Within-Season Changes in Land-Use Impact Pest Abundance in Smallholder African Cassava Production Systems.
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ABSTRACT:
SUBMITTER: Kalyebi A
PROVIDER: S-EPMC8005198 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:BackgroundLandscape composition is known to affect both beneficial insect and pest communities on crop fields. Landscape composition therefore can impact ecosystem (dis)services provided by insects to crops. Though landscape effects on ecosystem service providers have been studied in large-scale agriculture in temperate regions, there is a lack of representation of tropical smallholder agriculture within this field of study, especially in sub-Sahara Africa. Legume crops can provide important food security and soil improvement benefits to vulnerable agriculturalists. However, legumes are dependent on pollinating insects, particularly bees (Hymenoptera: Apiformes) for production and are vulnerable to pests. We selected 10 pigeon pea (Fabaceae: Cajunus cajan (L.)) fields in Malawi with varying proportions of semi-natural habitat and agricultural area within a 1 km radius to study: (1) how the proportion of semi-natural habitat and agricultural area affects the abundance and richness of bees and abundance of florivorous blister beetles (Coleoptera: Melloidae), (2) if the proportion of flowers damaged and fruit set difference between open and bagged flowers are correlated with the proportion of semi-natural habitat or agricultural area and (3) if pigeon pea fruit set difference between open and bagged flowers in these landscapes was constrained by pest damage or improved by bee visitation.MethodsWe performed three, ten-minute, 15 m, transects per field to assess blister beetle abundance and bee abundance and richness. Bees were captured and identified to (morpho)species. We assessed the proportion of flowers damaged by beetles during the flowering period. We performed a pollinator and pest exclusion experiment on 15 plants per field to assess whether fruit set was pollinator limited or constrained by pests.ResultsIn our study, bee abundance was higher in areas with proportionally more agricultural area surrounding the fields. This effect was mostly driven by an increase in honeybees. Bee richness and beetle abundances were not affected by landscape characteristics, nor was flower damage or fruit set difference between bagged and open flowers. We did not observe a positive effect of bee density or richness, nor a negative effect of florivory, on fruit set difference.DiscussionIn our study area, pigeon pea flowers relatively late-well into the dry season. This could explain why we observe higher densities of bees in areas dominated by agriculture rather than in areas with more semi-natural habitat where resources for bees during this time of the year are scarce. Therefore, late flowering legumes may be an important food resource for bees during a period of scarcity in the seasonal tropics. The differences in patterns between our study and those conducted in temperate regions highlight the need for landscape-scale studies in areas outside the temperate region.
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Project description:The present study aimed to classify smallholder dairy production systems by analyzing land allocation for various crop types and characterizing them based on integration with specific crops which is gap in earlier studies. A total of 360 smallholder farmers were interviewed to generate firsthand information in addition to using secondary data sources. The classification utilized K-means clustering, while discriminant analysis was applied to accentuate the distinct characteristics of dairy production systems (DPSs). Subsequently, for a particular crop to be considered dominant, the minimum farmland allocation had to exceed 30%. Based on this, the 360 respondent farmers in the study areas were categorized into four distinct DPSs: diversified crop-based (DCB) at 31%, enset-based (EB) at 28%, cereal-based (CB) at 24% and cash crop-based (CCB) with coffee, khat, vegetables, fruits, and sugarcane accounting for 17%. Within the CCB dairy production system, where cash crops were cultivated most dominantly, averaging 56% of the farmland, farmers reported the highest annual income and, consequently, acquired more improved dairy cows, facilitating their entry into intensive dairy production. Ownership of improved dairy cattle breeds, use of agro-industrial byproducts as feed, practicing stall feeding and better housing are observed practices in this DPS that relate to the intensification of dairy production. This positive relationship was observed between the commercialization of crops and the intensification of dairy production in the CCB dairy production system. In the EB dairy system, enset dominates with a 33% area share, leading to increased residues for cattle feed. They keep large herds of local cattle, limited crossbreeding experience, and prefer conventional feeding. The CB system allocates 47% of land to cereals, justifying cereal residues as primary dairy feed. Cultivating grasses like Pennisetum pedicellatum and Phalaris arundinacea is also highly valued in the system. The DCB system, with diverse crops (none exceeding 30%), implies varied residues for dairy feed. These findings reveal unique characteristics across dairy systems, indicating a positive correlation between crop commercialization and dairy intensification. Hence, understanding each type of DPS and its characteristics will help development experts or those in charge of designing agricultural policy to establish the best strategic plans for enhancing the productivity of dairy cattle under smallholder conditions.
