排序方式: 共有3条查询结果,搜索用时 0 毫秒
1
1.
Effects of exposure to a non-chemical (temperature) or chemical (organophosphate insecticide) stressor during larval development were compared in Culex quinquefasciatus mosquitoes. Stress was measured in two ways: using conventional life history traits (survival, development time and a measure of body size) and by calculating the degree of developmental instability from the departure from bilateral symmetry of wing characters (fluctuating asymmetry). Increasing insecticide dose, but not temperature, was observed to elevate wing fluctuating asymmetry in male but not female mosquitoes. Insecticide treatment reduced survival and was associated with a significant reduction in wing trait sizes in both females and males but did not significantly affect development time. Temperature was associated with a significant reduction in all life history traits in both sexes. Therefore wing fluctuating asymmetry in C. quinquefasciatus cannot be used as a general biomonitor of all stress, although it may have potential as a more specific monitor of chemical stress. It needs to be complimented with other measures such as life history and biochemical methods. The significant differences in response between sexes may impact on results of short-term larval exposures to insecticides. 相似文献
2.
Skarpe C Aarrestad PA Andreassen HP Dhillion SS Dimakatso T du Toit JT Duncan Halley J Hytteborn H Makhabu S Mari M Marokane W Masunga G Ditshoswane M Moe SR Mojaphoko R Mosugelo D Motsumi S Neo-Mahupeleng G Ramotadima M Rutina L Sechele L Sejoe TB Stokke S Swenson JE Taolo C Vandewalle M Wegge P 《Ambio》2004,33(6):276-282
Northern Botswana and adjacent areas, have the world's largest population of African elephant (Loxodonta africana). However, a 100 years ago elephants were rare following excessive hunting. Simultaneously, ungulate populations were severely reduced by decease. The ecological effects of the reduction in large herbivores must have been substantial, but are little known. Today, however, ecosystem changes following the increase in elephant numbers cause considerable concern in Botswana. This was the background for the "BONIC" project, investigating the interactions between the increasing elephant population and other ecosystem components and processes. Results confirm that the ecosystem is changing following the increase in elephant and ungulate populations, and, presumably, developing towards a situation resembling that before the reduction of large herbivores. We see no ecological reasons to artificially change elephant numbers. There are, however, economic and social reasons to control elephants, and their range in northern Botswana may have to be artificially restricted. 相似文献
3.
Christina Skarpe Per Arild Aarrestad Harry P. Andreassen Shivcharn S. Dhillion Thatayaone Dimakatso Johan T. du Toit Duncan J. Halley Hkan Hytteborn Shimane Makhabu Moses Mari Wilson Marokane Gaseitsiwe Masunga Ditshoswane Modise Stein R. Moe Rapelang Mojaphoko David Mosugelo Sekgowa Motsumi Gosiame Neo-Mahupeleng Mpho Ramotadima Lucas Rutina Lettie Sechele Thato B. Sejoe Sigbjrn Stokke Jon E. Swenson Cyril Taolo Mark Van 《Ambio-人类环境杂志》2004,33(6):254-260
博茨瓦纳北部及其毗邻地区分布着世界上最大的非洲象种群(Loxodonta africana),而在100年前,由于过度捕猎,大象的种群数量极为稀少. 相似文献
1