RESUMO

The acaricidal activity of combinations of thymol, carvacrol and eugenol was evaluated on larvae and engorged females of the cattle tick Rhipicephalus microplus. The first step assessed the compounds separately, in concentrations of 3.125, 6.25, 12.5 and 25 mg/mL. Then tests were performed with the compounds combined in the ratio of 1:1 at concentrations of 3.125 and 6.25 mg/mL, along with the control group treated with the solvent (3% DMSO). In the second step, combinations were tested incorporated in a formulation at the concentration de 6.25 mg/mL, using the larval packet and adult immersion tests. The associations carvacrol + thymol (3.125 mg/mL), carvacrol + eugenol and thymol + eugenol (6.25 mg/mL) presented synergism, while the other associations had an additive effect. In the experiments with formulation, all combinations caused 100% larval mortality, but the efficacy was under 15% against engorged females. Therefore, the combinations of thymol + carvacrol (3.125 mg/mL) as well as carvacrol + eugenol and eugenol + thymol (6.25 mg/mL) had a synergistic effect on engorged females, but when incorporated in the formulation, the acaricide activity was strong against larvae but weak against engorged females.

Assuntos

RESUMO

Rhipicephalus (Boophilus) microplus is the main cattle ectoparasite in tropical areas. Gir × Holstein crossbred cows are well adapted to different production systems in Brazil. In this context, we performed genome-wide association study (GWAS) and post-GWAS analyses for R. microplus resistance in an experimental Gir × Holstein F2 population. Single nucleotide polymorphisms (SNP) identified in GWAS were used to build gene networks and to investigate the breed of origin for its alleles. Tick artificial infestations were performed during the dry and rainy seasons. Illumina BovineSNP50 BeadChip (Illumina Inc., San Diego, CA) and single-step BLUP procedure was used for GWAS. Post-GWAS analyses were performed by gene ontology terms enrichment and gene transcription factors networks, generated from enriched transcription factors, identified from the promoter sequences of selected gene sets. The genetic origin of marker alleles in the F2 population was assigned using the breed of origin of alleles approach. Heritability estimates for tick counts were 0.40 ± 0.11 in the rainy season and 0.54 ± 0.11 in the dry season. The top ten 0.5-Mbp windows with the highest percentage of genetic variance explained by SNP markers were found in chromosomes 10 and 23 for both the dry and rainy seasons. Gene network analyses allowed the identification of genes involved with biological processes relevant to immune system functions (TREM1, TREM2, and CD83). Gene-transcription factors network allowed the identification of genes involved with immune functions (MYO5A, TREML1, and PRSS16). In resistant animals, the average proportion of animals showing significant SNPs with paternal and maternal alleles originated from Gir breed was 44.8% whereas the proportion of animals with both paternal and maternal alleles originated from Holstein breed was 11.3%. Susceptible animals showing both paternal and maternal alleles originated from Holstein breed represented 44.6% on average, whereas both paternal and maternal alleles originated from Gir breed animals represented 9.3%. This study allowed us to identify candidate genes for tick resistance in Gir × Holstein crossbreds in both rainy and dry seasons. According to the origin of alleles analysis, we found that most animals classified as resistant showed 2 alleles from Gir breed, while the susceptible ones showed alleles from Holstein. Based on these results, the identified genes may be thoroughly investigated in additional experiments aiming to validate their effects on tick resistance phenotype in cattle.

Assuntos

RESUMO

O estudo teve como objetivo avaliar a viabilidade de Heterorhabditis amazonensis isolado RSC-5 após exposição a diferentes carrapaticidas utilizados no controle de Rhipicephalus microplus. Foram constituídos seis tratamentos, cada um composto por um produto, sendo cada grupo com 75.000 nematoides (NEPs) em suspensão de 20 mL de solução de diferentes carrapaticidas, em concentração comercial. O controle foi formado por 75.000 NEPs e 20 mL de água destilada, e todos os grupos foram mantidos em câmara climatizada a 25°C. A avaliação do percentual de sobrevivência e infectividade em lagartas Galleria mellonella foi realizada 24 e 72 horas após o início do experimento. A mortalidade de lagartas no teste de infectividade foi analisada após 72 e 120 horas. Com 24 horas de exposição, o percentual de sobrevivência de H. amazonensis RSC-5 não foi significativamente reduzido (p > 0,05) somente na exposição ao princípio ativo deltametrina. O mesmo foi observado no período de 72 horas em relação à associação clorpirifós + cipermetrina + butóxido de piperonila + citronelal. Não foi constatada sobrevivência de nenhum juvenil infectivo nos grupos expostos à associação clorfenvinfós + diclorvós. A exposição ao clorfenvinfós resultou em percentual de sobrevivência inferior a 50% após 72 horas. O potencial de infectar lagartas de G. mellonella foi reduzido apenas no grupo tratado com o princípio ativo clorfenvinfós. Dessa forma, é possível concluir que o princípio ativo clorfenvinfós e a associação clorfenvinfós + diclorvós não foram compatíveis com H. Amazonenses RSC-5, causando redução no percentual de sobrevivência e infectividade dos juvenis desse nematoide. Os outros produtos foram compatíveis, não causando redução na infectividade do isolado testado.(AU)

