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Thomas Merckx Ruth E. Feber Philip Riordan Martin C. Townsend Nigel A.D. Bourn Mark S. Parsons David W. Macdonald 《Agriculture, ecosystems & environment》2009,130(3-4):177-182
How best to optimize the biodiversity gain from agri-environment schemes (AES) has recently been identified as a key policy-relevant question. Here, the effects of two features of lowland agricultural landscapes on the abundance and diversity of larger moths are contrasted. Although both features bring about positive effects, hedgerow trees have a larger impact than 6 m wide grassy field margins. Whilst AES payments are given to create and maintain grass margins, no financial reward is currently offered for the retention of hedgerow trees. Furthermore, it was only in areas where the amount of land under AES was experimentally increased, by targeting farmers, that the presence of hedgerow trees resulted in a substantially higher abundance (+60%) and diversity (+38%) of moths. Thus, by using larger moths as bio-indicators of landscape-scale quality, it is demonstrated that improvements to the cost-effectiveness of AES could be achieved, firstly, by providing more appropriate financial rewards to farmers for different landscape features, and secondly, through landscape-scale targeting of farmers to encourage participation in AES. 相似文献
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Madeleine Beekman Stephen J. Martin Falko Drijfhout Benjamin P. Oldroyd 《Behavioral ecology and sociobiology》2007,61(12):1847-1853
Anarchy, where honeybee workers produce males in the presence of a queen, is extremely rare in natural honeybee populations,
suggesting that there are colony-level costs associated with being anarchistic. Yet, no significant costs have yet been identified.
A possible reason for this may be that researchers have only focused on the behaviour of anarchistic workers, which have been
shown to perform worker-tasks as do wild-type workers. Possibly, therefore, costs associated with anarchy should be sought
in anarchistic queens and not workers. A potential cost could be a lower survival rate of eggs laid by anarchistic queens
perhaps because their egg-marking signal is not as clear as that of a wild-type queen. In this paper, we determined the removal
rate of eggs laid by anarchistic queens in standard worker-policing bioassays. Our results show that eggs laid by anarchistic
queens are removed at a higher rate than eggs laid by wild-type queens. This does not seem to be due to differences in hydrocarbons
found on the surface of eggs, as both egg types showed the same alkanes and alkenes in similar proportions. We postulate that
higher removal rates of queen-laid eggs due to recognition errors may be one reason that anarchy is rare in natural honeybee
populations. 相似文献
120.
Louis Hautier Jean-Claude Grégoire Jérôme de Schauwers Gilles San Martin Pierre Callier Jean-Pierre Jansen Jean-Christophe de Biseau 《Chemoecology》2008,18(3):191-196
Summary. Under laboratory conditions, the multicolored Asian lady beetle, Harmonia axyridis is well known as an intraguild predator of other ladybirds. However the real impact of this exotic species on native species
was poorly investigated in the field. Because many ladybird species produce alkaloids as defensive compounds, we propose here
a new method of intraguild predation monitoring in coccinellids based on alkaloid quantification by GC-MS. In laboratory experiments,
adaline was unambiguously detected in fourth instar larvae of H. axyridis having ingested one egg or one first instar larva of Adalia bipunctata. Although prey alkaloids in the predator decreased with time, traces were still detected in pupae, exuviae and imagines of
H. axyridis having ingested one prey when they were fourth instar larvae. Analysis of H. axyridis larvae collected in two potato fields shows for the first time in Europe the presence of exogenous alkaloids in 9 out of
28 individuals tested. This new method of intraguild predation detection could be used more widely to follow the interactions
between predators and potential chemically defended insect preys. 相似文献