canonical correspondence analysis (CCA) was used to identify general microhabitat associations. The CCA showed that most species had a trend towards riffle litter, except for Simulium nigrimanum associated with rocky substrate and Simulium cuasiexiguum associated with riparian vegetation. The DCA showed a well defined pattern of water velocity associations. The CA revealed that the species showed different speed associations from one site to another, suggesting different competitive pressures resulting in the occurrence of different realized niches.

Behavioural characteristics in phylogenetics : a case study using black fly (Diptera: Simuliidae) cocoon spinning behaviour

1-1 is torically, the predominan t method of reconstructing phylogenies has been through the use of morphological characters. There are new techniques now gaining acceptance, including molecular techniques al1d chromosomal information. Altl10ugh the study of behaviour has been used in a comparative framework, these analyses have, historically, been based on intuition. Hennig (1966) devised a neV\' method of reconstructing phylogenies which provided a 110ncircular method for formulating, testing and refining phylogenies. Subsequent s)Tstematists had virtually abandoned ecological and beha\lioural data as primary indicators of phylogenetic relationships (Brooks and McLennan 1991). Therefore, in a modern cladistic framework (sensu Hennig) the analysis of behavioural traits remains underrepresented as a method of reconstructing phylogenies. This thesis will reconstruct the phylogeny for species of black flies (Diptera: Simuliidae), using two steps. The first step is to thoroughl)' understand and explain the cocoon spinning in black fly larvae. There have bee115 previous descriptions of cocoon spinning, but all were incomplete or erroneous. The advances in technology, including video recorders and VCRs, have allowed this behaviour to be analyzed in great detail in 20 different species. A complete description of the cocoon spinning of Simulium \littatum is given. This description will be used as a template for the other species observed. The description and understanding of cococ)n spinning was the first step in undertaking a phylogenetic analysis using this behaviour. The behaviour was then broken down and analyzed, revealing 23 characters, 3 either qualitative and quantitative in nature. These characters were assessed in a cladistic framework (sensu Hennig) and a phylogenetic tree was reconstructed with a e.I of 0.91 and an R.I. of 0.96. This phylogenetic tree closely resembles a previously established pllylogenetic tree produced from morphological and cytological information. The importance of this result is the indication that, contrary to some authors, behavioural characters, if used properly, can add very informative characters to a data set.

Mosquitocidal bacterial toxins: diversity, mode of action and resistance phenomena

Bacteria active against dipteran larvae (mosquitoes and black flies) include a wide variety of Bacillus thuringiensis and B. sphaericus strains, as well as isolates of Brevibacillus laterosporus and Clostridium bifermentans. All display different spectra and levels of activity correlated with the nature of the toxins, mainly produced during the sporulation process. This paper describes the structure and mode of action of the main mosquitocidal toxins, in relationship with their potential use in mosquito and/or black fly larvae control. Investigations with laboratory and field colonies of mosquitoes that have become highly resistant to the B. sphaericus Bin toxin have shown that several mechanisms of resistance are involved, some affecting the toxin/receptor binding step, others unknown.

Evolution of insecticide resistance in non-target black flies (Diptera: Simuliidae) from Argentina

Black flies, a non-target species of the insecticides used in fruit production, represent a severe medical and veterinary problem. Large increases in the level of resistance to the pyrethroids fenvalerate (more than 355-fold) and deltamethrin (162-fold) and a small increase in resistance to the organophosphate azinphos methyl (2-fold) were observed between 1996-2008 in black fly larvae under insecticide pressure. Eventually, no change or a slight variation in insecticide resistance was followed by a subsequent increase in resistance. The evolution of pesticide resistance in a field population is a complex and stepwise process that is influenced by several factors, the most significant of which is the insecticide selection pressure, such as the dose and frequency of application. The variation in insecticide susceptibility within a black fly population in the productive area may be related to changes in fruit-pest control. The frequency of individuals with esterase activities higher than the maximum value determined in the susceptible population increased consistently over the sampling period. However, the insecticide resistance was not attributed to glutathione S-transferase activity. In conclusion, esterase activity in black flies from the productive area is one mechanism underlying the high levels of resistance to pyrethroids, which have been recently used infrequently. These enzymes may be reselected by currently used pesticides and enhance the resistance to these insecticides.