The aim of this study was to assess the viability of Heterorhabditis amazonensis strain RSC-5 after exposure to different acaricides used for Rhipicephalus microplus control. Six treatment groups were formed, one for each product. Each group was composed of 75,000 nematodes in a 20 mL solution of different acaricides, at commercial concentration. The control group was formed by the same number of nematodes in 20 mL of distilled water. All the groups were kept in a climate-controlled chamber at 25°C. The percentage of survival and infectivity in Galleria mellonella caterpillars were determined 24 and 72 hours after the beginning of the experiment. The mortality of the caterpillars in the infectivity test was assessed 72 and 120 hours. After 24 hours of exposure, only the active ingredient deltamethrin did not significantly reduce the survival percentage of H. amazonensis RSC-5 (p > 0.05). The same was observed after 72 hours of exposure to the combination of chlorpyriphos + cypermethrin + piperonyl butoxide + citronellal. There was no survival of infective juveniles in the groups exposed to the combination of chlorphenvinphos + dichlorvos. The exposure to chlorphenvinphos for 72 hours resulted in 50% of mortality. The potential to infect G. mellonella caterpillars was only reduced in the group treated with the active ingredient chlorphenvinphos. Chlorphenvinphos and the combination of chlorphenvinphos + dichlorvos were not compatible with H. amazonensis RSC-5, causing a reduction in the survival and infectivity of juveniles of this nematode, while the other products were compatible, causing no reduction in the infectivity of this isolate.(AU)

Assuntos

RESUMO

O estudo teve como objetivo avaliar a viabilidade de Heterorhabditis amazonensis isolado RSC-5 após exposição a diferentes carrapaticidas utilizados no controle de Rhipicephalus microplus. Foram constituídos seis tratamentos, cada um composto por um produto, sendo cada grupo com 75.000 nematoides (NEPs) em suspensão de 20 mL de solução de diferentes carrapaticidas, em concentração comercial. O controle foi formado por 75.000 NEPs e 20 mL de água destilada, e todos os grupos foram mantidos em câmara climatizada a 25°C. A avaliação do percentual de sobrevivência e infectividade em lagartas Galleria mellonella foi realizada 24 e 72 horas após o início do experimento. A mortalidade de lagartas no teste de infectividade foi analisada após 72 e 120 horas. Com 24 horas de exposição, o percentual de sobrevivência de H. amazonensis RSC-5 não foi significativamente reduzido (p > 0,05) somente na exposição ao princípio ativo deltametrina. O mesmo foi observado no período de 72 horas em relação à associação clorpirifós + cipermetrina + butóxido de piperonila + citronelal. Não foi constatada sobrevivência de nenhum juvenil infectivo nos grupos expostos à associação clorfenvinfós + diclorvós. A exposição ao clorfenvinfós resultou em percentual de sobrevivência inferior a 50% após 72 horas. O potencial de infectar lagartas de G. mellonella foi reduzido apenas no grupo tratado com o princípio ativo clorfenvinfós. Dessa forma, é possível concluir que o princípio ativo clorfenvinfós e a associação clorfenvinfós + diclorvós não foram compatíveis com H. Amazonenses RSC-5, causando redução no percentual de sobrevivência e infectividade dos juvenis desse nematoide. Os outros produtos foram compatíveis, não causando redução na infectividade do isolado testado.(AU)

The aim of this study was to assess the viability of Heterorhabditis amazonensis strain RSC-5 after exposure to different acaricides used for Rhipicephalus microplus control. Six treatment groups were formed, one for each product. Each group was composed of 75,000 nematodes in a 20 mL solution of different acaricides, at commercial concentration. The control group was formed by the same number of nematodes in 20 mL of distilled water. All the groups were kept in a climate-controlled chamber at 25°C. The percentage of survival and infectivity in Galleria mellonella caterpillars were determined 24 and 72 hours after the beginning of the experiment. The mortality of the caterpillars in the infectivity test was assessed 72 and 120 hours. After 24 hours of exposure, only the active ingredient deltamethrin did not significantly reduce the survival percentage of H. amazonensis RSC-5 (p > 0.05). The same was observed after 72 hours of exposure to the combination of chlorpyriphos + cypermethrin + piperonyl butoxide + citronellal. There was no survival of infective juveniles in the groups exposed to the combination of chlorphenvinphos + dichlorvos. The exposure to chlorphenvinphos for 72 hours resulted in 50% of mortality. The potential to infect G. mellonella caterpillars was only reduced in the group treated with the active ingredient chlorphenvinphos. Chlorphenvinphos and the combination of chlorphenvinphos + dichlorvos were not compatible with H. amazonensis RSC-5, causing a reduction in the survival and infectivity of juveniles of this nematode, while the other products were compatible, causing no reduction in the infectivity of this isolate.(AU)

