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The strategies to control the cattle tick, Rhipicephalus microplus are based mainly on the use of synthetic pesticides. However, the emergence, establishment, and development of resistance of ticks is rendering the main chemical groups ineffective. Finding new molecules to effectively control infestations by R. microplus is necessary to maintain the productivity of cattle herds, particularly of taurine breeds established in equatorial and tropical regions of the world. Ethanol extracts from the leaves, stems, and fruits of Piper tuberculatum were evaluated in bioassays at concentrations of 50, 25, 12.50, 6.25, 3.12 and 1.56 mg mL-1. The concentrations lethal to 50% of the individuals (LC50) of tick larvae after 24 hours of exposure were 3.62, 3.99 and 5.30 mg mL-1 for fruit, stem and leaf extracts, respectively. Against the engorged females, the highest efficacy rates were obtained at the concentration of 50 mg mL-1, corresponding to 71.57%, 68.38% and 37.03% of the fruit, leaf and stem extracts, respectively. The main effect of the ethanol extracts was on the egg hatching rate of ticks, with a reduction of 55.63% for the fruit and leaf extracts, and 20.82% for the stem extract. The results show that P. tuberculatum is a promising source of molecules for use as active ingredients in pesticide formulations for R. microplus control.

In the present study, we provide new tick records from Vilhena Municipality, in the Southeast of the State of Rondônia, Northern Brazil. Ticks collected from a capybara, Hydrochoerus hydrochaeris (Linnaeus), were identified as Amblyomma romitii Tonelli-Rondelli (1 female), and Amblyomma sp. (1 larva). Ticks collected from a harpy eagle, Harpia harpyja (Linnaeus), were identified as Amblyomma cajennense (Fabricius) (16 nymphs) and Haemaphysalis juxtakochi Cooley (1 nymph). Ticks collected from a yellow-footed tortoise, Chelonoidis denticulada (Linnaeus), were identified as Amblyomma rotundatum Koch (10 females, 2 nymphs), and Amblyomma sp. (2 larvae). The present record of A. romitii is the first in the State of Rondônia, and represents the southernmost record for this tick species, indicating that its distribution area is much larger than currently recognized. Although both A. cajennense and H. juxtakochi have been reported parasitizing various bird species, we provide the first tick records on a harpy eagle. A. rotundatum is widespread in the State of Rondônia, and has been previously reported on the yellow-footed tortoise. The present records increase the tick fauna of Rondônia to 26 species.

A produção de feijoeiro comum (Phaseolus vulgaris) é limitada, dentre outros fatores, pela ocorrência de doenças, destacando-se a mela do feijoeiro e o mofo cinzento, causados pelos fungos Rhizoctonia solani e Sclerotium rolfsii, respectivamente. Extratos vegetais com potencial fungicida se destacam como um método alternativo no controle de fitopatógenos. O objetivo deste trabalho foi avaliar extratos de espécies do gênero Piper no crescimento micelial dos fungos R. solani e S. rolfsii. Foram preparados extratos aquosos e alcoólicos nas proporções de 1:10, 1:100, 1:1000 e 1:10000mg/mL, obtidos a partir de materiais secos e frescos de folhas, talos e inflorescências de P. carniconnectivum, P. hispidum, P. nigrum, P. permucronatum, P. tuberculatum e P. umbellatum, cultivadas em casa de vegetação e campo, totalizando cento e um tratamentos. A atividade antifúngica foi avaliada pelo método de difusão em poços, utilizando meio BDA. Alíquotas de 10µL dos extratos avaliados foram depositadas em cada poço, e um disco de micélio de 0,5cm de diâmetro do patógeno desafiante adicionado no centro da placa. Os halos de inibição formados foram medidos a cada 24h, no sentido longitudinal e transversal. Testes in vivo foram conduzidos em folhas destacadas e em plântulas de feijoeiro. Folhas destacadas de feijoeiro foram acondicionadas em caixas tipo Gerbox, e mudas de feijoeiro mantidas em câmara úmida. Sobre as folhas foram pulverizados os extratos avaliados, e após 24h, uma suspensão de micélio do patógeno R. solani, na concentração de 1x106 fragmentos de micélio.mL-1 também foi pulverizada, avaliando-se a cada 24h a severidade da doença. O delineamento experimental dos testes in vitro e in vivo foi o inteiramente casualizado, com três testemunhas. Dentre os extratos testados in vitro, vinte e seis demonstraram potencial inibitório no controle de R. solani na maior concentração, e doze mantiveram-se eficientes até a concentração 1:100, destacando-se os extratos obtidos das espécies P. permucronatum e P. carniconnectivum. Nos ensaios com o fungo S. rolfsii, dez extratos mostraram eficiência na inibição do patógeno, destacando-se o extrato aquoso de P. tuberculatum na maior concentração. No ensaio in vivo com folhas destacadas dez extratos apresentaram eficiência no controle da mela do feijoeiro, sendo que os extratos obtidos a partir de P. permucronatum, P. carniconnectivum e P. nigrum apresentaram efeitos de controle semelhantes ao controle fungicida, permanecendo extratos de P. permucronatum eficientes em testes in vivo com mudas de feijão em câmara úmida. Os resultados obtidos sugerem que os extratos de espécies do gênero Piper podem vir a ser utilizados futuramente como fonte de novas moléculas bioativas, visando o controle destes patógenos.

The objective of this work was to evaluate the in vitro antibacterial activity of snake venoms and purified toxins on the phytopathogenic bacterium Ralstonia solanacearum. The evaluations were performed with 17 crude venoms (13 from Bothrops, 3 from Crotalus, and 1 from Lachesis) and seven toxins (1 from Bothrops and 6 from Crotalus). Antibacterial activity was assessed in MB1 medium containing solubilized treatments (1 μL mL-1). A total of 100 μL bacterial suspension (8.4 x 109 CFU mL-1) was used. After incubation at 28°C, the number of bacterial colonies at 24, 48, and 72 hours after inoculation was evaluated. SDS-PAGE gel at 15% was used to analyze the protein patterns of the samples, using 5 μg protein of each sample in the assay. Furthermore, the minimum inhibitory concentration (MIC) and lethal concentration (LC50) values were determined by the Probit method. Venoms and toxins were able to reduce more than 90% of R. solanacearum growth. These results were either equivalent to those of the positive control chloramphenicol or even better. While MIC values ranged from 4.0 to 271.5 μg mL-1, LC50 ranged from 28.5 μg mL-1 to 4.38 mg mL-1. Ten crude venoms (7 from Bothrops and 3 from Crotalus) and two purified toxins (gyroxin and crotamine) are promising approaches to control the phytopathogenic bacterium R. solanacearum.

The description of the larva of Amblyomma romitii Tonelli-Rondelli is based on optical and scanning electron microscopy. Larvae were obtained under laboratory conditions from an engorged female collected on capybara from Rurópolis municipality, State of Pará, Northern Brazil. Several characters are presented including the chaetotaxy of idiosoma, palpi and Haller's organ. The larval porotaxy (topographical and numerical patterns of integumentary structures) was presented and compared to that of the other Amblyomma spp. larvae. The mitochondrial 16S rDNA partial sequence of A. romitii generated in the present study was aligned with sequences previously determined for other Amblyomma species available in Genbank and with some species presently sequenced. The larval morphology of A. romitii and other Neotropical Amblyomma spp. larvae is discussed as well as the DNA sequence and its phylogenetic position among other species of the genus.