[MORPHOLOGICAL DIVERSITY OF FLEAS' STRUCTURES (SIPHONAPTERA) PART 3: GENERAL CHARACTERISTICS AND FEATURES OF THORACIC SETATION].

The paper continues a series of publications (Medvedev, 2015a, b) devoted to the analysis of flea structural features. In the present publication, structural features of flea thoracic setation are analyzed for the first time. Six characters with 53 states in the structure of the chaetom of the pronotum, meso-, and metathoracic. segments are distinguished. The author analyzes the cases of the formation of similar states stipulated by processes of reduction or, by contrast, by strengthening of the chaetom in fleas of separate genera belonging to different superfamilies in relation to the type or peculiarities of parasitism in different flea species. In spite of the presence of strong variability in arrangement and number of thoracic setae, some examples of marking of groups in the range families and superfamilies by certain states of the chaetotaxy of the pronotum and metepimera are revealed.

Jumping mechanisms and performance of snow fleas (Mecoptera, Boreidae).

Flightless snow fleas (snow scorpion flies, Mecoptera, Boreidae) live as adults during northern hemisphere winters, often jumping and walking on the surface of snow. Their jumping mechanisms and performance were analysed with high speed imaging. Jumps were propelled by simultaneous movements of both the middle and hind pairs of legs, as judged by the 0.2 ms resolution afforded by image rates of 5000 frames s(-1). The middle legs of males represent 140% and the hindlegs 187% of the body length (3.4 mm), and the ratio of leg lengths is 1:1.3:1.7 (front:middle:hind). In preparation for a jump the middle legs and hindlegs were rotated forwards at their coxal joints with the fused mesothorax and metathorax. The first propulsive movement of a jump was the rotation of the trochantera about the coxae, powered by large depressor muscles within the thorax. The acceleration time was 6.6 ms. The fastest jump by a male had a take-off velocity of 1 m s(-1), which required 1.1 µJ of energy and a power output of 0.18 mW, and exerted a force about 16 times its body weight. Jump distances of about 100 mm were unaffected by temperature. This, and the power per mass of muscle requirement of 740 W kg(-1), suggests that a catapult mechanism is used. The elastic protein resilin was revealed in four pads at the articulation of the wing hinge with the dorsal head of the pleural ridge of each middle leg and hindleg. By contrast, fleas, which use just their hindlegs for jumping, have only two pads of resilin. This, therefore, provides a functional reference point for considerations about the phylogenetic relationships between snow fleas and true fleas.

Four Species of Under-reported Parasitic Arthropods in Mexico and their Potential Role as Vectors of Pathogens.

Numerous arthropod taxa are important in human and veterinary medicine. The salivary secretions and feces of arthropods can cause allergic reactions in host vertebrates or harbor pathogens. Also, bites can be a risk factor for secondary infections. Documenting the diversity of arthropods of medical and veterinary importance remains an important aspect of disease control and prevention. We provide new records of ectoparasitic arthropods from Mexico that are of potential medical or veterinary relevance. Scanning electron microscopy along with amplification and sequencing of a fragment of the mitochondrial gene (16S rRNA) was used to confirm some species identities. We report the cat louse Felicola subrostratus from cats and the chewing louse Heterodoxus spiniger from dogs, which are common ectoparasites but largely not reported in Mexico. The chigger Eutrombicula alfreddugesi is common on wild lizards (Squamata). For the first time, E. alfreddugesi is reported on Hemidactylus frenatus (common house gecko). This reptile has a close relationship with humans and its chiggers can cause dermatitis (i.e., trombiculiasis) or transmit pathogens. In addition, the common bed bug Cimex lectularius is reported for the first time in the state of Yucatan, an atypical area for its natural distribution. Phylogenetic analysis revealed that Cimex lectularius from Yucatan is closely related to genetic sequences of Cimex lectularius from China. Knowing the regional distribution of arthropods allows the design and implementation of prevention strategies for those that have potential roles as reservoirs or vectors.

Uniquely insidious: Yersinia pestis biofilms.

Bubonic plague, one of history's deadliest infections, is transmitted by fleas infected with Yersinia pestis. The bacteria can starve fleas by blocking their digestive tracts, which stimulates the insects to bite repeatedly and thereby infect new hosts. Direct examination of infected fleas, aided by in vitro studies and experiments with the nematode Caenorhabditis elegans, have established that Y. pestis forms a biofilm in the insect. The extracellular matrix of the biofilm seems to contain a homopolymer of N-acetyl-d-glucosamine, which is a constituent of many bacterial biofilms. A regulatory mechanism involved in Y. pestis biofilm formation, cyclic-di-GMP signaling, is also widespread in bacteria; yet only Y. pestis forms biofilms in fleas. Here, the historical background of bubonic plague is briefly described and recent studies investigating the mechanisms by which these unique and deadly biofilms are formed are discussed.

