Hosts and distribution of Amblyomma auricularium and Amblyomma pseudoconcolor Aragão, 1908 (Acari: Ixodidae)

Collections of Amblyomma auricularium and A. pseudoconcolor Aragão, 1908 are discussed in relation to distribution and hosts. Three tick collections (two from Argentina and a third from the USA) house a total of 574 A. auricularium (307 males, 162 females, 73 nymphs and 32 larvae) and 179 A. pseudoconcolor (96 males, 74 females, 4 nymphs and 5 larvae). Apart from an adult A. pseudoconcolor found on a bird, Nothura maculosa Temminck, 1815, all ticks were found on mammals. The great majority of specimens of both ticks species were removed from the family Dasypodidae Gray, 1821 (84.9% and 93.8% of A. auricularium and A. pseudoconcolor, respectively). Amblyomma auricularium has also been found on wild hosts of the families Myrmecophagidae and occasionally Didelphidae, Caviidae, Chinchillidae, Hydrochaeridae, Muridae, Canidae, Mustelidae, Procyonidae and domestic animals (cattle, dogs, horses), while A. pseudoconcolor has also been found occasionally on wild hosts of the family Didelphidae and on domestic animals (cattle, dogs). Amblyomma pseudoconcolor appears to be restricted to the Neotropical region, covering northern Argentina and the eastern region of South America from Uruguay to Surinam, including south-eastern Paraguay, eastern Brazil and French Guiana. Amblyomma auricularium is distributed from northern Patagonia in Argentina throughout the Neotropics into the Nearctic region up to the southern USA (Texas, Florida), with collection localities also in Belize, Bolivia, Brazil, Colombia, Costa Rica, French Guiana, Honduras, Mexico, Nicaragua, Panama, Paraguay, Trinidad & Tobago, Uruguay and Venezuela. It is not known whether A. auricularium is an established resident of the USA.     

Occurrence of Ornithodoros brasiliensis Aragão (Acari: Argasidae) in São Francisco de Paula, RS, Southern Brazil

There have been no reports of the endemic Ornithodoros brasiliensis (Arag?o) in Rio Grande do Sul, southern Brazil, since the 1950s. In January 2007, 21 O. brasiliensis ticks were collected in a rural area named "Cruzinha" in the municipality of S?o Francisco de Paula, RS, and another population was sampled later that year (October) in Vargem do Cedro, another rural area of S?o Francisco de Paula, following reports of human parasitism by ticks. The reappearance of this tick is a reason for concern in terms of public health.     

Ticks (Acari: Ixodidae) associated with domestic dogs in Franca region,São Paulo,Brazil

Ticks on 140 domestic dogs from both urban and rural areas of Franca region in São Paulo state were identified with 102 dogs from urban areas and 38 from rural areas. Of urban dogs, 27.5% were infested exclusively by Rhipicephalus sanguineus ticks. Of the rural dogs, 36.8% were infested with the following tick species: R. sanguineus, Boophilus microplus, Amblyomma ovale and A. cajennense. Mixed infestations included a dog hosting A. cajennense and A. ovale and another with B. microplus and R. sanguineus. The most intense infestations were detected on urban dogs. Hemolymph tests of these ticks performed to detect rickettsial or Borrelia bacteria yielded negative results.     

Do the level of energy reserves, hydration status and Borrelia infection influence walking by Ixodes ricinus (Acari: Ixodidae) ticks?

Ixodes ricinus horizontal movement within a humidity gradient and the influence of infection by Borrelia burgdorferi sensu lato (s.l.) on tick walking were investigated. Nymphs were placed within an arena containing a humidity gradient ranging from 45 to 95% relative humidity (RH). After 1 h of acclimation at 70% RH ticks were released so that they could either stay, or walk towards either the wet or the dry end. Their position was recorded 2 h post-release. Fat content was quantified and Borrelia infection was detected using real-time PCR and PCR followed by Reverse Line Blotting. Among the 1500 ticks tested, 29·85% were infected. More low-fat nymphs walked inside the arena than high-fat individuals. When nymphs walked, more low-fat ticks walked towards wetter than drier air, whereas more high-fat individuals walked towards drier than wetter air. Among high-fat nymphs, a lower proportion of Borrelia-infected ticks walked inside the arena compared to uninfected individuals, as though spirochetes manipulated their arthropod vector to stay. However, Borrelia infection had no effect on walking direction towards the dry or the wet end. Hence, it appears that I. ricinus nymphs walk horizontally over short distances within a humidity gradient depending on both energy resources and Borrelia infection.     

