Economies of Pond Size for Hybrid Striped Bass Growout1

The objective of this study was to evaluate the relationship of pond size and hybrid striped bass growout profitability as an alternative source of farm income in the Mid-Atlantic region. A dynamic, whole farm, Montdarlo capital budgeting simulation model (AQUASIM) and stochastic dominance with respect to a function technique were used to analyze the economics of hybrid striped bass growout from phase II to market production stage for eight farms categorized by pond sizes. Three scenarios are assumed to examine the effects of pond-size dependent changes in feed conversion efficiency and fingerling survival rates on discounted after-tax net present values and probabilities of economic survival and success. Optimal pond sizes were found to be in the 2.5 acre to 10 acre range.     

Oils for weed control: Uses and mode of action

The role of oils in herbicide treatments is reviewed, both in terms of their own intrinsic activity and of their enhancement of the performance of other herbicides. The phytotoxicity of oils can be related to their physical properties. Their efficacy as adjuvants can vary with the plant/pesticide combination involved, and differences may also be observed between oils of mineral and vegetable origin. The possible mechanisms involved in the enhancement of activity by oils are discussed and areas of work that might elucidate these fun her are indicated.     

Das Ende der Nelkenwickler-Kalamität in Breslau-Hundsfeld

Ohne Zusammenfassung     

Zur Kenntnis der Obstbaumkarbolineumemulsionen

Ohne Zusammenfassung Mit 5 Abbildungen.     

Die Jagd zu Brandenberg in Tirol

Ohne Zusammenfassung     

Der Arsengehalt von Futtergras als Folge der Schädlingsbekämpfung

Ohne Zusammenfassung Mit 4 Abbildungen.     

Timing and order of different insecticide classes drive control of Drosophila suzukii; a modeling approach

The spotted-wing drosophila, Drosophila suzukii Matsumura, is an invasive pest causing significant damage to soft skinned fruits. Control of D. suzukii is critical since there is no tolerance for infested fruit in the market. While most insecticides control one or more D. suzukii life-stages (e.g., egg, larvae, and adult), the impact of insecticides that are toxic to immature stages  is unclear on the subsequent generation of a field population. Insecticides were applied at field recommended rates on cherries and blueberries in the laboratory to determine immature D. suzukii mortality. Spinetoram, cyantraniliprole, malathion, methomyl, spinosad, and phosmet resulted in relatively high mortality of all immature life stages. Zeta-cypermethrin, cyclaniliprole, and fenpropathrin resulted in lower mortality of egg and all larval instars. Malathion was also applied to lowbush blueberries with different fruit sizes (small, medium, and large) in the laboratory and there was no statistical difference in mortality rates depending on fruit sizes. Mortality data from the laboratory experiments were used to parameterize a refined D. suzukii population model. The model revealed that the timing and order of different insecticide classes are important to control D. suzukii population. Model runs that included early applications of more effective insecticides resulted in high immature mortality and greater reduction of D. suzukii populations compared to treatments applied later.

     

Mosquito larvicidal activity of alkaloids from Zanthoxylum lemairei against the malaria vector Anopheles gambiae

Four alkaloids, 10-O-demethyl-17-O-methylisoarnottianamide 1, 6-acetonyl-N-methyl-dihydrodecarine 2, nitidine 3, and chelerythrine 4 were isolated from the plant Zanthoxylum lemairei (Rutaceae) and evaluated for mosquito larvicidal activity against the malaria vector Anopheles gambiae. The mortalities of the larvae were determined after 24 h. The results of the larvicidal tests demonstrated that compounds 1 and 2 were the most potent with mortality rates of 96.7% and 98.3% at a concentration of 250 mg/L, respectively. Compound 3 was less potent with a mortality of 28.3% at the same concentration. The percent mortality of 100% was observed at a concentration of 500 mg/L. The least potent of the four alkaloids was compound 4, which achieved 100% mortality at 1000 mg/L. These findings could be useful in the research for newer more selective, biodegradable and natural larvicidal compounds or can be used as lead compounds for the development of larvicides.     

Seroepidemiological survey of sheep in Carinthia for the dissemination of ruminant pestiviruses

In this study serological investigations were performed to determine the prevalence of pestiviral infections in sheep in one Federal State of Austria, namely Carinthia. 1527 blood samples from sheep in 147 flocks were collected and tested by Enzyme-linked immunosorbent assay and virus-neutralisation tests for antibodies to ruminant pestiviruses. The estimated flock prevalence was 47.6%, the individual prevalence 16.3%. Significant geographical variations in the flock as well in the individual prevalence were found. The highest prevalence in sheep and in sheep flocks was established in the region Spittal/Drau with 25.9% and 69.7%.The individual and the flock prevalence was significantly higher on farms where cattle or sheep from other farms were present than on farms with no cattle (p < 0.017). All Enzyme-linked immunosorbent assay positive sera were tested for Bovine viral diarrhea virus-1 (strain NADL), Bovine viral diarrhea virus-2 (strain 125) and for Border disease virus (strain MOREDUN) by virus neutralisation tests. Seventy out of 249 positive samples revealed the highest titres (> or = two-fold) to Bovine viral diarrhea virus-1 and 25 to Border disease virus. The remaining positive samples did not show clear results because of cross reactions.