The role of insects in the productivity decline of cassava ( Manihot esculenta Crantz) on a slash and burn site in the amazon territory of Venezuela

Abstract

The consumption of bitter cassava by root boring, leaf chewing and leaf sucking insects was measured on a slash and burn agricultural site in the Amazon Territory of Venezuela. Chewing and boring insects consumed less than 3% of the tissue, possibly because of the presence of cyanogenic glucosides in the cassava plants. In contrast to the boring and chewing insects, leaf sucking insects were more effective herbivores. They may be able to consume the phloem sap without activating the hydrocyanic acid. However, even sucking insects consumed only about 14% of the phosphorus uptake of the plants. We conclude that insect herbivory did not play a major role in the decline of productivity on the slash and burn agricultural site.