Sand flea (Tunga spp.) infections in humans and domestic animals: state of the art.

Tungiasis is a parasitic disease of humans and animals caused by fleas (Siphonaptera) belonging to the genus Tunga. Two species, Tunga penetrans (L.) and Tunga trimamillata, out of 10 described to date, are known to affect man or domestic animals; the other eight are exclusive to a few species of wild mammals. Tunga penetrans and T. trimamillata originated from Latin America, although the first species is also found in sub-Saharan Africa (between 20 degrees N and 25 degrees S). Hundreds of millions of people are at risk of infection in more than 70 nations, mostly in developing countries. The second species has been reported only in Ecuador and Peru. Males and non-fertilized females of Tunga are haematophagous ectoparasites; pregnant females penetrate the skin where, following dilatation of the abdomen, they increase enormously in size (neosomy) and cause inflammatory and ulcerative processes of varying severity. The importance of Tunga infection in humans concerns its frequent localization in the foot, which sometimes causes very serious difficulty in walking, thereby reducing the subject's ability to work and necessitating medical and surgical intervention. Tungiasis in domestic animals can be responsible for economic losses resulting from flea-induced lesions and secondary infections. Because tungiasis represents a serious problem for tropical public health and because of the recent description of a new species (Tunga trimamillata), it seems appropriate to review current knowledge of the morphology, molecular taxonomy, epidemiology, pathology, treatment and control of sand fleas of the genus Tunga.

[Phenomenon of Yersinia pestis biofilm formation in flea organism].

For the first time substantiated was the role of the phenomenon of Yersinia pestis biofilm--extracellular matrix envelope (EME)--formation as the basis that determines the nature of plague agent interaction with flea organism. Implication of vector's proventriculus in the process of biofilm formation was demonstrated. Ultrastucture of plague microbe conglomerates in flea proventriculus and midgut was analysed and uniform mechanism of their formation was elucidated. The role of Yersinia pestis biofilm in plague agent preservation in the gut of ectoparasites and soil of rodents burrows was discussed. PCR analysis confirmed the presence of plague microbe in plague infected corpses and fleas excrements stored at +8-10 degreesC for 7 years 9 months.

Investigations on the biology, epidemiology, pathology and control of Tunga penetrans in Brazil. VI. Natural history of the infestation in laboratory-raised Wistar rats.

Tungiasis is endemic in many countries in Latin America, the Caribbean and sub-Saharan Africa, and it is associated with severe morbidity. The pathophysiological and immunological characteristics of the ectoparasitosis are not well understood, and no effective therapy is currently available. The aim of this study was to describe the natural history of tungiasis in laboratory-raised Wistar rats. The rats were exposed in the laboratory to the parasite or were kept in a natural environment with an intense transmission of Tunga penetrans. The time course of the infestation was determined, and lesions were photographed, described clinically in detail and biopsied. Biopsies were examined histopathologically and by light and scanning electron microscopy. Based on these findings, the natural history of tungiasis in Wistar rats was described and divided in five stages. Our data show that the natural history of tungiasis in Wistar rats and humans is almost identical, except that in the animals, the basement membrane disrupts 5 days after penetration and provokes an intense infiltration of the dermis, while in humans, the basement membrane remains intact. The study indicates that the Wistar rat is an appropriate model for the study of clinical and pathological aspects of tungiasis. Using this model should enable a better understanding of the pathophysiology and immunology of the ectoparasitosis.

Scanning electron microscopy studies of sensilla and other structures of the head of Polygenis (Polygenis) tripus (Siphonapera: Rhopalopsyllidae).

The external morphology of the head and appendages of adult Polygenis (Polygenis) tripus [Jordan, K., 1933. Descriptions of Siphonaptera. Nov. Zool. 39, 66-69] (Siphonaptera: Rhopalopsyllidae) was described based on scanning electron microscopy. Chaetal, trichoid and basiconic sensilla were encountered and their positions noted, comparisons being made between male and female specimens. Those of the basiconic type were particularly abundant on the frontal and occipital regions of the head and were surrounded by several pores, indicating the considerable sensory importance of these areas. Frontal tubercle was observed as a projection emerging from a depression in the frontal head region. The antennae of males were more developed, presenting greater number of sensilla on the scape and about 370 spatulate setae on the internal surface of the clava. Three large chemoreceptors, digitate sensilla ca. 11-13 microm were observed on the lateral surface of the antennal clava of both sexes between antennomeres 4-7. Females present a characteristic distribution of basiconic sensilla on the dorsal margin and median external surface of the clava. Trichoid sensilla were observed on all segments of the maxilary palps while basiconic sensilla were only recognized on the distal three segments.

