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Abstract

Effect of extracts of plants with insecticidal activity on the control of Microtheca ochroloma Stal (Col: Chrysomelidae) in the laboratory. Extracts  of plants with insecticidal activity were tested on the control of Microtheca ochroloma (Col.: Chrysomelidae), an important insect-pest of Brassica- ceae, in the larval and adult phases. Two 3-day-old larvae, kept  under laboratory conditions (25 ºC temperature, 70% relative humidity and 14 hours of photophase), were placed in a glass tube with a leaf of Chinese cabbage (Brassica chinensis) previously treated with aqueous extracts (10% p/v) of chinaberry leaf (Melia azedarach), chinaberry branch, and tobacco powder (Nicotiana tabacum). The same procedure was  repeated in  two assays with adult insects. In the fi rst assay, all the previously mentio ned extracts were used, in addition to DalNeem (commercial product of Azadirachta indica). In the second, the insects were  exposed to  extracts of tabasco pepper fruits (Capsicum frutes- cens),  Surinam cherry (Eugenia unifl ora), jambolan (Syzygium cuminii) and eucalyptus leaves (Eucalyptus sp.). All the tests consisted of  10 insects per treatment, with fi ve repetitions in the fi rst test using adult insects and six repetitions in the others. Observations were made daily up  to the fi fth day, aiming to evaluate the mortality of the insects. All the tested extracts resulted in an effective control of the larvae of M.ochro- loma. In relation to the adult insects, only the extracts of tobacco powder and DalNeem showed effective control.