Integrated Arthropod Pest Management Systems for Human Health Improvement in Africa

In a sub-Saharan African context, limited natural resources, infectious diseases, including those transmitted by arthropod vectors, and chronic exposure to food contaminated with mycotoxin-producing fungi which, among others, are vectored by insects, are among the major constraints to human health. Thus, pest control should be an important component in human health improvement projects. It appears that the advantages of preventive over curative methods are rarely recognised in Africa, with more emphasis being given to the search for the ‘silver bullet' than to integrated control approaches. Integrated pest management (IPM) systems can be assigned to different decision-making levels as well as to different integration levels, combining ecological (individual pest species, species communities, species assemblages) and management (crop, cropping systems, farms, communities) levels with the respective control systems. These levels produce a highly structured environment for decision-making, in which the use of modern information technology is important. Case studies show that IPM systems are developed and implemented at four integration levels, whereby most work is done on the lowest integration level, addressing a single pest or pest complex attacking a particular crop, group of livestock or human population, and the respective control measures undertaken. Coordinated efforts to develop and implement supplementary IPM systems at higher levels are concluded to be important elements in integrated pest management and a further contribution to human health improvement and poverty alleviatio

White lupin leads to increased maize yield through a soil fertility-independent mechanism: a new candidate for fighting Striga hermonthica infestation?

Nitrogen (N)-deficiency and lack of phosphorus (P) availability are major constraints to maize yields in Western Kenya. In a two-season field study in the lake Victoria basin, we tested the capacity of white lupin (Lupinus albus (L.), cv. Ultra), as a nitrogen-fixing crop with a highly efficient P-acquisition capacity, to increase maize yields when used as a companion or cover crop, or as a source of organic matter. Each experiment was performed on three different fields (Vertisols) differing in N/P availability, previous cropping history and in levels of infestation by the parasitic weed Striga hermonthica (Del.) Benth. Our results show that white lupin led to significantly higher yields of maize when used as a cover crop. When lupin was grown as a companion crop, it also slightly enhanced the yield of the co-cultivated maize. When lupin shoots were incorporated to the soil, the positive effect of lupin on maize growth was field-dependent and only occurred in the field most heavily infested with S. hermonthica. Despite the beneficial impact on maize yield, no clear effect of lupin on soil N and P availability or on maize N/P uptake were observed. In contrast, lupin significantly inhibited infestation of maize by S. hermonthica: when lupin was grown together with maize in pots inoculated with S. hermonthica, the emergence of the weed was strongly reduced compared to the pots with maize only. This work opens a new range of questions for further research on white lupin and its potential beneficial impact as a S. hermonthica-inhibiting cro

Parasitoids Associated with mussidia spp. (Lepidoptera: Pyralidae) in Kenya

http://dx.doi.org/10.1007/s12600-008-0012-

Measuring the economic value of redistributing parasitoids for the control of the maize stemborer Busseola fusca Fuller (Lepidoptera: Noctuidae) in Kenya

This study assesses the ex ante economic impact of the establishment of two parasitoids, the scelionid egg parasitoid Telenomus isis Polaszek from West Africa and a virulent strain of the braconid larval parasitoid Cotesia sesamiae Cameron from western Kenya, to control stemborer. Using a Cobb-Douglas production function, it was estimated that yields increased by 28.5% when pesticides were used to control stemborers. The benefit-cost ratio after the establishment of the parasitoids ranged from 1:1 to 777:1, with a net present value of up to US$192 million. The study demonstrates the potential of redistributing parasitoids indigenous to Africa for the control of African stemborers. Because the benefits of biological control are positively scale dependent, while the costs are generally scale irresponsive, biological control programs would accrue more benefits if parasitoids were released to a wider area

The economic value of releasing parasitoid for the control of maize stemborers in East and Southern Africa

The braconid larval parasitoid Cotesia flavipes Cameron was introduced from Asia into East and Southern African region starting in 1993 to control the invasive exotic maize stemborer Chilo partellus (Swinhoe) (Lepidoptera: Crambidae). A quasi-experiment was constructed using farmers that applied sublethal dosages of pesticide in assessing the counterfactual for the impact of the establishment of the introduced parasitoid in five countries in the region. Logistic regression method was used to estimate the probability that farmers’ would inadvertently exclude parasitoids in their maize field. Thereafter the propensity score matching method was used to find corresponding farmers excluding parasitoids among those who did not for yield comparison. The geographical information system (GIS) application software with ecological, agricultural and land cover data bases was used to classify and select the ecological zones surveyed, to estimate the spread of the parasitoid. Results indicate a rampant use of pesticides at sublethal dosage across the countries. Intensifying maize production by is likely to improve the effectiveness of parasitoids. The annual value of the economic impact of the introduced parasitoid is estimated to range from US $ 43 m – 76 m. It is apparent that the appropriate matching algorithm depends on the distribution of yield data available. The study demonstrates the potential of using biological agents to improve yields among the poor households who can seldom afford purchased inputs