Field trial of the efficacy of a combination of imidacloprid and permethrin against Tunga penetrans (sand flea, jigger flea) in dogs in Brazil.

In a field trial in Brazil 17 dogs penetrated by females of the jigger flea, Tunga penetrans, were topically treated with a combination of 10% imidacloprid and 50% permethrin (Advantix), while 17 dogs remained untreated. The follow-up controls on days 7, 14, 21 and 28 post-treatment clearly showed that, beginning from day 7, the flea load in treated dogs decreased, so that most of the dogs became free of tungiasis lesions, while in the untreated group the flea load remained high. Since the dogs distribute the flea eggs throughout the village, leading to a high incidence of tungiasis in humans, treatment of dogs probably also decreases the number of cases of tungiasis in the latter.

Infection of colonized cat fleas, Ctenocephalides felis (Bouché), with a rickettsia-like microorganism.

We report the ultrastructure of a rickettsia-like microorganism in a colonized population of the cat flea Ctenocephalides felis (Bouché). The microorganism occurs principally in the cytoplasm of midgut cells, but similar microorganisms were detected in the tracheal matrix, muscle, hypodermis, ovaries, and the epithelial sheath of the testes. The microorganism has a well-defined cell membrane consistent with rickettsia and measures 0.25-0.45 microns in diameter with lengths up to 1.5 microns. It was observed repeatedly in fleas of 1 laboratory colony, including newly emerged non-bloodfed specimens, but not in specimens from several other sources.

Ultrastructural comparison of the midgut epithelia of fleas with different feeding behavior patterns (Xenopsylla cheopis, Echidnophaga gallinacea, Tunga penetrans, Siphonaptera, Pulicidae).

This morphological study describes the ultrastructure of the midgut of three flea species, including temporary parasitic fleas (both sexes of Xenopsylla cheopis, males and immature females of Echidnophaga gallinacea and Tunga penetrans) and stationary parasitic fleas (mature females of E. gallinacea and T. penetrans). (1) Three cell types (a,b,c) constitute the midgut epithelium, each appearing in a characteristic and constant frequency along the whole midgut, a) The functional digestive cells form the main part of the epithelium as one layer of cylindric cells. Nuclear volume and nucleus/cytoplasm ratio have been estimated (with morphometric methods) to be the same in both sexes of E. gallinacea and T. penetrans. b) Some single regenerative cells or nests, containing 5-10 cells per section plane, lay at the base of the epithelium (2-3 cells or nests per cross section of a midgut). c) Secretory cells are characterized by their opaque cytoplasm which contains electron-dense vesicles. They have few microvilli and no basal labyrinth and are placed between digestive cells only as single cells (1-2 per cross section of a midgut). (2) After the first bloodmeal some ultrastructural changes occur in the midgut of all fleas. These changes are interpreted as a structural reflection of metabolic processes such as secretion of digestive enzymes, resorption, storage and transport of digested nutrients, and synthesis of digestive enzymes. (3) More conspicious changes occur in the midgut of the stationary parasitic and maturing females of E. gallinacea and T. penetrans. The nuclear volumes of the digestive cells reach the two-fold and eight-fold value, respectively. The nucleus/cytoplasm ratio decreases by half. The corresponding cytoplasmic growth of each cell is reflected in an enlargement of the whole midgut. The digestive cells form long apical cell extensions. The nucleus, basal labyrinth, rer, and golgi complex all change their morphology, and this can be interpreted as the result of a higher level of metabolic activity than during the first bloodmeal. (4) The midgut of the oviparous female of T. penetrans undergoes a process of compensatory hypertrophy which consists in the cellular hypertrophy of each digestive cell and in an extensive proliferation of the regenerative cells. A unique structure, called 'nuclear halo' appears within the process of cellular hypertrophy. This structure consists of a layer of 70-100 A thick filaments along the periphery of the nucleus. The nuclear halo contains few ribosomes and is screened from the cytoplasm by an rer cisterna. The filaments may contain RNA molecules which are on their way to the cytoplasm. It has been demonstrated that the structure of the midgut epithelium is influenced by the nutritive and parasitic behavior of the flea. The stationary and oviparous E. gallinacea and T. penetrans reveal an extensive and irreversible change of their midgut epithelium.