Biology of Triatoma klugi Carcavallo,Jurberg, Lent & Galvão 2001 (Heteroptera: Reduviidae) under laboratory conditions: effects of distinct blood sources and susceptibility to Trypanosoma cruzi and Trypanosoma rangeli

The life cycle of Triatoma klugi Carcavallo, Jurberg, Lent & Galv?o 2001 was compared under laboratory conditions using two groups of the F1 generation obtained from field-collected bugs. Among the 100 nymphs weekly fed on mice (Group A) or chicken (Group B), 77% of Group A and 67% of Group B reached the adult stage, and the mean time from the first nymphal stage to adult was 190.08 +/- 28.31 days and 221.23 +/- 40.50, respectively. The average span in days for each stage per group and the number of blood meals required for each stage were also evaluated. The overall mortality rate was 23% and 33% for Groups A and B, respectively. The mean number of eggs laid per month in a three-month period was of 56.20, 51.70 and 73.20 for Group A, and 64.50, 53.50 and 38.71 for Group B. Despite the blood source, comparative analysis revealed no statistically significant differences in the life cycle of T. klugi under laboratory conditions. Infection rates over 60% were observed for both Trypanosoma cruzi strains tested. Even revealing high infection rates of the hemolymph by T. rangeli strains, T. klugi revealed no salivary gland infections and was not able to transmit the parasite.     

γ-Aminobutyric acid (GABA) and other amino acids in tissues of the tick,Amblyomma hebraeum (Acari: Ixodidae) throughout the feeding and reproductive periods

We assayed a variety of tick (Amblyomma hebraeum Koch; Acari, Ixodidae) tissues for a number of amino acids throughout the feeding and early reproductive periods. Our HPLC assay could detect as little as 2–5 pmol per sample of the following: GABA, glycine, serine, glutamine, alanine, taurine, glutamate and aspartate. All of these amino acids could be detected in the salivary gland, synganglion (=total CNS in acarines), haemolymph, Gené's organ, seminal receptacle and ovary. GABA reached high levels in the salivary gland of freshly engorged ticks (685 nmol g^-1) and in the synganglion it exceeded 1000 nmol g^-1 throughout most of the feeding cycle and the first week post-engorgement. GABA also reached a peak titre in the haemolymph of 40 nmol ml^-1. Taurine levels peaked at 1065 nmol g^-1 in the salivary gland from large partially fed ticks. Glutamate and aspartate were likewise found in the salivary gland and synganglion at high concentrations. For most of the amino acids there is insufficient information to correlate these titres (and fluctuations of titres) to neuromodulatory functions. It is possible, however, that the high GABA titre in the salivary gland of engorged ticks is correlated with an augmented level of fluid secretion.Deceased: Department of Pharmacology, University of Alberta, Edmonton, Alberta, Canada, T6G 2E9.     

Insecticidal activity of cerrado plant extracts on Rhodnius milesi Carcavallo, Rocha, Galvão & Jurberg (Hemiptera: Reduviidae), under laboratory conditions

Chagas' disease is chiefly transmitted by feces of haematophagous bugs (Triatominae) that ingested Trypanosoma cruzi from blood of infected people or animals. Pyrethroids have been the main insecticides used against these insects. However, some populations of insects have shown significant levels of resistance to several pyrethroids, indicating the need of new insecticides for the control of triatomines. Insecticidal activity of 24 Cerrado plant extracts belonging to five species of four families were assayed on fourth instar nymphs of Rhodnius milesi Carcavallo, Rocha, Galv?o & Jurberg (Hemiptera: Reduviidae), under laboratory conditions. For the extract application on triatomines, 50 microg of the extract were topically applied in duplicate on dorsal tergites of ten insects. Insects topically treated with acetone, ethanol, as well as insects with no treatment were used as controls. Triatomines were observed over a 28-day period. Hexanic and ethanolic extracts of Simarouba versicolor, Guarea kunthiana, Guarea guidonia and Talauma ovata caused mortality between 20% and 95% of R. milesi in comparison with the controls, which showed no insect mortality. These preliminary data suggest that the ethanolic extract of the root bark of S. versicolor and the hexanic extract of the root of G. guidonia, responsible for a 95% and 75% insect mortality, respectively, should be chemically investigated and monitored through biological assays in order to determine their insecticidal components, that could be used as a molecular model or as biorational compounds for use in insect control programmes.     

