Elsevier

Crop Protection

Volume 139, January 2021, 105353
Crop Protection

Assessment of smallholder farmers’ awareness of bean fly (Ophiomyia spp.) and management practices in central and northern Malawi: Implications for resistance breeding

https://doi.org/10.1016/j.cropro.2020.105353Get rights and content

Abstract

The production of common bean (Phaseolus vulgaris L.) in East and Southern Africa (ESA) regions falls short of the demand partly due to insect pests and diseases, and a lack of high yielding varieties. Bean fly (Ophiomyia spp.) is one of the most devastating field insect pests of common bean in ESA and the development of host plant resistance to bean fly is an important strategy to combat yield losses caused by this insect pest. A survey involving 195 farmers in Kalira, Chipuka, Champhira and Luwerezi Agricultural Extension Planning Area (EPAs) in Malawi was conducted to assess their awareness of bean fly and their varietal selection criteria. Only 45% of the respondent farmers were aware of the bean fly pest and practiced integrated insect pest management strategies that included the use of chemical and botanical insecticides, and cultural control methods. The level of education, previous bean fly experience and farmer's location significantly (P < 0.001) influenced their awareness of bean fly. Principal component analysis identified disease resistance (with a loading score of (0.87), grain yield (0.34), insect pest resistance (0.35), early maturity (0.48) and cooking time (0.14) as the most important traits that influence farmers' varietal choice. Implementation of strategies such as farmer field schools and on farm field trials relating to bean fly and also introduction of adult literacy learning centers will promote awareness of bean fly. Therefore, common bean breeding programs should integrate and prioritize selection for these traits in varietal design for successful adoption of new cultivars among farmers in these and similar ecologies.

Introduction

Common bean (Phaseolus vulgaris L.) is a multipurpose grain legume grown worldwide (Luna-Vital et al., 2015). The crop is mainly grown for human consumption, serving as a source of dietary protein to supplement cereal-dominated diets of sub-Saharan Africa (SSA) (Schmutz et al., 2014). Despite being produced primarily for home consumption, farmers usually sell their surplus to generate household income (Katungi et al., 2009). The crop can also contribute to improve the soil health status in cereal-legume cropping systems through biological nitrogen fixation (Hungria and Kaschuk, 2014). Global production of common bean is approximately 30 million tonnes per annum on 34 million hectares, with Africa accounting for approximately 17.7% of the global production (FAO, 2018). Malawi produces 152,000 tonnes of common bean per annum from 348, 000 ha of land, translating to a national average grain yield of 500 kg/ha (FAO, 2018). This yield level is extremely low compared with a global mean of 2000 kg/ha (Margaret et al., 2014). The low productivity of the crop in sub-Saharan Africa, including Malawi, is caused by multitudes of biotic and abiotic stresses and socio-economic constraints.

Among the major biotic stresses of common bean is the bean fly (Ophiomyia phaseoli Tryon) (Letourneau, 1994). The bean fly is regarded as the most important production constraint of common bean in SSA (Ampofo and Massomo, 1998). The bean fly is a small insect pest that attacks common bean crop at the early stages of growth, even before the full formation of the first trifoliate leaves (Odendo et al., 2005). The extent and nature of damage caused by the bean fly is dependent on seasonal variation, time of planting, growth stage, geographical location, soil fertility and varietal tolerance (Ochilo and Nyamasyo, 2011; Nkhata et al., 2018). It is most severe in late-planted crops (Ochilo and Nyamasyo, 2011). Common bean is usually planted after the main summer crops such as maize in most sub-Sahara agriculture systems, which predisposes the common bean to be attacked by the insect pest. Moisture and nutrient stress exacerbate bean fly damage leading to severe damage (Ambachew et al., 2015). Symptoms of bean fly attack include stem damage, yellowing of leaves, defoliation and premature plant death. Total crop failure attributable to bean fly in individual bean fields has been reported previously (Nkhata et al., 2018).

Various options are recommended to control the bean fly such as the use of insecticides, cultural practices (e.g. early sowing, crop rotation, intercropping with maize, earthing up soil around the seedlings and fertilizer application) and host plant resistance (Kapeya et al., 2005). Early sowing allows the bean crop to avoid the insect pest in the field, while crop rotation and intercropping suppresses bean fly population in the field. The practice of earthing up promotes the development of new roots above the swelling caused by bean fly larva damage. The newly developed roots help to sustain the crop, while overcoming the impact of the damage. On the other hand, fertilizer application ensures availability of nutrients for plant growth and maintenance of vigor. Poor nutrition exacerbates the impact of insect pest damage, so the provision of adequate soil nutrients is recommended to reduce the damage caused by bean fly. Biological control involving the use of bean fly parasitoids can also reduce pest populations (Nkhata et al., 2018). The use of systemic insecticides to control the pest is also widely reported (Kapeya et al., 2005; Ambachew et al., 2015). Despite being very effective in controlling bean fly, chemical insecticides pose potential hazards to the environment and human health (Alavanja, 2009). The other disadvantage of chemical control is that it is too expensive for most smallholder farmers (Laizer et al., 2019). Additionally, pesticide resistance can occur due to excessive use (Damalas and Eleftherohorinos, 2011). Cultural practices are the most affordable components of insect pest management for the majority of small-holder farmers. However, the success of cultural control methods can be low especially under heavy insect pest pressure. Incorporating host resistance can be an effective, reliable and environment friendly method to control bean fly.

