Measurements were taken of Bt protein expressed in the leaves of transgenic cotton (Gos- sypium hirsutum) transformed with a synthesized Bt (Bacillus thuringiensis) cry1A gene and its persistent level in larval bodies...Measurements were taken of Bt protein expressed in the leaves of transgenic cotton (Gos- sypium hirsutum) transformed with a synthesized Bt (Bacillus thuringiensis) cry1A gene and its persistent level in larval bodies and faeces of a non-targeted insect pest, beet armyworm (Spodoptera exigua). We performed enzyme linked immunosorbent assays (ELISA) and bioassays using neonate larvae of cot- ton bollworm (Helicoverpa armigera) to detect the insecticidal activity of residual Bt protein at the sec- ond trophic level. The results showed that Bt protein content in functional leaves was different at various developmental stages and was different among plants at the same stage. Even though Bt protein concentration in the larval bodies and faeces de- creased 97.5%―99% compared to that found in cotton leaves subsequently fed to beet armyworm larvae, it still had a lethal effect on neonate cotton bollworm larvae. Therefore, Bt protein present at the second trophic level had insecticidal activity. This result is important in understanding and predicting the effect of transgenic plants on nontarget organisms.展开更多
In the present study, the herbicidal effects of two fungicides with the active ingredients expoxiconazole, fluxapyroxad, pyraclostrobin and fenpropimorph on the two arable weeds Lamium purpureum L. and Chenopodium alb...In the present study, the herbicidal effects of two fungicides with the active ingredients expoxiconazole, fluxapyroxad, pyraclostrobin and fenpropimorph on the two arable weeds Lamium purpureum L. and Chenopodium album L. were investigated. The experiments were conducted in a climate chamber under defined conditions. Sowing pods were prepared and plants at the cotyledon leaf stage were pricked out in test pods. Fungicides were applied at six application rates: 0%, 12.5%, 25%, 50%, 100% and 200% of the maximum registered dose rate in Germany. Seven days after application, the first assessment was conducted, regarding growth stage, quantity of plants and visible plant damage. Fourteen days after application, the second and final assessment was conducted, regarding growth stage, quantity of plants, visible plant damage and the fresh weight of the plants. There were herbicidal effects of the fungicides, which were presumably due to the active ingredient epoxiconazole. Epoxiconazole has effects on enzymes that are dependent on cytochrome P-450 and inhibits sterol biosynthesis and probably gibberellin synthesis. By doing so, these fungicides have similar effects to plant growth regulators. Weed species showed differential sensitivities, contractions and growth inhibition and ED50-values were calculated. Notwithstanding the probably minor relevance of the present results in agricultural practice, some effects on arable weeds might result if fungicides are applied at an early growth stage in the field. In some cases, the crop-weed competition could be shifted to the benefit of the crop. Nevertheless, the results are interesting for the field of weed research and for the assessment of the ecotoxicology of fungicides.展开更多
Despite their positive effect in reducing pest populations, exotic generalist predators sometimes become invasive and contribute to the displacement of indigenous species in the same trophic level. Although laboratory...Despite their positive effect in reducing pest populations, exotic generalist predators sometimes become invasive and contribute to the displacement of indigenous species in the same trophic level. Although laboratory experiments have linked intraguild predation （IGP） to these interactions, field evidence and quantification of IGP are still lacking for most systems. The recent establishment of the exotic Harmonia axyridis （Pallas） （Coleoptera： Coccinellidae） in Italy raises concern about the detrimental effect that the ladybird could have on native coccinellids. Here we assessed, under laboratory conditions, the acceptability and suitability of eggs of 2 native ladybirds, Adalia bipunctata L. and Oenopia conglobata （L.）, as prey items for H. axyridis larvae. Then we developed primers for molecular gut-content analysis to detect predation by H. axyridis on the 2 ladybirds and on the aphid Eucallipterus tiliae L. Species-specific 16S primers were developed for the 3 species and laboratory feeding trials were conducted to quantify the rate of prey DNA breakdown in the gut of//. axyridis. Moreover, to field evaluate primers, H. axyridis 4th instars （n = 132） were systematically collected from linden trees in northern Italy and screened for the presence of prey DNA. Seventy-three percent and 7% of field collected H. axyridis were positive for aphid and coccinellid DNA, respectively. Predation upon aphid and A. bipunctata was lower than predicted if density dependent consumption was expected, while predation upon O. conglobata was significantly higher. Here, we provided the first evidence of IGP among feral populations ofH. axyridis and indigenous ladybird beetles, occurring in Italy.展开更多
基金supported by part of a 973 Project(Grant No.2001CB109004)National Natural Science Foundation of China(Grant No.30270228)a grant of the President Foundation of CAS,China,to Wei Wei.
