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991.
Platycampus larvae are highly cryptic leaf feeders characterised by a dorso-ventrally flattened body, the dorsal integument resembling
a shield. Dorsal and ventral cuticles from Platycampus luridiventris were compared by histology and gel electrophoresis. By Azan-staining, a red and a blue layer were distinguished in the dorsal
cuticle, while the ventral cuticle showed one, almost uniform blue layer, as in both cuticles of control species. The two
cuticles from P. luridiventris had similar amounts and sodium dodecyl sulphate-polyacrylamide gel electrophoresis profiles of soluble proteins, but not
insoluble proteins. One insoluble protein (MW ≈ 41 kDa) was visible as a large band in the ventral cuticle only. It is likely
that this protein renders the cuticle elastic, and that the dorsal, red layer is the exocuticle, mainly composed of insoluble
proteins. We discuss eco-physiological implications of the exocuticle in insects. Further, data from the literature indicate
that the defence strategy in P. luridiventris larvae relies on being visually cryptic towards avian predators and tactically cryptic towards arthropod predators and parasitoids.
Crypsis in both senses is favoured by the shield effect, itself based on an abnormally thick dorsal exocuticle. Although the
larvae are external feeders, they may be considered as hidden from an ecological perspective. 相似文献
992.
Luis Lassaletta Héctor García-Gómez Benjamín S. Gimeno José V. Rovira 《Environmental Science & Policy》2010,13(5):423-433
The European Union Water Framework Directive (WFD) aims to achieve the “good status” of waters by 2015, through monitoring and control of human impacts on “bodies of surface water” (BSWs), discrete elements for quality diagnosis and management. Headwater streams, however, are frequently neglected as they are not usually recognised as BSW. This poses limitations for the management of river catchments, because anthropogenic impacts on headwaters can constrain the quality of downstream rivers. To illustrate this problem, we compared nitrate levels and land use pressures in a small agricultural catchment with those recorded in the catchment in which it is embedded (Ega), and in the Ebro River Basin (NE Spain) comprising both. Agriculture greatly influenced water nitrate concentration, regardless of the size of the catchments: R2 = 0.91 for headwater catchments (0.1–7.3 km2), and R2 = 0.82 for Ebro tributary catchments (223–3113 km2). Moreover, nitrate concentration in the outlet of a non-BSW small river catchment was similar to that of the greater downstream BSW rivers. These results are of interest since, despite representing 76% of the length of the Ega catchment hydrographical network, only 3.1% of the length of the headwater streams has been identified as BSWs. Human activities affecting headwater streams should therefore be considered if the 2015 objective of the WFD is to be achieved. 相似文献
993.
994.
Laura Rodríguez-Loeches Alejandro Barro Martha Pérez Frank Coro 《Die Naturwissenschaften》2009,96(4):531-536
Both sexes of Phoenicoprocta capistrata have functional tymbals. The scanning electron microscopy revealed differences in the morphology of these organs in males
and females. Male tymbals have a well-developed striated band, constituted by 21 ± 2 regularly arranged striae whereas female
tymbals lack a striated band. This type of sexual dimorphism is rare in Arctiidae. The recording of the sound produced by
moths held by the wings revealed that while males produced trains of pulses organized in modulation cycles, females produced
clicks at low repetition rate following very irregular patterns. Statistically, there are differences between sexes in terms
of the duration of pulses, which were 355 ± 24 μs in the case of males and 289 ± 29 μs for females. The spectral characteristics
of the pulses also show sexual dimorphism. Male pulses are more tuned (Q
10 = 5.2 ± 0.5) than female pulses (Q
10 = 2.7 ± 0.5) and have a higher best frequency (42 ± 1 kHz vs. 29 ± 2 kHz). To our knowledge, this is the first report on
an arctiid moth showing sexual dimorphism in tymbal’s anatomy that leads to a best frequency dimorphism. Males produce sound
at mating attempts. The sounds recorded during mating are modulation cycles with the same spectral characteristics as those
recorded when males are held by the wings. The morphological and acoustic features of female tymbals could indicate a process
of degeneration and adaptation to conditions under which the emission of complex patterns is not necessary.
