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.     

Laboratory investigation of the chemical disinfection against different developmental stages of the housefly (Musca domestica Linnaeus, 1758)

Possibilities for disinfection of the developmental stages from the housefly (Musca domestica) were investigated under laboratory conditions. The developmental stages (eggs, larvae I, II, III, pupae and adults) were sprayed with solutions of disinfectants on the basis of p-chlorine-m-cresol and o-phenylphenol at different concentrations (0.025%-3%). The effectiveness of both disinfectants was established by determining the emergence rate of eggs and pupae and of the live evidence of larvae and adults. Transmission electron microscopic investigations of the cover of the eggs revealed the bactericidal effect of both disinfectants. These results show the necessity of extending its use also to noxious arthropods.     

Hausrattennachweise (Rattus rattus L.) in bewohnten Wohnh?usern in Magdeburg

Storehouses and mills in the Magdeburg region are known to be infested with black (ore house) rats. In residential buildings, however, house rats (Rattus rattus L.) have not been detected for at least 20 years. Therefore, it was of much interest for the expert to note that this rat species had been seen in two occupied residential buildings (a refurbished old building and a terraced house). It has been suspected for a longer time that black rats can be found in certain residential buildings in towns or even cities.     

Erfolgreiche Bekämpfung der Orientalischen Schabe (Blatta orientalis) (L.) (Blattodea,Blattidae) and Hand eines Beispieles aus der Praxis

Zusammenfassung Die Orientalische Schabe (Blatta orientalis) wird in komplizierten Bekämpfungsterrains oft erfolglos bekämpft. Anhand eines Beispieles aus der Praxis werden Möglichkeiten aufgezeigt, wie man erfolgreich gegen die Orientalische Schabe vorgehen kann. Als entscheidender Gesichtspunkt wird die Aufspürung der Refugien angesehen. Die Orientalische Schabe zeigt eine hohe Affinität zu ihren Refugien. Die verschiedenen Bekämpfungsmethoden sollten sinnvoll kombiniert und aufeinander abgestimmt werden. Noch zu oft werden moderne Methoden der Schabenbekämpfung nicht angewendet und damit wichtige Einsatzmöglichkeiten vergeben. Die Ergebnisse der Arbeit vonFuchs, 1987) zum Verhalten vonBlatta orientalis sollten den Schädlingsbekämpfern auf Weiterbildungsveranstaltungen vermittelt werden.

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Successful control of the Oriental cockroach (Blatta orientalis) (L.) (Blattodea, Blattidae) demonstrated by way of an example of real control

Attempts to control the Oriental cockroach (Blatta orienitalis) have often failed in complex territories. An example of real control is presented to demonstrate how the Oriental cockroach can be satisfactorily controlled. Tracking down the refuges of the pests is considered the decisive approach to control. The Oriental cockroach shows a close affinity for its refuges. The various methods of control should be usefully combined and coordinated. It has been found that modern methods of cockroach control are not adopted in a great many cases and, therefore, potential fields of application are not adequately used. The results of the work ofFuchs (1987) investigating the behaviour ofBlatta orientalis should be conveyed to pest control experts in training courses.

     

Zur Lebensweise der Hausratte (Rattus rattus L.). Langjährige Beobachtungen in einer Getreidemühle bei Magdeburg

A large flour mill near Magdeburg was built in 1912 and has since been infested with house rats (Rattus rattus L.). Observations made over the past decades by personnel interested were acquired, and recorded together with own findings, in the course of which well-known facts of the habits of house rats were confirmed and thought-provoking shades added. Reference is made in this paper to varied issues including degree of infestation, skin colours, food, reproduction, as well as behavioural patterns and the problem area of control and extermination.     

Effect of high-pressure hot-water washing treatment on fruit quality, insects, and disease in apples and pears: Part I. System description and the effect on fruit quality of ‘d’Anjou’ pears

A manually operated high-pressure hot-water washing system consisting of a boiler, hot-water mixing tank, contact loop, heat exchanger, spray mixing tank, high-pressure hot-water washing manifold, low-pressure fresh water rinse manifold, and pressure pump was constructed and installed in a packingline. The system developed 20–50 °C washing water at pressures up to 980 kPa. ‘d’Anjou’ pears (Pyrus communis L.), shortly after harvest, and after storage for 3 and 4 months in regular air (RA) or for 4, 7 and 8 months in controlled atmosphere (CA) at −1 °C were washed through the packingline with different wetting agents (0.1% Silwet, 0.01 and 0.1% Defoamer, and water), water pressures (regular and high-pressure (210–980 kPa)), water temperatures (control (tap water, 4–22 °C), 40 °C, and 50 °C), and brushes (soft and firm), respectively. The effect of the washing conditions on fruit quality was investigated after 1 month of storage at −1 °C to simulate shipping condition, and then again after 1 week at 20 °C to simulate marketing condition. Hot-water caused severe heat scald. When nozzle temperature was 50 °C, the incidence of heat scald increased to over 50% for the fruit stored in RA for 3 months. Combined with hot-water, 540 kPa high-pressure washing increased the incidence of friction discoloration. There were lower incidences of friction discoloration and heat scald for fruit stored in CA for 7 months, in comparison to that in RA for 3 months. However, those fruit did not ripen properly as indicated by a high extractable juice content. Fruit washed at harvest had minor incidences of friction discoloration regardless of different brushes, water pressures, and wetting agents. Fruit washed after storages in either 4 months RA or 4 or 8 months CA suffered a high incidence of friction discoloration including scuffing symptoms and pressure marking. The firm brushes caused a higher incidence of friction discoloration mainly because of scuffing symptoms. However, no differences were found between different water pressures and wetting agents with respect to friction discoloration. Fruit stored for 4 months RA suffered 26–28% friction discoloration in comparison to 16–18% in CA stored fruit with firm brush washing. Extended CA storage increased friction discoloration even with soft brush washing. The results suggest that a washing system with high-pressure spray, <30 °C warm water, wetting agent Defoamer and rotating soft brushes were significantly effective in removing surface pests and decay control without causing internal or external damage of fruit.     

Kinetic isotope effects for the reactions of muonic helium and muonium with H2

The neutral muonic helium atom may be regarded as the heaviest isotope of the hydrogen atom, with a mass of ~4.1 atomic mass units ((4.1)H), because the negative muon almost perfectly screens one proton charge. We report the reaction rate of (4.1)H with (1)H(2) to produce (4.1)H(1)H + (1)H at 295 to 500 kelvin. The experimental rate constants are compared with the predictions of accurate quantum-mechanical dynamics calculations carried out on an accurate Born-Huang potential energy surface and with previously measured rate constants of (0.11)H (where (0.11)H is shorthand for muonium). Kinetic isotope effects can be compared for the unprecedentedly large mass ratio of 36. The agreement with accurate quantum dynamics is quantitative at 500 kelvin, and variational transition-state theory is used to interpret the extremely low (large inverse) kinetic isotope effects in the 10(-4) to 10(-2) range.     

Flip-flopping fractional flux quanta

The d-wave pairing symmetry in high-critical temperature superconductors makes it possible to realize superconducting rings with built-in pi phase shifts. Such rings have a twofold degenerate ground state that is characterized by the spontaneous generation of fractional magnetic flux quanta with either up or down polarity. We have incorporated pi phase-biased superconducting rings in a logic circuit, a flip-flop, in which the fractional flux polarity is controllably toggled by applying single flux quantum pulses at the input channel. The integration of p rings into conventional rapid single flux quantum logic as natural two-state devices should alleviate the need for bias current lines, improve device symmetry, and enhance the operation margins.