Developing bean fly resistant cultivars is the control method of choice under the smallholder production systems (Ojwang et al., 2009). Resistant cultivars are able to recover from insect damage or inhibit oviposition, development, growth or multiplication of the pest (Cardona et al., 1999; Ojwang et al., 2010). Numerous reports have examined the benefits of using resistant varieties, which include reduced insecticide use and low cost of production (Miklas et al., 2006; Ojwang et al., 2009). There are currently only limited common bean resistance breeding programs against the bean fly in SSA despite the economic significant of the pest (Nkhata et al., 2018). The few available resistant cultivars are not widely grown by farmers because they lack other important traits preferred by farmers (Kiptoo et al., 2016). Common bean cultivars that possess both preferred traits for farmers and exhibit resistance to bean fly could result in improved productivity, and rapid uptake by farmers.

Involving farmers during the preliminary stages of development of technologies such as agricultural practices and cultivar development is paramount to developing relevant products and technologies that can be rapidly adopted by farmers (Trutmann et al., 1996). Participatory rural appraisal (PRA) is a multidisciplinary tool used to solicit information from farmers and stakeholders. The technique is suitable for research purposes as it allows farmers and researchers to share knowledge (Ashby, 2009). The method has been used successfully to solicit farmers' knowledge and prioritization of insect pests in different crops such banana (Musa spp.) (Barraza et al., 2011), common bean (Laizer et al., 2019), cowpea (Vigna unguiculata L.) (Isubikalu et al., 2000), cotton (Gossypium hirsutum L.) (Sinzogan et al., 2004) and maize (Zea mays L.) (Kamanula et al., 2010). In addition to crop protection, the PRA method has been used in gathering information for crop variety development programs (Ceccarelli et al., 2000; Danial et al., 2007). Varieties developed through PRA have registered high adoption rates because they were relevant to farmers given that these varieties were bred with farmers preferred traits and attributes (Witcombe et al., 2003). Documentation of farmers' perception and knowledge of bean fly is limited despite being an insect pest of economic importance on common bean in Malawi (Letourneau, 1994), and there are no resistant cultivars commercially available in the country. Therefore, information on farmers’ perception, knowledge of bean fly and preferred traits for choosing bean varieties would be crucial in developing suitable cultivars for improving common bean productivity in Malawi. The objective of the study was to assess awareness of bean fly, and understand the preferred traits for choosing bean varieties among smallholder farmers in Malawi, in order to inform breeding for bean fly resistance in common bean.

Section snippets

Study areas

A participatory research appraisal study was conducted in June 2018 in the common bean growing areas of the central and northern Malawi. The areas were located in mid-altitude zones, ranging from 1000 to 1500 m above sea level, under a sub-tropical climate characterized by a unimodal rainfall distribution. The annual rainfall ranged between 800 mm and 1000 mm. The minimum and maximum temperatures of the areas were 16.6 (June) and 27.1 °C (October), respectively. The soils in the study sites are

Results

Demographic characteristics of common bean farmers in central and northern Malawi The Kruskal-Wallis test (Table 1) revealed significant differences in terms of gender distribution across the EPA, with Luwerezi having highest number of male respondent farmers (90%) and Champhira having the least (28%). Overall, 55% of the respondent were male farmers. The mean age of respondent farmers in Chipuka was 38 years, which was significantly lower than that of Champhira with 46, while the average age

Demographics of common bean farmers in central and northern Malawi

The present study assessed farmers’ awareness of bean fly and their trait preferences for common bean in central and northern Malawi. Common bean was identified as an important crop for food security and poverty alleviation among the farmers. Both male and female farmers from various demographic groups cultivated the crop, indicating that the crop was important to both sexes. Male participation in the study exceeded females although there is empirical evidence from several studies that, in

Conclusion

The study assessed socio-economic characteristics of bean farmers that influence awareness to bean fly and traits of preference of common bean varieties in Malawi. The findings of this showed that almost half of the interviewed farmers (55%) were not aware of the bean fly. Therefore, there is a need to intensify awareness campaigns on bean fly. This can be achieved through farmer field schools and farm field demonstrations. In Kalira EPA, the majority of respondent farmers were aware of the

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgement

The authors thank the Alliance for a Green Revolution in Africa (AGRA) and Chitedze Agricultural Research Station/Malawi for financial support and hosting the first author, respectively. Farmers of the study areas are sincerely acknowledged for making this study possible.

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