ABSTRACT
The effect of plant aqueous extracts was evaluated in the concentration of 10% on the development of Plutellax y lostella on disks of collard greens leaves, immersed in the extract. The disks were put in plates together with 12 caterpillars recently emerged, evaluating the viability and duration of the larval and pupal phases and weight of pupa after 24 hours.The larval mortality was affected by the extracts from Enterolobium contortisilliquum, Nicotiana tabacum, Sapindus saponaria and Trichilia pallida resulting in 100% of larvae mortality, followed by the extracts of T. pallida (93.8%), Azadirachta indica (89.6%), Symphytum officinale (77.1%), Bougainvillea glabra (72.9%), Achillea millefolium (70.8%) and Chenopodium ambrosioides (70.8%). The length of the larval stage varied from 8.2 days (control) to 10.7 days ( A. indica). There was direct correlation between the duration and the larvae mortality, since the extracts that induced higher mortality also increased the larval phase. Regarding the pupae weight, the biggest difference in relation to the control was observed in the treatment with the extract of B. glabra, which caused reduction of 1.2 mg. In all of the evaluated parameters, T. pallida showed higher toxicity in relation to Trichilia catigua and the branches were more poisonous than leaves in both of species, what was also observed for S. saponaria.
KEY WORDS
Insecta;
Plutella xylostella
; plant insecticide; Cruciferae