Sentinel prey can provide a direct, quantitative measure of predation under field conditions. Live sentinel prey provides more realistic data but rarely allows the partitioning of the total predation pressure; artific...Sentinel prey can provide a direct, quantitative measure of predation under field conditions. Live sentinel prey provides more realistic data but rarely allows the partitioning of the total predation pressure; artificial prey is less natural but traces left by different predators are identifiable, making it suitable for comparative studies. We reviewed the available evidence of the use of both types of invertebrate sentinel prey. Fifty- seven papers used real prey, usually measuring predation on a focal （often pest） species, with studies overwhelmingly from North America. The median predation was 25.8% d-1. Artificial sentinel prey （45 papers） were used in both temperate and tropical areas, placed more above ground than at ground level. The most commonly used artificial prey imitated a caterpillar. Up to 14 predator groups were identified, registering a median of 8.8% d J predation; half the studies reported only bird predation. Predation on real prey was higher than on artificial ones, but invertebrate predation was not higher than vertebrate predation. Invertertebrate but not vertebrate predation was negatively related to prey size. Predation near the Equator was not higher than at higher latitudes, nor in cultivated than noncultivated habitats. The use of sentinel prey is not yet standardised in terms of prey size, arrangement, exposure period or data reporting. Due to the simplicity and ease of use of the method, such standardisation may increase the usefulness of comparative studies, contributing to the understanding of the importance and level of predation in various habitats worldwide.展开更多
Humankind draws important benefits from large-scale ecological processes termed ecosystem services, yet the status of several of them is declining. Reliable monitoring methods are essential for tracking the status of ...Humankind draws important benefits from large-scale ecological processes termed ecosystem services, yet the status of several of them is declining. Reliable monitoring methods are essential for tracking the status of ecosystem services. Predation is the mainstay of natural pest control, a key ecosystem service. We used green plasticine caterpillars to monitor predation pressure, and to obtain baseline data on predator activity in transgenic Bt versus non-Bt maize fields in Old and New World countries. Predation pressure was measured at ground and canopy levels using an identical, small-plot experimental design in four European countries (Denmark, Slovakia, Romania and Italy) and Argentina. Total predation rate in maize was l l.7%d^-1 (min. 7.2%d^-1 in Argentina, max. 29.0%d^-1 in Romania). Artificial caterpillars were attacked both by invertebrates (mostly chewing insects with 42.0% of the attack marks, and ants with 7.1%, but also predatory and parasitoid wasps, spiders and slugs), and vertebrates (small mammals 25.5%, and birds 20.2%). Total predation at ground level (15.7%d^-1) was significantly higher than in maize canopies (6.0%d^-1) in all countries, except Argentina. We found no significant differences between predator pressure in Bt versus non-Bt maize plots. The artificial caterpillar method provided comparable, quantitative data on predation intensity, and proved to be suitable for monitoring natural pest control. This method usefully expands the existing toolkit by directly measuring ecological function rather than structure.展开更多
We evaluated whether protected European butterflies can potentially be at risk if transgenic maize is extensively grown in Central Europe.We explored potential consequences of both insect resistant(IR)and herbicide re...We evaluated whether protected European butterflies can potentially be at risk if transgenic maize is extensively grown in Central Europe.We explored potential consequences of both insect resistant(IR)and herbicide resistant(HR)transgenic maize.IR maize can produce pollen that is toxic to lepidopteran larvae,and this puts butterfly species at possible risk if the presence of young larvae coincides with maize flowering,during which large quantities of maize pollen can be deposited on vegetation.By considering the timing of maize flowering in Europe and the phenology of the protected Lepidoptera species,we found that 31 species had at least one generation where 50%of the larval stage overlapped with maize flowering,and 69 species for which first instar larvae were present during maize pollen shedding.HR maize allows high concentration herbicide treatments on fields without seasonal limitation,which can drastically reduce weed densities.In cases where such weed species are host plants for protected butterflies,reduced host plant/food availability can result,causing population decreases.By using published information,we first identified the important weed species in major maize-growing European countries.Subsequently,we checked whether the host plants of protected Lepidoptera included species that are common maize weeds.We identified 140 protected species having food plants that are common weeds in one or more of the major European maize-growing countries.If HR maize is grown in Europe,there is a potential hazard that their food plants will seriously decline,causing a subsequent decline of these protected species.展开更多
