Evolution of cacao-pests over a six year period

During a six year period (1991-1996) 284 cacao samples have been inspected for pests. Twenty six different taxa have been observed, but five of them r epresent 92% of the total population:,Ahasverus advena, Carpophilus obsolet es, Cryptolestes ferrugineus, Ephestia cautella and Tribolium castaneum. Ov er the total period, a trend cannot be shown neither in the number of pests nor in the number of taxa. The change of the composition of the population is mainly due to the substitution of A. advena by C. ferrigineus and later by C. obsoletes. Both Hill's indices are increasing during the first five years.