Elevated CO2 concentrations and stomatal density: observations from 17 plant species growing in a CO2 spring in central Italy

Stomatal density (SD) and stomatal conductance ( g _s) can be affected by an increase of atmospheric CO₂ concentration. This study was conducted on 17 species growing in a naturally enriched CO₂ spring and belonging to three plant communities. Stomatal conductance, stomatal density and stomatal index (SI) of plants from the spring, which were assumed to have been exposed for generations to elevated [CO₂], and of plants of the same species collected in a nearby control site, were compared. Stomatal conductance was significantly lower in most of the species collected in the CO₂ spring and this indicated that CO₂ effects on g _s are not of a transitory nature but persist in the long term and through plant generations. Such a decrease was, however, not associated with changes in the anatomy of leaves: SD was unaffected in the majority of species (the decrease was only significant in three out of the 17 species examined), and also SI values did not vary between the two sites with the exception of two species that showed increased SI in plants grown in the CO₂-enriched area. These results did not support the hypothesis that long-term exposure to elevated [CO₂] may cause adaptive modification in stomatal number and in their distribution.     

THE FUNCTIONAL BASIS OF NATURAL SELECTION FOR VERTEBRAL TRAITS OF LARVAE IN THE STICKLEBACK GASTEROSTEUS ACULEATUS

Previous studies have demonstrated selective predation for vertebral traits of larvae in the stickleback Gasterosteus aculeatus. I tested the hypothesis that this selection results from a direct functional advantage to particular vertebral phenotypes by direct measurement of the burst swimming performance of larvae. Within a narrow window of lengths, burst speed did depend on vertebral phenotype. As in the previous predation experiments, performance was related more directly to the ratio of abdominal to caudal vertebrae (VR) than to the total number of vertebrae (VN), and the optimal VR decreased as larval length increased. Changes with length in the vertebral phenotype frequencies of wild larvae provided evidence of selection for VR and for VN in the wild. Larvae with particular VR increased in frequency in the wild at just those lengths when their relative performance was superior in the laboratory. The observed pattern of length-dependent selection for vertebral number provides an explanation for the widespread trends in vertebral number that occur among populations of related fishes.     

Schistosoma mansoni, NIH-Sm-PR-2 strain, in non-susceptible Biomphalaria glabrata: protection by Echinostoma paraensei

Sullivan J. T., Richards C. S., Lie K. J. and Heyneman D. 1981. Schistosoma mansoni, NIH-Sm-PR-2 strain, in non-susceptible Biomphalaria glabrata: Protection by Echinostoma paraensei. International journal for Parasitology11:481–484. Among seven inbred genetic stocks of Biomphalaria glabrata that are non-susceptible for the NIH-Sm-PR-2 strain of Schistosoma mansoni (PR-2), five stocks revert to nearly complete susceptibility when first infected with Echinostoma paraensei. These include both stocks in which PR-2 sporocysts are normally destroyed within 3–7 days, and stocks in which sporocysts often survive undeveloped for at least 3 weeks. Hence, these five stocks are resistant to but physiologically suitable for the development of PR-2. Of the two remaining stocks, one remains partly non-susceptible to PR-2, since less than 50 % of echinostome-infected snails revert to susceptibility, while the other stock remains completely non-susceptible to PR-2 following echinostome infection, due perhaps to a high level of residual resistance and/or unsuitability.     

Whole-lake experimentation as a tool to assess ecosystem health,response to stress and recovery: the Experimental Lakes Area experience

The rationale and methods for and value of whole-lake experimentation are described using the Experimental Lakes Area (ELA), northwestern Ontario, as the example. The ELA consists of 46 lakes (< 100 ha in surface area), their watersheds, and several streams protected for research purposes in near-pristine boreal forest on the Precambrian Shield near Kenora, Ontario. Over more than 20 y, whole-lake experimentation has provided unique information on the effects on lakes of nutrient additions, acidification, Cd addition, and biomanipulation. Experiments are planned to study the effects of PCB addition and flooding. Recovery, mitigation, and remediation have been explored in some experiments. As well, the fate of radioactive metals in a lake and the effects of acidification on a poor fen and an upland watershed are studied. Comparison between the experimental systems and unmanipulated reference systems has proven to be essential. These reference systems also have a role in defining (absolute) aquatic ecosystem health for small, pristine Precambrian Shield lakes. The ELA experimental data base is available, as well, for calibrating indices of relative aquatic ecosystem health, i.e., environmental degradation, using the dose-responses of lakes to eutrophication, acidification, Cd addition, and other stressors.     