Assuntos

RESUMO

The aim of this study was to assess the viability of Heterorhabditisamazonensis strain RSC-5 after exposure to different acaricides used for Rhipicephalusmicropluscontrol. Six treatment groups were formed, one for each product. Each group was composed of 75,000 nematodes in a 20 mL solution of different acaricides, at commercial concentration. The control group was formed by the same number of nematodes in 20 mL of distilled water. All the groups were kept in a climate-controlled chamber at 25°C. The percentage of survival and infectivity in Galleria mellonella caterpillars were determined 24 and 72 hours after the beginning of the experiment. The mortality of the caterpillars in the infectivity test was assessed 72 and 120 hours. After 24 hours of exposure, only the active ingredient deltamethrin did not significantly reduce the survival percentage of H. amazonensis RSC-5 (p > 0.05). The same was observed after 72 hours of exposure to the combination of chlorpyriphos + cypermethrin + piperonyl butoxide + citronellal. There was no survival of infective juveniles in the groups exposed to the combination of chlorphenvinphos + dichlorvos. The exposure to chlorphenvinphos for 72 hours resulted in 50% of mortality. The potential to infect G. mellonella caterpillars was only reduced in the group treated with the active ingredient chlorphenvinphos. Chlorphenvinphos and the combination of chlorphenvinphos + dichlorvos were not compatible with H. amazonensisRSC-5, causing a reduction in the survival and infectivity of juveniles of this nematode, while the other products were compatible, causing no reduction in the infectivity of this isolate.

O estudo teve como objetivo avaliar a viabilidade de Heterorhabditisamazonensis isolado RSC-5 após exposição a diferentes carrapaticidas utilizados no controle de Rhipicephalusmicroplus. Foram constituídos seis tratamentos, cada um composto por um produto, sendo cada grupo com 75.000 nematoides (NEPs) em suspensão de 20 mL de solução de diferentes carrapaticidas, em concentração comercial. O controle foi formado por 75.000 NEPs e 20 mL de água destilada, e todos os grupos foram mantidos em câmara climatizada a 25°C. A avaliação do percentual de sobrevivência e infectividade em lagartas Galleria mellonella foi realizada 24 e 72 horas após o início do experimento. A mortalidade de lagartas no teste de infectividade foi analisada após 72 e 120 horas. Com 24 horas de exposição, o percentual de sobrevivência de H. amazonensis RSC-5 não foi significativamente reduzido (p > 0,05) somente na exposição ao princípio ativo deltametrina. O mesmo foi observado no período de 72 horas em relação à associação clorpirifós + cipermetrina + butóxido de piperonila + citronelal. Não foi constatada sobrevivência de nenhum juvenil infectivo nos grupos expostos à associação clorfenvinfós + diclorvós. A exposição ao clorfenvinfós resultou em percentual de sobrevivência inferior a 50% após 72 horas. O potencial de infectar lagartas de G. mellonella foi reduzido apenas no grupo tratado com o princípio ativo clorfenvinfós. Dessa forma, é possível concluir que o princípio ativo clorfenvinfós e a associação clorfenvinfós + diclorvós não foram compatíveis com H. AmazonensesRSC-5, causando redução no percentual de sobrevivência e infectividade dos juvenis desse nematoide. Os outros produtos foram compatíveis, não causando redução na infectividade do isolado testado.

RESUMO

The monitoring of resistance of cattle tick populations in Brazil to the chemical bases in use is largely limited to investigation of the phenotypic profile. There are few studies investigating the role played by the genotypic profile in acaricide resistance in the country. Therefore, the aim of the present study was to carry out molecular characterization and trace out the genetic profile of populations of Rhipicephalus microplus with respect to resistance to the organophosphate and pyrethroid chemical groups. For that purpose, larvae were genotyped belonging to 587 populations for pyrethroids and 306 for organophosphates, using the polymerase chain reaction technique. It was found that 75.49% and 97.44% of the larvae studied showed resistance to the organophosphates and pyrethroids, respectively. Among the populations resistant to pyrethroids, 91.9% were heterozygotes, showing that most of the resistant populations have only one allele responsible for resistance. Therefore, it is possible to conclude that the genotyped populations have high resistance to organophosphates, and even more so to pyrethroids. This information is fundamental for understanding the mechanisms of resistance of R. microplus to acaricides, to enable improvement of control techniques.

