Histopathology of Rhipicephalus sanguineus (Acari: Ixodidae) ticks fed on resistant hosts

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Interferência de Brachiaria Ruziziensis sobre plantas daninhas em sistema de consórcio com milho

Regarding tropical forage plants, the specie Brachiaria ruziziensis are prominence for to be most acceptable for cattle when compared with others Brachiaria species, besides the excellent competitive ability with weeds. Then, this study aimed to evaluate the effects of Brachiaria ruziziensis density in intercropping with corn crop, about weeds control and weeds development in the crop-cattle integration system. The experiment was realized during the period between December/2007 to May/2008, in the experimental area of Escola Superior de Agricultura "Luiz de Queiroz", Piracicaba - SP. The treatment was composed in a factorial arrangement, by combination of four Brachiaria ruziziensis density (0, 10, 15 and 20 kg ha(-1)) and three weed species ((Ipomoea grandifolia, Digitaria horizontalis e Cenchrus echinatus), in intercropping with corn crop. The evaluations realized were: weed infestation (density m(-2)), the dry biomass (g plant(-1)) and leaf area (cm(2) plant(-1)). It was noted that Brachiaria ruziziensis reduced the all of weeds infestation evaluated. Also, it was checked that Digitaria horizontalis and Ipomoea grandifolia were the weeds with most difficult control.

Avaliação Comparativa da Agressividade de Meloidogyne javanica e M. incognita à Variedade SP 911049 de Cana-de-açúcar

Nematodes cause extensive losses to sugarcane in Brazil and also in other producing regions. Meloidogyne incognita, M. javanica and Pratylenchus zeae are the key species for this culture worldwide. In the present study, the aggressiveness of M. javanica and M. incognita to sugarcane variety SP 911049 was evaluated comparatively,. The following parameters were compared: reproduction factor (RF) of these nematodes, effect of nematodes in the natural incidence of pests, and the influence on the development and technological characteristics of sugarcane. Considering the data of RF, biometrics, natural infestation of pests, mortality of plants, and technological variables, it was concluded that M. javanica was more aggressive to sugarcane, although its rate of multiplication was much smaller than the one of M. incognita.

Parasitoses em lactentes de 0-12 meses atendidos na Faculdade de Medicina de Botucatu - São Paulo

Infestation by protozoa and/or helminths is considered to be extremely rare in infants. We therefore reviewed the records of all infants up to 12 mth of age attending the Paediatric Department from January 1973 to June 1977, in order to assess the frequency of stool examinations for parasites within this age group, the percentage of positive results in these examinations, and some personal characteristics which propitiated parasitic infestation. Some characteristics of the investigated infants were compared to those of a representative sample of the total number of infants attending during the same period. Stool examinations were realized in 11.8% of the 1,162 attending patients and of those, 15.3% were positive. The proportion of positive cases became 24.0% when the infants in whom there was a history of parasites being passed were included. Ascaris lumbricoides and Giardia lamblia were the parasites most frequently found, respectively in 42.8% and 37.1% of the positive cases. The only detected difference between the control group and the group of infants who had parasitologic examinations was the presence of diarrhea, significantly more frequent in the investigated group. The proportion of positive cases was significantly greater in girls, in infants older than 6 mth and when diarrhea was present for up to 15 days, than in boys, in infants up to 6 mth of age and in chronic diarrhea, respectively. Our results show that parasites were investigated in only a small percentage of infants under 1 yr of age, but that in this age group already, parasitic infestation does occur with a certain frequency. As investigated cases were selected, mainly due to the presence of diarrhea, the real prevalence of parasitism in infants under 1 yr of age was impossible to evaluate.

Epidemiology of sheep myiases in São Paulo State, Brazil

A survey of Diptera species causing cutaneous myiases on sheep in Botucatu, São Paulo, Brazil was made to determine seasonal incidence, predilection sites and the factors predisposing to infestation. Sheep were checked daily for myiases for one year. At two week intervals larvae from wounds were collected for identification. Only larvae of Dermatobia hominis and Cochliomyia hominivorax were found. Myiases due to C. hominivorax were observed during the whole year with high incidence from January to April. The feet, vulva, tail and scrotum were most frequently infested. Wounds were the commonest predisposing factor. © 1992 Centre for Tropical Veterinary Medicine, University of Edinburgh.

Prevalência de Demodex folliculorum e Demodex brevis em uma amostra da população de Botucatu, São Paulo, Brasil.

