ABSTRACT: The demand for effective insecticides in pest control with low toxicity to the non-target organisms, such as natural enemies and pollinators, is increasing steadily. A good alternative for synthetic insecticides is natural compounds, including essential oils (EO). This work assessed toxicity of essential oils extracted from Artemisia annua, A. absinthium, A. camphorata, A. dracunculus and A. vulgaris against the melonworm Diaphania hyalinata (Linnaeus, 1758) (Lepidoptera: Crambidae) larvae, a pest of Cucurbitaceae, and their selectivity for fire ant Solenopsis saevissima (Smith) (Hymenoptera: Formicidae) and jataí bee Tetragonisca angustula (Latreille) (Meliponinae). The plants were grown in a greenhouse with mineral fertilization and were used for EO extraction. The insects in the bioassay belonged to the second instar of D. hyalinata and adult forms of S. saevissima and T. angustula. Essential oil from A. annua induced a high mortality rate in D. hyalinata (96 %) over a 48 h period. The same essential oil was selective for predator S. saevissima (42 % mortality) and pollinator T. angustula (74 % mortality), while causing high mortality in D. hyalinata. The insecticidal activity of A. annua oil was attributed to the synergism of its constituents viz., camphor and 1,8-cineole. Therefore, this essential oil contains constituents that are promising for effective use as insecticide due to its high toxicity and rapid action against D. hyalinata as well as low toxicity for predator and pollinator.

Phytochemical investigation of the aerial parts and roots of Mucuna cinerea led to the isolation of a mixture of fatty acids, triacylglicerols, beta-sitosterol, stigmasterol, stigmasterol glucoside, daucosterol, asperglaucide (4) and the isoflavonoids prunetin (1), genistein (2), medicarpin (3), daidzein (5), 7-O-alpha-glycopiranosyl daidzein (6). An in vitro bioassay was carried out with compounds 1-4, at the concentration of 50 and 5 mug mL-1 against the phytonematodes M. incognita and H. glycines. Although the four compounds showed some nematocidal property, the most active was (1), causing 70% mortality of M. incognita at the concentration of 50 mug mL-1.

3,5-Dimethoxybenzylic alcohol was converted into the 2-acetoxy-5-methoxy-3-(pent-1-yl)-1,4-benzoquinone (12), in seven steps, with an overall yield of 14.6%. The natural quinone sorgoleone (1) was isolated from Sorghum bicolor and converted into the corresponding quinone (13) having a saturated side chain. The selective effects of these compounds (1, 12 and 13), at the dose of 5.6 mug of a.i./ g of substrate, on the growth of Cucumis sativus, Lactuca sativa, Desmodium tortuosum, Hyptis suaveolens and Euphorbia heterophylla were evaluated. All three compounds caused some inhibition on the root growth of the test plants (0.0-69.19%) with the aerial parts less affected. The results showed that the triene unit of the sorgoleone side chain is not essential for the phytotoxicity and also the synthetic quinone was as active as the natural product.

O estudo químico das cascas de Ochroma lagopus Swartz levou ao isolamento e ou, identificação de uma mistura de ácidos graxos e triacilglicerídeos, de b-sitosterol (1), estigmasterol (2), daucosterol (3), estigmasterol-3-O-b-D-glicosídeo (4) e manitol (5).

Phytochemical investigation of the bark from Ochroma lagopus Swartz led to the isolation and or identification of a mixture of fatty acids and triacylglycerides, sitosterol (1), stigmasterol (2), daucosterol (3), stigmasterol-3-O-b-D-glycoside and mannitol (5).