RESUMEN
In the Colombian Amazon, there has been long-term and sustained loss of primary forest threatening biodiversity and climate change mitigation. Silvopastoral practices that integrate trees into livestock production could help address both local economic and wider environmental challenges.We aimed to assess the effects of silvopastoral practices on invertebrate communities on smallholder farms in Caquetá, Colombia. Using sweep nets and malaise trapping, invertebrate communities were compared between traditional pasture, silvopasture and forest edge habitats.Invertebrate communities collected using sweep nets were contrasting among habitat types, communities were significantly different between traditional pasture and forest edge habitats and diversity and evenness were greatest in forest edges compared to traditional pastures. It appears that silvopasture areas, by supporting similar invertebrate assemblages to both traditional pasture and forest edges, may be acting as an intermediate habitat.When individual invertebrate orders were compared, Lepidoptera and Coleoptera were found in greater abundance in the forest edge habitats, while Hemiptera were more abundant in traditional pasture. Hemipterans are often pests of forage plants in pasture systems and these differences in abundance may have implications for ecosystem services and disservices.Silvopastoral approaches cannot replace the unique biodiversity supported by native forests but could deliver benefits for invertebrate conservation and ecosystem services if integrated into landscapes.
Resumen: En la Amazonía colombiana ha habido una pérdida sostenida y a largo plazo de bosque primario que amenaza la biodiversidad y la mitigación del cambio climático. Las prácticas silvopastoriles que integran los árboles en la producción ganadera podrían ayudar a abordar tanto los desafíos económicos locales como los ambientales.Nuestro objetivo fue evaluar los efectos de las prácticas silvopastoriles en comunidades de invertebrados en pequeñas fincas en Caquetá, Colombia. Las comunidades de invertebrados se compararon entre las pasturas nativas, el sistema silvopastoril y los hábitats del borde del bosque mediante el uso redes entomológicas de barrido y trampas Malaise.Las comunidades de invertebrados recolectadas usando redes entomológicas de barrido contrastaban entre los tipos de hábitat. Las comunidades eran significativamente diferentes entre las pasturas nativas y el borde de bosque. Pareciera que las áreas de silvopastoreo, al soportar conjuntos de invertebrados similares tanto a las pasturas nativas como a los bordes del bosque, pueden estar actuando como un hábitat intermedio.Cuando se compararon los órdenes individuales de invertebrados, los lepidópteros y los coleópteros se encontraron en mayor abundancia en los hábitats del borde del bosque, mientras que los hemípteros eran más abundantes en las pasturas nativas. Los hemípteros son a menudo plagas de plantas forrajeras en sistemas de pastoreo y estas diferencias en abundancia pueden tener implicaciones y perjuicios para los servicios ecosistémicos.Los sistemas silvopastoriles no pueden reemplazar la biodiversidad única apoyada por los bosques nativos, pero podrían ofrecer beneficios para la conservación de invertebrados y los servicios ecosistémicos si se integran en los paisajes.
RESUMEN
Control measures are being introduced globally to reduce the prevalence of antibiotic resistance (ABR) in bacteria on farms. However, little is known about the current prevalence and molecular ecology of ABR in bacterial species with the potential to be key opportunistic human pathogens, such as Escherichia coli, on South American farms. Working with 30 dairy cattle farms and 40 pig farms across two provinces in central-eastern Argentina, we report a comprehensive genomic analysis of third-generation cephalosporin-resistant (3GC-R) E. coli, which were recovered from 34.8% (cattle) and 47.8% (pigs) of samples from fecally contaminated sites. Phylogenetic analysis revealed substantial diversity suggestive of long-term horizontal and vertical transmission of 3GC-R mechanisms. CTX-M-15 and CTX-M-2 were more often produced by isolates from dairy farms, while CTX-M-8 and CMY-2 and co-carriage of amoxicillin/clavulanate resistance and florfenicol resistance were more common in isolates from pig farms. This suggests different selective pressures for antibiotic use in these two animal types. We identified the ß-lactamase gene blaROB, which has previously only been reported in the family Pasteurellaceae, in 3GC-R E. coli. blaROB was found alongside a novel florfenicol resistance gene, ydhC, also mobilized from a pig pathogen as part of a new composite transposon. As the first comprehensive genomic survey of 3GC-R E. coli in Argentina, these data set a baseline from which to measure the effects of interventions aimed at reducing on-farm ABR and provide an opportunity to investigate the zoonotic transmission of resistant bacteria in this region. IMPORTANCE: Little is known about the ecology of critically important antibiotic resistance among bacteria with the potential to be opportunistic human pathogens (e.g., Escherichia coli) on South American farms. By studying 70 pig and dairy cattle farms in central-eastern Argentina, we identified that third-generation cephalosporin resistance (3GC-R) in E. coli was mediated by mechanisms seen more often in certain species and that 3GC-R pig E. coli were more likely to be co-resistant to florfenicol and amoxicillin/clavulanate. This suggests that on-farm antibiotic usage is key to selecting the types of E. coli present on these farms. 3GC-R E. coli and 3GC-R plasmids were diverse, suggestive of long-term circulation in this region. We identified the de novo mobilization of the resistance gene blaROB from pig pathogens into E. coli on a novel mobile genetic element, which shows the importance of surveying poorly studied regions for antibiotic resistance that might impact human health.