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Azadirachtin, a triterpenoid substance from the neem tree, Azadirachta indica A. Juss., Meliaceae, was evaluated for its antifeedant and insecticidal properties to the European corn borer Ostrinia nubilalis Hübner. The 50% protective concentration for larval feeding on treated corn disks (PC50) was 3.5 ppm for neonate larvae and 24 ppm for third instar larvae. Azadirachtin severely reduced larval growth at 1 and 10 ppm in a meridic diet and eventually caused 100% mortality at 10 ppm and 90% at 1 ppm. At 0.1 ppm azadirachtin showed no significant effect on larvae but altered the sex ratio in favor of male moths during adult emergence and arrested oviposition of female moths. Nutritional indices for naive and habituated third instar larvae suggested that reduction of growth was due to toxicity as shown by a lowered efficiency of conversion in the azadirachtin treated groups, rather than changes in digestibility. No clear evidence of tolerance was observed in the habituated group. The data suggest that at 10 ppm azadirachtin is an effective botanical insecticide for control of O. nubilalis. RÉSUMÉ Propriétés anti‐appètantes et insecticides de l'azadirachtine envers la pyrale du maïs, Ostrinia nubilalis On a examiné les propriétés anti‐appétantes et insecticides de l'azadirachtine, une substance triterpénoïde provenant d'Azadirachta indica envers la pyrale du maïs Ostrinia nubilalis. La concentration effective pour causer 50% d'inhibition de l'alimentation larvaire (PC50) sur des disques foliaires a été de 3.5 ppm pour les larves de premier stade et de 24 μg/8 pour celle de troisième stade. L'azadirachtine a sévèrement réduit la croissance larvaire à des concentrations de 1 et 10 ppm dans une diète méridique et, éventuellement, a causé 100% de mortalité à 10 ppm et 90% à 1 ppm. A 0.1 ppm l'azadirachtine n'a pas eu d'effet significatif sur les larves maïs a modifié l'indice de masculinité en faveur des mâles au moment de l'émergence et a empêché l'oviposition chez les femelles. Les indices nutritionnels pour les larves naïves de troisième âge et celles ayant subi une accoutumance suggèrent que la réduction de croissance est le résultat d'une intoxication comme le démontre une efficacité réduite de transformation chez les groupes traités à l'azadirachtine, plutôt que des changements de digestibilité. Il n'y a pas d'évidence claire de tolérance dans le groupe ayant subi l'accoutumance. Les résultats suggèrent qu'à 10 ppm l'azadirachtine est un insecticide botanique efficace envers O. nubilalis.

Located on the northwest coast of Heard Island, a World Heritage-listed sub-Antarctic territory of Australia, Atlas Cove served as the site of the first permanently occupied Australian National Antarctic Research Expedition (ANARE) station (1947–55). Subsequent to its closure, Atlas Cove Station was abandoned and left largely to the mercy of the natural elements, although it has been visited and occupied on an infrequent basis by ANARE. All activities on the island are now subject to the provisions of the Heard Island Wilderness Reserve Management Plan. During 2000–2001 a major clean-up of the site was undertaken, with most of the remaining structures demolished and material collected for return to Australia and disposal. To assess the extent and intensity of contamination within the station area, soil and water samples were collected and analysed for petroleum hydrocarbons and heavy metals. Assessment of site contamination was made with reference to specific background control limits calculated for Atlas Cove Station, and comparison was also made with Australian and New Zealand guidelines for the protection of aquatic and terrestrial ecosystems. Contamination by heavy metals is evident throughout the station but not at levels of sufficient magnitude to infer a significant potential toxic impact on local ecosystems. Hence remedial action to reduce the concentration and mobility of heavy metals in soil and water is not a high priority, although monitoring of changes at the site through time is recommended. Contamination by petroleum hydrocarbons is at a level that may cause a significant toxic impact on the environment and requires further investigation to assess impacts and possibly to undertake remedial action. Given the large quantity of petroleum-contaminated soil present, remediation processes that can be carried out in situ are likely to be the preferable clean-up options. The benefits of remediation, however, must be balanced against any negative effect this might exert on the plant and animal wildlife that have recolonised this historically important site.

SUMMARY1. Isolated Lymnaea stagnalis heart ventricle cells contain cation-conducting channels with properties characteristic of Ca2+ channels. These channels, which carry inward Na+ currents in the absence of Ca2+, are activated by the molluscan cardioactive peptides FMRFamide and FLRFamide, and are blocked by Co2+ ions.2. FMRFamide also activated inward Ba2+ currents at the cell's resting potential. These currents, which were also blocked by Co2+ ions, reversed at a membrane potential of + 70 mV.3. Both sodium and barium currents were initiated when the peptides were applied to the cell outside of the patch pipette indicating that a secondary messenger is likely to be involved in the FMRFamide response.

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