Assuntos

RESUMO

Since horn fly populations became established throughout Brazil, complaints regarding control failure have increased around the country. A broad survey to evaluate the susceptibility of horn flies to both organophosphate (OP) and pyrethroid insecticides was conducted from October 2000 to April 2003. Bioassays using filter papers impregnated with cypermethrin, permethrin or diazinon were conducted on 154 horn fly populations in 14 states and 78 municipalities. Resistance to cypermethrin, the active ingredient present in most insecticide products for horn fly control in Brazil, was detected in 98.46% of the populations, with resistance ratios (RR) ranging from 2.5 to 719.9. Resistance to permethrin (RRs < 6.3) was found in 96.67% of the populations, despite its lack of use. In general, pyrethroid resistance was detected in 97.18% of the horn fly populations, with frequencies greater than 87% in all regions of the country. The status of susceptibility of horn fly populations in Brazil to insecticides can be characterized by high susceptibility to OPs and widespread resistance to pyrethroids, potentially compromising the efficacy of pyrethroid products in most cases. Although some partial results have previously been presented, a general picture of horn fly susceptibility in Brazil is presented here for the first time.

Assuntos

RESUMO

Since horn fly populations became established throughout Brazil, complaints regarding control failure have increased around the country. A broad survey to evaluate the susceptibility of horn flies to both organophosphate (OP) and pyrethroid insecticides was conducted from October 2000 to April 2003. Bioassays using filter papers impregnated with cypermethrin, permethrin or diazinon were conducted on 154 horn fly populations in 14 states and 78 municipalities. Resistance to cypermethrin, the active ingredient present in most insecticide products for horn fly control in Brazil, was detected in 98.46% of the populations, with resistance ratios (RR) ranging from 2.5 to 719.9. Resistance to permethrin (RRs < 6.3) was found in 96.67% of the populations, despite its lack of use. In general, pyrethroid resistance was detected in 97.18% of the horn fly populations, with frequencies greater than 87% in all regions of the country. The status of susceptibility of horn fly populations in Brazil to insecticides can be characterized by high susceptibility to OPs and widespread resistance to pyrethroids, potentially compromising the efficacy of pyrethroid products in most cases. Although some partial results have previously been presented, a general picture of horn fly susceptibility in Brazil is presented here for the first time.

Desde a dispersão da mosca-dos-chifres, no Brasil, queixas sobre seu controle aumentaram em todo o país. Um amplo levantamento objetivando avaliar a suscetibilidade da mosca a inseticidas organofosforados (OF) e piretróides foi realizado de outubro de 2000 a abril de 2003. Bioensaios com papéis de filtro impregnados com cipermetrina, permetrina ou diazinon foram conduzidos em 154 populações da mosca-dos-chifres de 14 Estados e 78 municípios. Resistência à cipermetrina, ingrediente ativo presente na maioria dos produtos para controle da mosca-dos-chifres no Brasil, foi detectada em 98,46% das populações, com fatores de resistência (FR) variando de 2,5 a 719,9. Resistência à permetrina (FR < 6,3) foi encontrada em 96,67% das populações testadas, apesar da falta de uso de produtos contendo este princípio ativo. Em geral, resistência a piretróides foi detectada em 97,18% das populações, com frequências acima de 87% em todas as regiões do país. A situação da suscetibilidade da mosca-dos-chifres a inseticidas, no Brasil, pode ser caracterizada por uma elevada suscetibilidade aos organofosforados e ocorrência generalizada de resistência aos piretróides, potencialmente comprometendo a eficácia desses produtos na maioria dos casos. Embora resultados parciais tenham sido apresentados anteriormente, um quadro geral da suscetibilidade da mosca-dos-chifres no Brasil é apresentado pela primeira vez.

Assuntos

RESUMO

Since horn fly populations became established throughout Brazil, complaints regarding control failure have increased around the country. A broad survey to evaluate the susceptibility of horn flies to both organophosphate (OP) and pyrethroid insecticides was conducted from October 2000 to April 2003. Bioassays using filter papers impregnated with cypermethrin, permethrin or diazinon were conducted on 154 horn fly populations in 14 states and 78 municipalities. Resistance to cypermethrin, the active ingredient present in most insecticide products for horn fly control in Brazil, was detected in 98.46% of the populations, with resistance ratios (RR) ranging from 2.5 to 719.9. Resistance to permethrin (RRs < 6.3) was found in 96.67% of the populations, despite its lack of use. In general, pyrethroid resistance was detected in 97.18% of the horn fly populations, with frequencies greater than 87% in all regions of the country. The status of susceptibility of horn fly populations in Brazil to insecticides can be characterized by high susceptibility to OPs and widespread resistance to pyrethroids, potentially compromising the efficacy of pyrethroid products in most cases. Although some partial results have previously been presented, a general picture of horn fly susceptibility in Brazil is presented here for the first time.(AU)