A survey was conducted to determine the prevalence of D. folliculorum and D. brevis for the first time in Brazil. In this study, association between the presence of mites and host factors (age, sex and race) were analysed. Samples were obtained from 100 individuals submitted to a facial cleaning in an aesthetic clinic in Botucatu city. All the samples were mounted in Berlese's medium and examined by dark-field phase microscopy. From 100 studied individuals, 72 were positive, among the positive cases, 51% showed D. folliculorum, 2% showed D. brevis and 19% both species. The parasite distribution in relation to sex was not taken in account because the sex ratio favoured females (90%). According to age, prevalence was high in all age groups. The factors influencing this distribution could be due. 1. the examination of extensive skin areas, 2. the group examined composed of individuals in treatment in an anaesthetic clinic could be more infested than a normal population, 3. the fact that in tropics, the prevalence is often high in all ages.

Immunisation of dogs, hamsters and guinea pigs against Rhipicephalus sanguineus using crude unfed adult tick extracts

Naive experimental groups of dogs, hamsters and guinea pigs were inoculated three times subcutaneously with unfed adult extract of the tick Rhipicephalus sanguineus and challenged with adult R. sanguineus to evaluate resistance. The acquisition of resistance was based on alterations of some reproductive and feeding performance parameters of female ticks such as female and egg mass weights, engorgement, pre-oviposition and incubation periods, larval hatchability rate and efficiency rates of female ticks in converting their food reservoir to eggs and larvae. Dogs did not develop resistance under these experimental conditions; guinea pigs and hamsters, to a lesser extent, acquired an effective immunity to ticks as demonstrated by the impairment of the reproductive and feeding performance. However, the resistance induced by inoculation of the extract in the rodents seemed not to be as efficient as that induced by successive infestations.

Cutaneous hypersensitivity induced in dogs and guinea-pigs by extracts of the tick Rhipicephalus sanguineus (Acari: Ixodidae)

The cutaneous hypersensitivity induced by Rhipicephalus sanguineus tick extract in dogs (natural host) and guinea-pigs (laboratory host) was evaluated. The left ear of infested and control (tick-bite naive) dogs and guinea-pigs was injected intradermally with an extract from unfed adult ticks and the right ear with phosphate buffered saline (PBS). Ear thickness variations were then measured after 10 min and 1, 2, 6, 18, 24, 48, 72 and 96 h post-injection. Results were expressed as percentual changes in the ear thickness in relation to pre-inoculation values. The final variation in ear thickness induced by the extract was given by subtracting, in each animal, the right ear percentual increase from that of the left ear. Guinea-pigs were tested at two different times following infestation and with two different doses of extract. Infested guinea-pigs from the three experiments developed an immediate (within the first 2 h post-inoculation) and a strong delayed reaction (24 h) to the extract. Dogs, unlike guinea-pigs, developed only a strong immediate reaction whereby an 80% increase in ear thickness was observed. Control animals, with the exception of one dog, did not develop any significant reaction to the extract. Only mild reactions were induced by PBS in the right ear of all animals. The correlation between the absence of a strong delayed type reaction to tick extract and the lack of resistance of the natural host to R. sanguineus tick is discussed. © 1995 Chapman & Hall.

Western blot analysis of tick antigens from a Rhipicephalus sanguineus unfed larval extract and identification of antigenic sites in tick sections using immunohistochemistry. A comparative study between resistant and susceptible host species

Most parasite-host relationships are characterized by the development of resistance by the host, thus limiting the number of parasites. However, some cases are very unusual. In the relationship of the domestic dog with the brown dog-tick Rhipicephalus sanguineus this does not occur, whereas guinea pigs develop efficient resistance. Sera from domestic dogs, crab-eating foxes and guinea pigs collected before and after infestation with R. sanguineus ticks, and after immunization with a whole tick adult or larval homogenate, were used in Western blot analysis to compare and identify potential important antigens from a tick larval homogenate. The same sera were tested in an indirect immunohistochemistry assay in an attempt to compare relevant antigenic sites on histological tick sections. The immunoblotting displayed antigens recognized only by the guinea pigs, as well as several shared antigens between host species, depending on the kind of immunization. Immunohistochemistry revealed probable antigenic sites on the cells and tissues of ticks, which varied depending on the kind of immunization (infestation or vaccination) and the animal species involved.

Phenological aspects of flowering and fruiting at the Ecological Station of Paulo de Faria-SP-Brazil

The present work was carried out at 'Estacao Ecologica de Paulo de Faria', north of the state of Sao Paulo, southeast of Brazil (19°55'-19°58'S and 49°31'-49°32'W). The flowering and fruiting phenology of trees, shrubs, and lianas species were observed from April 1993 to December 1995. The results were compaired with those surveyed at other forests from Sao Paulo state: Santa Genebra (Campinas). Serra do Japi (Jundiai) and lianas of Mata Atlantica. The majority of species of lianas flowered from January to April and trees and shrubs between September to December. The most intense frutification period occurred during May to August. Similarly to Santa Genebra, the flowering season at 'Estacao Ecologica de Paulo de Faria' started at the beginning of the wet season while frutification during the dryest period of the year. At Serra do Japi, the flowering and frutification occurred from the end of dry and beginning of the rainy season. Considering the liana at Mata Atlantica presented two peaks of flowering, while at 'Estacao Ecologica de Paulo de Faria' occurs only one. Regarding the fruiting phenology is similar for both area, most species producing fruits during the first semestre.

