Redução do Crescimento, Deformidades e Mortalidade de Spodoptera littoralis (Boisduval) (Lepidoptera: Noctuidae) Causadas por Azadiractina RESUMO -A azadiractina é o composto mais eficiente extraído da planta Azadirachta indica A. Juss, com propriedades insecticidas e que afetam o crescimento de diversas espécies de insetos. Seus efeitos no desenvolvimento e na sobrevivência de Spodoptora littoralis (Boisduval) foram estudados em condições de laboratório. Larvas de terceiro ínstar foram aliementada individualmente em dieta artificial tratada com azadiractina (de 0,01 ppm a 1 ppm p/v), por dois dias, e transferidas para dieta pura. A sobrevivência, a duração dos estágios e deformidades foram observados diariamente. Em um segundo experimento, os efeitos da azadiractina sobre lagartas de terceiro ínstar e lagartas de último ínstar foram comparados, após alimentar as lagartas por dois dias, utilizando-se 0,3 ppm e 0,6 ppm do composto e uma testemunha (água). O período de dois dias de alimentação prolongou os ínstares larvais, reduziu a taxa média de crescimento relativo (MRGR), impediu a ecdise, provocou anormalidades morfológicas e causou mortalidade em S. littoralis, de forma dependente da dose. Quando as concentrações mais altas foram empregadas, os efeitos aparecerem logo após o tratamento e a mortalidade foi mais elevada. Muitos insetos morreram após permanecerem inativos por vários dias ou durante ecdises prolongadas. Em concentrações mais baixas, se a ecdise foi completada, alterações no crescimento e anormalidades geralmente ocorreram nos estádios subseqüêntes. Quando a azadiractina foi oferecida às lagartas de último ínstar, intermediários "larva-pupa" foram produzidos e a mortalidade foi mais alta do que para as lagartas de terceiro ínstar. A azadiractina se mostrou promissora para o controle de S. littoralis não apenas por causar mortalidade, mas também por afetar o desenvolvimento e por causar deformidades envolvidas em atividades vitais dos insetos como alimentar-se, caminhar ou voar, o que pode torná-los vulneráveis a diversos tipos de agentes de mortalidade ou evitar que os mesmos causem dano à cultura.PALAVRAS-CHAVE: Insecta, Azadirachta indica, nim, inseticida botânico, intermediário larvapupa.ABSTRACT -Azadirachtin is the most effective compound of the neem tree, Azadirachta indica A. Juss, with insecticidal and growth disruption properties on several species of insects. Its effects on the development and survival of Spodoptora littoralis (Boisduval) were studied under laboratory conditions. Third-instar larvae were individually fed on artificial diet treated with azadirachtin (from 0.01 ppm to 1 ppm wt/v), for two days, and transferred to plain diet. Survival, duration of stages and deformities were recorded daily. In a second experiment, the effects of azadirachtin on 3 rd instar larvae and on last instar larvae were compared, by feeding the larvae with treated diet (0.3 ppm, 0.6 ppm and a control group), during the same period. A two-day feeding period promoted prolongation of the larval insta...
Neotropical Entomology 34(4): 601-606 (2005) ABSTRACT -The compatibility of a commercial formula of emulsible neem oil (Azadirachta indica A. Juss.) and of aqueous extracts of neem seeds and leaves with Beauveria bassiana (Bals.) Vuill. was evaluated in vitro. Three experiments were conducted to evaluate the effect of each product on the fungus vegetative growth and on conidia production and viability. The products were incorporated to a culture medium (BDA+E) and distributed into petri dishes, in the following concentrations: 0.15%; 1.5% and 15% (leaf aqueous extract), 1%; 2% and 4% (seed aqueous extract) and 0.5%; 1% and 1.5% (emulsible oil). Vegetative growth and conidia production were the basis for characterization of the aqueous extracts of seeds and leaves and of the emulsible oil, using the T classification model for compatibility of products. Seed and leaf extracts were less harmful to B. bassiana than the emulsible oil. Under the tested concentrations, the oil was not compatible with B. bassiana, inhibiting conidia vegetative growth significantly and decreasing production and viability of conidia, particularly at higher concentrations. Neem seed and leaf extracts were compatible with the entomopathogen in all concentrations. The seed extracts reduced conidia vegetative growth and production, but it did not affect the viability of spores. Leaf extract at 15% had a small negative impact on vegetative growth, and on production and viability of conidia, but it was still compatible with the fungus B. bassiana, according to the T model.