Desde a dispersão da mosca-dos-chifres, no Brasil, queixas sobre seu controle aumentaram em todo o país. Um amplo levantamento objetivando avaliar a suscetibilidade da mosca a inseticidas organofosforados (OF) e piretróides foi realizado de outubro de 2000 a abril de 2003. Bioensaios com papéis de filtro impregnados com cipermetrina, permetrina ou diazinon foram conduzidos em 154 populações da mosca-dos-chifres de 14 Estados e 78 municípios. Resistência à cipermetrina, ingrediente ativo presente na maioria dos produtos para controle da mosca-dos-chifres no Brasil, foi detectada em 98,46% das populações, com fatores de resistência (FR) variando de 2,5 a 719,9. Resistência à permetrina (FR < 6,3) foi encontrada em 96,67% das populações testadas, apesar da falta de uso de produtos contendo este princípio ativo. Em geral, resistência a piretróides foi detectada em 97,18% das populações, com frequências acima de 87% em todas as regiões do país. A situação da suscetibilidade da mosca-dos-chifres a inseticidas, no Brasil, pode ser caracterizada por uma elevada suscetibilidade aos organofosforados e ocorrência generalizada de resistência aos piretróides, potencialmente comprometendo a eficácia desses produtos na maioria dos casos. Embora resultados parciais tenham sido apresentados anteriormente, um quadro geral da suscetibilidade da mosca-dos-chifres no Brasil é apresentado pela primeira vez.(AU)

Assuntos

RESUMO

With the objective of encouraging the use of rabbits as alternative hosts for the cattle tick, four rabbits were infested on the ears and back. From the second day of infestation the developmental stages were observed. e duration of larval engorgement and changes were estimated between six and eight days in the region of the back and between 've and seven days in the pinna. e nymphal engorgement and changes occurred at approximately 10.80 ± 2.65 days in the dorsal and 11.00 ± 2.52 days in the ear, with the engorgement of adults and copulation occurring at 7.03 ± 2.45 days, on the dorsal region and 8.55 ± 1.82 days in the region of the pinna. e parasitic period ranged from 21 to 29 days (back) and from 23 to 30 days (pinna). e engorged females of the back and ear weighed on average 34.43 ± 18.73 and 36.30 ± 18.10 mg, respectively. e nutritional and reproductive efficiency indexes were 17.38 ± 14.27 and 26.85 ± 17.13% (back) and 17.42 ± 12.22% and 30.70 ± 19.80% (pinna). Although not appropriate to maintain successive generations of Rhipicephalus (Boophilus) microplus, rabbits can be used for different stages of engorgement of the ixodid, allowing experimental studies.

Assuntos

RESUMO

With the objective of encouraging the use of rabbits as alternative hosts for the cattle tick, four rabbits were infested on the ears and back. From the second day of infestation the developmental stages were observed. e duration of larval engorgement and changes were estimated between six and eight days in the region of the back and between 've and seven days in the pinna. e nymphal engorgement and changes occurred at approximately 10.80 ± 2.65 days in the dorsal and 11.00 ± 2.52 days in the ear, with the engorgement of adults and copulation occurring at 7.03 ± 2.45 days, on the dorsal region and 8.55 ± 1.82 days in the region of the pinna. e parasitic period ranged from 21 to 29 days (back) and from 23 to 30 days (pinna). e engorged females of the back and ear weighed on average 34.43 ± 18.73 and 36.30 ± 18.10 mg, respectively. e nutritional and reproductive e/ciency indexes were 17.38 ± 14.27 and 26.85 ± 17.13% (back) and 17.42 ± 12.22% and 30.70 ± 19.80% (pinna). Although not appropriate to maintain successive generations of Rhipicephalus (Boophilus) microplus, rabbits can be used for di:erent stages of engorgement of the ixodid, allowing experimental studies.

Com objetivo de viabilizar o uso de coelhos como hospedeiros alternativos do carrapato bovino, foram infestados quatro coelhos nas orelhas e no dorso. A partir do segundo dia da infestação, foram observados os estágios de desenvolvimento dos carrapatos. A duração do ingurgitamento e muda larval foi estimada entre seis e oito dias na região do dorso e entre cinco e sete dias no pavilhão auricular. O ingurgitamento e muda ninfal ocorreram em aproximadamente, 10,80 ± 2,65 dias na região dorsal e 11,00 ± 2,52 dias no pavilhão auricular; e o ingurgitamento e cópula dos adultos ocorreu em 7,03 ± 2,45 dias, na região do dorso e em 8,55 ± 1,82 dias na região do pavilhão auricular . O período parasitário variou de 21 a 29 dias (dorso) e de 23 a 30 dias (pavilhão auricular). As fêmeas ingurgitadas do dorso e orelha pesaram, em média, 34,43 ± 18,73 e 36,30 ± 18,10 mg, respectivamente. Os índices de e'ciência reprodutiva e nutricional foram de 17,38 ± 14,27 e 26,85 ± 17,13% (região do dorso) e de 17,42 ± 12,22% e 30,70 ± 19,80% (pavilhão auricular). Embora não sejam adequados para manter sucessivas gerações de Rhipicephalus (Boophilus) microplus, os coelhos podem ser empregados para o ingurgitamento dos diferentes estádios deste ixodídeo, viabilizando estudos experimentais.

