Effects of phytoextracts and natural enemy to control Plutella xylostella L. (Lepidoptera: Plutellidae) in cabbage

Aqueous extracts of Argemone mexicana (Papaveraceae), Vetiveria zizanioides (Graminae), Murraya koenigii (Rutaceae), Annona murricata (Annonaceae), Lantana camara (Verbenaceae), Ocimum basilicum (Labiateae), Ligustrum robustum (Oleaceae), Chenopodium ambrosioides (Chenopodiaceae), Piper betel (Piperaceae), Psidium guajava (Myrtaceae), were tested for their larvicidal, antifeedant and oviposition deterrent effects on Plutella xylostella and for their toxicity to Cotesia plutellae. The A. mexicana, V. zizanioides, M. koenigii, A. murricata and L. camara, which showed the highest bioactivity in laboratory bioassays, were investigated further for their performance under field conditions. Cabbage plants sprayed weekly with phytoextracts, protected the cabbage from P. xylostella to varying degrees. Mortality of C. plutellae and the extent of its parasitism also varied, as did the yield and quality of harvested cabbage heads. A. mexicana was most effective, followed by V. zizanioides, A. murricata, M. koenigii and L. camara. Although the negative effects of A. mexicana on C. plutellae may restrict its use, but the other four plant species showed potential to control P. xylostella in combination with biological control.