文摘Measurements were taken of Bt protein expressed in the leaves of transgenic cotton (Gos- sypium hirsutum) transformed with a synthesized Bt (Bacillus thuringiensis) cry1A gene and its persistent level in larval bodies and faeces of a non-targeted insect pest, beet armyworm (Spodoptera exigua). We performed enzyme linked immunosorbent assays (ELISA) and bioassays using neonate larvae of cot- ton bollworm (Helicoverpa armigera) to detect the insecticidal activity of residual Bt protein at the sec- ond trophic level. The results showed that Bt protein content in functional leaves was different at various developmental stages and was different among plants at the same stage. Even though Bt protein concentration in the larval bodies and faeces de- creased 97.5%―99% compared to that found in cotton leaves subsequently fed to beet armyworm larvae, it still had a lethal effect on neonate cotton bollworm larvae. Therefore, Bt protein present at the second trophic level had insecticidal activity. This result is important in understanding and predicting the effect of transgenic plants on nontarget organisms.
文摘In the present study, the herbicidal effects of two fungicides with the active ingredients expoxiconazole, fluxapyroxad, pyraclostrobin and fenpropimorph on the two arable weeds Lamium purpureum L. and Chenopodium album L. were investigated. The experiments were conducted in a climate chamber under defined conditions. Sowing pods were prepared and plants at the cotyledon leaf stage were pricked out in test pods. Fungicides were applied at six application rates: 0%, 12.5%, 25%, 50%, 100% and 200% of the maximum registered dose rate in Germany. Seven days after application, the first assessment was conducted, regarding growth stage, quantity of plants and visible plant damage. Fourteen days after application, the second and final assessment was conducted, regarding growth stage, quantity of plants, visible plant damage and the fresh weight of the plants. There were herbicidal effects of the fungicides, which were presumably due to the active ingredient epoxiconazole. Epoxiconazole has effects on enzymes that are dependent on cytochrome P-450 and inhibits sterol biosynthesis and probably gibberellin synthesis. By doing so, these fungicides have similar effects to plant growth regulators. Weed species showed differential sensitivities, contractions and growth inhibition and ED50-values were calculated. Notwithstanding the probably minor relevance of the present results in agricultural practice, some effects on arable weeds might result if fungicides are applied at an early growth stage in the field. In some cases, the crop-weed competition could be shifted to the benefit of the crop. Nevertheless, the results are interesting for the field of weed research and for the assessment of the ecotoxicology of fungicides.
文摘Despite their positive effect in reducing pest populations, exotic generalist predators sometimes become invasive and contribute to the displacement of indigenous species in the same trophic level. Although laboratory experiments have linked intraguild predation （IGP） to these interactions, field evidence and quantification of IGP are still lacking for most systems. The recent establishment of the exotic Harmonia axyridis （Pallas） （Coleoptera： Coccinellidae） in Italy raises concern about the detrimental effect that the ladybird could have on native coccinellids. Here we assessed, under laboratory conditions, the acceptability and suitability of eggs of 2 native ladybirds, Adalia bipunctata L. and Oenopia conglobata （L.）, as prey items for H. axyridis larvae. Then we developed primers for molecular gut-content analysis to detect predation by H. axyridis on the 2 ladybirds and on the aphid Eucallipterus tiliae L. Species-specific 16S primers were developed for the 3 species and laboratory feeding trials were conducted to quantify the rate of prey DNA breakdown in the gut of//. axyridis. Moreover, to field evaluate primers, H. axyridis 4th instars （n = 132） were systematically collected from linden trees in northern Italy and screened for the presence of prey DNA. Seventy-three percent and 7% of field collected H. axyridis were positive for aphid and coccinellid DNA, respectively. Predation upon aphid and A. bipunctata was lower than predicted if density dependent consumption was expected, while predation upon O. conglobata was significantly higher. Here, we provided the first evidence of IGP among feral populations ofH. axyridis and indigenous ladybird beetles, occurring in Italy.
