DIET OF ZONOCERUS-VARIEGATUS (L.) (ORTH., ACRIDIDAE) IN CASSAVA FIELDS IN CONGO

This paper presents the results of a study on the diet of Zonocerus va riegatus on cassava at Kombe, near Brazzaville in the Republic of Cong o. Diet was determined by the analysis of plant fragments in the faece s of insects sampled in the fields. Cassava and Chromolaena odorata ar e the major food plants for Z. variegatus in the ecosystem. Z. variega tus eats leaves and flowers of C. odorata. During the dry season it ha s a broader diet than during the wet season. This was contrary to expe ctation, as it was expected that water content and flora diversity wou ld affect the diet. The dry season is also the time when C. odorata le aves are found in the faeces of both adults and nymphs. The decrease i n nutritional value of plants may oblige Z. variegatus to diversify it s diet. Cassava and C. odorata replace each other in the diet of Z. va riegatus during the year. The choice of food plants is not determined by the frequency of plant species in the field. For major food plants, the age and the physiological state of plants play an important role. At Kombe, nymphs and adults are present throughout the year. Therefor e, the diet exhibited each month does not depend on the development st age of insects.