Structure—activity relationships for some organotin molluscicides

Bioassay data are reported for 12 organotin compounds, R₃SnX, against the adult snail, Biomphalaria glabrata, an intermediate host of schistosomiasis. The relationship between the molluscicidal activity and the nature of the R and X groups in the organotin compounds is discussed, as well as the possible mode of toxic action of these compounds.     

Biochemical effects in mice following exposure to wheat treated with chlorfenvinphos and carbophenothion under laboratory and field conditions

The wood mouse (Apodemus sylvaticus) has been used as an indicator species to assess, both in the field and the laboratory, the effects of carbophenothion and, in the laboratory, the effects of chlorfenvinphos as seed dressings on winter wheat. Wood mice were fed in the laboratory with wheat treated with carbophenothion and chlorfenvinphos and the effects on esterase levels were determined for periods of up to 7 days and on returning the mice to untreated wheat. The significant inhibition of plasma acetylcholinesterase and cholinesterase and brain and liver nitrophenyl acetate esterase during the 6-month period after carbophenothion-treated grain was drilled was found to reflect the carbophenothion residue in the gut contents of the mice. The degree of esterase inhibition differentiated mice trapped on the field from those caught in adjacent woodland. Inhibition of the plasma, brain, and liver esterases in wood mice fed wheat treated with the recommended rate of carbophenothion confirmed that the continued esterase inhibition obtained in the field-trapped mice during the field trial was due to chronic pesticide exposure. The pattern of esterase inhibition in the wood mice reflected the persistence of the two organophosphorus pesticides.     

Potentielle Photosyntheseintensität von Gerstensorten des Gaterslebener Sortiments

Zusammenfassung Die potentielle (maximale) Photosyntheseintensität der Fahnenblattspreiten von zehn zweizeiligen und acht mehrzeiligen Sommergerstensorten des Gaterslebener Sortiments wurde gemessen, um die Variabilität dieses Merkmals innerhalb der Art zu ermitteln. Die Werte für die apparente Photosynthese liegen bei den zweizeiligen Gersten zwischen 8,7 und 19,8 mg CO₂/dm²·h und bei den mehrzeiligen zwischen 8,2 und 13,8 mg CO₂/dm²·h. Die Korrelation dieser Werte zu dem Korngewicht/Ähre ist erwartungsgemäß nicht sehr eng (0,65 bei den mehrzeiligen) beziehungsweise fehlt (0,22 bei den zweizeiligen). Dies ist auf den Einfluß anderer an der Ertragsbildung beteiligter Komponenten zurückzuführen. Die Variabilität des Merkmals potentielle Photosyntheseintensität ist groß genug, um den Gedanken an eine Selektion nahezulegen. Gegenwärtig stehen dem noch methodische Schwierigkeiten gegenüber.

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Summary The potential (maximum) photosynthetic rate of flag leaves of 10 two-rowed and 8 six-rowed spring barleys from the Gatersleben collection was measured to find out the variability of this character among the speciesHordeum vulgare. The values of apparent photosynthetic rate of the two-rowed barleys were between 8,7 and 19,8 mg CO₂/dm² · h and between 8,2 and 13,8 mg CO₂/dm² · h for the six-rowed varieties. The correlation between these values and the grain weight/ear is small (0,75) for the six-rowed, respectively insignificant (0,22) for the two-rowed barleys. This is caused by the influence of other yield-forming components. The variability of the potential photosynthetic rate is large enough to take into consideration a selection of positive extrems, but this is essentially a methodical problem.

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() 10 8 , . () 8,7 19,8 CO₂ ¶rt;M ² 8,2 13,8 — . , , ¶rt; (0,65 ) (0,22 ). . , . .

     

The degradation of aldicarb and oxamyl in soil

The breakdown of oxamyl was studied in three downland chalk soils, a peat loam, a sandy loam, and the same sandy loam modified by adding peat. The kinetics of aldicarb degradation via its sulphoxide and aldoxycarb (aldicarb sulphone) were also studied in these two sandy loam soils. All the reactions followed first-order kinetics, the reaction being faster in the original than in the modified sandy loam. Rates of reaction were slower at low moisture contents, and decreased markedly when the temperature was reduced from 10 to 5°C though less so than from 15 to 10°C.     

The Use of Case History Studies to Differentiate Potentially Infected from Potentially Noninfected Herds with Reactors to Brucella abortus Antigens

Data on farm characteristics and the results of the first herd test for brucellosis were collected for 74 reactor and 74 negative herds in Wellington County, Ontario. Each reactor herd was classified as either probably infected or probably not infected using the occurrence of abortions prior to the first herd test or during the testing period, the total number of cattle removed and/or the spread of reactors within the herd as criteria of infection.