The Emerald ash borer （EAB, Agrilus planipennis Fairmaire） an exotic invasive insect pest has killed millions of ash trees （Fraxinus spp.） across North America and threatens billions more. We validated six A. plan...The Emerald ash borer （EAB, Agrilus planipennis Fairmaire） an exotic invasive insect pest has killed millions of ash trees （Fraxinus spp.） across North America and threatens billions more. We validated six A. planipennis reference genes （actin, ACT; beta tubulin, E-TUB; glyceraldehyde-3-phosphate dehydrogenase, GAPDH ; ribosomal protein, RPL7; translation elongation factor 1~, TEF-la; and ubiquitin, UBQ） using geNorm, Normfinder and BestKeeper for accurate determination of target messenger RNA levels in gene expression studies. The stability of the six reference genes was evaluated in different larval tissues, developmental stages and two treatments ofA. planipennis using quantitative real-time polymerase chain reaction. Although there was no consistent ranking observed among the reference genes across the samples, the overall analysis revealed TEF-la as the most stable reference gene. GAPDH and ACT showed least stability for all the samples studied. We conclude that TEF-I~ is the most appropriate reference gene for gene expression studies in A. planipennis. Results obtained can be applicable for transcript profiling in other invasive insect pests. Further, these validated reference genes could also serve as the basis for selection of candidate reference genes in any given insect system post-validation.展开更多
Recent advances of Piwi-interacting RNAs （piRNAs） have enabled a better understanding of their putative roles in the protection of gerrn cells against selfish genetic elements. The germ plasm proteins namely, PIWI a...Recent advances of Piwi-interacting RNAs （piRNAs） have enabled a better understanding of their putative roles in the protection of gerrn cells against selfish genetic elements. The germ plasm proteins namely, PIWI and VASA, are key players in regulation of piRNAs. However, the biogenesis of piRNAs remains poorly understood. We report the characterization and the transcript profiles of a PIWI and VASA gene in various tissues and developmental stages of the emerald ash borer （Agrilusplanipennis）, an exotic invasive insect pest that has attained a high impact status worldwide. The deduced amino acid sequences of both these genes （herein referred to ＂ApPIWI and ApVASA＂） revealed homology with similar proteins from other insect and non-insect taxa. Peak transcript levels for ApPIWI and ApVASA were observed in the ovaries （compared to the other tissues assayed） and in adults （compared to the other developmental stages assayed）. To our knowledge this is the first report of profiling piRNA pathway genes in A. planipennis. These results provide new insights into the putative function of the PIWI and VASA proteins in insects.展开更多
Pest preference and subsequent susceptibility of a host individual is likely related to previous growth patterns in that host.Emerald ash borer(Agrilus planipennis Fairmaire)is a pestiferous beetle introduced to North...Pest preference and subsequent susceptibility of a host individual is likely related to previous growth patterns in that host.Emerald ash borer(Agrilus planipennis Fairmaire)is a pestiferous beetle introduced to North America from Asia.While all species of ash are susceptible to attack,some individual trees appear to survive infestation.We selected ash trees in southeastern Michigan,collected cores and categorized trees as high tolerance to emerald ash borer attack(high overall health,low crown dieback),low tolerance(low overall health,high crown dieback)and intermediate tolerance(in-between the other categories).We artificially wounded trees and measured wound closure after 3 years.Ring width indices were not correlated between high and low tolerance trees.Regression slopes comparing growth and years were significantly different between the three tolerance categories,with high tolerance trees having the steepest slope.Wound closure was greatest in high tolerance trees.High tolerance trees demonstrating more rapid(steeper regression slope),consistent(lower variance),and effective(greater wound closure)growth.Those vigorously growing trees likely had more capacity to repair damage caused by emerald ash borer,leading to healthier trees in our categorization.Linking previous host growth patterns to health may have implications related to identifying individual trees potentially tolerant to attack.展开更多
Many natural enemies employ plant- and/or herbivore-derived signals for host/prey location. The larval parasitoid Tetrastichus planipennisi Yang （Hymenoptera： Eulophidae） is 1 of 3 biocontrol agents currently being...Many natural enemies employ plant- and/or herbivore-derived signals for host/prey location. The larval parasitoid Tetrastichus planipennisi Yang （Hymenoptera： Eulophidae） is 1 of 3 biocontrol agents currently being released in an effort to control the emerald ash borer （EAB）, Agrilus planipennis Fairmaire （Coloeptera： Burprestidae） in North America. To enhance its efficiency, allelochemicals that attract it need to be assessed. In this study, ash phloem volatile organic compounds （VOCs） of black, green, and white ash, and EAB larval frass were compared. Foraging behavior of T. planipennisi females in response to VOCs of white ash or frass from EAB larvae feeding on white ash phloem was tested using a Y-tube olfactometer. Results indicated that the 3 ash species had similar VOC profiles. EAB larval frass generally contained greater levels of VOCs than phloem. Factor analysis indicated that the 11 VOCs could be broadly divided into 2 groups, with c^-bisabolol, fl-caryophyllene, （E）-2-hexenal, （Z）-3-hexenal, limonene, methyl benzoate, methyl indole-3-acetic acid, methyl jasmonate, methyl salicylate as the first group and the rest （i.e., methyl linoleate and methyl linolenate） as a second. Abundance of VOCs in white ash phloem tissue and frass, nevertheless, did not attract T. planipennisi females. The concealed feeding of EAB larvae might explain the selection for detectable and reliable virbrational signals, instead of undetectable and relatively unreliable VOC cues from phloem and frass, in short-range foraging by T. planipennisi. Alternatively, it is possible that T. planipennisi is not amenable to the Y-tube olfactometer assay employed.展开更多
文摘The Emerald ash borer （EAB, Agrilus planipennis Fairmaire） an exotic invasive insect pest has killed millions of ash trees （Fraxinus spp.） across North America and threatens billions more. We validated six A. planipennis reference genes （actin, ACT; beta tubulin, E-TUB; glyceraldehyde-3-phosphate dehydrogenase, GAPDH ; ribosomal protein, RPL7; translation elongation factor 1~, TEF-la; and ubiquitin, UBQ） using geNorm, Normfinder and BestKeeper for accurate determination of target messenger RNA levels in gene expression studies. The stability of the six reference genes was evaluated in different larval tissues, developmental stages and two treatments ofA. planipennis using quantitative real-time polymerase chain reaction. Although there was no consistent ranking observed among the reference genes across the samples, the overall analysis revealed TEF-la as the most stable reference gene. GAPDH and ACT showed least stability for all the samples studied. We conclude that TEF-I~ is the most appropriate reference gene for gene expression studies in A. planipennis. Results obtained can be applicable for transcript profiling in other invasive insect pests. Further, these validated reference genes could also serve as the basis for selection of candidate reference genes in any given insect system post-validation.
