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Andrei Alyokhin - One of the best experts on this subject based on the ideXlab platform.
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Population Variability and Persistence of Three Aphid Pests of Potatoes Over 60 Years
Canadian Entomologist, 2020Co-Authors: Robert J. Lamb, P.a. Mackay, Andrei AlyokhinAbstract:Abstract Abundance, persistence, and variability of populations of Macrosiphum euphorbiae (Thomas), Myzus persicae (Sulzer), and Aphis nasturtii Kaltenbach (Hemiptera: Aphididae) in potato plots for intervals of 58 years (n = 1), 29 years (n = 2), 19–20 years (n = 3), and 9–10 years (n = 6) were compared. The abundance of M. euphorbiae showed no trend among decades and varied 2.4-fold, whereas that of M. persicae and A. nasturtii declined and showed 54-fold and 3700-fold variation, respectively. All three aphid species persisted through the first five decades and M. euphorbiae also persisted through the sixth (last) decade, but M. persicae and A. nasturtii failed to persist for 1 and 3 years of the last decade, respectively. Population variability (a proportion between 0 and 1) measured over a 58-year interval was high: 0.585 for M. euphorbiae, 0.771 for M. persicae, and 0.830 for A. nasturtii. During the first three but not the last three decades, population variability increased with sampling interval, ...
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Estimating population variability of aphids (Hemiptera: Aphididae): how many years are required?
Canadian Entomologist, 2016Co-Authors: Robert J. Lamb, Patricia A. Mackay, Andrei AlyokhinAbstract:AbstractVariability is an important characteristic of population dynamics, but the length of the time series required to estimate population variability is poorly understood. To this end, population variability of Macrosiphum euphorbiae (Thomas), Myzus persicae (Sulzer), and Aphis nasturtii (Kaltenbach) (Hemiptera: Aphididae) was investigated. Population variability (measured as PV, a proportion between 0 and 1) was estimated for time series of 3–62 years, giving replicate estimates for time series of 3–20 years that were normally distributed. Mean values for PV were more uniform for a time series of 12 years or longer than for shorter ones. The standard deviation of PV declined to a minimum at 12–15 years, as the length of the time series increased. Discrimination of estimates of PV was reliable for 15-year time series and longer, but not necessarily for shorter ones. Although M. euphorbiae had a relatively low PV, the coefficient of variation of that PV (12.5), was higher than for the other two species (3.5, 4.5). For robust estimates of PV, a time series of 15 years is recommended, because it minimises the standard deviation of PV, and discriminates values of PV that differ by 0.06 on a 0–1 scale.
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Seasonal dynamics of three coexisting aphid species: implications for estimating population variability
The Canadian Entomologist, 2013Co-Authors: Robert J. Lamb, Patricia A. Mackay, Andrei AlyokhinAbstract:AbstractSeasonal patterns of abundance and population variability were determined for Macrosiphum euphorbiae (Thomas), Myzus persicae (Sulzer), and Aphis nasturtii (Kaltenbach) (Hemiptera: Aphididae) in potato plots from weekly samples for 28 years. All species showed a single annual peak, but arrived and reached peak abundance at different times. Population variability (PV, a proportion between 0 and 1) for the week of peak abundance was close to that of other sample weeks and mean seasonal abundance. Based on mid-season abundance, PV of 0.76 for M. persicae differed significantly from 0.80 for A. nasturtii, as well as from 0.59 for M. euphorbiae. A weekly time scale for abundance, initiated at an early stage of plant growth, produced slightly different estimates of PV early and late in the season than a scale centred on peak abundance for each species. PV at the time of invasion differed from estimates for the rest of the summer. The annual abundance used to estimate PV was best determined in the context of aphid life history. Nevertheless, PV provided a robust and precise metric for comparing population variability among the three species, regardless of their seasonal patterns of abundance.
