Analysis of the Biological Control of Cassava Pests In SubSaharan Africa (with IITA Nigeria)

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Models for cassava (Manihot esculenta Crantz) growth, development and yields as modified by weather, soil water and nitrogen, and natural enemies were developed. Rainfall-induced mortality and plant carbohydrate stress were the major determinants of P. manihoti population patterns prior to the introduction of exotic natural enemies. The cassava model was the basis for examining  the effects of the cassava mealybug (Phenacoccus manihoti Mat.-Ferr.) and cassava green mite (Mononychellus tanajoa (Bondar)) on yields. The model was also the basis for examining the effects of natural enemies introduced for the control of these pests.

West Africa Cassava Model
The upper right figure shows the components of the cassava system model, the upper left figure shows the biological control over time of the cassava mealybug, and the lower right show a cassava market in Nigeria.

Specifically, the contribution of the introduced parasitoid Epidinocarsis lopezi (DeSantis) and indigenous lady beetle predators (Hyperaspis and Exochomus) to the biological control of P. manihoti was assessed. Native coccinellid predators were not important regulating agents of P. manihoti before the introduction of exotic parasitoids. The contribution of native coccinellids to total P. manihoti mortality appears largely dispensible after the introduction of E, lopezi.

References

Gutierrez, A. P., B. Wermelinger, F. Schulthess, J. U. Baumgartner, J. S. Yaninek, H. R. Herren, P. Neuenschwander, B. Lohr, W. N. O. Hammond and C. K. Ellis. 1987 An overview of a system model of cassava and cassava pests in Africa. Insect Sci. Applic. 8: 919-924.

Yaninek, J. S., H. R. Herren and A. P. Gutierrez. 1987 The biological basis for the seasonal outbreak of cassava green mites in Africa. Insect Sci. Applic. 8: 861-865.

Gutierrez, A. P., B. Wermelinger, F. Schulthess, J. U. Baumgärtner, H. R. Herren, C. K. Ellis and J. S. Yaninek. 1988. Analysis of biological control of cassava pests in Africa: I. Simulation of carbon nitrogen and water dynamics in cassava. J. Appl. Ecol. 25: 901-920

Gutierrez, A. P., P. Neuenschwander, F. Schulthess, H. R. Herren, J. U. Baumgärtner, B. Wermelinger, J. S. Yaninek and C. K. Ellis. 1988 Analysis of biological control of cassava pests in Africa: II. Cassava mealybug Phenacoccus manihoti. J. Appl. Ecol. 25: 921-940

Gutierrez, A. P., J. S. Yaninek, B. Wermelinger, H. R. Herren and C. K. Ellis. 1988 Analysis of biological control of cassava pests in Africa: III. Cassava green mite Mononychellus tanajoa. J. Appl. Ecol. 25: 941-950.

Neuenschwander, P., W.N.O. Hammond, A. P. Gutierrez, A. R. Cudjoe, R. Adjakloe, J. U. Baumgärtner and U. Regev. 1989. Impact assessment of the biological control of the cassava mealybug, Phenacoccus manihoti Matile-Ferrero (Hemiptera: Pseudococcidae), by the introduced parasitoid Epidinocarsis lopezi (De Santis) (Hymenoptera: Encyrtidae). Bull. ent. Res. 79: 579-594.

Gutierrez, A. P., J. S. Yaninek, P. Neuenschwande and C. K. Ellis. 2000 A physiologically based tritrophic metapopulation model of the African cassava foodweb. Frustula Entomologica. 123:2138-158.