Successive applications of insecticides to control Plutella xylostella L. (Lepidoptera: Plutellidae) have resulted in the emergence of resistant populations of this insect. A novel control measure for this target insect could be the use of botanical insecticides derived from plant tissues. Hence, we experimentally tested aqueous extracts of Alibertia edulis (Rich.), Alibertia intermedia (Mart.), and Alibertia sessilis (Vell.) K. Schum. found in the Brazilian savannah in order to investigate their potential to disrupt the life cycle of P. xylostella. Aqueous extracts of the leaves of A. intermedia and A. sessilis negatively affected the development of P. xylostella in all stages of the life cycle, prolonging the larval stage and causing mortality in the larval or pupal stages. Treatments with A. intermedia and A. sessilis extracts caused the lowest fecundity and the number of hatched larvae. The harmful effects of these aqueous extracts on the life cycle of P. xylostella may be attributable to the flavonoids and other phenolic compounds present in A. intermedia and A. sessilis. These aqueous botanical extracts are low in toxicity when compared to non-aqueous pesticides, and may emerge as an effective approach for control of populations of P. xylostella.

Este trabalho teve como objetivo avaliar o crescimento inicial das mudas de Guazuma ulmifolia (mutambo) sob diferentes regimes hídricos. As mudas receberam os seguintes tratamentos de água: 100%, 50%, 25% e 12,5% da capacidade de campo e foram avaliadas aos 35 e 83 dias de cultivo nos diferentes tratamentos. A sobrevivência das mudas a 12,5%cc foi menor que nos demais tratamentos, podendo ser avaliadas apenas aos 35 dias. A altura, diâmetro, área foliar, massas seca de parte aérea e raiz foram maiores sob maior disponibilidade de água, entretanto o comprimento médio das raízes não variou entre os tratamentos. A condutância estomática, fotossíntese e transpiração foram menores sob 12,5%cc, porém a eficiência no uso da água não variou entre as diferentes cc. A taxa assimilatória líquida, taxa de crescimento relativo, razão de área foliar e a abertura dos ostíolos diminuíram com as menores cc. Para a produção de mudas de Guzuma ulmifolia o regime hídrico na fase inicial deve ser de 100% da capacidade de campo, porém as mudas crescem satisfatoriamente sob 50%cc. Abaixo de 25%cc as mudas entram em estresse hídrico antes dos 35 dias de cultivo.

Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) causes significant losses in corn crops and necessitates the use of alternative control strategies, such as the application of bioinsecticides. We report the effect of methanolic leaf extracts of Annona dioica, Annona cacans, and Annona coriacea on the development and reproduction of S. frugiperda. A quantitative analysis was carried out to determine the total concentration of phenolics, flavonoids, and condensed tannin (CT) in leaf extracts. Corn leaves were immersed in a 1% methanolic leaf extract solution and fed to second instars of S. frugiperda. Leaf disks dipped in the synthetic insecticide Connect® (Bayer CropScience Ltda) composed of a neonicotinoid (imidacloprid) and a pyrethroid (β-cyfluthrin), which are harmful to S. frugiperda, was used as positive control. Distilled water was used as a negative control treatment. The leaf extract of A. coriacea decreased larval survivorship, arrested pupal development, and affected the weight gain of S. frugiperda. A. dioica also affected larval survivorship, but its effects were more pronounced for the adult stage, as fecundity, fertility, egg hatchability, and embryonic development were severely affected. Leaf extracts from A. cacans had no effect on S. frugiperda. The leaf extracts of A. dioica and A. coriacea showed a higher content of flavonoids and phenols, respectively. Our results indicated that both A. dioica and A. coriacea have the potential for development as botanical insecticides.