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Differential Effects of Weather and Natural Enemies on Coexisting Aphid Populations
Environmental Entomology, 2011Co-Authors: Andrei Alyokhin, Gary H. Sewell, Francis A. Drummond, Richard H. StorchAbstract:Study of mechanisms responsible for regulating populations of living organisms is essential for a better comprehension of the structure of biological communities and evolutionary forces in nature. Aphids (Hemiptera: Sternorrhyncha) comprise a large and economically important group of phytophagous insects distributed worldwide. Previous studies determined that density-dependent mechanisms play an important role in regulating their populations. However, only a few of those studies identified specific factors responsible for the observed regulation. Time series data used in this study originated from the untreated control plots that were a part of potato (Solanum tuberosum L.) insecticide trials in northern Maine from 1971 to 2004. The data set contained information on population densities of three potato-colonizing aphid species (buckthorn aphid, Aphis nasturtii; potato aphid, Macrosiphum euphorbiae; and green peach aphid, Myzus persicae) and their natural enemies. We used path analysis to explore effects of weather and natural enemies on the intrinsic growth rates of aphid populations. Weather factors considered in our analyses contributed to the regulation of aphid populations, either directly or through natural enemies. However, direct weather effects were in most cases detectable only at P ≤ 0.10. Potato aphids were negatively affected by both fungal disease and predators, although buckthorn aphids were negatively affected by predators only. Parasitoids did not have a noticeable effect on the growth of any of the three aphid species. Growth of green peach aphid populations was negatively influenced by interspecific interactions with the other two aphid species. Differential population regulation mechanisms detected in the current study might at least partially explain coexistence of three ecologically similar aphid species sharing the same host plant.
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Density-dependent regulation in populations of potato-colonizing aphids
Population Ecology, 2005Co-Authors: Andrei Alyokhin, Francis A. Drummond, Gary SewellAbstract:Scarcity of long-term (over 30 years) data series represents a major challenge for an accurate estimation of the role of density-dependent processes in population regulation. We analyzed population densities of the wingless parthenogenic morphs of buckthorn aphid (BA), Aphis nasturtii Kaltenbach, potato aphid (PA), Macrosiphum euphorbiae (Thomas), and green peach aphid (GPA), Myzus persicae (Sulzer) from 1949 to 2003 for signs of density-dependent regulation. We found strong evidence of density-dependent regulation, with detection of density dependence being fairly consistent among the different statistical techniques. Direct density dependence was detected for the populations of all three species. There was also evidence of delayed density dependence for PA. The periodicity of population fluctuations for BA and GPA was 6.1 years and 3.9 years, respectively. The periodicity for PA was not explicit, being highly variable throughout the time series. Effects of density-independent weather factors were relatively minor compared to density-dependent regulation. The BA populations experienced a significant reduction in both density and annual oscillations starting in 1995, while GPA populations experienced a similar reduction in 1991. No such change was apparent for PA. The most likely explanation for the observed phenomenon is a change in the composition of the lady beetle community following the establishment of two alien coccinellid species, and/or changes in insecticide use by commercial growers in the area of the study.
Gilles Boiteau - One of the best experts on this subject based on the ideXlab platform.
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Cytochrome c oxidase mRNA as an internal control for detection of Potato virus Y and Potato leafroll virus from single aphids by a co-amplification RT-PCR assay.
Journal of virological methods, 2006Co-Authors: Changzheng He, Teresa A Molen, Xingyao Xiong, Gilles BoiteauAbstract:Using cytochrome c oxidase subunit 1 (COX1) mRNA as the internal control, a triplex reverse transcription-polymerase chain reaction (RT-PCR) for detection of Potato virus Y (PVY) and Potato leafroll virus (PLRV) with co-amplification of COX1 from single specimens of various aphid species has been developed. Partial length cDNA of COX1 from green peach aphid, Myzus persicae (Sulzer), potato aphid, Macrosiphum euphorbiae (Thomas), buckthorn aphid, Aphis nasturtii (Kaltenbach), and pea aphid, Acyrthosiphom pisum (Harris), was cloned and sequenced. These sequences, together with existing COX1 sequences from other aphid species capable or suspected to be capable of transmitting PVY and/or PLRV, were analyzed. The sequence identity between any two aphid species ranged from 97 to 100% at the putative protein level, and 89 to 94% at the nucleic acid level. Two highly conserved COX1 nucleotide sequence stretches were selected to design universal primers Aph F and Aph R. This primer pair, together with two existing universal primer pairs (C1-J-2183 and C1-N-2329; Favret F and Favret R), were evaluated at the optimal annealing temperature using RNA from M. persicase, M. euphorbiae, and A. nasturtii. The Aph primer pair performed well in the monoplex RT-PCR but poorly in the triplex RT-PCR in the presence of the PVY- and PLRV-specific primers. On the other hand, the Favret and C1 primer pairs performed well in both monoplex and triplex RT-PCR formats using single aphids of M. persicase, M. euphorbiae and A. nasturtii, demonstrating their suitability to indicate the successfulness of RT-PCR assays for PVY and PLRV. Using the Favret, PVY and PLRV primer sets, single aphids of M. persicase, M. euphorbiae and A. nasturtii that had been exposed to PLRV-infected and/or PVY-infected potato plants were assessed for their acquisition of the viruses by the triplex RT-PCR assay. Although majority (175/180) of the aphid samples produced the COX1 fragment, five aphid samples failed to produce either the COX1- or the virus-specific band, indicating failed RT-PCR in these samples. This method offers a sensitive tool for detection of viruliferous aphids combined to an effective quality control measure.
