International Journal of Agricultural Economics and Extension

International Journal of Agricultural Economics and Extension ISSN: 2329-9797 Vol. 1 (6), pp. 042-046, July 2013. © International Scholars Journals

Full Length Research Paper

Functional response of Exochomus flavipes Thunberg (Coleoptera: Coccinellidae), a local predator of the cassava mealybug Phenacoccus manihoti Matile Ferrore,(Homoptera: Pseudococcidae)

Essien, Rosemary Anietie1*, Odebiyi, Johnson Adebayo2 Ekanem, Mfon Sunday3, Umoetok, Sylvia Bassey Akpassam4

1*Department of Crop Science, Akwa Ibom State University, PMB 1167, Uyo, Akwa Ibom State, Nigeria.

2Department of Crop Protection and Environmental Biology, University of Ibadan, Ibadan, Nigeria

3Department of Zoology, University of Uyo, Akwa Ibom State, Nigeria.

4Department of Crop Science, University of Calabar, Cross River State, Nigeria.

*Corresponding author E-mail: rosemary.essien@yahoo.com Tel.: +234-8027022191.

Accepted 10 July 2013

Abstract

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.  

Keywords: Predator, prey, functional response, cassava mealybug, Exochomus flavipes, larval instars, prey dens