ABSTRACT The importance of in-vitro tests using larvae and adults of the tick Rhipicephalus (Boophilus) microplus in investigating new inputs for its biological control serves as a basis for continuation of field experiments. This article presents in-vitro efficacy data on the fungus Purpureocillium lilacinum (IBCB 130) tested using larvae and engorged females of the tick R. microplus according to modified techniques of SHAW (1966) and MONTEIRO (2014). The efficacy results from the tests on engorged females ranged from 99.6 at the highest concentration used (2x109 conidia/mL) to 51% at the lowest concentration (1x107 conidia/mL). The 50, 90 and 99% lethal concentrations found in the tests on larvae were, respectively, 5.1x108, 5.2x109, and 3.3x1011 conidia/mL. The results from this investigation have enabled field experiments to control the tick R. microplus using the IBCB 130 isolate of the fungus P. lilacinum.

ABSTRACT The presence of capybaras (Hydrochoerus hydrochaeris) in urban and periurban areas has caused increased numbers of cases of Brazilian spotted fever. With the aim of investigating the presence of the parasitoid Ixodiphagus hookeri in Amblyomma sculptum ticks in the municipality of Salto, state of São Paulo, samples were collected monthly from 14 sites. Thirty samples were placed in containers for observation of the emergence of microhymenopterans and 88 samples were subjected to molecular testing to identify the presence of I. hookeri DNA. Neither dissections nor observation of emergence indicated any presence of I. hookeri larvae in ticks. Samples subjected to polymerase chain reaction (PCR) amplification of the mCOX I region of I. hookeri did not reveal its presence, although fragments corresponding to mRNA 16S of Amblyomma sculptum ticks were amplified in all samples tested.

ABSTRACT The aim of the present study was to evaluate the resistance of tick populations on 16 family farms that were members of the agricultural producers’ cooperative of the São Pedro region of the state of São Paulo (COOPAMSP). Bioassays were conducted on nine commercial products in 2018 and 2019. Their active agents were as follows: deltamethrin, amitraz, cypermethrin + chlorpyrifos + citronella, cypermethrin + chlorpyrifos + fenthion, cypermethrin + chlorpyrifos + piperonyl butoxide, dichlorvos + chlorpyrifos, cypermethrin, chlorfenvinphos + dichlorvos, and ivermectin. On some farms, a larval packet test (LPT) was also performed. Overall, four acaricides presented mean efficacy greater than 89%, among which two were associations of pyrethroids + organophosphates and two were associations of organophosphates + organophosphates. Deltamethrin, cypermethrin and ivermectin presented mean efficacy lower than 50%. In the bioassays using the LPT, all five farms showed resistance to diazinon, while only one farm presented resistance to cypermethrin. The results were handed over to each farmer with appropriate guidance for treatments. This study demonstrated that the important points to be implemented related directly to use control strategies, based on direct assistance for farmers and diagnosis of tick population sensitivities.

Resumo Em virtude de alta infestação por carrapatos do complexo Amblyomma cajennense, parasitos que transmitem a bactéria Rickettsia rickettsii, causadora da Febre Maculosa Brasileira, adotou-se um sistema de controle integrado dos carrapatos numa propriedade rural localizada no munícipio de Itu – SP. Na propriedade, que margeia o rio Tietê, os animais domésticos mantinham contato com populações de capivaras. Seis locais foram avaliados e monitorados nos anos de 2015 a 2017. Dentre os 1271 espécimes capturados (adultos e ninfas) um foi identificado como Amblyomma dubitatum e os demais com Amblyomma sculptum. De um modo geral, houve controle da infestação de carrapatos visto que todos os estágios ao final de 2017 apresentaram níveis próximos ou igual a zero. A população de adultos teve queda no primeiro ano e a de larvas no segundo. As ninfas apresentaram queda nos dois anos, sendo mais acentuada no primeiro ano. A média da estimativa do nível de infestação para cada estágio do carrapato nos seis locais monitorados não chegou a 1 indivíduo ao final do experimento, sendo que a média da estimativa para as ninfas foi de zero em todos esses locais.

Abstract Ticks of the Amblyomma cajennense complex present high infestation rates. These ticks transmit the bacterium Rickettsia rickettsii, which causes Brazilian Spotted Fever. For this reason, an integrated tick control system was adopted on a farm in the municipality of Itu, state of São Paulo. On this farm, which borders the Tietê river, domestic animals are in contact with populations of capybaras. Six locations were monitored and evaluated between the years of 2015 and 2017. During this work 1271 nymphs and adult ticks were caught, all of them from the Amblyomma sculptum species, except for a single individual from the Amblyomma dubitatum species. The integrated tick management reduced the overall infestation levels to zero. Adult tick population dropped in the first year of the study, while larvae population dropped in the second year. Nymph population dropped in both years, decreasing in higher numbers in the first year. The estimated mean infestation levels for all of the tick’s life cycle forms in the six monitored spots did not reach one individual in the end of the study. Estimated mean infestation levels for nymphs in these places equaled zero.

O controle do carrapato Rhipicephalus(Boophilus) microplus no Brasil é feito principalmente com produtos acaricidas, sem uma política de controle oficial. A venda destes produtos continua ocorrendo de maneira indiscriminada, o que tem contribuído para generalizar o problema da resistência em todo o país, tornando essencial seu diagnóstico e monitoramento. Bioensaios (teste do pacote de larvas) foram conduzidos com populações de carrapatos do Rio Grande do Sul e Mato Grosso do Sul, com relação à sua suscetibilidade a três princípios ativos piretróides. Todas as amostras analisadas mostraram resistência à cipermetrina (10), com fatores de resistência (FR) de 5,6 a 80,3, e à deltametrina, com FR variando de 2,4 a 83,1. Seis das oito amostras foram resistentes à flumetrina (FR de 3,8 a 8,2). Análises moleculares utilizando PCR demonstraram que em todas as populações amostradas não foram encontrados alelos com a mutação T2134A no gene do canal de sódio controlado por voltagem. Os resultados deste estudo evidenciam a situação crítica da resistência do carrapato bovino ao grupo dos piretróides sintéticos nas regiões estudadas. Novos estudos são necessários para identificar os mecanismos responsáveis pelos fenótipos resistentes observados nos bioensaios. Este é o primeiro relato da resistência a flumetrina no Brasil.

Cattle ticks Rhipicephalus(Boophilus) microplus are mainly controlled in Brazil by means of acaricide products, without any official policies in this regard. Acaricides continue to be sold indiscriminately, and this has contributed towards making the problem of resistance widespread, thus making diagnosis and monitoring of tick resistance essential. Here, bioassays (larval packet test) were performed on tick populations from the states of Rio Grande do Sul and Mato Grosso do Sul regarding their susceptibility to cypermethrin, deltamethrin and flumethrin. All the tick samples tested showed resistance to cypermethrin (10) (resistance factor (RF) ranging from 5.6 to 80.3) and deltamethrin (10) (RF ranging from 2.4 to 83.1). Six out of eight populations were resistant to flumethrin (RF ranging from 3.8 to 8.2). PCR molecular analyses did not show any T2134A mutations in the voltage-gated sodium channel gene, in any of the sampled populations. The results from this study highlight the critical status of resistance of the cattle tick to synthetic pyrethroids in the regions studied. Further studies are needed to identify the mechanisms responsible for the resistant phenotypes observed in the bioassays. This was the first detection of flumethrin resistance in Brazil.