Assuntos

RESUMO

With the objective of encouraging the use of rabbits as alternative hosts for the cattle tick, four rabbits were infested on the ears and back. From the second day of infestation the developmental stages were observed. e duration of larval engorgement and changes were estimated between six and eight days in the region of the back and between 've and seven days in the pinna. e nymphal engorgement and changes occurred at approximately 10.80 ± 2.65 days in the dorsal and 11.00 ± 2.52 days in the ear, with the engorgement of adults and copulation occurring at 7.03 ± 2.45 days, on the dorsal region and 8.55 ± 1.82 days in the region of the pinna. e parasitic period ranged from 21 to 29 days (back) and from 23 to 30 days (pinna). e engorged females of the back and ear weighed on average 34.43 ± 18.73 and 36.30 ± 18.10 mg, respectively. e nutritional and reproductive e/ciency indexes were 17.38 ± 14.27 and 26.85 ± 17.13% (back) and 17.42 ± 12.22% and 30.70 ± 19.80% (pinna). Although not appropriate to maintain successive generations of Rhipicephalus (Boophilus) microplus, rabbits can be used for di:erent stages of engorgement of the ixodid, allowing experimental studies.(AU)

Com objetivo de viabilizar o uso de coelhos como hospedeiros alternativos do carrapato bovino, foram infestados quatro coelhos nas orelhas e no dorso. A partir do segundo dia da infestação, foram observados os estágios de desenvolvimento dos carrapatos. A duração do ingurgitamento e muda larval foi estimada entre seis e oito dias na região do dorso e entre cinco e sete dias no pavilhão auricular. O ingurgitamento e muda ninfal ocorreram em aproximadamente, 10,80 ± 2,65 dias na região dorsal e 11,00 ± 2,52 dias no pavilhão auricular; e o ingurgitamento e cópula dos adultos ocorreu em 7,03 ± 2,45 dias, na região do dorso e em 8,55 ± 1,82 dias na região do pavilhão auricular . O período parasitário variou de 21 a 29 dias (dorso) e de 23 a 30 dias (pavilhão auricular). As fêmeas ingurgitadas do dorso e orelha pesaram, em média, 34,43 ± 18,73 e 36,30 ± 18,10 mg, respectivamente. Os índices de e'ciência reprodutiva e nutricional foram de 17,38 ± 14,27 e 26,85 ± 17,13% (região do dorso) e de 17,42 ± 12,22% e 30,70 ± 19,80% (pavilhão auricular). Embora não sejam adequados para manter sucessivas gerações de Rhipicephalus (Boophilus) microplus, os coelhos podem ser empregados para o ingurgitamento dos diferentes estádios deste ixodídeo, viabilizando estudos experimentais.(AU)

Assuntos

RESUMO

The aim of this study was to assess the influence of different exposure times of engorged female the Rhipicephalus microplus to infective juveniles of Heterorhabditis bacteriophora isolate HP88. The engorged females were divided into seven groups (six treatments and one control) of 20 ticks each with statistically similar average weights (p>0.05) and exposed to concentrations of 300 nematodes/tick for periods of 3, 6, 12, 24, 48 and 72 h. The following biological parameters were monitored: pre-oviposition period; egg mass weight; hatching percentage; and efficacy of treatment. There was no influence of the exposure time on the pre-oviposition period (p>0.05), while there were significant differences (p<0.05) between the groups exposed for 24, 48 and 72 h and the control group with respect to the egg mass weight, and 24h for hatching percentage. Treatment efficacy reached 100% after exposure for 48 and 72 h. These results demonstrate that infective juveniles of H. bacteriophora HP88, under laboratory conditions, interfere in the majority of the biological parameters of the non-parasitic phase of engorged R. microplus females when the exposure time is greater than or equal to 24h.

Assuntos

RESUMO

One hundred semi-systematized interviews were applied with the aim of surveying the perceptions of milk producers in the municipality of Divinópolis, Minas Gerais regarding the biology of the tick Rhipicephalus (Boophilus) microplus. Content analysis was conducted on each of the variables surveyed and their descriptions, highlighting the higher frequencies in order to construct profiles of perceptions about each of the matters surveyed. In addition, each of the producers was categorized regarding their readiness to proceed with efficient control, from the assessment of their responses. Among the variables surveyed were the tick lifespan, duration of parasitic life, time of greatest incidence, survival in pastures and egg-laying volume. These questions are considered important for defining the knowledge needed for rational combat. It was concluded that the information needed for adopting effective practices to combat ticks was insufficient among the milk farm properties in Divinópolis. Moreover, the producers interviewed had a good perception of what they observed in their daily routine, but did not have complementary information about the tick life cycle.

Assuntos

RESUMO

Semi-systematized interviews were conducted with 100 dairy cattle producers in the municipality of Divinópolis, Minas Gerais, with the aim of ascertaining their perceptions regarding the importance of Rhipicephalus (Boophilus) microplus and of combating it. Content analysis was performed and the frequency distribution of each of the variables was used to construct profiles of the producers interviewed. The production losses caused by ticks were perceived incompletely by the producers, who were unaware of the pathogen transmission caused by the parasite and the indirect losses through combating it, such as the cost of acaricide and labor. The combat operations were performed in a traditional manner, with an excessive number of inefficient treatments that aimed to control the level of infestation at that moment. The quality of the acaricide dipping/spraying applied was affected by the quality of the equipment used to apply the products, lack of knowledge of the mode of action of these products, lack of the specific information needed and lack of motivation caused by unawareness of the disadvantages of chemical combat. It was concluded that the lack of knowledge about combat methods and the acceptance of endemicity of the parasitosis were impediments to changing the realities encountered.

