FUNCTIONAL-RESPONSES OF IPHISEIUS-DEGENERANS AND NEOSEIULUS-TEKE (ACARI, PHYTOSEIIDAE) TO CHANGES IN THE DENSITY OF THE CASSAVA GREEN MITE,MONONYCHELLUS-TANAJOA (ACARI, TETRANYCHIDAE)

The functional responses of protonymph and adult female Iphiseius dege nerans and Neoseiulus teke to increasing density of three stages of th eir prey, the cassava green mite (CGM), Mononychellus tanajoa, were st udied on excised cassava leaf discs under laboratory conditions. The r esponses obtained were predominantly sigmoid type III curves with the highest plateau when both stages of I. degenerans and N. teke were pre ying on CGM eggs. In all cases, the predation rate of the former speci es exceeded that of the latter. The empirical data were fitted by four different models. From the models, the attack coefficient (a') and ha ndling time (T-h) were estimated. For a given predator stage (protonym ph or adult female), the predator's attack coefficient declines and ha ndling time increases as the prey gets larger. For a given prey stage, the predator's attack coefficient increases and handling time decreas es as the predator stage becomes larger.