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Project description:BackgroundThe majority of the African population lives in rural areas and depends on agriculture for their livelihoods. To increase the productivity and sustainability of their farms, they need access to affordable yield-enhancing inputs of which parasite control is of paramount importance. We therefore determined the status of current tick species with the highest economic impact on cattle by sampling representative numbers of animals in each of seven sub-Saharan countries.MethodsData included tick species' half-body counts from approximately 120 cattle at each of two districts per country, collected four times in approximately 1 year (to include seasonality). Study sites were chosen in each country to include high cattle density and tick burden.ResultsEast Africa (Ethiopia, Uganda and Tanzania) showed overall a higher diversity and prevalence in tick infestations compared to West African countries (Benin, Burkina Faso, Ghana and Nigeria). In East Africa, Amblyomma variegatum (vector of Ehrlichia ruminantium), Rhipicephalus microplus (Babesia bovis, B. bigemina, Anaplasma marginale), R. evertsi evertsi (A. marginale) and R. appendiculatus (Theileria parva) were the most prevalent tick species of economic importance. While the latter species was absent in West Africa, here both A. variegatum and R. microplus occurred in high numbers. Rhipicephalus microplus had spread to Uganda, infesting half of the cattle sampled. Rhipicephalus appendiculatus is known for its invasive behaviour and displacement of other blue tick species, as observed in other East and West African countries. Individual cattle with higher body weights, as well as males, were more likely to be infested. For six tick species, we found reduced infestation levels when hosts were treated with anti-parasiticides.ConclusionsThese baseline data allow the determination of possible changes in presence and prevalence of ticks in each of the countries targeted, which is of importance in the light of human-caused climate and habitat alterations or anthropogenic activities. As many of the ticks in this study are vectors of important pathogens, but also, as cattle may act as end hosts for ticks of importance to human health, our study will help a wide range of stakeholders to provide recommendations for tick infestation surveillance and prevention.
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Project description:BackgroundDiet is a key driver of equine hindgut microbial community structure and composition. The aim of this study was to characterize shifts in the fecal microbiota of grazing horses during transitions between forage types within integrated warm- (WSG) and cool-season grass (CSG) rotational grazing systems (IRS). Eight mares were randomly assigned to two IRS containing mixed cool-season grass and one of two warm-season grasses: bermudagrass [Cynodon dactylon (L.) Pers.] or crabgrass [Digitaria sanguinalis (L.) Scop.]. Fecal samples were collected during transitions from CSG to WSG pasture sections (C-W) and WSG to CSG (W-C) on days 0, 2, 4, and 6 following pasture rotation and compared using 16S rRNA gene sequencing.ResultsRegardless of IRS or transition (C-W vs. W-C), species richness was greater on day 4 and 6 in comparison to day 0 (P < 0.05). Evenness, however, did not differ by day. Weighted UniFrac also did not differ by day, and the most influential factor impacting β-diversity was the individual horse (R2 ≥ 0.24; P = 0.0001). Random forest modeling was unable to accurately predict days within C-W and W-C, but could predict the individual horse based on microbial composition (accuracy: 0.92 ± 0.05). Only three differentially abundant bacterial co-abundance groups (BCG) were identified across days within all C-W and W-C for both IRS (W ≥ 126). The BCG differing by day for all transitions included amplicon sequence variants (ASV) assigned to bacterial groups with known fibrolytic and butyrate-producing functions including members of Lachnospiraceae, Clostridium sensu stricto 1, Anaerovorax the NK4A214 group of Oscillospiraceae, and Sarcina maxima. In comparison, 38 BCG were identified as differentially abundant by horse (W ≥ 704). The ASV in these groups were most commonly assigned to genera associated with degradation of structural carbohydrates included Rikenellaceae RC9 gut group, Treponema, Christensenellaceae R-7 group, and the NK4A214 group of Oscillospiraceae. Fecal pH also did not differ by day.ConclusionsOverall, these results demonstrated a strong influence of individual horse on the fecal microbial community, particularly on the specific composition of fiber-degraders. The equine fecal microbiota were largely stable across transitions between forages within IRS suggesting that the equine gut microbiota adjusted at the individual level to the subtle dietary changes imposed by these transitions. This adaptive capacity indicates that horses can be managed in IRS without inducing gastrointestinal dysfunction.
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