خيارات البحث
النتائج 1 - 5 من 5
Short- and medium-term effects of experimental nitrogen fertilization on arthropods associated with Calluna vulgaris heathlands in north-west Spain
2008
Cuesta, D. | Taboada, A. | Calvo, L. | Salgado, J.M.
We studied the short- and medium-term effects of experimental nitrogen fertilization (3 and 15 months after the treatment) on the arthropods of Calluna vulgaris heathlands in NW Spain. Three heathland sites were selected with two permanent plots per site: control and fertilized. Ammonium nitrate fertilizer (56 kg N ha-1 yr-1) was applied monthly and insects were caught using pitfall traps. We found mainly species-level responses to nitrogen addition. Seven species (e.g. Lochmaea suturalis) showed a consistent trend (benefited or harmed) in both periods and were proposed as possible reliable indicators of the effects of nitrogen deposition in these ecosystems. We also found variable arthropod trophic-group responses: (a) herbivores (leaf beetles, true bugs) increased in abundance on a short-term scale; (b) predators (carabid beetles, true bugs) showed opposite and less clear responses in both periods. Further long-term studies are needed to determine the mechanisms underlying the observed arthropod responses. We observed consistent species-level and variable trophic-group responses to nitrogen addition in one of the southern-most locations for Calluna vulgaris heathlands within Europe.
اظهر المزيد [+] اقل [-]Short-term effects of dimethoate on metabolic responses in Chrysolina pardalina (Chrysomelidae) feeding on Berkheya coddii (Asteraceae), a hyper-accumulator of nickel
2007
Augustyniak, M. | Migula, P. | Mesjasz-Przybylowicz, J. | Tarnawska, M. | Nakonieczny, M. | Babczynska, A. | Przybylowicz, W. | Augustyniak, M.G.
Berkheya coddii Roessler (Asteraceae) is a hyper-accumulator of nickel, which can be used in phytomining and phytoremediation. Chrysolina pardalina Fabricius (Chrysomelidae) is a phytophagous leaf beetle, which may be useful in controlling population levels of B. coddii after it has been introduced into a new habitat. The aim of this study was to investigate the response of C. pardalina to topical application of dimethoate. Data recorded included the activity of acetylcholinesterase (AChE), the concentration of glutathione (GSH), and the activity of selected enzymes connected with GSH metabolism. Assays were carried out several times during the first 24 h after exposure to dimethoate. At the dosages used in this study, dimethoate was not as toxic as expected. AChE activity was significantly decreased 14 and 24 h after application. GST activity was significantly decreased 24 h after application. GSTPx activity was significantly decreased 2, 14 and 24 h after application. GR activity was significantly increased 4 h after application. GSH concentration was significantly increased 24 h after application. Long-term exposure to high levels of nickel may have caused adaptive changes in the enzymes that enable C. pardalina to deal with other stressors, including organophosphate pesticides. Long-term exposure to high levels of nickel may have caused adaptive changes in the enzymes that enable Chrysolina pardalina to deal with other stressors, including organophosphate pesticides.
اظهر المزيد [+] اقل [-]The effects of simulated acid rain on growth and susceptibility to predation of Phratora polaris (Col., Chrysomelidae)
1995
Palokangas, P. | Neuvonen, S. | Haapala, S. (Kevo Subarctic Research Institute, University of Turku, A777 Kevo, FIN-99800 Ivalo (Finland))
Trirhabda geminata (Coleoptera: Chrysomelidae) resistance to the direct impact of simulated acidic fog on larval growth and mortality
1995
Redak, R.A. | Paine, T.D. | Trumble, J.T. (Department of Entomology, University of California, Riverside, California 92521 (USA))
Interactions between the Encelia leaf beetle and its host plant, Encelia farinosa: the influence of acidic fog on insect growth and plant chemistry
1997
Redak, R.A. | Trumble, J.T. | Paine, T.D. (Department of Entomology, University of California, Riverside, CA 92521 (USA))