Wild birds as hosts of Amblyomma cajennense (Fabricius, 1787) (Acari: Ixodidae).

We evaluated the prevalence, mean intensity and relative density of ticks in 467 wild birds of 67 species (12 families) from forest and cerrado habitats at two protected areas of Minas Gerais, between March and September 1997. Ticks collected (n=177) were identified as larvae and nymphs of Amblyomma cajennense and four other species of Amblyomma. We report for the first time 28 bird species as hosts of the immature stages of A. cajennense, demonstrating the lack of host specificity of the larvae and nymphs. A. cajennense had 15% prevalence on birds, with a mean infestation intensity of 0.37 ticks per host sampled, and 2.5 ticks per infested bird. Prevalence varied in relation to host species, diet and between birds from forests at two successional stages. There were no differences in relation to host forest dependence, participation in mixed flocks of birds, and nest type constructed. A. cajennense is a species of medical and veterinary importance, occurring on domestic animals but is known little of its occurrence on wildlife.     

Lack of parthenogenesis by Amblyomma cajennense (Acari: Ixodidae)

Some reproductive parameters of adult stages of Amblyomma cajennense ticks were studied. The capacity of virgin females to reproduce by parthenogenesis was evaluated, during an experimental infestation, in absence of males, on a horse (Equus cabalus). Ticks were spread either completely free or in limited sites on the body of the animal. The engorged virgin females showed longer feeding periods and lighter body weights than those that had been fertilized. Some of these unmated females produced smaller egg masses, which had no embryonary development. On the other hand, females that had been inseminated produced larger egg masses, with normal embryonary development that led to viable larvae. Under the studied conditions, A. cajennense females did not reproduce by parthenogenesis.     

Ticks (Acari: Ixodidae) from yellow armadillo, Euphractus sexcinctus (Cingulata: Dasypodidae), in Brazil's Pantanal wetlands

Tick species parasitizing yellow armadillo, Euphractus sexcinctus, were recorded from October 2006 to October 2007 in Pantanal. A total of 89 ticks were collected from 23 yellow armadillos. Most ticks (n=50) were identified as Amblyomma cajennense (Fabricius) (32 males and 18 females). The only other species found was Amblyomma parvum (Arag?o) (three females and two males). The remaining ticks were immatures of Amblyomma (29 nymphs and five larvae). The prevalence of A. cajennense was 55%, the mean intensity was 2.7±0.5 (SE) (n=17) and the mean abundance was 1.5±0.4 (n=31).     

Toxicity of extract of Magonia pubescens (Sapindales: Sapindaceae) St. Hil. to control the brown dog tick, Rhipicephalus sanguineus (Latreille) (Acari: Ixodidae)

The action of crude ethanol extract of the stem bark of the soapberry Magonia pubescens St. Hil. was studied upon larvae of the Brown Dog tick Rhipicephalus sanguineus (Latreille). Tick larvae were obtained by maintaining gravid females in an incubator, after collecting them from naturally infested kennels. The tick larvae were placed in envelopes of filter paper impregnated with different concentrations of the extract dissolved in dimethylsulfoxide (DMSO) and distilled water. Four tests were repeated with each solution (n > 120). The control was carried out in DMSO and distilled water. The bioassays were performed at 27 +/- 1 degrees C, RH > 80% and 12:12 light cycle. Mortality was observed after 48 h exposure. All motionless larvae were considered to be dead. The extract of M. pubescens showed larvicidal potential against R. sanguineus. The lethal concentrations of 1503 ppm (LC50) and 9991 ppm (LC99) were obtained. There was no mortality in the control group. Based on the results of the current study, M. pubescens should be recognized as an future alternative acaricide for the control of Brown Dog tick. These results reinforce the importance of the preservation of this soapberry in its natural biome.     