Changes in Habitat Suitability for the Tick Ixodes ricinus (Acari: Ixodidae) in Europe (1900–1999)

Climatic changes may lead to drastic changes in the distribution of arthropods important in human health. We tracked changes in habitat suitability for the tick Ixodes ricinus in Europe from 1900 to 1999, using a geographically extensive gridded climate data set. For the whole period, 52% of the territory was always unsuitable for the tick. In the grid, 6.11% of the cells were classified as having a deterministic drift with positive trend and 7.4% as deterministic drift with a negative trend. A total of 17.25% of cells were classified as exhibiting a random walk behavior, with a trend to increase of habitat suitability (9.57%) or decrease (7.68%). Zones of deterministic trend extend into most of Ireland and parts of the United Kingdom and France. Total and summer rainfall primarily drive changes in habitat suitability in these sites. Areas of random walk are common in Scandinavia, central Europe, and the Balkans, with summer rainfall and temperature largely directing the changes. Sites of reported increased abundance of I. ricinus coincided with areas of increased habitat suitability over the last 20–30 years, but this feature showed a long-term random walk negative trend. Habitat suitability for I. ricinus remains relatively stable in Europe, with no sites showing permanent changes in habitat suitability (negative to sustained positive or vice versa). However, some zones in the continent showed a clear trend to increase or decrease.     

Environmental variables and intertidal beach annelids of São Sebastião Channel (State of São Paulo,Brazil)

Benthic annelid communities were studied during a one-year period (August/95 to July/96) in two sectors of the beaches Engenho d'Agua and S?o Francisco, S?o Sebasti?o Channel (S?o Paulo, Brazil), where the substrate is composed by a mixture of sand and rock fragments. Abiotic parameters such as salinity of interstitial water and sediment properties were used to characterize the environment. The polychaetes were well represented in the two sectors and their distribution was related with sediment type. The density of individuals and the number of taxa was higher at S?o Francisco, while the diversity and the evenness were higher at Engenho d'Agua. This difference can be a consequence of organic enrichment caused by domestic input, and of the lower and more variable salinity at S?o Francisco. Due to these factors, the high density of opportunistic species, like Capitella capitata ssp., Scolelepis squamata, Laeonereis acuta and several oligochaetes, represented 75.5% of total abundance at this sector.     

Outbreaks of Trialeurodes vaporariorum (West.) (Hemiptera: Aleyrodidae) under field conditions in the State of São Paulo, Brazil

Trialeurodes vaporariorum (West.) is a pest of greenhouse vegetables and ornamentals and infests crops in Europe and in the American continent. In Brazil, just a few cases are known on economic crops, being all restricted to greenhouse crops. In 2003, in Itatiba and neighboring localities of State of S?o Paulo, Brazil, field infestations of T. vaporariorum were observed, mainly on tomato and green bean. So far, whitefly infestation in this area expanded to squash and kale also. Field studies are needed for determining interactions of T. vaporariorum with plants and natural enemies, injury levels, and methods of control.     

Morphology and structural organization of gené's organ in Dermacentor reticulatus (Acari: Ixodidae)

Scanning and transmission electron microscopical investigations revealed that Gené's organ in unfed and ovipositing females of Dermacentor reticulatus is formed as a double-sac-structure consisting of an outer epithelial and an inner cuticular sac. In ovipositing ticks the latter emerges through the camerostomal aperture to the exterior. Gené's organ in unfed ticks consists of a corpus, two posterior horns and a pair of undeveloped glands at each side, which differentiate in ovipositing ticks to compound, branched tubular glands with a main efferent duct for each gland opening into the lumen between the epithelial and the cuticular sac. Gené's organ of egg-laying females corresponds basically in morphology and structural organization to that of unfed ticks. Compared with unfed ticks, however, in ovipositing ticks the corpus and horns are longer and broader, the glands are fully developed and the cuticular sac is evertable. The epithelial sac as the outermost part of Gené's organ is continuous with the hypodermis of the basis capituli and the scutum, arises at the camerostomal aperture, forms the corpus and the two blind-ending horns, passes into the epithelium of the main excretory ducts of the glands and envelops the cuticular sac. The cuticular sac passes into the cuticle of the basis capituli and the scutum, arises at the camerostomal aperture, is folded, expands into the horn tips and consists inwards of a smooth epicuticula and outwards of a fibrous endocuticula. Muscles originating from the scutum pass caudomedially through the epithelial sac and are inserted into the cuticular sac. The entire surface of the maximally everted cuticular sac is covered with an amorphous mass. In cleaned samples, ledge-like structures appear on the lateral surface. These ledges turn into balloon-like structures which extend over the medial and dorsal surface. The entire surface including the balloon-like structures and the ledges are provided with numerous cribrate pits.     

