Browsing by Author "Darbyshire, Iain"

Now showing 1 - 3 of 3

Enhancing knowledge among smallholders on pollinators and supporting field margins for sustainable food security
(Elsevier Ltd., 2019-08) Elisante, Filemon; Ndakidemi, Patrick; Arnold, Sarah; Belmain, Steven; Gurr, Geoff; Darbyshire, Iain; Xie, Gang; Tumbo, Julie; Stevenson, Philip
Agro-ecological intensification (AEI) harnesses natural processes, such as pollination, that support sustainable crop production and can buffer against future food security risks. However, the transition from conventional agriculture, which relies on inputs that can damage natural ecosystem processes, to more sustainable food production under AEI, is knowledge-intensive. Here, we investigated knowledge gaps among smallholder farmers about pollinators and field margins in a bean agri-system in Tanzania. While 77% of farmers were familiar with and identified honeybees correctly prior to training, only 52% understood their role as a pollinator of crops. Furthermore, 80% and 98% of farmers were unaware of the significance of wild (solitary) bees or the importance of hoverflies as pollinators. A high level of synthetic agrochemical use was reported for the management of pests and weeds, particularly in the more agriculturally intensive production systems. However, an end-line survey conducted one year after training showed an increase in knowledge and the majority of farmers, 99%, 54% and 62% subsequently recognised honeybees, hoverflies and solitary bees respectively, by name. Furthermore, 95%, 69% and 60% of farmers understood the importance of honeybees, hoverflies and solitary bees respectively, as crop pollinators and natural enemies (for hoverflies). Similarly, a majority of farmers recognised the benefits of biopesticides as environmentally safer over synthetic pesticides as well as the value of field margins in supporting pollinators and other ecosystem services. We argue that, improving understanding among smallholder farmers of ecosystem services and their ecological requirements is both feasible and essential to achieving sustainable intensification in small holder farming systems.
Identifying the right plants for diverse biocontrol agents in tropical smallholder bean farming systems
(African Journals OnLine (AJOL), 2022-10-20) Mkenda, ‪Prisila; Ndakidemi, Patrick; Stevenson, Philip; Arnold, Sarah; Belmain, Steven; Darbyshire, Iain; Gurr, Geoff
Biocontrol agents such as predators, parasitoids and pathogens potentially regulate crop pests populations. The agents feed directly on the pests, oviposit in the pest body or cause disease in the pest. While biocontrol has become a commercial enterprise in temperate horticulture, there is much less information on the biocontrol agents present in smallholder agricultural systems in the tropics and little knowledge about the importance of plant diversity in supporting their biocontrol activities. A standardized botanical survey walk combined with observations of plant insect interactions was conducted on field margin vegetation of 24 smallholder fields of common beans (Phaseolus vulgaris L.) in three elevation zones of a tropical ecosystem. Sweep nets were also used to capture the biocontrol agents and stored in 70% ethanol for detailed taxonomy where identification in the field was not possible. A wide range of biocontrol agents interacting with the field margin plants, particularly flowering forbs were revealed. The most preferred field margin plants were Ageratum conyzoides, Commelina benghalensis, Pennisetum purpureum, Panicum maximum and Tripsacum sp. The most common biocontrol agents found to interact with the field margin plants were spiders (Araneae), long-legged flies (Dolichopodidae), predatory and parasitic wasps (Ichneumonids and braconids), hoverflies (Syrphidae) and assassin bugs (Reduviidae). Preferences of the biocontrol agents to certain plant species were similar across all three zones, indicating the importance of such plants in terms of food resources, shelter or nesting sites. The preference of the biocontrol agents to some plant species indicates the need to identify the specific benefits of these species to the biocontrol agents to determine whether non-crop habitat manipulation might enhance natural pest regulation.Biocontrol agents such as predators, parasitoids and pathogens potentially regulate crop pests populations. The agents feed directly on the pests, oviposit in the pest body or cause disease in the pest. While biocontrol has become a commercial enterprise in temperate horticulture, there is much less information on the biocontrol agents present in smallholder agricultural systems in the tropics and little knowledge about the importance of plant diversity in supporting their biocontrol activities. A standardized botanical survey walk combined with observations of plant insect interactions was conducted on field margin vegetation of 24 smallholder fields of common beans (Phaseolus vulgaris L.) in three elevation zones of a tropical ecosystem. Sweep nets were also used to capture the biocontrol agents and stored in 70% ethanol for detailed taxonomy where identification in the field was not possible. A wide range of biocontrol agents interacting with the field margin plants, particularly flowering forbs were revealed. The most preferred field margin plants were Ageratum conyzoides, Commelina benghalensis, Pennisetum purpureum, Panicum maximum and Tripsacum sp. The most common biocontrol agents found to interact with the field margin plants were spiders (Araneae), long-legged flies (Dolichopodidae), predatory and parasitic wasps (Ichneumonids and braconids), hoverflies (Syrphidae) and assassin bugs (Reduviidae). Preferences of the biocontrol agents to certain plant species were similar across all three zones, indicating the importance of such plants in terms of food resources, shelter or nesting sites. The preference of the biocontrol agents to some plant species indicates the need to identify the specific benefits of these species to the biocontrol agents to determine whether non-crop habitat manipulation might enhance natural pest regulation.
Insect pollination is important in a smallholder bean farming system.
(PeerJ, 2020-10-20) Elisante, Filemon; Ndakidemi, Patrick; Arnold, Sarah; Belmain, Steven; Gurr, Geoff; Darbyshire, Iain; Xie, Gang; Stevenson, Philip
Many crops are dependent on pollination by insects. Habitat management in agricultural landscapes can support pollinator services and even augment crop production. Common bean ( L.) is an important legume for the livelihoods of smallholder farmers in many low-income countries, particularly so in East Africa. While this crop is autogamous, it is frequently visited by pollinating insects that could improve yields. However, the value of pollination services to common beans (Kariasii) yield is not known. We carried out pollinator-exclusion experiments to determine the contribution of insect pollinators to bean yields. We also carried out a fluorescent-dye experiment to evaluate the role of field margins as refuge for flower-visitors. Significantly higher yields, based on pods per plant and seeds per pod, were recorded from -pollinated and -pollinated flowers compared to plants from which pollinators had been excluded indicating that flower visitors contribute significantly to bean yields. Similarly, and -pollinated plants recorded the highest mean seed weight. Extrapolation of yield data to field scale indicated a potential increase per hectare from 681 kg in -pollinated beans to 1,478 kg in -pollinated beans indicating that flower visitors contributed significantly to crop yield of beans. Our marking study indicated that flower-visiting insects including bees, flies and lepidopterans moved from the field margin flowers into the bean crop. Overall, these results show that insect pollinators are important for optimising bean yields and an important food security consideration on smallholder farms. Field margin vegetation also provides habitat for flower-visiting insects that pollinate beans. Hence, non-crop habitats merit further research focusing on establishing which field margin species are most important and their capacity to support other ecosystem services such as natural pest regulation or even pests.