Spotted fever group Rickettsia infecting ticks (Acari: Ixodidae) in the state of Santa Catarina, Brazil

During 2006-2008, a total of 260 adult ticks were collected from domestic and wild animals in different regions of the state of Santa Catarina (SC), Brazil, including areas where human cases of Brazilian spotted fever have been reported. Collected ticks belonging to nine species (Amblyomma aureolatum, Amblyomma cajennense, Amblyomma dubitatum, Amblyomma longirostre, Amblyomma ovale, Amblyomma tigrinum, Dermacentor nitens, Rhipicephalus microplus and Rhipicephalus sanguineus) were tested by polymerase chain reaction (PCR) for rickettsial infection. Overall, eight (3.1%) ticks were found to be infected with Rickettsia species. After sequencing the PCR products, we determined that the sequences generated from three A. aureolatum, one A. ovale and one R. sanguineus from the municipality of Blumenau, one A. ovale from the municipality of águas Mornas and one A. ovale from the municipality of Urussanga were identical to the corresponding partial rickettsial ompA gene sequence of Rickettsia parkeri strain Atlantic rainforest. The sequence generated from one A. longirostre from Blumenau was 100% identical to the corresponding partial rickettsial ompA gene sequence of Rickettsia amblyommii strain AL. Because R. parkeri strain Atlantic rainforest was recently shown to have caused two cases of human spotted fever in other states of Brazil, the role of this rickettsial agent as a possible etiological agent of spotted fever in SC is discussed.     

Ticks (Acari: Ixodidae) associated with small terrestrial mammals in the state of Minas Gerais, southeastern Brazil

From June 2005 to November 2010, 43 small mammals encompassing 6 species of Didelphimorphia, 8 species of Rodentia, and 1 species of Lagomorpha were found parasitized by ticks in the state of Minas Gerais, southeastern Brazil. Nine tick species, in total 186 specimens, were identified as follows: Amblyomma cajennense (larvae and nymphs) on opossums and rodents; Amblyomma ovale (nymphs) on rodents; Amblyomma parvum (nymphs) on rodents; Amblyomma coelebs (nymphs) on opossums; Amblyomma dubitatum (nymph) on opossums; Ixodes amarali (females, nymphs, and larvae) on opossums and rodents; Ixodes loricatus (male, females, nymph) on opossums; Ixodes schulzei (female) on rodents; and Haemaphysalis leporispalustris (female) on rabbits. Most of the tick-host associations found in the present study have never been recorded in the literature; those include three new host records for I. amarali, four for A. cajennense, one for A. dubitatum, two for A. ovale, and one for A. coelebs. In addition, we provide the first record of A. coelebs in the state of Minas Gerais.     

Comparison of feeding efficiency, development time and survival of Tasmanian eucalyptus leaf beetle larvae Chrysophtharta bimaculata (Olivier) (Coleoptera: Chrysomelidae) on two hosts

The native Eucalyptus leaf beetle Chrysophtharta bimaculata (Olivier) (Coleoptera: Chrysomelidae) has become a pest of the introduced, plantation species, Eucalyptus nitens Maiden in Tasmania, Australia. However, in the field it prefers to oviposit on the Tasmanian native species, E. regnans F. Muell. This laboratory study found that the performance of C. bimaculata larvae was superior on foliage of E. nitens compared with E. regnans . Larval development was 4 days shorter on E. nitens than on E. regnans foliage. Total food consumption per larva and relative consumption rates were about 30% lower while relative growth rates and weight of emergent adults were more than 25% higher on E. nitens than E. regnans . Efficiency of conversion (ECI) of fresh food into larval wet weight was 0.26 on E. nitens compared with 0.14 on E. regnans . Mortality of larvae feeding on E. nitens (23%) was only one third of that on E. regnans (69%), a result of high first instar mortality on E. regnans . Although the amount of foliage consumed per larva was lower on E. nitens (0.23 g vs 0.32 g), the differential mortality meant that the amount of E. nitens consumed per egg batch was 60% more than that of E. regnans . If these results occurred in the field, then the same monitored population of C. bimaculata eggs may result in heavier defoliation of plantation E. nitens than of E. regnans . These data show that the reported oviposition preference of C. bimaculata for E. regnans in the field cannot be explained by selection of host factors related to superior larval performance.     

