Aquaponics has the potential to produce sustainable, high‐quality food through integration of hydroponics and aquaculture, but its commercialization is stalled by bottlenecks in pest and disease management. We reviewed integrated pest and disease management steps and techniques in hydroponics to qualify as suitable techniques for different aquaponic designs. Non‐chemical prophylactic measures are highly proficient for pest and disease prevention in all designs. Still, the use of chemical control methods remains highly complicated for all systems. We simulated 10–20% runoff concentrations of 9 pesticides in the common UVI design and compared them with NOEC, LC50 of fish. Endosulfan seems most toxic with runoff AI (20.7 μg L−1) exceeding LC50 (10.2 μg L−1) and NOEC (0.05 μg L−1). At 20% runoff, most chemical pesticides pose risks in aquaponic systems. Natural pesticides were also discussed as potential alternatives with low acute toxicity to fish, but little is known about their effects on water and bacteria. While insecticides and herbicides are replaceable by well‐established commercial biocontrol measures, fungicides and nematicides would still be relevant in aquaponics due to low efficiency of alternatives (e.g. natural enemies, entomopathogenic fungus). Monitoring and cultural control are the first approaches to contain pest population below the action threshold. Biological controls, in general, are adaptable to a larger extent. Further studies are required on how to utilize indigenous microbial community in aquaponics (dominated by Proteobacteria; effective at ~103–109 CFU mL−1) as a frontline defence.
Addressing undesirable changes associated with the driving forces of land use cover change are critical to sustainable land management, and the future modeling of land use systems in developing countries. The study accentuates local drivers of land use cover change in Southwestern Ghana using a mixed-method approach. The approach aided in identifying key land-use drivers, using different research strategies for comparisons through confidence level analysis and Analytic Hierarchy Process. We used expert interviews, existing literature and geostatistical tools to ascertain the driving forces triggering such unprecedented changes. Landsat imagery 5 MSS, 4 and 5 TM, 7 ETM + and 8 OLI/TIRS were acquired from the United States Geological Survey’s website. Land-use analysis revealed a decline in forests (− 82.41%) and areas covered by waterbodies (− 27.39%). A fundamental drift in built-up (+ 1288.36%) and farmlands/shrubs (+ 369.81%) areas were also observed. The contribution rate of change analysis revealed built-environment and increasing population contributed the most to surface temperature and land-use change. A steady increase in surface temperature can be attributed to the undesirable changes associated with land-use systems over the past 50 years. Socio-economic development in Southwestern Ghana is fuelling interest in studies related to land use cover change. Biophysical, cultural and technological factors are considered key drivers despite the “medium-to-very low confidence” in results generated. They could potentially impact climate-sensitive sectors that significantly modify land-use systems from the pessimists’ and optimists’ perspectives. Standpoints established through this study will enrich basic datasets for further studies at the continental level. Supplementary Information The online version contains supplementary material available at 10.1007/s12665-022-10481-y.
Shrimp farming is a key component of Vietnamese aquaculture contributing ~5% to their gross domestic product annually. Environmental hazards and socio‐economic parameters among other factors influence shrimp productivity in Vietnam. The present study employed the stochastic frontier production approach to investigate how technical efficiency (TE) of semi‐intensive and intensive shrimp farms is influenced by socio‐economic factors and environmental hazards. A questionnaire was administered to ascertain farmers' cost of major inputs (labour, seed, feed and lime), socio‐economic factors, coupled with environmental hazards (flood, pollution and drought experience). Findings revealed a mean TE of approximately 65% and 76% for semi‐intensive and intensive farms respectively (though, non‐significant as p ≥ 0.05). The input variables, shrimp seeds, feed and lime were found to be important variables in the intensive systems, as they positively correlated with TE in intensive systems. In the inefficiency model, education positively correlated with the TE in both systems, indicating that educated farmers are more efficient. Pollution negatively correlated with TE in both systems. With <80% of the farmers extremely affected by floods and droughts, and about 95% affected by pollution, the present study concludes there is a thorough impact of the above environmental hazards on farmers' technical efficiency.
Aquaponics has the potential to produce sustainable and accessible quality food through the integration of hydroponics and aquaculture. Plants take up dissolved nutrients in fish wastewater, allowing water reuse for fish. However, the simultaneous presence of fish and plants in the same water loop has made phytosanitary treatments of diseases such as powdery mildew problematic due to risks of toxicity for fish and beneficial bacteria, limiting its commercialization. Entomopathogenic and mycoparasitic fungi have been identified as safe biological control agents for a broad range of pests. This study aimed to investigate the efficacy of entomopathogenic fungi, Lecanicillium attenuatum (LLA), Isaria fumosorosea (IFR), and mycoparasitic fungus Trichoderma virens (TVI) against Podosphaera xanthii. Also, we investigated the possible harmful effects of the three fungal biocontrol agents in aquaponics by inoculating them in aquaponics water and monitoring their survival and growth. The findings showed that the three biocontrol agents significantly suppressed the powdery mildew at 107 CFU/ml concentration. Under greenhouse conditions (65-73% relative humidity (RH)), a significant disease reduction percentage of 85% was recorded in L. attenuatum-pretreated leaves. IFR-treated leaves had the least AUDPC (area under disease progress curve) of ~434.2 and disease severity of 32% under 65-73% RH. In addition, L. attenuatum spores were the most persistent on the leaves, the spores population increased to 9.54 × 103 CFUmm-2 from the initial 7.3 CFUmm-2 under 65-73%. In contrast, in hydroponics water, the LLA, IFR, and TVI spores significantly reduced by more than 99% after 96 hrs. Initial spore concentrations of LLA of 107 CFU/ml spores were reduced to 4 x 103 CFU after 96 hrs. Though the results from this study were intended for aquaponics systems, relevance of the results to other cultivation systems are discussed.
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