Sublethal concentrations of azadirachtin incorporated into artificial diet and offered to third-instar larvae of Spodoptera littoralis (Boisduval) prolonged larval instars and reduced food intake. These effects were observed after the treated larvae had been transferred to plain diet; the reduced food intake was therefore a secondary antifeedant effect. Azadirachtin did not influence digestion efficiency but diminished the ability of the larvae to convert both ingested and digested nutrients into growth, particularly immediately after treatment. This effect declined with time once the treatment with azadirachtin had ceased. Growth was more severely reduced than food intake, and the reduction in growth also occurred during periods when food intake was not affected, possibly due to post-ingestive effects.
-The effects of the neem seed oil aqueous solutions on survival and performance of egg, larva and adult stage of the Coccinelid predator Cycloneda sanguinea (L.) were evaluated under laboratory conditions. In a first trial, eggs and 2 nd -instar larvae were sprayed with the neem solutions at 0; 0.5 and 2.25 ml/l and kept at 25 ± 1 o C, 70% RH and 14h photoperiod. Egg viability and duration and larvae and pupae survival were evaluated as well as the predatory capacity of the larvae, adult longevity and reproduction. Egg spraying did not affect egg hatch or larvae survival and development. When the larvae were sprayed, significant mortality was observed only at the higher concentration (P < _ 0.05) and larval development and predatory capacity were not affected. Also, adults originated from treated larvae showed no alterations on sex rate, fecundity, fertility and longevity, thus indicating that at the tested concentrations the neem oil do not reduce the reproductive potential of the species. In a second experiment, adults collected in the field were sprayed with neem oil or kept on Parthenium sp. twigs sprayed with the neem oil aqueous solution at 5 ml/l, to evaluate survival. The neem oil at this concentration caused no mortality to the adults, since all of them, sprayed or kept on sprayed twigs, presented a longevity curve similar to untreated ones. The results indicate that the neem oil presents potential to be used in association with biological control of pests, when C. sanguinea is present. PALAVRAS-CHAVE: Meliaceae, biological control, botanical insecticide, predator, ladybird, Parthenium RESUMO -Os efeitos de soluções aquosas do óleo de sementes de nim sobre o predador Cycloneda sanguinea (L.), nos estágios de ovo, larva e adulto, foram avaliados em laboratório. Em um primeiro experimento, ovos e larvas de 2 o ínstar foram pulverizados com as soluções de nim nas concentrações de 0; 0, 5 e 2,25 ml/l de água apresentaram mortalidade significativa (P < _ 0,05) somente na maior concentração e o desenvolvimento larval e a capacidade predatória não foram afetados. Os adultos originados de larvas tratadas não apresentaram alterações da razão sexual, fecundidade, fertilidade e longevidade, indicando que nas concentrações testadas o óleo de nim não reduz o potencial reprodutivo da espécie. Em um segundo experimento, adultos da joaninha coletados no campo foram pulverizados com a solução aquosa de óleo de nim ou mantidos sobre ramos de losna-branca pulverizados na concentração de 5 ml/l de água, para avaliação da sobrevivência. A pulverização do óleo de nim nesta concentração não causou mortalidade nos adultos de C. sanguinea, uma vez que os insetos de ambos tratamentos apresentaram curva de longevidade semelhante à da testemunha. Os resultados demonstram que o nim apresenta potencial para ser utilizado em associação com o controle biológico de pragas, quando C. sanguinea for empregada.
-Aqueous solutions of neem oil and aqueous extracts of neem seeds and leaves were sprayed on coffee fruits for laboratory evaluation of their effi ciency in reducing infestation of the coffee borer, Hypothenemus hampei (Ferrari), in multi-choice preference assays in laboratory. Neem oil and extracts reduced infestation of fruits in a dose-dependent manner, acting as a repellent. At 0.5%, 1% and 1.5%, the oil reduced fruit infestation by 30.2%, 42.5% (P > 0.05), and 58.6% (P 0.05), respectively, as compared with the control. Seed extracts at 1%, 2% and 4% (w/v) reduced infestation by 30.9%, 38.3% (P > 0.05) and 70.2% (P 0.05), respectively; seed extracts at 0.15%, 1.5% and 15% (w/v) reduced fruit infestation by 16.5%, 38.5% (P > 0.05) and 56.9% (P 0.05), respectively. Spraying the emulsifi able oil at 1% on coffee fruits and adult borers was compared with spraying on fruits or adults only. Adult-only spraying caused low mortality (P > 0.05) and low reduction on the number of damaged fruits (P > 0.05). Fruit-only spraying signifi cantly reduced insect survival rates and the number of damaged fruits (P 0.05). However, spraying on adults and fruits caused the greatest reduction in adult survival (55.6%; P 0.05) and in fruit infestation (78.7%; P 0.05), probably due to insect mortality and neem oil repellence acting together.
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