Gynandromorphism in Amblyomma cajennense and Rhipicephalus sanguineus (Acari: Ixodidae)

During a survey of ticks on horses in November 2000, at the University of S?o Paulo farm in Pirassununga county, S?o Paulo, Brazil, 1 gynandromorph of Amblyomma cajennense was collected from a naturally infested horse. In another survey on dogs in March 2001, in the urban area of Monte Negro, Rond?nia, Brazil, a gynandromorph of Rhipicephalus sanguineus was collected from a naturally infested dog. Both specimens are described and classified as perfect bipartite protogynanders.     

Susceptibility of the cattle tick Boophilus microplus (Acari: Ixodidae) to isolates of the fungus Beauveria bassiana

The susceptibility of the tick Boophilus microplus to Beauveria bassiana was evaluated by inoculating eggs, larvae and engorged females of the tick with five fungal isolates at concentrations of 10⁶, 10⁷ and 10⁸ conidia/ml. Tick eggs (0.25 g) were immersed in 1 ml of a suspension of the different conidial concentrations for 1 min. Similar exposure was performed by immersion of 2000 larvae and homogeneous groups of nine engorged females in 2 and 20 ml of conidial suspension, respectively. Treated eggs, larvae and adults were placed in an incubator at 27 ± 1 °C and relative humidity above 80% for evaluation of the fungal action. All fungal isolates applied at all conidial concentrations reduced the hatching rate of larvae from treated eggs by 1.36–65.58% and increased the mortality rate of inoculated larvae by 0.8–70.49%. In the bioassay with engorged females, oviposition period was reduced by 9.69–47.80%, egg mass weight by 4.71–53.87%, estimated reproduction by 8.3–60.62%, egg production index by 5.03–54.20%, percent larval hatching by 0.27–13.96%, and the mortality rate of treated females was increased by 96.60–100%. The reduction of the estimated reproduction obtained for the treated groups ranged from 8.37 to 64.52%. The sporulation of the pathogen on dead females ranged from 3.70 to 88.88% depending on the isolate and concentration used. Isolates AM 09, CB 7 and JAB 07 were the most effective and effectiveness increased with increasing concentrations of conidia in the suspensions.     

Susceptibility of immature Ixodes scapularis (Acari: Ixodidae) to desiccants and an insecticidal soap

Efficacy of commercially available formulations of desiccants (Drione, Dri-dic, diatomaceous earth) and insecticidal soap (Safer's) comprised of active ingredients were evaluated against Ixodes scapularis Say immatures in petri dish and grass turf bioassays. In petri dish bioassays at label rate, all products, except diatomaceous earth, provided a high degree of control by 24 and 48 h (71–100% mortality). Mortality of larvae exceeded 94% by 4 h after treatment with Drione (10× label rate held at 85% RH), Dri-die (label rate held at both 85% and 98% RH) and Safer's insecticidal soap (10× label rate held at 98% RH). Nymphal mortality was highest by 4 h after treatment with Safer's insecticidal soap (up to 96%). Larvae were more susceptible than nymphs to desiccants, however, nymphs were more susceptible than larvae to Safer's insecticidal soap. Immature ticks treated with Safer's insecticidal soap exhibited sublethal effects with significantly decreased attachment to hosts and no engorgement. In grass turf bioassays, mortality of nymphs was equivalent (85–95%) between treatments of chlorpyrifos (0.6 kg [AI]/ha, Safer's insecticidal soap, and Drione. In the same bioassays, nymphal mortality was moderate after treatment with Dri-die (23–29%) and low following application with diatomaceous earth (16%) and for untreated controls (6%).     

