Abstract

Essien RA, Odebiyi JAE, Mfon S and Umoetok SBA

Functional response of first and fourth larval instars of Exochomus flavipes, as a predator of Phenacoccus
manihoti was studied in the laboratory. Day old (24 hours) first and fourth instars E. flavipes were each fed on
one day old eggs of P.manihoti at densities of 100, 200, 300, 400, 500, 600 and 700. This was replicated 10 times.
Daily eggs consumption (functional response), was recorded. Functional response of fourth instar to different
prey densities increased from 100 to a plateau between 500 and 700. For the first instar, eggs consumption was
lower than that of fourth instar. There was a correlation between mean number of prey eggs consumed and the
prey density, r = 0.982 and 0.995 for the first and fourth instars, respectively. Rate of discovery by predator was
reduced with increase in prey density. There was a negative correlation between the rate of discovery and
number of P.manihoti eggs consumed by the fourth instar (r = - 0.973). Functional response of E flavipes to
increasing number of P. manihoti showed a density dependent action in this study. E. flavipes shows a
potential to be exploited as a biocontrol agent of P. manihoti.