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Background: Head louse infestation is difficult to control because of increasing lice resistance to synthetic pediculicidal drugs., Objective: To test the activity of extract and oil obtained from fruits of Melia azedarach L. against the head louse Pediculus humanus capitis., Methods: A filter paper diffusion bioassay was carried out in order to determine the pediculicidal and ovicidal activity of extract and oil from M azedarach L. fruits., Results: Both vegetable products, tested either individually or in combinations, showed high levels of mortality on adult lice, with values ranging between 62.9% and 96.5%. The highest mortality rate was obtained with a combination of 20% ripe fruit extract with 10% ripe fruit oil. A formulation made with both extract and oil at 10% plus the addition of emulsifier and preserving agents showed 92.3% pediculicidal activity. The products were also successful in delaying or inhibiting nymph emergence, with the formulation being the most effective, with a complete inhibition of emergence., Limitations: Because adult lice are sensitive to starvation and therefore control mortalities are often higher than 20% in tests with field specimens, the results may not reflect the direct effect of the extract., Conclusions: These results demonstrate the possibility of using Melia products for controlling head lice, which are difficult to control because of their resistance to the currently used anti-louse agents.

In the continuous search for antifungal compounds from plants, the hydroxycoumarin scopoletin (1) was isolated from seed kernels of Melia azedarach L. from which three other compounds, vanillin (2), 4-hydroxy-3-methoxycinnamaldehyde (3), and (+/-) pinoresinol (4), have also been isolated. Guided fractionation through autobiography on TLC using Fusarium verticillioides (Saccardo) Nirenberg as test organism led to the isolation of 1, which exhibited a minimum inhibitory concentration (MIC) of 1.50 mg/mL in the microbroth dilution method. Despite its own weak activity, when the coumarin was combined with the above-mentioned compounds, a strong enhancement of the antifungal effect was observed, even showing a complete inhibition in the growth of the pathogen when 1 was added at a concentration of up to 5% of its MIC value. The same level of effectiveness was observed when the synthetic antifungal agents Mancozeb and Carboxin were each combined with compounds 1-4, in which cases it became possible to decrease the effective concentrations of these commercial compounds by up to 2.5 and 3%, respectively.

Extracts from different parts of Melia azedarach L. were studied as potential antifungal agents for selected phytopathogenic fungi. In a serial agar dilution method, hexanic and ethanolic extracts from fruit, seed kernels, and senescent leaves exhibited fungistatic activity against Aspergillus flavus,Diaporthe phaseolorum var. meridionales, Fusarium oxysporum, Fusarium solani, Fusarium verticillioides, and Sclerotinia sclerotiorum. Both hexanic extract from senescent leaves and ethanolic extract from seed kernel were highly effective on all tested fungi, with minimum inhibitory concentration (MIC) values ranging from 0.5 to 25 mg/mL and 0.5 to 5 mg/mL, respectively. In addition, all of the above-mentioned extracts showed fungicidal activity on these fungi, with ethanolic seed kernel extract being the most active. Three compounds displaying activity against F. verticillioides were isolated from the ethanolic seed kernel extract and were characterized as vanillin (1), 4-hydroxy-3-methoxycinnamaldehyde (2), and (+/-)-pinoresinol (3), with MICs of 0.6, 0.4, and 1.0 mg/mL, respectively. These compounds also showed a synergistic effect when combined in different concentrations, needing four times less concentration to reach complete inhibition in the growth of F. verticillioides.

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Abstract: Extracts from the fruit of Melia azedarach L. (Meliaceae) have shown antifeedant and toxic effects on several insect species, including various pests, but the action of these compounds on natural enemies such as predators and parasitoids is less understood. The purpose of this work was to assess extract effects on Cotesia ayerza (Brèthes) (Hymenoptera: Braconidae), a parasitoid of the alfalfa defoliator Colias lesbia Fab. (Lepidoptera: Pieridae). The extract was first tested on butterfly larvae, in order to determine sublethal concentrations, and thus enable the evaluation of extract effects on parasitoid development from treated hosts. Direct effects of the extract through ingestion or contact (topical application) on adult wasp survival were also evaluated. An extract concentration of 0.2% was selected for parasitoid tests, since it allowed butterfly larvae to survive and pupate at normal rates, while inducing sublethal effects manifested as lower body weight. The indirect effects of the extract, through parasitoid development on treated hosts, were seen only in a female-biased sex ratio, without significant effects on either cocoon formation time, number of cocoons or adult parasitoids emerged. Adult wasps suffered increased mortality when their food was treated with extract, but were unaffected by topical application. These results suggest that M. azedarach extracts could represent an interesting tool for integrated pest management of C. lesbia populations. [Copyright &y& Elsevier]