In order to develop biological control of aphids by a "push-pull"approach, intercropping using repellent emitting plants was developed in different crop and associated plant models. Garlic is one of the pote...In order to develop biological control of aphids by a "push-pull"approach, intercropping using repellent emitting plants was developed in different crop and associated plant models. Garlic is one of the potential plant that could be inserted in crops to decrease the pest occurrence in neighboring crop plots. In this study, field works were conducted in wheat fields in Langfang Experimental Station, Hebei Province in China from October 2009 to July 2010 during wheat developmental season. The effect of wheat intercropping with garlic but also the volatiles emission on the incidence of the English grain aphid, Sitobion avenae Fabricius (Homoptera: Aphididae) was assessed. Natural beneficial occurrence and global yields in two winter wheat varieties that were susceptible or resistant to cereal aphid were also determined comparing to control plots without the use of garlic plant intercrop nor semiochemical releaser in the fields. S. avenae was found to be lower in garlic oil blend treatment (GOB), diallyl disulfide treatment (DD) and wheat-garlic intercropping treatment (WGI) when compared to the control plots for both two varieties (P<0.01). Both intercropping and application of volatile chemicals emitted by garlic could improve the population densities of natural enemies of cereal aphid, including ladybeetles and mummified aphids. Ladybeetle population density in WGI, GOB and mummified aphids densities in WGI, DD were significantly higher than those in control fields for both two varieties (P<0.05). There were significant interactions between cultivars and treatments to the population densities of S. avenae. The 1 000-grain weight and yield of wheat were also increased compared to the control. Due to their potential alternatives as a biological control agent against cereal aphid, garlic intercropping and related emitted volatiles are expected to contribute to the further improvement of integrated pest management systems and to potentially reduce the amount of traditional synthetic pesticides applied in wheat fields.展开更多
These last few years the multicolored Asian ladybird, Harmonia axyridis (Pallas), previously introduced in Europe and North America as a biological control agent, has swiftly spread out on those territories and turns ...These last few years the multicolored Asian ladybird, Harmonia axyridis (Pallas), previously introduced in Europe and North America as a biological control agent, has swiftly spread out on those territories and turns out to be a pest in several ways. In order to improve understanding of several key points of the biology of this ladybird, a novel fast-GC method of quantification of harmonine, the main defense alkaloid of H. axyridis, has been designed and validated using the accuracy profile concept for concentrations ranging from 13 to 264 μg/individual. This method allows quantifying harmonine in a single insect with a maximal error risk of 20%. For ladybirds collected in spring, mean harmonine concentration observed was 106.6 μg/individual with a very high standard deviation of 80.2 μg/individual, which can easily be explained by the strong asymmetry of the results distribution. Males and females seem equally chemically protected as the harmonine concentration did not significantly differ between sexes. This method is currently used to improve our comprehension of several key points of H. axyridis biology including aggregation behavior and aposematism.展开更多
基金supported by grants from the Cooperation Project between Belgium and China (CUD\PIC Shandong, 2010DFA32810)
文摘In order to develop biological control of aphids by a "push-pull"approach, intercropping using repellent emitting plants was developed in different crop and associated plant models. Garlic is one of the potential plant that could be inserted in crops to decrease the pest occurrence in neighboring crop plots. In this study, field works were conducted in wheat fields in Langfang Experimental Station, Hebei Province in China from October 2009 to July 2010 during wheat developmental season. The effect of wheat intercropping with garlic but also the volatiles emission on the incidence of the English grain aphid, Sitobion avenae Fabricius (Homoptera: Aphididae) was assessed. Natural beneficial occurrence and global yields in two winter wheat varieties that were susceptible or resistant to cereal aphid were also determined comparing to control plots without the use of garlic plant intercrop nor semiochemical releaser in the fields. S. avenae was found to be lower in garlic oil blend treatment (GOB), diallyl disulfide treatment (DD) and wheat-garlic intercropping treatment (WGI) when compared to the control plots for both two varieties (P<0.01). Both intercropping and application of volatile chemicals emitted by garlic could improve the population densities of natural enemies of cereal aphid, including ladybeetles and mummified aphids. Ladybeetle population density in WGI, GOB and mummified aphids densities in WGI, DD were significantly higher than those in control fields for both two varieties (P<0.05). There were significant interactions between cultivars and treatments to the population densities of S. avenae. The 1 000-grain weight and yield of wheat were also increased compared to the control. Due to their potential alternatives as a biological control agent against cereal aphid, garlic intercropping and related emitted volatiles are expected to contribute to the further improvement of integrated pest management systems and to potentially reduce the amount of traditional synthetic pesticides applied in wheat fields.
基金financially supported by a PhD grant from the Fonds pour la formation a la Recherche dans l’Industrie et dans l’Agriculture(FRIA)(Belgium).
文摘These last few years the multicolored Asian ladybird, Harmonia axyridis (Pallas), previously introduced in Europe and North America as a biological control agent, has swiftly spread out on those territories and turns out to be a pest in several ways. In order to improve understanding of several key points of the biology of this ladybird, a novel fast-GC method of quantification of harmonine, the main defense alkaloid of H. axyridis, has been designed and validated using the accuracy profile concept for concentrations ranging from 13 to 264 μg/individual. This method allows quantifying harmonine in a single insect with a maximal error risk of 20%. For ladybirds collected in spring, mean harmonine concentration observed was 106.6 μg/individual with a very high standard deviation of 80.2 μg/individual, which can easily be explained by the strong asymmetry of the results distribution. Males and females seem equally chemically protected as the harmonine concentration did not significantly differ between sexes. This method is currently used to improve our comprehension of several key points of H. axyridis biology including aggregation behavior and aposematism.