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Comparative propensity for dispersal of apterous and alate morphs of three potato-colonizing aphid species
Canadian Journal of Zoology, 1997Co-Authors: Gilles BoiteauAbstract:The relative ability of apterous and alate morphs of aphids to disperse from one potato leaflet to another was similar within species. Three species were tested: the buckthorn aphid, Aphis nasturtii Kaltenbach, the potato aphid, Macrosiphum euphorbiae (Thomas), and the green peach aphid, Myzus persicae (Sulzer). The average percentage of aphids moving daily from one leaflet to another never exceeded 2.5% for nymphs of the three species, but reached 45% for the adult winged buckthorn aphid. During the first half of the reproductive period, adult potato aphids were 1.5 times as likely as buckthorn aphids and twice as likely as green peach aphids to relocate daily. In a flight chamber, buckthorn aphids flew 4.5 times longer than green peach or potato aphids. The maiden flights of these summer forms were interrupted by repeated landings lasting less than 2 min. The maiden flights were interrupted more than twice as often for the buckthorn aphid as for the potato aphid. The number of flight interruptions was i...
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Residual Activity of lmidacloprid Controlling Colorado Potato Beetle (Coleoptera: Chrysomelidae) and Three Species of Potato Colonizing Aphids (Homoptera: Aphidae)
Journal of Economic Entomology, 1997Co-Authors: Gilles Boiteau, W.p.l. Osborn, M. E. DrewAbstract:Field tests done between 1992 and 1994 indicated that imidacloprid applied at 0.03 g (AI)/m to the soil can control overwintered adult Colorado potato beetles, Leptinotarsa decemlineata (Say), and their larval progeny. Summer generation adults colonizing potatoes in treated fields can be controlled by foliar applications of imidacloprid at 50 g (AI)/ha at intervals of 7 d or more. Soil applications of imidacloprid at 0.03 g (AI)/m also provided effective control of the potato aphid, Mocrosiphum euphorbiae (Thomas); green peach aphid, Myzus persicae Sulzer; and buckthorn aphid, Aphis nasturtii Kaltenbach, for at least 62-65 d after plant emergence. Foliar applications of imidacloprid at a rate of 50 g (AI)/ha required that the aphids be exposed for at least 5 d to attain 50-75% control. Imidacloprid applied in the furrow at a rate of 0.03 g (AI)/m reduced significantly the number of nymphs produced per aphid for each of the 3 species tested early in the season, but not for aphids exposed to plants > 1 mo old. Imidacloprid applied to the soil at a rate of 0.03 g (AI)/m has a long residual activity against Colorado potato beetle adults and larvae, the potato aphid, the green peach aphid, and the buckthorn aphid. This pattern makes imidacloprid an effective control agent for insect pest management on potatoes, but its comparatively slow mode of action may limit its ability to reduce the spread of virus diseases unless the ability of treated aphid vectors to disperse and probe is also reduced.
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Detection of stylet-borne and circulative potato viruses in aphids by duplex reverse transcription polymerase chain reaction.
Journal of Virological Methods, 1996Co-Authors: Rudra P. Singh, J. Kurz, Gilles BoiteauAbstract:Abstract A reverse transcription polymerase chain reaction (RT-PCR) assay was designed to amplify stylet-borne potato virus Yo (PVYo) in aphids using primers located in the viral capsid gene. A 480 bp long product was detected in aphids exposed to PVYo-infected potato plants. Approximately 40% of Myzus persicae and 15% of Aphis nasturtii exposed briefly to PVYo-infected plants acquired the virus. This rate of acquisition by both species of aphids was typical of our earlier observation of the virus transmission tests. No significant difference in virus detection was observed whether the aphids were tested immediately after exposure to virus sources or stored for up to 45 days in ethanol at room temperature. The addition of a second pair of primers located in the capsid gene of circulative potato leafroll virus (PLRV) allowed simultaneous amplification of two viruses (duplex RT-PCR) in single aphids. Acquisition of PVYo by the aphids already viruliferous with PLRV was significantly reduced, compared to aphids not carrying PLRV. Duplex RT-PCR for PVYo and PLRV could be applied to analyze aphids collected from the field to ascertain the relative presence of both viruses in a single test.
Sławomir Wróbel - One of the best experts on this subject based on the ideXlab platform.
