Chemo-profiling and bioassay of phytoextracts from Ageratum conyzoides for acaricidal properties against Rhipicephalus (Boophilus) microplus (Acari: Ixodidae) infesting cattle and buffaloes in India.

In India, Rhipicephalus (Boophilus) microplus populations have developed a certain level of resistance to most of the acaricides marketed against tick species. To manage the problem, the present study was undertaken to evaluate the acaricidal potential of Ageratum conyzoides plants against acaricides-resistant ticks infesting cattle and buffaloes. The regression analysis of dose-response data of ethanolic extract of A. conyzoides revealed LC90 value of 8.91% against reference susceptible IVRI-1 line of R.(B.) microplus. The ethanolic extract was found efficacious against 76.7-90% acaricides-resistant field ticks and adversely affected oviposition showing 7.04-31.3% reduction in egg laying capacity. The extract was also showed an in vitro efficacy of 52.5 and 76.7% against reference resistant IVRI-4 and 5 lines. The GC/MS/MS profiling of hexane extract, two bioactive sub-fractions and essential oils revealed the presence of 6,7-dimethoxy-2,2-dimethyl-2H-1-benzopyran (precocene II) as a major phyto-compound. The bioactive sub-fractions showed 96.2-97.5% efficacy against larvae of IVRI-1 and 77.1-94.9% against multi-acaricide resistant larvae of IVRI-5 line of R.(B.) microplus. The results of this study provided significant support for the development of a phyto-formulation based on A. conyzoides species.

In vitro acaricidal properties of Semecarpus anacardium fruit and Datura stramonium leaf extracts against acaricide susceptible (IVRI-I line) and resistant (IVRI-V line) Rhipicephalus (Boophilus) microplus.

In an attempt to identify plants having anti-tick properties, the 95% ethanolic and 50% hydro-ethanolic extracts of the fruits of Semecarpus anacardium and leaves of Datura stramonium were evaluated against reference tick lines of Rhipicephalus (Boophilus) microplus. The 95% ethanolic extracts of S. anacardium and D. stramonium caused 50% and 20% mortality, respectively, within 72 h of treatment by adult immersion test. The LC90 value of the ethanolic fruit extract of S. anacardium was determined as 13.5% (CI 12.05-15.12). The extract was also found efficacious (73.3%±3.3%) against the multi-acaricide-resistant IVRI-V line of R.(B.) microplus. The S. anacardium extract significantly affected the reproductive physiology of treated ticks by inhibiting the oviposition and was found safe. The HPTLC fingerprinting profile revealed the presence of pyrocatechol as a marker compound. The acaricidal property of S. anacardium against chemical acaricide-resistant R. (B.) microplus was discussed.

Acaricidal activity of petroleum ether extract of leaves of Tetrastigma leucostaphylum (Dennst.) Alston against Rhipicephalus (Boophilus) annulatus.

The acaricidal activity of the petroleum ether extract of leaves of Tetrastigma leucostaphylum (Dennst.) Alston (family: Vitaceae) against Rhipicephalus (Boophilus) annulatus was assessed using adult immersion test (AIT). The per cent of adult mortality, inhibition of fecundity, and blocking of hatching of eggs were studied at different concentrations. The extract at 10% concentration showed 88.96% inhibition of fecundity, 58.32% of adult tick mortality, and 50% inhibition of hatching. Peak mortality rate was observed after day 5 of treatment. Mortality of engorged female ticks, inhibition of fecundity, and hatching of eggs were concentration dependent. The LC50 value of the extract against R. (B.) annulatus was 10.46%. The HPTLC profiling of the petroleum ether extract revealed the presence of at least seven polyvalent components. In the petroleum ether extract, nicotine was identified as one of the components up to a concentration of 5.4%. However, nicotine did not reveal any acaricidal activity up to 20000 ppm (2%). Coconut oil, used as diluent for dissolving the extract, did not reveal any acaricidal effects. The results are indicative of the involvement of synergistic or additive action of the bioactive components in the tick mortality and inhibition of the oviposition.

Toxic effects of various solvents against Rhipicephalus (Boophilus) annulatus.

The current need of identification of a new acaricidal agent which is acceptable to public as environmentally safe is a daring task. Use of herbal acaricides is such an alternative. Most of the herbal extracts or fractions are dissolved in polar or non-polar solvents or detergents before tested for acaricidal activity. The solvent or detergent to be used for dissolving the herbal extract should be of little acaricidal activity. In the present study, experimentations were carried out on adult engorged female ticks to detect the toxicity of different solvents, viz. hexane, petroleum ether, n-butanol, isopropyl alcohol, chloroform, glycerol, ethyl acetate, acetone, ethanol, and methanol. The study revealed that methanol was the least toxic solvent against Rhipicephalus (Boophilus) annulatus.

Molecular characterization of Theileria orientalis causing fatal infection in crossbred adult bovines of South India.

The disease condition attributed to have been caused by Theileria orientalis is generally benign. However, it is also thought that the parasite, at least some strains of it, can cause fatal disease. The present communication deals with the clinical signs, postmortem lesions and diagnosis of a fatal disease due to T. orientalis which caused mortality in crossbred adult bovines of South India. High body temperature, lacrimation, nasal discharge, swollen lymph nodes and haemoglobinuria were the symptoms observed. The postmortem lesions observed were punched out ulcers in abomasum, enlargement of spleen, massive pulmonary oedema, frothy exudates in trachea, epicardial and endocardial haemorrhage and haemorrhagic duodenitis. Peripheral blood smear examination revealed rod shaped Theileria sp. organisms. Polymerase chain reaction that amplify the T. orientalis specific P(32/33) gene, followed by cloning and sequencing, revealed maximum homology with Narathiwat (Thailand) and Jingole -1 (Indonesia) isolates which were positioned as isolate type 7 of T. orientalis.

Eclosion blocking effect of ethanolic extract of Leucas aspera (Lamiaceae) on Rhipicephalus (Boophilus) annulatus.

The crude ethanolic extract of aerial parts of Leucas aspera was tested for its acaricidal properties against Rhipicephalus (Boophilus) annulatus. The per cent adult mortality, inhibition of fecundity and hatching of laid ova were studied at concentrations of 1.56, 3.13, 6.25, 12.5, 25, 50 and 100mg/ml. Adult tick mortality was significant at the highest concentration tested. Inhibition of fecundity of treated groups differed significantly from control and was concentration dependent. L. aspera extract also produced complete failure of eclosion of eggs from the treated ticks even at lower dilutions of the extract.