Résumé of the Siphonaptera (Insecta) of the world.

The world fauna of the order Siphonaptera is reviewed with respect to undescribed taxa, endangered species, taxonomic specialists, developmental stages, ultrastructure, taxonomic characters, host specificity, literature, fossil record, and the phylogenetic affinities of and within the order. The 15 currently recognized families are discussed with respect to their subfamilial, tribal, and generic classification. The numbers of species in these taxa are discussed and their general distribution and host preferences are briefly outlined. The current numbers of tribes, genera, and species, including invalid names, are listed.

Larvae of the woodrat fleas Anomiopsyllus amphibolus and Atyphlocerus echis echis (Siphonaptera: Hystrichopsyllidae).

The external morphology of Anomiopsyllus amphibolus Wagner, 1936 and Atyphloceras echis echis Jordan and Rothschild, 1915 larvae (Siphonaptera: Hystrichopsyllidae) from woodrat (Neotoma lepida) nests is described. Among known flea larvae, the genus Anomiopsyllus (Anomiopsyllinae, Anomiopsyllini) is as distinctive in larval form as are the adults. Among other distinctive features, only Anomiopsyllus are known to have only two ventrolateral setae. Atyphloceras (Hystrichopsyllinae, Hystrichopsyllini) larvae seem more similar in morphology to those of Typhloceras (Hystrichopsyllini) than to Hystrichopsylla, the other genus placed within the Hystrichopsyllini. Characters used to distinguish flea larvae found in Neotoma nests are discussed.

Toxicity and histopathology of the growth regulator pyriproxyfen to adults and eggs of the cat flea (Siphonaptera:Pulicidae).

Adult cat fleas, Ctenocephalides felis (Bouché), exposed continuously to pyriproxyfen died within 8-10 d. Microscopic examination of 7-d-old adults indicated death was caused by histopathological damage to fat body, Malpighian tubules, midgut epithelia, salivary gland cells, and other internal tissues. Fleas were killed by pyriproxyfen regardless of whether they were held as unfed adults on treated filter paper or as feeding adults on treated dog hair. In addition to these toxic effects on adults, pyriproxyfen also induced formation of large autophagic vacuoles in maturing oocytes leading to partial reabsorption of yolk, degeneration of the nucleus, and lysis of the follicular epithelium. Consequently, most of the eggs laid by treated fleas lacked a nucleus, had a poorly formed chorion, and were ruptured during ovulation. These laboratory results suggest that continuous exposure of fleas to pyriproxyfen on a host animal could prevent deposition of viable eggs and eventually kill adults, thereby controlling all stages of flea development.

Susceptibility to insect growth regulators and cuticle deposition of the cat flea (Siphonaptera: Pulicidae) as a function of age.

Wandering larval, pharate pupal, pupal, and pharate adult stages of the cat flea, Ctenocephalides felis (Bouché), were identified by examination of cuticular cross sections via scanning electron microscopy. Visible morphological characteristics of each stage were identified and described. Various stages of the flea throughout metamorphosis were exposed to juvenile hormone mimics and insect developmental inhibitors. Wandering larvae treated with juvenile hormone mimics were unable to pupate, whereas treated pharate pupae ecdysed to the pupal stage but were unable to enclose. Pupae and pharate adults did not succumb to juvenile hormone mimic exposure, even at concentrations 3 orders of magnitude greater than those that killed 100% of the wandering larvae and the pharate pupae. Adult females were more susceptible to juvenile hormone mimics than males. Possible explanations for the variation in tolerance to juvenile hormone mimics of the differing stadia are discussed. None of the stages were susceptible to insect developmental inhibitor exposure. Analysis of catecholamines that are precursors of cuticle sclerotization and melanization were measured in the wandering larval through the pharate adult stages of the cat flea. N-acetyldopamine concentration was highest in the pupa stage when the flea had a hard, clear cuticle; N-beta-alanyldopamine concentration was highest during the production of the hard, dark cuticle of the pharate adult; and dopamine fluctuated throughout development but was highest in the pupal stage.

New record of Nosopsyllus (Nosopsyllus) barbarus (Jordan and Rothschild, 1912) (Aphaniptera: Dolichopsyllidae) from Sicily. Morphology at scanning electron microscopy of N. (N.) barbarus and N. (N.) fasciatus (Bosc D'Antic, 1800).

