Proportionality principle revisited – relationship between application rates and pesticide residue concentrations in food commodities

BACKGROUND

The proportionality principle has been broadly used for over 10 years in regulatory assessments of pesticide residues. It allows extrapolation of supervised field trial data conducted at lower or higher application rates compared to the use pattern under evaluation by adjustment of measured concentrations, assuming direct proportionality between the rates applied and the resulting residues. This work revisits the principle idea by using supervised residue trials sets conducted under identical conditions but with deviating application rates. Four different statistical methods were used to investigate the relationship between application rates and residue concentrations and to draw conclusions on the statistical significance of the direct proportionality assumed.

RESULTS

Based on over 5000 individual trial results, the assumption of direct proportionality was not confirmed to be statistically significant (P > 0.05) using three models: direct comparison of application rates and residue concentrations ratios and two linear log-log regression models correlating application rate and residue concentration or only residue concentrations per se. In addition, a fourth model analysed deviations between expected concentrations following direct proportional adjustment and measured residue values from corresponding field trials. In 56% of all cases, the deviation was larger than ±25%, which represents the tolerance usually accepted for the selection of supervised field trials in regulatory assessments.

CONCLUSION

Overall, the assumption of direct proportionality between application rates and resulting residue concentrations of pesticides was not statistically significant. Although the proportionality approach is highly pragmatic in regulatory practice, its use should be considered carefully on a case-by-case basis. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.     

Review of ground-based methods to measure the distribution of biomass in forest canopies

? Context

Ecological research and an effective forest management need accurate information on the structure of the forest canopy to understand the biochemical, physiological and biogeochemical processes within a forest.

? Research question

This paper reviews the currently available instruments for measuring the distribution of biomass within forest canopies. We compare the most well-established approaches and present the different measurable parameters. A special focus lies on the resolution of the obtained data.

? Results

It was found that only 3D laser scanners offer data with the resolution required by ecologists, private landholders, the forest industry and the public to detect trends in tree growth patterns and canopy interactions in all three spatial dimensions. But data validation, data analysis and parameter extraction are still under development, and the price of the instrument is quite high.

? Conclusion

Research should focus on the parameter extraction from terrestrial laser scanner data as this could allow the calculation of functional attributes for different sections of a canopy on a high spatial resolution. It could also help ecologists characterize the structure of forest stands in a quick and precise way.     

Honey as the Potential Natural Source of Cholinesterase Inhibitors in Alzheimer’s Disease

Plant Foods for Human Nutrition - Alzheimer’s disease (AD) is a progressive neurodegenerative disease characterized, among others by abnormal levels of acetyl- and butyrylcholinesterase in...     

Accurate machine learning-based germination detection,prediction and quality assessment of three grain crops

Photosynthesis is one of the most important biological reactions and forms the basis of crop productivity and yield on which a growing global population relies. However, to develop improved plant cultivars that are capable of increased productivity, methods that can accurately and quickly quantify photosynthetic efficiency in large numbers of genotypes under field conditions are needed. Chlorophyll fluorescence imaging is a rapid, non-destructive measurement that can provide insight into the efficiency of the light-dependent reactions of photosynthesis. To test and validate a field-deployed fluorescence imaging system on the TERRA-REF field scanalyzer, leaves of potted sorghum plants were treated with a photosystem II inhibitor, DCMU, to reduce photochemical efficiency (FV/FM). The ability of the fluorescence imaging system to detect changes in fluorescence was determined by comparing the image-derived values with a handheld fluorometer. This study demonstrated that the imaging system was able to accurately measure photochemical efficiency (FV/FM) and was highly correlated (r = 0.92) with the handheld fluorometer values. Additionally, the fluorescence imaging system was able to track the decrease in photochemical efficiency due to treatment of DCMU over a 7 day period. The system’s ability to capture the temporal dynamics of the plants’ response to this induced stress, which has comparable dynamics to abiotic and biotic stressors found in field environments, indicates the system is operating correctly. With the validation of the fluorescence imaging system, physiological and genetic studies can be undertaken that leverage the fluorescence imaging capabilities and throughput of the field scanalyzer.     

Analysis of the immunoproteome of Mycoplasma mycoides subsp. mycoides small colony type reveals immunogenic homologues to other known virulence traits in related Mycoplasma species

