Action of plants extracts on oviposition and on mortality of diamondback moth/Acao de extratos de plantas na oviposicao e na mortalidade da traca-das-cruciferas

The diamondback moth, Plutella xylostella (L.) (Lepidoptera, Yponomeutidae), is one of the most important insect pest species of the Brassicaceae family plants in Brazil and in the world. The use of insecticidal plants extracts in the control of this insect is a promising alternative. Therefore, this research goal is to evaluate, in laboratory, the plants extracts effect on the oviposition and mortality of P. xylostella. In order to analyze the effect on the oviposition, kale leaf pieces were treated, in cage, as following: aqueous extracts (10% p/v) of leaf of chinaberry (Melia azedarach), of branch of chinaberry, of tobacco powder (Nicotiana tabacum), besides DalNeem (commercial product, based on Azadirachta indica), at 10% v/v. Inside the cage, 50 adults of P. xylostella were put and, 48h later, the egg number per leaf was counted, in seven repetitions. A second assay was consisted of the exposition of three larvae to the same cited extracts, in glass tube with a kale leaf piece previously treated. Three glass tubes were used per treatment, with four repetitions. The number of death larvae was evaluated daily. The aqueous extracts of chinaberry leaf, chinaberry branch and tobacco powder, besides DalNeem, reduce the oviposition of P. xylostella and the use of tobacco powder extract, DalNeem and chinaberry branch extract result in efficient control of P. xylostella larvae after the second, fifth and sixth days after application, respectively. Key words: Plutella xylostella (Lepidoptera: Yponomeutidae), Melia azedarach, Azadirachta indica. A traca-das-cruciferas, Plutella xylostella (L.) (Lepidoptera: Yponomeutidae), e uma das principais especies de inseto-praga de plantas da familia Brassicaceae no Brasil e no mundo. A utilizacao de extratos de plantas inseticidas no controle desse inseto e uma alternativa promissora. O presente trabalho teve como objetivo avaliar, em laboratorio, o efeito de extratos de plantas na oviposicao e na mortalidade de P. xylostella. Para analise do efeito sobre a oviposicao, pedacos de folhas de couve foram expostos, em gaiola, aos seguintes tratamentos: extratos aquosos (10% p/v) de folha de cinamomo (Melia azedarach), de ramo de cinamomo, de po-de-fumo (Nicotiana tabacum), alem de DalNeem (produto comercial a base de Azadirachta indica), a 10% v/v. No interior da gaiola, foram liberados 50 adultos de P. xylostella e, apos 48h, foi contado o numero de ovos por folha, em sete repeticoes. Um segundo ensaio constou da exposicao d