Nosopsyllus (N.) fasciatus, species or complex cosmopolitan and very polymorphic, is established in most of Italian regions, in association with murine rodents, especially domestic species. N. (N.) barbarus, similar to N. fasciatus in modified segments of the male and perhaps in ecology, is presently known from North Africa regions and a few Mediterranean islands; in Italy it is reported from Sardinia and Egadi islands. In this note the N. barbarus presence in Sicily (Palermo) and the contemporary record of N. fasciatus from the same country and host species (Rattus rattus frugivorus) are reported for the first time. The coexistence of both species was shown until now, only in Sardinia. A scanning electron microscope was used to describe the clasper of the male of N. fasciatus and the main diagnostic surface differences between females of N. fasciatus and N. barbarus.

Fleas and lice on scrub hares (Lepus saxatilis) in South Africa.

A total of 380 scrub hares (Lepus saxatilis) from 5 localities, ranging from the north-eastern Transvaal to the eastern and the south-western Cape Province of South Africa, were examined for fleas and lice. Ctenocephalides felis damarensis was almost exclusively responsible for the flea infestations on hares at 4 of the 5 sites. At 4 localities the prevalence and abundance of this flea reached peaks between August and October and declined thereafter to their lowest levels between February and April. Its prevalence and abundance in the north-eastern Transvaal were not correlated with the breeding cycle of the hares in this region. The 2 louse species recovered, sometimes sympatrically, were Haemodipsus lyriocephalus and Haemodipsus setoni. Listrophorus leporicolus was the only mite species recovered.

A primary animal health care approach to treatment and control of flea (Ctenocephalides felis) infestation in indigenous goats kept on communal grazing.

This paper describes a primary health care approach to an infestation of indigenous goats by the common cat flea, Ctenocephalides felis. The flea species was identified using scanning electron microscopy. The infested goats were kept on communal grazing at Winterveld in the North-West Province. They were penned at night in housing made of wire and corrugated iron. The owner complained that the goats were lethargic. Fleas were found on the goats and flea larvae were found in the kraal. Haematology and blood biochemistry performed on the infested goats revealed no abnormalities; however, infestation caused irritation that made the animals lethargic. Available flea control methods for domestic animals were appraised in terms of cost, availability and ease of administration at a primary animal health care level using participatory extension methods. It was found that a carbamate powder was available, affordable and effective for flea control in this small flock of goats kept under communal grazing conditions. Although the authors had observed fleas on goats kept under similar conditions elsewhere in Mpumalanga and the North-West Province, this was the 1st time that the species had been identified.

[The proventriculus of the Xenopsylla cheopis flea studied by scanning electron microscopy]. / Izuchenie predzheludka blokhi Xenopsylla cheopis v skaniruiushchem élektronnom mikroskope.

The proventriculus of the flea X. cheopis was studied by means of scanning electron microscopy. The external surface of the proventriculus is a rigid structure with an alveolate surface ("wasp nest") formed by muscular cords. The internal surface of the proventriculus is represented by numerous acanthae which fall close together. They have a shape of bent dens with longitudinal sharply angular edges and concave spaces between them. Some edges are crenate.

[Peculiarities of thoracic and abdominal combs of fleas (Siphonaptera)]. / Osobennosti stroeniia grudnykh i briushnykh ktenidiev blokh (Siphonaptera).

The structure of pseudosetae, spinelets, and spines of combs (ctenidia) was studied by means of light and SE microscopy in 80% of genera and subgenera of the World fauna. It is found out that peculiarities of ctenidiae in the prothorax and in tergites of the abdomen are characteristics of families and infraorders of fleas. Some characters of ctenidiae found in certain flea genera are reductions and apparently caused by habitation in some extremal conditions. An absence of ctenidiae in the unfraorder Pulicomorpha is compensated by more developed posterior margin of prothorax and general abbreviation of all thoracal segments. Reasons of ctenidiae absence, which is observed in certain genera of the infraorders Ceratophyllomorpha, Pygiopsyllomorpha and Hystricopsillomorpha associated with the same hosts, is not clear. It is confirmed, that distance between ctenidiae in different flea species associated with the same species host species, however it is recovered, that this distance correlates with the diameter of most thin hair of host. In some flea species the distance between ctenidia spices in females is larger, than in males. It is found, that sexual dimorphism by this character may not be expressed in certain species of closely related species group of fleas. It is suggested that ctenidiae were present even in the common ancestor of fleas. The hypothesis on origin of spines and pseudosetae from setae of the posterior walls of toracal and abdominal segments in the common ancestor of fleas is proposed.