Estudio de seis extractos de plantas amazónicas sobre el insecto Plutella xylostella L. (Brassica oleracea L. var. Itálica cv. Avenger)

Abstract

This investigation aims: to evaluate the watery extracts of Witheringia solanacea (Tsimbio), Dieffenbachia costata (Lalu), Lonchocarpus nicou (Barbasco), Clibadium sp. (Kakllambi), Xanthosoma purpuratum (Shungupanga) and Cymbopogon nardus (Grass Luisa) on the insect pest Plutella xylostella L. (Lepidopterous: Plutellidae) in broccoli (Brassica oleracea L. var. Italic cv. Avenger) under field conditions developed in Riobamba-Chimborazo; a desing of finished blocks was used at random with eigth treatments and five repetitions: six botanical extracts, a chemist insecticide (clorpirifos lambda cihalotrina) and a water treatment, all of them accompanied by soap as fixing agent with 2 mL/L of extract. There were 30 plants transplanted with arranged repetition in three ruts, from them the evaluated plants were ten belonging to the central rut; been expected a natural infestation of the insect. The application of the extracts began 30 days after the transplant; this process was developed for seven consecutive weeks performing counts eight days post-application. This essay was developedin two periods, dry and rainy, equally in agronomic treatment. The first period (dry season) which started from July until October and the second (rainy) period from September until December, 2015. The efficiency of the treatments decided for the number of living larvae of P. xylostella registered. In both periods, the chemical presented the least population; the water treatment presented statistical similarity with the insecticide in 50%. The action of the botanical extracts did not have a linear behavior but its action was determined for diverse factors especially environmental. In the first period Dieffenbachia costata and Lonchocarpus nicou, they presented a better control of P. xylostella, while Clibadium sp, and Witheringia solanacea had the best results in the second period.

Key Words: Plutella xylostella, botanical extracts, broccoli, alternative control