Economics of biological control of cereal stemborers in Eastern Africa: a case study of maize and sorghum production in Kenya
Loading...
Date
2018-01
Authors
Midingoyi, Soul-Kifouly Gnonna
Journal Title
Journal ISSN
Volume Title
Publisher
Kenyatta University
Abstract
The International Centre of Insect Physiology and Ecology (icipe), undertook a biological
control (BC) programme for control of stemborers from 1993 to 2008, to reduce cereal yield
losses due to stemborer attack in East and Southern Africa. The programme released four
biological control agents—Cotesia flavipes, Cotesia sesamiae, Telenomus isis and
Xanthopimpla stemmator—to control the economically important stemborer pests Busseola
fusca, Chilo partellus and Sesamia calamistis. The purpose of this research was to assess the
ex-post economic impact of the BC program among smallholder farmers in Kenya. Specifically,
the study sought to: i) determine the productivity-effects of BC at farm level, ii) assess the
impact of BC on food security and poverty and iii) estimate the global welfare-effect from the
BC. Primary data was obtained from biological and household surveys. The household survey
was conducted to collect socio-economic data on 600 households randomly sampled across
maize agro-ecological zones of Kenya. Secondary data included time-series evolution of maize
and sorghum production, yield, cropped area, market prices, price-elasticity of supply and
demand and GIS information of the release locations. Methodologically, econometrics-based
damage control function framework was adopted to address the first objective, the
counterfactual framework using continuous treatment regression analysis for the second
objective and economic surplus model analysis to address the third objective. Findings from
productivity analysis show a reduction of insecticide use with the BC, thus demonstrating the
potential environmental hazard-reducing effect of BC. Additionally, results show that BC has
a positive impact on productivity and the derived marginal physical product show that 1%
increase in BC level is associated with at least 12 kilograms per hectare increase in yield. The
dose response functions (DRF) and the Marginal Treatment Effect (MTE) from the continuous
treatment models provide evidence that BC has had a positive and increasing impact on poverty
outcomes and food security components exept dietary diversity. For poverty, on average one
percent increase in BC intensity is associated with a US$ 1.15 increase of household
expenditures and a 0.5% reduction in poor households. With regards to food security, a one
percent increase in BC level increased food expenditures by US$ 1.24 and calorie intake by
6.94 Kcal, and reduced the number of food-insecure households by 0.16%. Findings from the
global welfare-effect show that BC intervention has contributed to an aggregate monetary
surplus of US$ 0.74 billion to the Kenyan economy over 20 years period (1993 to 2013), with
76.71% ($US 568.06 million) from maize and the remaining 23.29% ($US 172.45 million)
from sorghum. The net present value was estimated at US$ 142 million for both crops. The
attractive internal rate of return (IRR) of 113% as well as the estimated benefit–cost ratio (BCR)
of 276:1, illustrate the efficiency of investment in the BC research and intervention. The
estimated number of people that could be lifted out of poverty was on average 57,400 persons
(consumers and producers) per year, representing an annual average reduction of poor
populations of 0.35%. These findings underscore the need for increased investment in BC
research to sustain cereal production, and developing BC can be seen as an additional
environmentally-friendly tool in the fight against food insecurity and poverty in Kenya. Policy
implications are two-folds: boosting the effectiveness of the BC in regions with low level of
control through augmentative and conservative BC, and up-scaling the BC strategy to regions
with serious stemborers invasion.
Description
A thesis submitted in fulfilment of the requirements for the award of the degree of doctor of philosophy (agricultural economics) in the school of agriculture and enterprise development of Kenyatta University. January 2018