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Hexane extract of chinaberry, Melia azedarach L., unripe fruits obtained from different municipalities of Goiás State, Brazil, were evaluated on the southern cattle tick, Rhipicephalus (Boophilus) microplus (Canestrini), engorged females. Hexanic extracts were assayed in decreasing concentrations from 0.25 to 0.0156% to determine effects on egg production and hatching. Efficacy on engorged females decreased as a result of the extracts from Goiânia (100%), Professor Jamil (97.5 ± 3.0%), Pirenópolis (95.1 ± 2.4%), Morrinhos (86.8 ± 9.4%), Caturaí (41.8 ± 29.3%), and Bela Vista de Goiás (17.1 ± 0.9%) municipalities. Canonical redundancy analysis indicated that the extract bioactivity was positively correlated with soil Ca2+, Mg2+, and P and negatively correlated with silt, K+, potential acidity, and organic matter. This study demonstrates that M. azedarach hexanic extract can dramatically reduce R. (B.) microplus reproductive capacity and that efficacy is strongly influenced by differences in soil constituents between collection sites.

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. A 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.

The use of a concentrate emulsion of Melia azedarach green fruits and a suspension of the fungus Beauveria bassiana was evaluated in the control of Rhipicephalus microplus on artificially infested cattle. The evaluation was conducted following the protocol established by the Brazilian Agriculture Ministry. Five groups of 4 or 5 animals were allocated to one of the following treatments: emulsion concentrate of M. azedarach at 0.25% (T AZED 0.25%), emulsion concentrate of M. azedarach at 0.5% (T AZED 0.5%), B. bassiana at 2.4 × 10 8 conidia (T BASS), association of the concentrate of M. azedarach at 0.25% with B. bassiana at 2.4 × 10 8 conidia (T AZED 0.25% + BASS), and control (untreated). The association of the two compounds provided better results than any one isolated treatment, indicating compatibility or perhaps a synergy between M. azedarach and B. bassiana . This treatment resulted in fewer engorged females (129 ± 70) than in the control group (233 ± 82), showing high performance against all developmental stages of the tick. Results revealed an apparent synergistic effect of M. azedarach and B. bassiana in the control of R. microplus that should be further investigated.

This study was developed to evaluate the repellent activity of N,N-diethyl-3-methylbenzamide (DEET) against Amblyomma cajennense nymphs. Two repellent bioassays were compared and the effective concentration and repellent time were calculated. The fingertip test was accomplished to evaluate in vivo four concentrations of the compound (0.200; 0.100; 0.050 and 0.025 mg.cm-2) and the filter-paper bioassay to evaluate in vitro the two highest concentrations. The compound provided repellence higher than 90% in all concentrations and at least 95% repellency in the highest concentration over 5 hours. The effective concentration against 50% of tested nymphs (EC50) was 0.006 mg.cm-2 and the EC99 was 0.036 mg.cm-2. Those concentrations were lower than the ones obtained against other tick species, denoting the effectiveness of DEET against A. cajennense. The repellency time against 50% of the ticks (RT50) was 4.8 hours and the RT90 was 2.7 hours. Both bioassays were adequate to evaluate A. cajennense repellency and provided similar results; however the in vivo test is more appropriate to estimate the effective concentration and repellency time. Este estudo foi conduzido com o objetivo de avaliar a atividade repelente do N,N-diethyl-3-methylbenzamide (DEET) sobre ninfas de Amblyomma cajennense. Dois bioensaios para a avaliação de repelência foram comparados e cálculos da concentração eficaz e do tempo de repelência foram realizados. Foram empregados o bioensaio da ponta do dedo, para avaliação in vivo de quatro concentações do químico (0,200; 0,100; 0,050 e 0,025 mg.cm-2) e o bioensaio do papel filtro, para a avaliação in vitro das duas concentrações mais altas. O composto conferiu mais de 90% de repelência em todas as concentrações utilizadas e 95% de repelência por mais de cinco horas na maior concentração. A concentração do composto efetiva contra 50% das ninfas testadas (CE50) foi de 0,006 mg.cm-2 e a CE99 foi de 0,036 mg.cm-2. Estas concentrações são mais baixas do que as observadas em outras espécies de carrapatos, denotando a efetividade do princípio contra A. cajennense. O tempo de repelência de 50% dos carrapatos (TR50) foi de 4,8 horas e o TR90 de 2,7 horas. Os dois bioensaios avaliados permitiram a observação de percentuais de repelência igualmente altos e se mostraram adequados para tal avaliação, sendo que o teste in vivo é mais indicado para cálculo da concentração eficaz e da duração da repelência.

