Reducing insecticide and fungicide loads in runoff from plastic mulch with vegetative-covered furrows

A common management practice for the production of fresh-market vegetables utilizes polyethylene (plastic) mulch because it increases soil temperature, decreases weed pressure, maintains soil moisture, and minimizes soil contact with the product. However, rain events afford much more erosion and runoff because 50-75% of the field is covered with an impervious surface. A plot study was conducted to compare and to quantify the off-site movement of soil, insecticides, and fungicides associated with runoff from plots planted with Sunbeam tomatoes (Lycopersicon esculentum Mill) using the conventional polyethylene mulch management practice vs an alternative management practice-polyethylene mulch-covered beds with cereal rye (Secale cereale) planted in the furrows between the beds. The use of cereal rye-covered furrows with the conventional polyethylene system decreased runoff volume by more than 40%, soil erosion by more than 80%, and pesticide loads by 48-74%. Results indicate that vegetative furrows are critical to minimizing the negative aspects of this management practice.     

Obesity and related risk factors among low socio-economic status minority students in Chicago

OBJECTIVES: To assess overweight and related risk factors among urban low socio-economic status (SES) African-American adolescents in an attempt to study the underlying causes of ethnicity and gender disparities in overweight. METHODS: Cross-sectional data collected on anthropometric measures, diet, physical activity and family characteristics from 498 students in grades 5-7 in four Chicago public schools were analysed to study the risk factors for overweight using stepwise regression analysis. RESULTS: Only 37.2% of the students lived with two parents. Nearly 90% had a television (TV) in their bedroom, and had cable TV and a video game system at home. Overall. 21.8% (17.7% boys versus 25.1% girls) were overweight (body mass index (BMI) >/= 95th percentile); and 39.8% had a BMI >/= 85th percentile. Compared with national recommendations, they had inadequate physical activity and less than desirable eating patterns. Only 66.1% reported having at least 20 min vigorous exercise or 30 min of light exercise in >/= 5 days over the past 7 days; 62.1% spent >3 h days- 1 watching TV/playing video games/computer, while 33.1% spent >/= 5 h days- 1. Their vegetable and fruit consumption was low, and they consumed too many fried foods and soft drinks: 55.1% consumed fried food twice or more daily and 19.5% four times or more daily; 70.3% consumed soft drinks twice or more daily and 22.0% four times or more daily on average. Gender, physical activity and pocket money were significant predictors of overweight (P < 0.05). CONCLUSIONS: Several factors in the students' behaviours, school and family environments may increase overweight risk among this population. There is a great need for health promotion programmes with a focus on healthy weight and lifestyle, and targeting urban low-SES minority communities.     

P450-mediated resistance in Myzus persicae (Sulzer) (Hemiptera: Aphididae) reduces the efficacy of neonicotinoid seed treatments in Brassica napus

BACKGROUND

The prophylactic use of seeds treated with neonicotinoid insecticides remains an important means of controlling aphid pests in canola (Brassica napus) crops in many countries. Yet, one of the most economically important aphid species worldwide, the peach potato aphid (Myzus persicae), has evolved mechanisms which confer resistance to neonicotinoids, including amplification of the cytochrome P450 gene, CYP6CY3. While CYP6CY3 amplification has been associated with low-level resistance to several neonicotinoids in laboratory acute toxicity bioassays, its impact on insecticide efficacy in the field remains unresolved. In this study, we investigated the impact of CYP6CY3 amplification on the ability of M. persicae to survive neonicotinoid exposure under laboratory and semi-field conditions.

RESULTS

Three M. persicae clones, possessing different copy numbers of CYP6CY3, were shown to respond differently when exposed to the neonicotinoids, imidacloprid and thiamethoxam, in laboratory bioassays. Two clones, EastNaernup209 and Osborne171, displayed low levels of resistance (3–20-fold), which is consistent with previous studies. However, in a large-scale semi-field trial, both clones showed a surprising ability to survive and reproduce on B. napus seedlings grown from commercial rates of neonicotinoid-treated seed. In contrast, an insecticide-susceptible clone, of wild-type CYP6CY3 copy number, was unable to survive on seedlings treated in the same manner.

CONCLUSION

Our findings suggest that amplification of CYP6CY3 in M. persicae clones substantially impairs the efficacy of neonicotinoid seed treatments when applied to B. napus. These findings highlight the potentially important real-world implications of resistances typically considered to be ‘low level’ as defined through laboratory bioassays. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.     

Lake trout (Salvelinus namaycush) otoliths indicate effects of climate and lake morphology on growth patterns in Arctic lakes

Climate change is occurring rapidly in the Arctic, and an improved understanding of the response of aquatic biota and ecosystems will be important for this data-limited region. Here, we applied biochronology techniques and mixed-effects modelling to assess relationships among growth increments found on lake trout (Salvelinus namaycush) otoliths (N = 49) captured from 13 lakes on the Arctic Coastal Plain of northern Alaska, observed and modelled climate patterns, and individual-level fish and lake characteristics. We found that annual growth varied by year, fish growth slowed significantly as individuals aged, and females grew faster than males. Lake trout had higher growth in flow-through lakes relative to lakes that were perennially or seasonally connected. Annual growth was positively correlated with observed air temperature measurements from a local weather station for the period 1998–2014, but no clear warming trend was evident for this period. Modelled August air temperatures from 1978–2014 predicted lake trout annual growth (root mean squared error = 0.045 mm) and indicated increasing temperatures and annual lake trout growth over the period 1950–2014. This study demonstrated that biochronology techniques can reconstruct recent climate patterns and provide a better understanding of trends in Arctic lake ecosystems under a changing climate.     