文摘Sentinel prey can provide a direct, quantitative measure of predation under field conditions. Live sentinel prey provides more realistic data but rarely allows the partitioning of the total predation pressure; artificial prey is less natural but traces left by different predators are identifiable, making it suitable for comparative studies. We reviewed the available evidence of the use of both types of invertebrate sentinel prey. Fifty- seven papers used real prey, usually measuring predation on a focal （often pest） species, with studies overwhelmingly from North America. The median predation was 25.8% d-1. Artificial sentinel prey （45 papers） were used in both temperate and tropical areas, placed more above ground than at ground level. The most commonly used artificial prey imitated a caterpillar. Up to 14 predator groups were identified, registering a median of 8.8% d J predation; half the studies reported only bird predation. Predation on real prey was higher than on artificial ones, but invertebrate predation was not higher than vertebrate predation. Invertertebrate but not vertebrate predation was negatively related to prey size. Predation near the Equator was not higher than at higher latitudes, nor in cultivated than noncultivated habitats. The use of sentinel prey is not yet standardised in terms of prey size, arrangement, exposure period or data reporting. Due to the simplicity and ease of use of the method, such standardisation may increase the usefulness of comparative studies, contributing to the understanding of the importance and level of predation in various habitats worldwide.
文摘Humankind draws important benefits from large-scale ecological processes termed ecosystem services, yet the status of several of them is declining. Reliable monitoring methods are essential for tracking the status of ecosystem services. Predation is the mainstay of natural pest control, a key ecosystem service. We used green plasticine caterpillars to monitor predation pressure, and to obtain baseline data on predator activity in transgenic Bt versus non-Bt maize fields in Old and New World countries. Predation pressure was measured at ground and canopy levels using an identical, small-plot experimental design in four European countries (Denmark, Slovakia, Romania and Italy) and Argentina. Total predation rate in maize was l l.7%d^-1 (min. 7.2%d^-1 in Argentina, max. 29.0%d^-1 in Romania). Artificial caterpillars were attacked both by invertebrates (mostly chewing insects with 42.0% of the attack marks, and ants with 7.1%, but also predatory and parasitoid wasps, spiders and slugs), and vertebrates (small mammals 25.5%, and birds 20.2%). Total predation at ground level (15.7%d^-1) was significantly higher than in maize canopies (6.0%d^-1) in all countries, except Argentina. We found no significant differences between predator pressure in Bt versus non-Bt maize plots. The artificial caterpillar method provided comparable, quantitative data on predation intensity, and proved to be suitable for monitoring natural pest control. This method usefully expands the existing toolkit by directly measuring ecological function rather than structure.
基金This is a scientific output of the AMIGA Project,supported by the EC(grant agreement no.289706).
文摘We evaluated whether protected European butterflies can potentially be at risk if transgenic maize is extensively grown in Central Europe.We explored potential consequences of both insect resistant(IR)and herbicide resistant(HR)transgenic maize.IR maize can produce pollen that is toxic to lepidopteran larvae,and this puts butterfly species at possible risk if the presence of young larvae coincides with maize flowering,during which large quantities of maize pollen can be deposited on vegetation.By considering the timing of maize flowering in Europe and the phenology of the protected Lepidoptera species,we found that 31 species had at least one generation where 50%of the larval stage overlapped with maize flowering,and 69 species for which first instar larvae were present during maize pollen shedding.HR maize allows high concentration herbicide treatments on fields without seasonal limitation,which can drastically reduce weed densities.In cases where such weed species are host plants for protected butterflies,reduced host plant/food availability can result,causing population decreases.By using published information,we first identified the important weed species in major maize-growing European countries.Subsequently,we checked whether the host plants of protected Lepidoptera included species that are common maize weeds.We identified 140 protected species having food plants that are common weeds in one or more of the major European maize-growing countries.If HR maize is grown in Europe,there is a potential hazard that their food plants will seriously decline,causing a subsequent decline of these protected species.