Frank Coro no longer works at Universidad de La Habana. 相似文献
995.
Johannes Kroiss Erhard Strohm Cédric Vandenbem Jean-Pol Vigneron 《Die Naturwissenschaften》2009,96(8):983-986
Chrysidid wasps in the subfamily Chrysidinae are brood parasitoids or cleptoparasites of other insects and famous for their
cuticular iridescence. In this study, we examine the dorsal abdominal cuticle of the chrysidid wasp Hedychrum rutilans to identify the underlying color mechanism. Using scanning electron microscopy, reflectance spectral analysis, and theoretical
calculations, we demonstrate the presence of an epicuticular multilayer reflector consisting of six lamellae with a thickness
of 185 nm each. The lamellae exhibit a rough surface probably functioning as spacers between the individual layers. The reflector
has a measured reflectance maximum at λ = 630 nm, i.e., in the red part of the visible spectrum of light at normal incidence and the reflectance maximum shifts to
green as the angle of incidence increases. Complementary theoretical modeling corroborates the view that the epicuticular
multilayer generates the iridescent color of the chrysidid cuticle.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
996.
997.
Miguel Vences Mariana L. Lyra Jordan G. Kueneman Molly C. Bletz Holly M. Archer Julia Canitz Svenja Handreck Roger-Daniel Randrianiaina Ulrich Struck Sabin Bhuju Michael Jarek Robert Geffers Valerie J. McKenzie Christoph C. Tebbe Célio F. B. Haddad Julian Glos 《Die Naturwissenschaften》2016,103(3-4):25
998.
999.
Anna Elofsson Nora Smedby Jörgen Larsson Jonas Nässén 《Journal of Environmental Policy & Planning》2018,20(5):578-594
Global greenhouse gas emissions from air travel (GHG-A) are on the rise, and projections point towards a rapid growth in the coming decades. This study aims to examine how local government (cities), addresses GHG-A in their Sustainable Energy Action Plans (SEAP). To fulfil this aim, over 200 SEAPs were analysed focusing on three issues: (1) Treatment of GHG-A in local emissions inventories; (2) Policy initiatives within this domain; and (3) The cities’ perceptions of the conflicts of interests. Results showed that more than half of the cities acknowledge the challenge of GHG-A, around one third include GHG-A in their emissions inventories, and more than one quarter have initiated policy interventions. To categorise these interventions, we have added a mode ‘governing by agenda setting’ to an existing analytical framework, ‘Modes of governing’. With their authority limited to the local setting, this mode of governing is a common channel for cities to push changes at higher levels. 相似文献
1000.
Faith E. Bartz Domonique Watson Hodge Norma Heredia Anna Fabiszewski de Aceituno Luisa Solís Lee-Ann Jaykus Santos Garcia Juan S. Leon 《Food and environmental virology》2016,8(3):221-226
Somatic coliphages were quantified in 459 produce and environmental samples from 11 farms in Northern Mexico to compare amounts of somatic coliphages among different types of fresh produce and environmental samples across the production steps on farms. Rinsates from cantaloupe melons, jalapeño peppers, tomatoes, and the hands of workers, soil, and water were collected during 2011–2012 at four successive steps on each farm, from the field before harvest through the packing facility, and assayed by FastPhage MPN Quanti-tray method. Cantaloupe farm samples contained more coliphages than jalapeño or tomato (p range <0.01–0.03). Across production steps, jalapeños had higher coliphage percentages before harvest than during packing (p = 0.03), while tomatoes had higher coliphage concentrations at packing than all preceding production steps (p range <0.01–0.02). These findings support the use of targeted produce-specific interventions at multiple points in the process of growing and packing produce to reduce the risk of enteric virus contamination and improve food safety during fruit and vegetable production. 相似文献