Assuntos

RESUMO

One hundred semi-systematized interviews were applied with the aim of surveying the perceptions of milk producers in the municipality of Divinópolis, Minas Gerais regarding the biology of the tick Rhipicephalus (Boophilus) microplus. Content analysis was conducted on each of the variables surveyed and their descriptions, highlighting the higher frequencies in order to construct profiles of perceptions about each of the matters surveyed. In addition, each of the producers was categorized regarding their readiness to proceed with efficient control, from the assessment of their responses. Among the variables surveyed were the tick lifespan, duration of parasitic life, time of greatest incidence, survival in pastures and egg-laying volume. These questions are considered important for defining the knowledge needed for rational combat. It was concluded that the information needed for adopting effective practices to combat ticks was insufficient among the milk farm properties in Divinópolis. Moreover, the producers interviewed had a good perception of what they observed in their daily routine, but did not have complementary information about the tick life cycle.

Foram aplicadas 100 entrevistas semissistematizadas com o objetivo de levantar a percepção dos produtores de leite do município de Divinópolis, Minas Gerais, sobre a biologia do carrapato Rhipicephalus (Boophilus) microplus. Foi feita "análise de conteúdo" de cada uma das variáveis levantadas e sua descrição com destaque das maiores frequências para a construção de perfis de percepção sobre cada um dos aspectos levantados. Além disso, cada um dos produtores foram categorizados quanto a estar ou não apto a proceder um controle eficiente pela avaliação de suas respostas. Algumas das variáveis levantadas foram tempo de vida do carrapato, tempo de vida parasitária, época de maior incidência, sobrevivência nas pastagens e volume de postura, questões consideradas importantes para se definir o conhecimento necessário a um combate racional. Concluiu-se que as informações necessárias à adoção de práticas efetivas de combate aos carrapatos são insuficientes nas propriedades de leite de Divinópolis e, ainda, que os produtores entrevistados têm boa percepção no que se observa no dia a dia e não têm informações complementares sobre o ciclo de vida dos carrapatos.

Assuntos

RESUMO

Semi-systematized interviews were conducted with 100 dairy cattle producers in the municipality of Divinópolis, Minas Gerais, with the aim of ascertaining their perceptions regarding the importance of Rhipicephalus (Boophilus) microplus and of combating it. Content analysis was performed and the frequency distribution of each of the variables was used to construct profiles of the producers interviewed. The production losses caused by ticks were perceived incompletely by the producers, who were unaware of the pathogen transmission caused by the parasite and the indirect losses through combating it, such as the cost of acaricide and labor. The combat operations were performed in a traditional manner, with an excessive number of inefficient treatments that aimed to control the level of infestation at that moment. The quality of the acaricide dipping/spraying applied was affected by the quality of the equipment used to apply the products, lack of knowledge of the mode of action of these products, lack of the specific information needed and lack of motivation caused by unawareness of the disadvantages of chemical combat. It was concluded that the lack of knowledge about combat methods and the acceptance of endemicity of the parasitosis were impediments to changing the realities encountered.

Entrevistas semissistematizadas foram aplicadas a 100 produtores de bovinos leiteiros do município de Divinópolis, Minas Gerais, com o objetivo de verificar a sua percepção sobre a importância de Rhipicephalus (Boophilus) microplus e seu combate. Foi feita "análise de conteúdo" e a distribuição de frequência de cada uma das variáveis para a construção de perfis dos produtores entrevistados. Os prejuízos causados à produção pelo carrapato são percebidos de forma incompleta pelos produtores, que ignoram a transmissão de patógenos pelo parasito e as perdas indiretas pelo combate, como o custo do carrapaticida e da mão de obra. O combate era feito de maneira tradicional com número excessivo de tratamentos ineficientes, com o objetivo de controlar o nível da infestação naquele momento. A qualidade da aplicação do banho carrapaticida foi afetada pelo equipamento utilizado para aplicação dos produtos, pelo desconhecimento do modo de ação desses, pela falta de informações específicas necessárias e pela falta de motivação gerada no desconhecimento das desvantagens do combate químico. Conclui-se que a falta de conhecimento sobre modos de combate e a aceitação da endemicidade da parasitose impedem a mudança da realidade encontrada.