A quantitative resazurin assay to determinate the viability of Trichomonas vaginalis and the cytotoxicity of organic solvents and surfactant agents

Trichomonas vaginalis causes trichomonosis, the most common, non-viral sexually transmitted disease. To test anti-Trichomonas agents, usually many with low water solubility, organic solvents and surfactant agents should be used. Therefore, the minimal inhibitory concentration (MIC) of acetone, methanol, ethanol, isopropanol, DMSO, Tween 20, Tween 80, and Triton X-100 was determined against T. vaginalis isolates using the quantitative resazurin method. Our results showed that solvents and surfactant agents can be employed as vehicles to test bioactive compounds at lower concentrations than MIC values and we suggest acetone and DMSO as preferential. Moreover, a new methodology is established to substitute or to complement the counting of viable trophozoites. The amount of resazurin reduced by T. vaginalis can be quantified by fluorescence spectroscopy, making the test a quantitative determination of cell viability. These results contribute for pharmacological investigations of bioactive compounds that need the use of solvents as solubilization vehicles to test anti-Trichomonas activity.     

Acaricide susceptibility ofAmblyomma variegatum (Acari: Ixodidae) from Puerto Rico and Guadeloupe

Base-line data on acaricide susceptibility of larvae and of larvae and nymphs of the tropical bont tick,Amblyomma variegatum (Fabricius), from Puerto Rico and Guadeloupe were collected on 14 and six compounds, respectively. Nymphs 7–8 weeks old from Puerto Rico and Guadeloupe, and larvae 3–4 weeks old from Guadeloupe, were exposed for 24 or 48 h to residues of acetone dilutions of technical-grade or commercial formulations of acaricides on disposable glass pipettes. Effectiveness of the acaricides in killing nymphs (lc ₅₀) from Guadeloupe and Puerto Rico ranged from 0.0001% for deltamethrin to 0.269% for malathion. For Puerto Rico, the susceptibility to toxaphene and amitraz, but not to dioxathion, increased with increasing age of nymphs. Nymphs from Guadeloupe were 9.5 times more susceptible to chlorpyrifos than nymphs from Puerto Rico. The susceptibility of larvae from Guadeloupe to acaricides tested ranged fromlc ₅₀ 0.000012% for deltamethrin to 0.0141% for ethion. There was no evidence of development of acaricide resistance in ticks from Guadeloupe or Puerto Rico.     

Pathogenicity of entomopathogenic fungi to different developmental stages of Rhipicephalus sanguineus (Acari: Ixodidae).

The pathogenicity of 4 species of entomopathogenic fungi (Hyphomycetes species: Beauveria bassiana, Metarhizium anisopliae, Metarhizium flavoviride, and Paecilomyces fumosoroseus) to various developmental stages of Rhipicephalus sanguineus (Acari: Ixodidae) ticks was compared under laboratory conditions. The most virulent isolate, M. anisopliae-108, caused 92-96% mortality to unfed larvae and nymphs on day 7 postinfection (PI) and 100% mortality to unfed adults and engorged females on day 21 PI. The pathogenicity of M. anisopliae-108 to engorged larvae and nymphs was lower--82.6 and 60%, respectively. All tested B. bassiana, M. flavoviride, and P. fumosoroseus isolates were significantly less virulent (P < 0.05) or avirulent toward most life stages of R. sanguineus. The M. anisopliae and M. flavoviride isolates also prevented or reduced the ability of the ticks to lay eggs several days before their deaths. Female ticks infected by the fungi achieved only 11.3-60.8% of their egg-laying capacity compared with the controls.     

Cold-hardiness of Dermacentor marginatus (Acari: Ixodidae)

The cold-hardiness of Dermacentor marginatus using laboratory-reared offspring of ticks collected in Germany was characterized. Investigations of unfed stages revealed that adult ticks suffered 50% mortality at –10°C after 4–5 months, but larvae and nymphs suffered mortality within few days, whereas –15°C was lethal for all stages within a very short period. Larval hatch and moulting of engorged larvae and nymphs did not occur at 10°C. Embryonic development of eggs with larval hatch was considerably reduced by exposure of eggs to 10°C. Engorged females did not lay eggs at 10°C, the oviposition capability, however, persisted over 6 months at 10°C, 5 months at 5°C, 3 months at 0°C and 2 months at –10°C without substantial decrease of the oviposition capacity or reduction of viable eggs. These results present evidence that unfed adult ticks are the ecoepidemiologically most effective stages, which are capable to tolerate long and extremely cold winters without substantial impairment of the population density. It is also considered that engorged females interrupt their oviposition at low and subzero temperatures delaying it for months and so contribute in bypassing winter conditions. None of the stages survived supercooling indicating that D. marginatus is freeze intolerant. Mean supercooling point (SCP) ranged between –26°C in eggs and –12, 6°C in engorged females. Compared with eggs, the SCP of the other stages was significantly higher. In conclusion, the SCP is considered to have no predictive value in the context with cold-hardiness.     