Contagious bovine pleuropneumonia (CBPP) caused by Mycoplasma mycoides subsp. mycoides small colony type (MmmSC) has been eradicated in the developed world, but it is still present in many countries of sub-Saharan Africa. After initially successful control measures in the 1960s it has been spreading due to a lack of money, fragmentation of veterinary services, uncontrolled cattle movement, insufficient vaccine efficacy and sensitivity of current diagnostic tests.In this study we used two-dimensional polyacrylamide gel electrophoresis followed by immunoblot with sera from MmmSC-infected animals and MALDI-ToF mass spectrometry to identify novel immunogenic proteins as candidate molecules for improved diagnostics and vaccines. We identified 24 immunogens recognized by pooled sera from experimentally infected cattle. Furthermore, a serum from an animal with acute clinical disease as well as severe pathomorphological lesions recognized 13 additional immunogens indicating variation in the antibody responses to CBPP amongst cattle. Most immunogens showed compelling similarity to protein/gene sequences in the two ruminant pathogens M. capricolum subsp. capricolum and M. mycoides subsp. mycoides large colony type both belonging to the mycoides cluster. Three of these proteins, namely glycerol-3-phosphate oxidase, adenylosuccinate synthase, and glyceraldehyde-3-phosphate dehydrogenase, had no compelling homologue in the other distantly related bovine pathogen M. agalactiae. In addition, translation elongation factor Tu, heat shock protein 70, pyruvate dehydrogenase, and FKBP-type peptidyl-prolyl isomerase, which have been found to mediate adhesion to host tissue in other mycoplasmas were shown to be expressed and recognized by sera. These proteins have potential for the development of improved diagnostic tests and possibly vaccines.     

Surgical management of a canine intracranial abscess due to a bite wound

Objective – To describe the successful surgical management of a brain abscess in a dog secondary to bite wound. Case Summary – A 10‐year‐old neutered female Welsh Corgi/Chihuahua, weighing 5.3 kg, was presented for evaluation of seizures, ataxia, and falling to the left 8 days after a presumptive fight with another dog. On examination at presentation, the dog was alert, responsive, and ambulatory with tetra‐ataxia, falling to the left, left‐sided postural deficits, and absent left menace response. Within 24 hours, the dog progressed to nonambulatory tetraparesis with minimal motor, absent postural reactions of all limbs, left nasal hypalgesia, reduced gag reflex, and depressed mentation. Computed tomographic images of the brain were suggestive of a bite wound fracture of the right parietal bone with secondary meningoencephalitis, right parietal lobe abscessation, and white matter edema adjacent to the bone fracture. A modified right rostrotentorial craniectomy was performed, the abscess was identified, contents of the abscess were removed, and the surgical site was flushed extensively before closing. Corynebacterium spp. was cultured from within the abscess. Within hours of surgery, the dog was quiet but alert, responsive, and sitting up in her cage. In addition to surgical intervention, intensive care, broad‐spectrum IV antimicrobials, and supportive therapy led to significant neurologic improvement with only occasional seizures and mild postural reaction deficits of the left hindlimb remaining. New or Unique Information Provided – Abscess formation within the CNS is uncommon in dogs and cats and is associated with a high mortality rate. In veterinary medicine the management of brain abscesses is controversial with limited information available regarding treatment. This is the first case report that demonstrates surgical intervention in combination with antimicrobial therapy can be used successfully in the treatment of a canine brain abscess.     

Equivalence or complementarity of soil‐solution extraction methods

Several methods are used for the extraction of soil solution. The objective of this study was to find out to what extent the different extraction methods yield complementary or equivalent information. Soil solutions were sampled once at 10 different forest sites in Germany, with 4 sampling points per site, using 5 different extraction methods. Concentrations of the major ions in the 1:2 extracts and the equilibrium soil‐pore solutions (obtained from percolation of field‐fresh soil cores) were generally lower than in desorption solutions, suction‐cup solutions, and saturation extracts. Surprisingly, the latter three methods generally yielded equivalent results. However, possible systematic differences between these methods could have been masked by the high small‐scale spatial variability within the sites.     

BKCa-Cav channel complexes mediate rapid and localized Ca2+-activated K+ signaling

Large-conductance calcium- and voltage-activated potassium channels (BKCa) are dually activated by membrane depolarization and elevation of cytosolic calcium ions (Ca2+). Under normal cellular conditions, BKCa channel activation requires Ca2+ concentrations that typically occur in close proximity to Ca2+ sources. We show that BKCa channels affinity-purified from rat brain are assembled into macromolecular complexes with the voltage-gated calcium channels Cav1.2 (L-type), Cav2.1 (P/Q-type), and Cav2.2 (N-type). Heterologously expressed BKCa-Cav complexes reconstitute a functional "Ca2+ nanodomain" where Ca2+ influx through the Cav channel activates BKCa in the physiological voltage range with submillisecond kinetics. Complex formation with distinct Cav channels enables BKCa-mediated membrane hyperpolarization that controls neuronal firing pattern and release of hormones and transmitters in the central nervous system.     

Traces of human migrations in Helicobacter pylori populations

Helicobacter pylori, a chronic gastric pathogen of human beings, can be divided into seven populations and subpopulations with distinct geographical distributions. These modern populations derive their gene pools from ancestral populations that arose in Africa, Central Asia, and East Asia. Subsequent spread can be attributed to human migratory fluxes such as the prehistoric colonization of Polynesia and the Americas, the neolithic introduction of farming to Europe, the Bantu expansion within Africa, and the slave trade.