ABSTRACT
The present study was aimed to assess the effect of organic fertilization, plant spacing, rhizome seed size, leaf surface and canopy height on populations of arthropods associated with yutia Xanthosoma mafaffa. No attack of arthropods was found in yutia rhizomes, and there was only a low attack density in the leaves (0.40/ leaf). The spacing of yutia plants did not present any significant effect on the occurrence of arthropods. Treatments using 40 t.ha-1 of organic fertilization presented a higher attack of Aphis sp. (Hemiptera: Aphididae) per leaf face than that observed at the other fertilization levels. Higher densities of Tetranychus sp. (Acari: Tetranychidae) and the presence of spiders (predators) appeared on leaves of the plants originating from “small” rhizomes as compared to other rhizome sizes. A higher number of Aphis sp., of Frankliniella sp. (Thysanoptera: Thripidae), of Tetranychus sp. and of natural enemies Chrysoperla sp. (Neuroptera: Chrysopidae) and spiders was observed on the abaxial face than on the adaxial face of yutia leaves. Yutia leaves located in apical parts showed a higher density of herbivorous insects such as Aphis sp., Tetranychus sp., Chrysomelidae and Lagriidae, as well as natural enemies such as spiders, than did those located in the medial or basal parts. Higher defoliation and greater Aphis sp. population were observed in the initial phase of the development of the crop, while Frankliniella sp. and Tetranychus sp. occurred more in the final phase of the crop.
KEY WORDS
Yutia;
Xanthosoma mafaffa
; spacing; organic fertilization; cormel seed; arthropods