Ticks (Acari: Ixodidae) of the state of Amazonas,Brazil

The tick fauna of Brazil is currently composed by 72 species. The state of Amazonas is the largest of Brazil, with an area of ≈ 19% of the Brazilian land. Besides its vast geographic area, only 19 tick species have been reported for Amazonas. Herein, lots containing ticks from the state of Amazonas were examined in three major tick collections from Brazil. A total of 5933 tick specimens were examined and recorded, comprising 2693 males, 1247 females, 1509 nymphs, and 484 larvae. These ticks were identified into the following 22 species: Amblyomma cajennense sensu lato, Amblyomma calcaratum, Amblyomma coelebs, Amblyomma dissimile, Amblyomma dubitatum, Amblyomma geayi, Amblyomma goeldii, Amblyomma humerale, Amblyomma latepunctatun, Amblyomma longirostre, Amblyomma naponense, Amblyomma oblongoguttatum, Amblyomma ovale, Amblyomma rotundatum, Amblyomma scalpturatum, Amblyomma varium, Dermacentor nitens, Haemaphysalis juxtakochi, Ixodes cf. Ixodes fuscipes, Ixodes luciae, Rhipicephalus microplus, Rhipicephalus sanguineus sensu lato. Ticks were collected from 17 (27.4%) out of the 62 municipalities that currently compose the state of Amazonas. The following four species are reported for the first time in the state of Amazonas: A. coelebs, A. dubitatum, H. juxtakochi, and Ixodes cf. I. fuscipes. The only tick species previously reported for Amazonas and not found in the present study is Amblyomma parvum. This study provides a great expansion of geographical and host records of ticks for the state of Amazonas, which is now considered to have a tick fauna composed by 23 species. It is noteworthy that we report 1391 Amblyomma nymphs that were identified to 13 different species.     

The life cycle of Amblyomma pseudoparvum (Acari: Ixodidae) in the laboratory

A colony of Amblyomma pseudoparvum was started with male and female ticks collected from the cavy-like rodent Dolichotis salinicola, in the Province of Salta, Argentina. These ticks and their progenies were fed on rabbits and the non-parasitic stages maintained in darkness at 27±1°C, 83–86% RH. The life cycle (pre-feeding and oviposition periods not tested) of A. pseudoparvum had a mean duration of 90.9 days. The mean time (days) for the different periods of the cycle were as follows: Feeding of females, 12.3; pre-oviposition, 5.1; minimum egg incubation, 33.4; feeding of larvae, 5.6; pre-moult to nymphs, 11.5; feeding of nymphs, 6.9; pre-moult to adults, 16.1. The mean recovery rates of larvae, nymphs and females were 16.0%, 18.7% and 53.0%, respectively.     

Larval gregariousness and neonate establishment of the eucalypt-feeding beetle Chrysophtharta agricola (Coleoptera: Chrysomelidae: Paropsini)

The selective advantage offered to individuals living within groups may relate to natural enemy defence, but in leaf feeding insects may also relate to overcoming plant defences, especially with respect to feeding establishment. We conducted a series of experiments focusing on neonate larval survival, examining the effect of group size and leaf age on the survival of a eucalypt-feeding beetle, Chrysophtharta agricola , which formed groups of up to 43 larvae on the foliage of Eucalyptus nitens in the field. In the laboratory, in the absence of natural enemies, we found that initial density, leaf age and damage to the leaf margin significantly affected larval survival. Survival of solitary first-instar larvae on young foliage was around 80% whereas on older foliage it was around 11%. Prior damage to the leaf margin significantly increased survival on older leaves to around 61%. Initial larval density also affected survival, although mortality was always significantly higher on older leaves. On older leaves the larval group size above which mortality increased no further was over two-fold that on young leaves. Observations of group feeding behaviour at each instar showed that the majority of larvae (75.7%) were aligned facing away from the feeding site and that only around 7.5%, or just 1–2 larvae per group, fed at any one time. Feeding larvae chewed the leaf edge by straddling the leaf margin. Measurements of leaf margins showed that older leaves had significantly thicker leaf margins and 'thickness' ratios (leaf margin to leaf lamina proper). In the field, approximately 85% of all larvae occurred on the first two expanded leaf pairs, and larval mortality was highest between eclosion and establishment of the first instar. However, beetles apparently did not adjust clutch size according to leaf age.     