Potential of Acarophenax lacunatus (Prostigmata: Acarophenacidae) as a biological control agent of Rhyzopertha dominica (Coleoptera: Bostrichidae)

A recent report of the parasitic mite species Acarophenax lacunatus (Cross and Krantz) (Prostigmata: Acarophenacidae) attacking populations of Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae) led to the present investigation. Maximum female size and average number of progeny per female mite were assessed at eight different temperatures (ranging from 20 to 41°C) and 60% r.h. using R. dominica as the host. The ability of the mite species to suppress eggs, first instar larvae, and adults of R. dominica was assessed at 30°C and 60% r.h. The largest female sizes of the mite and progeny numbers were obtained around 30°C (259 μm and 17 offspring/female respectively) with minimum values obtained at the most extreme temperatures used in this study. Mite densities of at least four individuals per 500 ml jar containing 50 adults of R. dominica, resulted in almost complete suppression of eggs, first instar larvae, and adults of the host species after 45 days. This same range of mite densities led to reductions of wheat weight losses of 15 and 25% after 45 and 60 days after infestation respectively. Acarophenax lacunatus shows good potential as a biological control agent of R. dominica.

Ticks (Acari: Ixodidae) associated with wild animals in the Pantanal region of Brazil

This paper describes the identification of ticks from wild animals of the Pantanal region in Brazil as part of a comprehensive study about established and emerging tick-host relationships and related pathological aspects. Eighty-one animals were captured (representing 13 species six orders), and ticks were found on 63 (78%). Tick species identified included Boophilus microplus (Canestrini), Amblyomma cajennense (F.), Amblyomma parvum Aragão, Amblyomma pseudoconcolor Aragão, Amblyomma scalpturatum Neumann, Amblyomma nodosum Neumann, Amblyomma ovale Koch, and Amblyomma tigrinum Koch. Dragging from grasslands yielded negative results compared with the high concentration of ticks that were collected from leaves in the forests.

Ticks associated with wild animals in the Nhecolândia Pantanal, Brazil

A study of ticks associated with wild animals was carried out from September 1996 to April 1998 at the Fazenda Alegria (21,000 ha), in the Nhecolândia Pantanal, State of Mato Grosso do Sul, Brazil, a sunken plain bordering the upper Paraguay river, located 19 × 08′S; 56 × 46′W. A total of 81 wild animals (13 species, 6 orders) were captured with the aid of nets, and ticks were found on 63 (78%). Tick species identified included Boophilus microplus (Canestrini), Amblyomma cajennense (F.), A. parvum (Aragão), A. pseudo-concolor (Aragão), A. scalpturatum (Neumann), A. nodosum (Neumann), A. ovale (Koch), and A. tigrinum (Koch). Dragging from grasslands (campos) yielded negative results compared to the high concentration of ticks, mainly nymphs, that were collected from leaves in the forests (capão). Predominance of immature instars (Amblyomma genera) was observed in the end of winter (August-September). Ticks were associated mainly with coatis, deer (Mazama gouazoubira) and anteater, and these animals may play a role in the epidemiology of tick-transmitted pathogens in the Pantanal if one considers their coexistence with local domestic animals.

Skin test and tick immune status in susceptible and resistant cattle in Brazil

A cutaneous hypersensitivity test (CHT) was used to correlate host resistance to ticks and type of reaction elicited to unfed larval extract-ULE of the cattle tick Boophilus microplus in European and Indian cattle. Twenty calves were separated into four groups of five animals each: naïve or preinfested Indian or European cattle. CHT was induced by intradermal inoculation of 0.1 ml of ULE cattle tick B. microplus (50 μg protein) in the calf ear. Ear thickness was measured using calipers before and 10 min, 1, 2, 6, 18, 24, 48, 72, 96, and 144 h postinoculation (PI). Preinfested European calves showed only an immediate type reaction with maximum response (75% increase in ear thickness) at 10 min PI. On the other hand, preinfested Indian calves presented an immediate response with maximum reaction (70% increase in ear thickness) between 10 min and one hour PI, and a delayed type reaction at 72 h PI (60% increase in ear thickness). These results point out the crucial role of the cellular immune response of cattle in the expression of resistance to cattle tick B. microplus. Skin test might be useful in the ranking of cattle according to the susceptibility/resistance to ticks.