Inaction levels for the red imported fire ant, Solenopsis invicta (hym.: formicidae): A predator of the boll weevil, Anthonomus grandis (col.: curculionidae)

The density of red imported fire ants, Solenopsis invicta Buren (Hymenoptera: Formicidae), necessary to limit boll weevil abundance, Anthonomus grandis Boheman (Coleoptera: Curculionidae), below the action level was determined. An inaction level of 0.4 fire ants per shake bucket sample (i.e., four ants per 10 plant terminals) will provide boll weevil control approximately 90% of the time. A dynamic inaction level is also provided. Total mortality of boll weevil developmental stages including eggs through teneral adults averaged 97.9%. Of 100 boll weevil eggs deposited in cotton squares (flower buds), an average of two adults survive of which about half are female. Thus, the net replacement rate per generation (R_o is 1.0 which, in this case, indicates a stable boll weevil population.     

Linearbeschleuniger und Tandem-van-de-Graaffs: Werkzeuge der Schwerionenforschung

The basic principles of dc-tandem and high-frequency linear accelerator are discussed by referring to the pioneering work of H. Kallmann and R. Wideröe. The 30 MV Supertandem in Daresbury, the Heidelberg combination of tandem and linac, and the universal linear accelerator Unilac of the GSI at Darmstadt serve as examples of modern heavy-ion accelerators.     

Lorenz Oken

Lorenz Oken, 1. Aug. 1779 Bohlsbach (Baden, Germany) — 11. Aug. 1851 Zurich (Switzerland). Philosopher and Zoologist. He studied at Freiburg i. Br. and Würzburg, was called from Göttingen to the university of Jena (1807–1819), München (1827–1832), Zurich (1833–1851). Oken came very early under the influence of Schelling and became the typical German Naturphilosoph. This did not prevent him from doing distinguished biological work. Oken was one of the best comparative anatomists of his days, his works on embryology are classics. He gave an interesting forecast of the modern cell doctrine. He founded a biological journal (Isis, 1816–1848) which for thirty years published articles of unquestioned value. He instituted the meetings of the “Gesellschaft Deutscher Naturforscher und Ärzte” (1821). By his “Naturgeschichte für alle Stände”, 13 vols. (1833–1845) he is one of the first to popularize natural science.     

Cercaricidal activity of some essential oils of plants from Brazil

Extended screening tests on the cercaricidal activity of various plants from northeast Brazil have shown that the extracts of the leaves and fruits ofPiper marginatum,Protium heptaphyllum, andCapsicum annuum show a remarkable effect on the cercaria ofSchistosoma mansoni. In the case of the oils ofPiper marginatum andCapsicum annuum, 90–96% of the cercaria ofSchistosoma mansoni were killed within 15 min. According to the NMR spectra, the active principles of the extracts seem to be water-soluble unsaturated compounds from the oils or their hydrolysis products. Natural substances provide an attractive alternative for preventive actions against schistosomiasis, as the perturbation of the ecological equilibrium of natural waters can be avoided in this manner.