Seasonal analysis of the number of aeropiles in Anocentor nitens (Neumann, 1897) (Acari: Ixodidae) from the State of Rio de Janeiro, Brazil

Variation between aeropile numbers of the right and left peritrematic plate in male and female Anocentor nitens (Neumann, 1897) is reported from a site in Brazil. From January to December 1998, 146 males and 247 females of A. nitens were recovered from Equus caballus L. in Silva Jardim District, State of Rio de Janeiro. Asymmetry of numbers of aeropiles between right and left plates occurred in 83.6% of the males and 82.2% of the females. Differences in the number of aeropiles between the sexes were not significant. Quantitative variation of aeropiles was correlated to the period of recovery, with significant asymmetry detected in August-September and November-December, mainly in males. Results suggest an adaptation, especially in the male ticks, that expresses itself as greater variation in the number of aeropiles in some periods of the year.     

Ticks (Acari: Ixodidae) on wild animals from the Porto-Primavera Hydroelectric power station area,Brazil

From June 2000 to June 2001, a total of 741 ticks were collected from 51 free-living wild animals captured at the Porto-Primavera Hydroelectric power station area, located alongside an approximately 180 km course of the Paran river, between the states of S o Paulo and Mato Grosso do Sul, comprising 9 species of 3 genera: Ambly-omma (7 species), Boophilus (1) and Anocentor (1). A total of 421 immature Amblyomma ticks were reared in laboratory until the adult stage, allowing identification of the species. A. cajennense was the most frequent tick species (mostly immature stages) collected on 9 host species: Myrmecophaga tridactyla, Tamandua tetradactyla,Cerdocyon thous, Puma concolor,Tayassu tajacu, Mazama gouazoubira,Hydrochaeris hydrochaeris,Alouatta caraya, Cebus apella. Other tick species were less common, generally restricted to certain host taxa.     

Fluorene biodegradation and identification of transformation products by white-rot fungus Armillaria sp. F022

A diverse surfactant, including the nonionic Tween 80 and Brij 30, the anionic sodium dodecyl sulphate, the cationic surfactant Tetradecyltrimethylammonium bromide, and biosurfactant Rhamnolipid were investigated under fluorine-enriched medium by Armilaria sp. F022. The cultures were performed at 25 °C in malt extract medium containing 1 % of surfactant and 5 mg/L of fluorene. The results showed among the tested surfactants, Tween-80 harvested the highest cell density and obtained the maximum specific growth rate. This due Tween-80 provide a suitable carbon source for fungi. Fluorane was also successfully eliminated (>95 %) from the cultures within 30 days in all flasks. During the experiment, laccase production was the highest among other enzymes and Armillaria sp. F022-enriched culture containing Non-ionic Tween 80 showed a significant result for laccase activity (1,945 U/L). The increased enzyme activity was resulted by the increased biodegradation activity as results of the addition of suitable surfactants. The biotransformation of fluorene was accelerated by Tween 80 at the concentration level of 10 mg/L. Fluorene was initially oxidized at C-2,3 positions resulting 9-fluorenone. Through oxidative decarboxylation, 9-fluorenone subjected to meta-cleavage to form salicylic acid. One metabolite detected in the end of experiment, was identified as catechol. Armillaria sp. F022 evidently posses efficient, high effective degrader and potential for further application on the enhanced bioremediation technologies for treating fluorene-contaminated soil.