Assuntos

RESUMO

One hundred semi-systematized interviews were applied with the aim of surveying the perceptions of milk producers in the municipality of Divinópolis, Minas Gerais regarding the biology of the tick Rhipicephalus (Boophilus) microplus. Content analysis was conducted on each of the variables surveyed and their descriptions, highlighting the higher frequencies in order to construct profiles of perceptions about each of the matters surveyed. In addition, each of the producers was categorized regarding their readiness to proceed with efficient control, from the assessment of their responses. Among the variables surveyed were the tick lifespan, duration of parasitic life, time of greatest incidence, survival in pastures and egg-laying volume. These questions are considered important for defining the knowledge needed for rational combat. It was concluded that the information needed for adopting effective practices to combat ticks was insufficient among the milk farm properties in Divinópolis. Moreover, the producers interviewed had a good perception of what they observed in their daily routine, but did not have complementary information about the tick life cycle.(AU)

Foram aplicadas 100 entrevistas semissistematizadas com o objetivo de levantar a percepção dos produtores de leite do município de Divinópolis, Minas Gerais, sobre a biologia do carrapato Rhipicephalus (Boophilus) microplus. Foi feita "análise de conteúdo" de cada uma das variáveis levantadas e sua descrição com destaque das maiores frequências para a construção de perfis de percepção sobre cada um dos aspectos levantados. Além disso, cada um dos produtores foram categorizados quanto a estar ou não apto a proceder um controle eficiente pela avaliação de suas respostas. Algumas das variáveis levantadas foram tempo de vida do carrapato, tempo de vida parasitária, época de maior incidência, sobrevivência nas pastagens e volume de postura, questões consideradas importantes para se definir o conhecimento necessário a um combate racional. Concluiu-se que as informações necessárias à adoção de práticas efetivas de combate aos carrapatos são insuficientes nas propriedades de leite de Divinópolis e, ainda, que os produtores entrevistados têm boa percepção no que se observa no dia a dia e não têm informações complementares sobre o ciclo de vida dos carrapatos.(AU)

Assuntos

RESUMO

Semi-systematized interviews were conducted with 100 dairy cattle producers in the municipality of Divinópolis, Minas Gerais, with the aim of ascertaining their perceptions regarding the importance of Rhipicephalus (Boophilus) microplus and of combating it. Content analysis was performed and the frequency distribution of each of the variables was used to construct profiles of the producers interviewed. The production losses caused by ticks were perceived incompletely by the producers, who were unaware of the pathogen transmission caused by the parasite and the indirect losses through combating it, such as the cost of acaricide and labor. The combat operations were performed in a traditional manner, with an excessive number of inefficient treatments that aimed to control the level of infestation at that moment. The quality of the acaricide dipping/spraying applied was affected by the quality of the equipment used to apply the products, lack of knowledge of the mode of action of these products, lack of the specific information needed and lack of motivation caused by unawareness of the disadvantages of chemical combat. It was concluded that the lack of knowledge about combat methods and the acceptance of endemicity of the parasitosis were impediments to changing the realities encountered.(AU)

Entrevistas semissistematizadas foram aplicadas a 100 produtores de bovinos leiteiros do município de Divinópolis, Minas Gerais, com o objetivo de verificar a sua percepção sobre a importância de Rhipicephalus (Boophilus) microplus e seu combate. Foi feita "análise de conteúdo" e a distribuição de frequência de cada uma das variáveis para a construção de perfis dos produtores entrevistados. Os prejuízos causados à produção pelo carrapato são percebidos de forma incompleta pelos produtores, que ignoram a transmissão de patógenos pelo parasito e as perdas indiretas pelo combate, como o custo do carrapaticida e da mão de obra. O combate era feito de maneira tradicional com número excessivo de tratamentos ineficientes, com o objetivo de controlar o nível da infestação naquele momento. A qualidade da aplicação do banho carrapaticida foi afetada pelo equipamento utilizado para aplicação dos produtos, pelo desconhecimento do modo de ação desses, pela falta de informações específicas necessárias e pela falta de motivação gerada no desconhecimento das desvantagens do combate químico. Conclui-se que a falta de conhecimento sobre modos de combate e a aceitação da endemicidade da parasitose impedem a mudança da realidade encontrada.(AU)

Assuntos

RESUMO

This study evaluates milk producers' knowledge regarding cattle ticks and practices for controlling them. Ninety-three dairymen in Minas Gerais were interviewed. These producers had no information regarding acaricide efficiency tests. To analyze the information, open responses were categorized through "content analysis", and descriptive analysis consisting of extracting the profile highlighted by the highest frequencies. The association between schooling level and knowledge was tested by means of chi-square trend tests. It was observed that 92.3% had no knowledge of the nonparasitic period. For 96.4%, what determined the time to apply treatment was the degree of tick infestation; 93.3% used spray guns to apply the acaricide. In seeking to cross-correlate the biological and control variables with education, cooperative action, length of experience and herd size, it was found that there was a linear association between schooling level and implementation of acaricide solution preparation. The other factors didn't show any significant association. These data demonstrated the need to instruct the producers in relation to the biology and control of Rhipicephalus (Boophilus) microplus. It was concluded that the majority of milk producers were unaware of cattle tick biology and the factors that influence choosing an acaricide, which makes it difficult to implement strategic control.

Assuntos