Extratos hexânicos obtidos dos frutos de Melia azedarach foram testados sobre fêmeas ingurgitadas e larvas de Rhipicephalus (Boophilus) microplus. Foram produzidos quatro extratos: um de frutos verdes e três com frutos maduros, sendo um com os frutos imediatamente processados, outro com frutos armazenados por cinco meses e um testado após armazenamento do extrato por 2 (dois) anos a 4ºC. Os testes foram feitos em triplicata, em diluições de 0,25% a 0,0156%. A eficácia dos extratos foi avaliada através da comparação da Reprodução Estimada dos lotes "controle e tratado" para fêmeas, da mortalidade para as larvas, e do cálculo das DL50 e da potência relativa para larvas e fêmeas. O extrato de frutos verdes apresentou uma eficácia variando de 3,6% a 100% para fêmeas, e o de frutos maduros variou de 5,2% a 99,7%. Os dois extratos causaram uma mortalidade de 100% das larvas nas maiores concentrações. O extrato de frutos armazenados apresentou eficácia de 14% a 83% sobre fêmeas, enquanto o extrato armazenado em geladeira apresentou eficácia de 8,4% a 100% e ambos não apresentaram efeito larvicida. Os resultados obtidos demonstram uma superioridade do extrato verde, com uma menor DL50 e potência 1,497 vezes superior ao extrato de frutos maduros. Hexanic extracts gotten of the fruits of cinamomo (Melia azedarach) were tested on engourged females and larvae of Rhipicephalus (Boophilus) microplus. Four extracts were produced: one of unripe fruits and three of ripe fruits, being one with the fruits immediately processed, another one with fruits stored for five months and one tested after storage of the extract for 2 (two) years at 4ºC. The tests were made in triplicate, in 0.25%- 0.0156% dilutions. The effectiveness of extracts was evaluated through the comparison of the Reproduction Estimate of the groups "controlled and treated" for females, of mortality for the larvae, and of the calculation of the DL50 and the relative power for larvae and females. The extract of unripe fruits presented the effectiveness varying the 3.6% - 100% for females, and of ripe fruits it varied of 5.2% - 99.7%. The two extracts caused a mortality of 100% of the larvae in the highest concentrations. The extract of stored fruits presented effectiveness of 14% - 83% on females, while the extract stored in refrigerator presented effectiveness of 8.4% 100% and both did not present larvicidal effect. The results demonstrate a superiority of the unripe extract, with a minor DL50 and superior power 1.497 times to the extract of ripe fruits.

This study aimed to analyze ovary histology and quantify total protein in the hemolymph of Rhipicephalus (Boophilus)microplus females treated with hexane extracts from green fruits of Melia azedarach. Eight engorged females were immersed in the extract at 0.25% concentration, and eight in water containing 5% acetone (control). The females were dissected 72 hours after treatment, and the ovaries were weighed and subjected to standard histological techniques. The total protein concentration was measured in the hemolymph of 200 females, of which 100 were treated as described above and 100 served as a control. In the treated group, ovary weight reduction and predominance of immature oocytes were observed. In addition, there were decreases in the diameters of the cytoplasm and germ vesicle of the oocytes in the treated group, compared with the controls. The protein concentration in the hemolymph was higher in the treated group than in the controls. The morphological changes observed in the treated ovaries included: presence of vacuolization; alteration of oocyte morphology, which changed from rounded to elongated; deformation of the chorion; and disorganization of the yolk granules. These results demonstrate the action ofM. azedarach fruit extracts on R.(B.) microplus oogenesis. Este estudo foi desenvolvido, visando analisar a histologia do ovário e quantificar as proteínas totais na hemolinfa de fêmeas deRhipicephalus (Boophilus)microplus tratadas com extrato hexânico de frutos verdes deMelia azedarach. Oito fêmeas ingurgitadas foram tratadas por imersão com o extrato na concentração de 0,25%, e oito com água contendo 5% de acetona (controle). As fêmeas foram dissecadas 72 horas após o tratamento e os ovários foram pesados e submetidos a técnicas histológicas padrões. A concentração total de proteína foi mensurada na hemolinfa de 200 fêmeas, sendo 100 tratadas como descrito anteriormente e 100 como controle. Foi observada redução do peso dos ovários, predomínio de ovócitos imaturos e houve diminuição nos diâmetros do citoplasma e da vesícula germinal dos ovócitos do grupo tratado em comparação ao controle. A concentração de proteína na hemolinfa foi mais alta no grupo tratado que no controle. As alterações morfológicas observadas nos ovários tratados foram a presença de vacuolizações, alteração da morfologia dos ovócitos que mudaram de redondos para alongados, deformação do córion e desorganização dos grânulos de vitelo. Estes resultados demonstram a ação do extrato de M. azedarach na ovogênese de R.(B.) microplus.