Diversity of phytoseiid mites (Acari: Mesostigmata: Phytoseiidae) in the Atlantic Forest of São Paulo

The objective of this study was to evaluate the diversity of Phytoseiidae in the Atlantic Forest of São Paulo State, Brazil, and to estimate the possible role of this ecosystem as a reservoir for mites of this family. Samples were taken from 187 plant species belonging to 73 plant families in three vegetation types of the Atlantic Forest, from February 2001 to October 2002. In total, 1102 specimens of 54 species belonging to 20 genera of the three phytoseiid subfamilies were found. Most specimens (93%) and species (91%) belonged to the Amblyseiinae. The majority of species found belong to taxonomic groups largely composed of generalist predators (especially Amblyseius and Euseius). In general, the more abundant mites were found on a diversity of plant species, but a few of the abundant species were found on only a small number of plant species. Only nine of the mites encountered during this study are of known agricultural importance. The results obtained suggest the importance of the wide plant diversity in the region to sustain a wide diversity of phytoseiids. The extensive clearance of the Brazilian Atlantic Forest is a threat to the diversity of these mites, important predators of mite pests.     

Functional morphology of Gené's organ inHaemaphysalis longicornis (Acari: Ixodidae)

The structure and function of Gené's organ, which secretes the egg wax, were investigated inHaemaphysalis longicornis. The hatching rates of eggs deposited before and after the prevention of the eversion of Gené's organ were compared at the conditions of 30°C, 100% RH and soaking in liquid paraffin. The movement of Gené's organ was observed, and the structures of this organ in unfed and ovipositing females were examined with both light and scanning electron microscopes.The hatching rates of eggs without contact with Gené's organ were markedly lower (4.9%) than that of normal eggs (94.5%) even at the suitable condition for eggs (30°C, 100% RH). In contrast, the hatching rates of eggs soaked in liquid paraffin without contact of Gené's organ were considerably higher (71.8%) than that of eggs without both Gené's organ contact and soaking in liquid paraffin.When oviposition commenced, the camerostome of the female was widened by a downswing of the capitulum, the paired horns of Gené's organ emerged through it, and the oviposited egg from the genital aperture was coated with egg wax. At the same time of retraction of the horns which grip an egg, the capitulum was swung up and the egg was loaded on the scutum.Gené's organ included the outer and inner cuticles, and the outer one is highly folded like bellows when the horns of this organ were retracted into the haemocoel. The undeveloped glands lying in the peripheral region of Gené's organ in the unfed stage commenced their enlargement at the time of the onset of feeding, and they became large tubular glands in the 1-day ovipositing female. The columnar glandular cells of the tubular glands extended their domed apical region into the lumen and contained numerous secretory granules during oviposition.These results suggest that the tubular glands secrete the egg wax which is indispensable for egg survival by serving as a waterproofing agent.     

Mites (Acari: Arachnida) associated with Bauhinia variegata L. (Leguminosae) in northeast of State of São Paulo, Brazil

The occurrence of mites on Bauhinia variegata L., a species introduced in Brazil as ornamental, was studied. Two plants of this species were sampled monthly from May 2000 to April 2001. A total of 8,482 mites, belonging to 25 species in 11 families were collected. The abundance of phytophagous mites was higher, being Lorryia formosa Cooreman the dominant species. The dominance of L. formosa might be caused by stress conditions of sampled plants and low number of predaceous mites on those plants.     

Virus–Pesticide interactions in Ixodes persulcatus and Amblyomma hebraeum ticks (Acarina: Ixodidae)

Sublethal doses of the organophosphate Dursban were tested on non-infected and tick-borne encephalitis virus (TBEV)-infected nymphs of Amblyomma hebraeum and Ixodes persulcatus. It was shown that contact with this pesticide enhanced the survival of non-infected ticks, whereas TBEV infection reduced survival. This effect of TBEV infection was greater in I. persulcatus than in A. hebraeum ticks. This phenomenon may be the result of a virus-specific action on nymphs, whereby the virus may enhance activity and thus food reserves may deplete faster. Our data emphasize that the acaricidal action on non-infected ticks and those infected by different tick-borne pathogens may be different.