Co-designing integrated pest and disease management strategies in eggplant production in Bangladesh
Integrated Pest Management (IPM) was developed in response to the crisis caused by unrestricted use of pesticides. The IPM concept matured over time and today, it stands on a solid conceptual basis and millions of farmers across the globe, especially in developing countries, have been trained in it through the Farmers’ Field School approach. Nevertheless, adoption rate remains frustratingly low. This thesis tries to understand why IPM is so difficult to implement for smallholder farmers in developing countries and what is needed to make IPM work for them. Eggplant production in Bangladesh was taken as a case and it involved various disease and insect problems. Involving farmers in the research, this study aimed to craft IPM options for farmers that could function in their context, that maximally use natural enemies and that significantly reduce pesticide use. It also assessed the possible reasons for IPM research failures and possible factors contributing to the success or failure of the crafted IPM.Farmers participated through interviews, group discussions and field experimentation in tailoring IPM. Negotiations and discussions with these farmers were used to get a better grip on the underlying complexity of all tested IPM options that might hamper adoption. Moreover, a few in vitro and screen house studies were carried out to identify the source of infection of the diseases and to disentangle relative roles of selected IPM components in reducing infections. For each of the disease and insect problems, farmers’ conventional practice of spraying proved ineffective. In contrast, a combination of IPM options proved technically sound and economically viable. However, bottlenecks to scale out these IPM options still remain. For damping-off (caused by several pathogens), soil application of Trichoderma harzianum (T. harzianum) in the nursery combined with seed treatment with hot water was effective, producing 25-64 percentage points more healthy seedlings than farmers’ conventional practice of spraying. This combined treatment also improved seedling quality traits. Laboratory and screen house studies confirmed soil as the major source of pathogen and T. harzianum as major player in both reducing damping-off and enhancing seedling growth. Seedlings raised either by improved practice or farmer’s practice were also transplanted either with or without soil application of T. harzianum in the production field. Transplanting seedlings from improved practice alone reduced wilt and fruit rot, increased marketable yield and farmers’ income compared with their conventional practice of spraying. An additional effect was found when T. harzianum was applied to the field soil. T. harzianum persisted in the improved management fields at the end of the growing season and reduced wilt and rot pathogens. For the management of the eggplant shoot and fruit borer moth (ESFB), pheromone trapping alone or combined with trap-catch-based biorational insecticide spraying reduced fruit infestation, increased yield and income at costs comparable to farmers’ conventional practice. These two IPM options did not affect predatory ladybird beetles and parasitoids Trichogramma spp. and Bracon spp. Farmers’ proposed conventional insecticide spraying with pheromone trapping did not provide further control beyond the trapping alone, rather it affected natural enemies. Farmers’ practice did not reduce infestation but reduced populations of natural enemies. Therefore, installing trap only or adding biorational insecticide spraying with trapping both can be recommended to farmers. However, farmers lacked knowledge of ESFB biology; they need such knowledge to understand the trapping mechanism and its efficacy. As trapping was tested in a network of nearby fields of these smallholder farmers, there was a shared concern from researcher and farmers whether the use of mass trapping as an individual farmer with a small plot would be effective; traps might attract male moths from surroundings outweighing the local depletion. Indeed trapping in a single field (4 trap) was found ineffective as it showed comparable fruit infestation with farmers’ practice field. In contrast, when traps were installed in an array of 4 × 6: 24 traps (combination of 3-4 adjacent fields) and in networks of nearby fields (3-5 fields at a distance of 10-25 m), infestation was substantially reduced compared with farmers’ standard practice. Per trap, catch of a 4-trap field was three times higher than in 24-trap and network fields; however, infestation in 4-trap field was higher than in 24-trap or network fields, indicating moths were attracted in a 4-trap field from surrounding untrapped fields. For effective trapping, concerted action is needed either by neighbours with directly adjacent fields allowing an array of 4 × 6 traps or by farmers of nearby fields.For each of the participatory studies, farmers desired some chemical treatment with IPM options. Although farmers dropped the chemical treatment after a year of study, still it is questionable whether they will continue with purely IPM options because these farmers are used to spray. Therefore it is better to include spraying with biorationals. Farmers rejected labour-intensive practices. IPM options, generated from this thesis, proved technically and economically viable, but there were some bottlenecks: unavailability of T. harzianum, seed treating machine and pheromone lures, a mismatch between farmers’ knowledge and use of pheromone trapping, and the need for social organisation for trapping to be effective. To alleviate these obstacles, extension and institutional support are required.
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| Format: | Doctoral thesis biblioteca |
| Language: | English |
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Wageningen University
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| Subjects: | Life Science, |
| Online Access: | https://research.wur.nl/en/publications/co-designing-integrated-pest-and-disease-management-strategies-in |
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