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As hyperparasitoids may have a considerable influence on the control of herbivorous arthropods, analyzing the host-mediated impact of Bacillus thuringiensis-plants (Bt-plants) on hyperparasitoids is of interest. Laboratory-scale experiments were conducted in order to assess the potential effect of Bt-corn leaf material on the facultative hyperparasitoid Tetrastichus howardi (Olliff) (Hymenoptera: Eulophidae), mediated through the herbivore Chilo partellus Swinhoe (Lepidoptera: Crambidae) and its primary parasitoid Cotesia flavipes (Cameron) (Hymenoptera: Braconidae). In the Bt-group, significantly less C. flavipes larvae per host spun cocoons and pupated than in the control, and the mean fresh weight of a single C. flavipes cocoon was significantly reduced compared to the control. All C. flavipes cocoons of one host formed cocoon clusters. T. howardi females of the Bt-group parasitized significantly less cocoon clusters than in the control. Moreover, significantly fewer C. flavipes cocoons per cocoon cluster were successfully parasitized as compared to the control. As a consequence, T. howardi females of the control had more offspring than in the Bt-group. Adult female T. howardi offspring of the Bt-group weighed significantly less than in the control, but there was no significant weight difference between males of both groups. Our results suggest that transgenic insect-resistant plants could affect hyperparasitoids indirectly. However, it remains to be determined whether facultative hyperparasitoids prefer to develop as primary or secondary parasitoids under field conditions. 相似文献
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Hari Bansha Dulal Gernot Brodnig Kalim U. Shah 《Mitigation and Adaptation Strategies for Global Change》2011,16(1):1-23
Agriculture is one of the major sources of greenhouse gas (GHG) emission. It accounts for approximately 15% of the total global
anthropogenic emissions of GHGs. Emissions could be twice as much if indirect emissions are also taken into the consideration.
However, unlike other high emitting sectors such as transport or energy, agriculture is potentially a significant carbon “sink”.
It has high technical potential as a carbon sink and if tapped, can substantially enhance global sequestration efforts. The
technical potential, however, may not translate into actual GHG reduction because of the capital assets and institutional
constraints faced by the smallholder farmers in the developing countries. In this paper we develop a capital assets based
framework of physical, financial, social, human and natural barriers to agricultural carbon mitigation initiatives and through
analysis of current initiatives, we set out policy based options to reduce each of these barriers. Fundamentally, barrier
removal will entail designing agricultural carbon mitigation initiatives in collaboration with farmer communities, through
strengthening local institutions, understanding land tenure and natural resource cultures, ensuring legitimacy and equity
in payments and fast tracking training and information. We provide a framework that simultaneously aids the dual objectives
of alleviating poverty in the poor farming communities of developing countries and lowering global greenhouse gas emissions. 相似文献
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