Hidden talents of natural killers: NK cells in innate and adaptive immunity

Natural killer (NK) cells are innate immune lymphocytes capable of killing target cells and producing immunoregulatory cytokines. Herein, we discuss recent studies that indicate that NK cells span the conventional boundaries between innate and adaptive immunity. For example, it was recently discovered that NK cells have the capacity for memory‐like responses, a property that was previously thought to be limited to adaptive immunity. NK cells have also been identified in multiple tissues, and a subset of cells that specialize in the production of the T_H17 cytokine IL‐22, NK‐22s, was recently described in mucosal‐associated lymphoid tissue. Finally, we review work that shows that NK cells develop at sites that were traditionally thought to be occupied only by adaptive immune cells, including the thymus and lymph nodes.     

Chrysoperla carnea predation on Heliothis virescens larvae parasitized by Microplitis croceipes

Predation by third instar larvae of Chrysoperla (=Chrysopa) carnea (Stephens) (Chrysopidae) did not alter the ratio of unparasitized Heliothis virescens (F.) (Noctuidae) larvae to H. virescens larvae parasitized by Microplitis croceipes (Cresson) (Braconidae) when these second instar larvae were exposed together to the predator on cotton (Gossypium hirsutum L., Malvaceae) in field cages. This indicates that C. carnea larvae did not prefer either parasitized or unparasitized larvae.

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Prédation par Chrysopa carnea des chenilles d'Heliothis virescens parasitées par Microplitis croceipes

Résumé Les prédations de chenilles d'Heliothis virescens, parasitées ou saines, élevées sur coton (Gossypium hirsutum L.), de la variété Stoneville 213, ont été comparées, dans des cages de 10 m² chacune placées dans la nature. Des chenilles du second stade ont été placées sur des pieds de coton dans 10 cages, à raison de 160 chenilles préalablement exposées à M. croceipes pendant leur premier stade et 40 chenilles saines par cage. Des larves du troisième stade de Chrysopa carnea ont été ajoutées dans 6 cages, à raison de 500/cage, et 4 cages ont servi de témoins pour évaluer les autres causes de mortalité. L'expérience a été répétée 2 fois. Les chenilles d'H. virescens ont été retirées au bout d'un jour dans une expérience et au bout de 2 jours dans l'autre. C. carnea n'a fait aucun choix entre chenilles parasitées ou non; la fréquence moyenne de chenilles parasitées n'a pas présenté de différence significative entre les cages avec ou sans C. carnea. Qui qu'il en soit, C. carnea a réduit significativement la survie des chenilles d'H. virescens parasitées ou non.

     

合理用药生态控制茶小绿叶蝉主要措施与评价

合理用药生态控制茶小绿叶蝉主要措施与评价张觉晚,王沅江（湖南省茶叶研究所,长沙４１０１４５）ＰｒｉｎｃｉｐａｌＴｅｃｈｎｉｑｕｅｓｏｆＲａｔｉｏｎａｌＵｓｅｏｆＰｅｓｔｉｃｉｄｅｆｏｒＥｃｏｌｏｇｉｃａｌＣｏｎｔｒｏｌｏｖｅｒＴｅａＧｒｅｓｎＬｅａｆ...     

世界麦双尾蚜研究进展：防治方法和策略*

The Russian wheat aphid (RWA), Diuraphis noxia (Mordvilko), was a worldwide cereal pest. The control measures to this pest were reviewed, emphasizing on natural enemies and plant resistance. First, spring wheat with earlier planting dates had higher yield and could resist RWA infestation to a more extent, while winter wheat with later planting dates could escape infestation of Russian wheat aphid with very few exceptions. So, manipulation of wheat planting dates was suggested in worldwide scale for the aphid control. Second, the natural enemies were considered as the most important factor to reduced the pest status. Introduced and native natural enemies were evaluated for their potential as biological agents in South Africa, United States, and Australia. In South Africa, an introduced parasitoid and a predator were selected for releasing. In the United States, the project on exploring and releasing the natural enemies was unprecedented in biological control history. The endeavor in USA has been proved primarily successful today and will be afterward. The RWA control in Chile was considered most successful, partly because of their introduction of natural enemies before the aphid arrival. The native enemies together with other factors in central Asia and Europe apparently suppressed the aphids to a low level. The screen for resistant wheat was another important research project in fighting with RWA. In South Africa and USA, resistant wheat and barley were bred, and some of them had been put in commercial use for RWA control. The overwhelming mechanisms in resistant wheat varieties were antibiosis, tolerance or their combination. Though chemical insecticide spraying was proved as an effective method for aphid control, more and more research has switched from this method to non chemical control measures as required by IPM. Future research should put more emphasis on augmentation of the natural enemies, revealing the relationship between RWA and agricultural ecosystem and integration of all effective measures.