文摘Recent advances of Piwi-interacting RNAs （piRNAs） have enabled a better understanding of their putative roles in the protection of gerrn cells against selfish genetic elements. The germ plasm proteins namely, PIWI and VASA, are key players in regulation of piRNAs. However, the biogenesis of piRNAs remains poorly understood. We report the characterization and the transcript profiles of a PIWI and VASA gene in various tissues and developmental stages of the emerald ash borer （Agrilusplanipennis）, an exotic invasive insect pest that has attained a high impact status worldwide. The deduced amino acid sequences of both these genes （herein referred to ＂ApPIWI and ApVASA＂） revealed homology with similar proteins from other insect and non-insect taxa. Peak transcript levels for ApPIWI and ApVASA were observed in the ovaries （compared to the other tissues assayed） and in adults （compared to the other developmental stages assayed）. To our knowledge this is the first report of profiling piRNA pathway genes in A. planipennis. These results provide new insights into the putative function of the PIWI and VASA proteins in insects.
基金supported in part by the Purdue University Fort Wayne Honors Programthe John Z.Duling Grant Program from the Tree Research and Education Fund
文摘Pest preference and subsequent susceptibility of a host individual is likely related to previous growth patterns in that host.Emerald ash borer(Agrilus planipennis Fairmaire)is a pestiferous beetle introduced to North America from Asia.While all species of ash are susceptible to attack,some individual trees appear to survive infestation.We selected ash trees in southeastern Michigan,collected cores and categorized trees as high tolerance to emerald ash borer attack(high overall health,low crown dieback),low tolerance(low overall health,high crown dieback)and intermediate tolerance(in-between the other categories).We artificially wounded trees and measured wound closure after 3 years.Ring width indices were not correlated between high and low tolerance trees.Regression slopes comparing growth and years were significantly different between the three tolerance categories,with high tolerance trees having the steepest slope.Wound closure was greatest in high tolerance trees.High tolerance trees demonstrating more rapid(steeper regression slope),consistent(lower variance),and effective(greater wound closure)growth.Those vigorously growing trees likely had more capacity to repair damage caused by emerald ash borer,leading to healthier trees in our categorization.Linking previous host growth patterns to health may have implications related to identifying individual trees potentially tolerant to attack.
文摘Many natural enemies employ plant- and/or herbivore-derived signals for host/prey location. The larval parasitoid Tetrastichus planipennisi Yang （Hymenoptera： Eulophidae） is 1 of 3 biocontrol agents currently being released in an effort to control the emerald ash borer （EAB）, Agrilus planipennis Fairmaire （Coloeptera： Burprestidae） in North America. To enhance its efficiency, allelochemicals that attract it need to be assessed. In this study, ash phloem volatile organic compounds （VOCs） of black, green, and white ash, and EAB larval frass were compared. Foraging behavior of T. planipennisi females in response to VOCs of white ash or frass from EAB larvae feeding on white ash phloem was tested using a Y-tube olfactometer. Results indicated that the 3 ash species had similar VOC profiles. EAB larval frass generally contained greater levels of VOCs than phloem. Factor analysis indicated that the 11 VOCs could be broadly divided into 2 groups, with c^-bisabolol, fl-caryophyllene, （E）-2-hexenal, （Z）-3-hexenal, limonene, methyl benzoate, methyl indole-3-acetic acid, methyl jasmonate, methyl salicylate as the first group and the rest （i.e., methyl linoleate and methyl linolenate） as a second. Abundance of VOCs in white ash phloem tissue and frass, nevertheless, did not attract T. planipennisi females. The concealed feeding of EAB larvae might explain the selection for detectable and reliable virbrational signals, instead of undetectable and relatively unreliable VOC cues from phloem and frass, in short-range foraging by T. planipennisi. Alternatively, it is possible that T. planipennisi is not amenable to the Y-tube olfactometer assay employed.
