The evolution of resistance of Rhipicephalus (Boophilus) microplus to synthetic acaricides has given rise to the need for new scientific investigations on alternative ways to control this tick. In this regard, various studies on plants have been developed in an attempt to find extracts with acaricidal properties. Evaluations on plant extracts for controlling R. (B.) microplus have grown intensely over the last decade. There are many advantages from using plant extracts: for example, they can be used in organic cattle farming or even replace synthetic acaricides and they are associated with lower environmental and food contamination, slower development of resistance and lower toxicity to animals and humans. In vitro studies on plant extracts have shown promising results, but most of these extracts have not been tested on animals to validate their use. Difficulties in preparing proper formulations, differences in the chemical composition of plants of the same species due to extrinsic and intrinsic factors and sparse information on active acaricide compounds are hindrances that need to be addressed in order to enable progress within this scientific field.Keywords: Phytotherapy, cattle tick, Rhipicephalus (Boophilus) microplus, in vitro bioassays, in vivo bioassays. ResumoA evolução da resistência do Rhipicephalus (Boophilus) microplus aos acaricidas sintéticos tem impulsionado novas investigações científicas sobre métodos alternativos para controlar este carrapato. Considerando isso, vários estudos com plantas têm sido desenvolvidos numa tentativa de encontrar extratos com propriedades acaricidas. Avalições de extratos de plantas para o controle de R. (B.) microplus tem sido intensificadas nesta última década. Existem muitas vantagens com o uso de extratos de plantas no controle deste carrapato, como: eles podem ser utilizados na produção orgânica de bovinos, ou mesmo substituir os acaricidas sintéticos, além do mais, estão associados com baixa contaminação ambiental e dos alimentos, desenvolvimento mais lento de resistência e baixa toxicidade para animais e seres humanos. Estudos in vitro de extratos de plantas têm apresentado resultados promissores, mas a maioria destes extratos não têm sido testada em animais para validar estes resultados. Dificuldades para preparar formulações apropriadas, diferenças na composição química de plantas de uma mesma espécie devido a fatores intrínsecos e extrínsecos e informações esparsas.sobre os princípios ativos são entraves que precisam ser solucionados visando o desenvolvimento deste campo de pesquisa.Palavras-chave: Fitoterapia, carrapato de bovinos, Rhipicephalus (Boophilus) microplus, testes in vitro, testes in vivo.

A total of 73 ethanol extracts from different anatomical parts of 44 plant species belonging to 24 families, native to the Mid-Western region of Brazil, were assessed in vitro for their effect on the reproductive cycle of engorged females of the cattle tick Rhipicephalus (Boophilus) microplus, using the adult immersion test. All extracts were evaluated at the concentration of 0.2 % and, among the extracts tested, the one obtained from the fruits of Guarea kunthiana (Meliaceae) proved to be highly efficacious, showing 99.1 % of product effectiveness. Extracts from other three species were shown to be moderately active, namely Nymphaea amazonum trunk (Nymphaeaceae) [51.7 %], Strychnos pseudoquina trunk (Loganiaceae) [48 %] [corrected] and Ocotea lancifolia leaves (Lauraceae) [34.5 %], while the remaining extracts were shown to be weakly active or inactive. This is the first report on the bioactivity of these species on egg production by engorged females of R. microplus.

Chemical investigation of Guarea kunthiana fruits, guided by their effect on the reproductive cycle of engorged females of the cattle tick Rhipicephalus (Boophilus) microplus-a major economic problem to the livestock industry worldwide-led to isolation of 3β-O-tigloylmelianol, a new protolimonoid, from the bioactive hexane phase obtained by partitioning the crude ethanol extract. An adult immersion test was performed. The compound strongly inhibited egg-laying and hatchability (99.2% effectiveness at a 0.01% concentration). Melianone, isolated from the same phase, yielded unremarkable results in the adult immersion test. From the dichloromethane phase, melianol, melianodiol, meliantriol, and a new protolimonoid, OPEN ACCESSMolecules 2015, 20 112 3β-O-tigloylmeliantriol, were isolated, all of which, in the same manner as melianone, exhibited unremarkable results in the test. The structures of new and known compounds were mostly established by 1D-and 2D-NMR analyses and mass spectrometry data. This is the first report on the bioactivity of protolimonoids on the reproductive cycle of engorged females of R. (B.) microplus. 3β-O-Tigloylmelianol proved a promising candidate for the development of a biocontrol agent against the cattle tick investigated, as an alternative to environmentally hazardous synthetic acaricides.

Essential oils from species of the genus Hyptis are well-known for their significant biological properties, including antimicrobial and acaricidal activities. The essential oil from the aerial parts of H. crenata was obtained by hydrodistillation; borneol (17.8%), 1,8-cineol (15.6%) and p-cimene (7.9%) were characterized by GC-MS as its major constituents. The essential oil was evaluated in vitro for its antimicrobial activities against six fungal and five bacterial strains, by measuring the respective MICs, MFCs and MBCs, using broth microdilution methods. The strongest bactericidal activities were shown against Staphylococcus aureus and Enterococcus faecalis, while the strongest fungicidal activities were against Cryptococcus neoformans, Candida glabrata and Candida tropicalis. The oil was also assessed for its anti-tick properties and, at a concentration of 2.5%, it significantly inhibited in vivo oviposition of engorged females of the cattle tick Rhipicephalus (Boophilus) microplus, using the adult immersion test., with an effectiveness of 94.4%.

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