Chrysomya albiceps (Wiedemann) and Hemilucilia segmentaria (Fabricius) (Diptera, Calliphoridae) used to estimate the postmortem interval in a forensic case in Minas Gerais, Brazil

ABSTRACT. Chrysomya albiceps (Wiedemann) and Hemilucilia segmentaria (Fabricius) (Diptera, Calliphoridae) used to estimate the postmortem interval in a forensic case in Minas Gerais, Brazil. The corpse of a man was found in a Brazilian highland savanna (cerrado) in the state of Minas Gerais. Fly larvae were collected at the crime scene and arrived at the laboratory three days afterwards. From the eight pre-pupae, seven adults of Chrysomya albiceps (Wiedemann, 1819) emerged and, from the two larvae, two adults of Hemilucilia segmentaria (Fabricius, 1805) were obtained. As necrophagous insects use corpses as a feeding resource, their development rate can be used as a tool to estimate the postmortem interval. The post-embryonary development stage of the immature collected on the body was estimated as the difference between the total development time and the time required for them to become adults in the lab. The estimated age of the maggots from both species and the minimum postmortem interval were four days. This is the first time that H. segmentaria is used to estimate the postmortem interval in a forensic case.

Tropical dermatology: Venomous arthropods and human skin Part I. Insecta

Although many tropical insects carry infectious diseases, cutaneous injury can occur by other mechanisms, for example erucism (envenomation by caterpillars) or lepidopterism (dermatitis from moths). Pararama is a unique form of erucism seen in workers in contact with rubber trees in the Amazon, and it is caused by Premolis larvae, resulting in progressive periarticular fibrosis, ankylosis, and the loss of articulation. Ants and aquatic insects of the Belostomatidae family can cause painful bites and stings. Anaphylactic shock and death can result from the venom of bees and wasps. Beetles can cause vesicular dermatitis via cantharidin or paederin. Myiasis results from fly larvae (maggots) feeding on live or necrotic tissue of humans or other hosts, while New World screwworm fly larvae feed only on living tissue and burrow (ie, screw) more deeply when attempts are made to remove them. Tungiasis is characterized by very pruritic and painful papules and ulcers resulting from a Tunga flea penetrating the host's skin. Dermatologists should be able to diagnose and treat the cutaneous manifestations of these tropical insects and educate their patients on prevention. (J Am Acad Dermatol 2012; 67:339.e1-14.)

Prevalence of gastric lesions (ulcers and/or erosions) and their relationship to possible stressfull factors in asymptomatic Quarter Horse foals: endoscopic survey

A úlcera gástrica constitui-se numa das mais importantes causas de desconforto abdominal em eqüinos jovens. Com o objetivo de se verificar a prevalência de lesões gástricas (úlceras e/ou erosões) e sua relação com fatores como estresse, idade, e sexo, sessenta potros da raça Quarto de Milha não portadores de sinais clínicos compatíveis com lesões gástricas foram submetidos à gastroscopia. Os potros foram divididos em quatro faixas etárias de 15 animais cada uma, sendo: 1 a 30 dias, 31 a 60 dias, 61 a 90 dias e 91 a 120 dias de idade. A prevalência de lesões gástricas foi de 43,3%. Animais com idade entre 61 a noventa dias foram os mais acometidos. Não houve diferença significativa entre as faixas etárias. Descamações do epitélio aglandular ocorreram em nove potros (60%) entre um e trinta dias, em seis (40%) entre 31 e sessenta dias e em apenas dois (6,6%) com idade superior a sessenta dias. Fatores considerados estressantes, como infestação intensa por carrapatos (29), problemas respiratórios (3), dermatopatias (3), babesiose (2), onfaloflebite (1), diarréia (1), problemas ortopédicos (1) e ferida lacerante com presença de miíase (1) não influenciaram a ocorrência das lesões. Machos e fêmeas foram igualmente acometidos.