Exogenous polyunsaturated fatty acids (PUFAs) influence permeability,antimicrobial peptide resistance,biofilm formation and membrane phospholipid structure in an A-layer and non-A-layer strain of Aeromonas salmonicida

Aeromonas salmonicida is a Gram-negative bacterium that can infect a wide host range of fish populations, including salmonids and non-salmonids as well as freshwater and marine life. Some strains of A. salmonicida cause the disease furunculosis, which can cause lethargy, intestinal inflammation, ulcers, haemorrhaging and death. The infection is spread through fish-to-fish contact, and the presence of infection can have devastating effects on cultivated fish populations. The purpose of this study was to explore the ability of non-A-layer and A-layer A. salmonicida strains to incorporate polyunsaturated fatty acids (PUFAs) into their lipid profile and test the phenotypic effects thereof. Lipids were extracted from PUFA-exposed cultures and analysed for lipid modification by thin-layer chromatography and ultraperformance liquid chromatography-mass spectrometry, showing A. salmonicida, regardless of A-layer, capable of incorporating all seven of the PUFAs studied. Phenotypic effects were determined through the use of assays that tested for biofilm formation, membrane permeability and cyclic peptide susceptibility. Temperature-dependent effects on biofilm formation were observed, and PUFA exposure showed significant (p < .001) increases in membrane permeability as tested by the uptake of the hydrophobic compounds crystal violet and ethidium bromide. Additionally, some PUFAs elicited modest protection and vulnerability against the membrane-targeting cyclic peptides polymyxin B (PMB) and colistin. The diverse, strain-specific responses to exogenous PUFAs may allude to evolved adaptive strategies that enhance survival, persistence and virulence of non-pathogenic and pathogenic members of bacteria that oscillate between environmental and fish host niches.     

Biological life-history and farming scenarios of marine aquaculture to help reduce wild marine fishing pressure

Aquaculture (freshwater and marine) has largely supplemented fisheries, but in theory could help reduce fishing pressure on wild stocks. Although not the sole factors, some potential benefits depend on aquaculture pressures on fished species, including collection of wild ‘seed’ material—earlier to later life stages—for rearing in captivity and the capacity of aquaculture to increase. Here we first classify 203 marine (saltwater and brackish) animal species as being produced by either open-cycle capture-based aquaculture (CBA) or closed-cycle domesticated aquaculture (DA)—based on their likely reliance on wild seed—and assess the extent to which these forms of aquaculture could support seafood production and greater wild biomass. Using a data-limited modelling approach, we find evidence that current aquaculture practices are not necessarily helping reduce fishing to sustainable levels for their wild counterparts—consistent with emerging scientific research. However, if some wild capture species (87 equivalent spp.) were instead produced through CBA, almost a million extra tonnes could theoretically be left in the wild, without reducing seafood production. Alternatively, if reliance on wild seed inputs is further reduced by shifting to DA production, then a little less than doubling of aquaculture of the overexploited species in our study could help fill the ‘production gap’ to support fishing at maximum sustainable levels. While other ecological (e.g. escapes), social and economic considerations (e.g. market substitution) are important, we focused on a critical biological linkage between wild fisheries and aquaculture that provides another aspect on how to improve management alignment of the sectors.     

Effects of an oil-based substrate (The Water Cleanser™) and bacterial additives on nitrogen and phosphorous dynamics in freshwater crayfish (Cherax cainii,Austin and Ryan 2002) aquaculture

Two experiments were conducted to evaluate the efficacy of an oil-based substrate, The Water Cleanser? (TWC). The first experiment studied the effects two substrates of different oil composition (TWC, TWC?+), and a commercial bacterial additive (Bio-Aid) on concentrations of nitrogen and phosphorous in indoor aquaria. The second experiment studied the effects of TWC, a bacterial additive, and a combination (TWC?+?B) on concentrations of nitrogen and phosphorous, phytoplankton abundance and diversity in outdoor freshwater crayfish (Cherax cainii, Austin and Ryan, Invertebr Syst 16:357–367, 2002) tanks. In the first experiment, the concentration of TAN decreased more rapidly with Bio-Aid, whilst the maximum concentrations of NO₂-N and NO₃-N were reduced with the substrates. The concentration of orthophosphate was reduced in aquaria with TWC?+?. In the second experiment, concentrations of TAN, NO₂-N, NO₃-N and total phosphate were not significantly affected by TWC. After addition of TWC?+?B, there was a significant decrease in the concentrations of nitrate and total phosphate, and a higher abundance of phytoplankton was maintained than with other treatments. Additionally, a population Bacillus sp. was found on the substrate surface. TWC had no adverse effects on phytoplankton abundance or diversity, or C. cainii physiology, weight gain or survival. TWC and TWC?+?were effective bioremediators of eutrophic water, whilst a combination of TWC?+?B was effective in short term bioremediation and in promoting phytoplankton abundance in C. cainii tank culture.