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Assessment of Possibilities of Microtuber and in vitro Plantlet Seed Multiplication in Field Conditions. Part 1: PVY, PVM and PLRV Spreading
American Journal of Potato Research, 2014Co-Authors: Sławomir WróbelAbstract:Actualmente, las plántulas in vitro y los microtubérculos suministran el sustento para la producción de semillas pre-básicas de papa, de las cuales se producen los minitubérculos bajo cubierta, que después sirven como material de siembra para ser plantado en el campo. El propósito de esta investigación fue determinar la posibilidad para multiplicación de material producido in vitro directamente bajo condiciones de campo. La investigación analizó la infección por PVY, PVM, y PLRV en tubérculos derivados de plantas que crecieron directamente de plántulas in vitro, microtubérculos, minitubérculos y semilla-tubérculo tradicional de papas sembradas en el campo en diferentes tiempos. Además, en pruebas de laboratorio se determinó la susceptibilidad de estas plantas a la infección viral mediante inoculación artificial de Myzus persicae y Aphis nasturtii . Se encontró que la infección de tubérculos derivados de plántulas in vitro y microtubérculos era mayor que la del tubérculo-semilla y minitubérculos. Sin embargo, parece ser que la razón para su mayor nivel de infección fue el resultado, no de la susceptibilidad de la planta o por su mayor atractivo a los áfidos, sino por otra causa mayor desconocida. La siembra temprana de microtubérculos y las plántulas in vitro en el campo, en el caso de la variedad más resistente y seguramente más tarde en relación con la fecha principal de siembra, tuvieron impacto en la limitación de la infección de tubérculos por PVY y PVM. De aquí que la multiplicación de microtubérculos y de plántulas in vitro, bajo condiciones de campo, pudiera ser muy económica usando variedades relativamente resistentes a los virus. No obstante, la adopción de una fecha de siembra más tarde de lo normal (a fines de junio) y aplicando una cubierta adicional de protección (como una malla agrícola) en el primer período de crecimiento de la planta, estimula la multiplicación de microtubérculos y de plántulas in vitro en condiciones de campo en variedades con bajos niveles de resistencia. Currently in vitro plantlets and microtubers provide the basis for pre-base production of potato seeds, from which minitubers are produced under covers – they serve later as seed material to be planted in the field. The aim of the research was to determine the possibility for multiplication of material produced in vitro directly in field conditions. The research assessed PVY, PVM and PLRV infection of potato tubers derived from plants grown directly from in vitro plantlets, microtubers, minitubers and traditional seed potatoes planted in the field at different times. Moreover, testing in laboratory conditions, the susceptibility of these plants to virus infection was determined for the case of artificial inoculation of Myzus persicae and Aphis nasturtii . It was found that the infection of tubers derived from in vitro plantlets and microtubers was greater than that of seed potatoes and minitubers. Yet it seems that the reason for their higher infection level resulted not from the plant’s sensitivity or its greater attractiveness to aphids but from a largely unknown cause. Earlier planting of microtubers and in vitro plantlets in the field in case of the more resistant cultivar and certainly later in relation to the main time of planting had an impact on limiting the PVY and PVM infection of potato tubers. Hence multiplication of microtubers and in vitro plantlets in field conditions could be very economical using cultivars which are relatively resistant to viruses. However, adopting a later than usual planting period (end of June) and applying an additional protective cover (such as non-woven agricultural fabric) in the first period of a plant’s growth, promotes multiplication of microtubers and in vitro plantlets in field conditions for cultivars with low resistance levels.
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Assessment of Possibilities of Microtuber and in vitro Plantlet Seed Multiplication in Field Conditions. Part 1: PVY, PVM and PLRV Spreading
American Journal of Potato Research, 2014Co-Authors: Sławomir WróbelAbstract:Currently in vitro plantlets and microtubers provide the basis for pre-base production of potato seeds, from which minitubers are produced under covers – they serve later as seed material to be planted in the field. The aim of the research was to determine the possibility for multiplication of material produced in vitro directly in field conditions. The research assessed PVY, PVM and PLRV infection of potato tubers derived from plants grown directly from in vitro plantlets, microtubers, minitubers and traditional seed potatoes planted in the field at different times. Moreover, testing in laboratory conditions, the susceptibility of these plants to virus infection was determined for the case of artificial inoculation of Myzus persicae and Aphis nasturtii. It was found that the infection of tubers derived from in vitro plantlets and microtubers was greater than that of seed potatoes and minitubers. Yet it seems that the reason for their higher infection level resulted not from the plant’s sensitivity or its greater attractiveness to aphids but from a largely unknown cause. Earlier planting of microtubers and in vitro plantlets in the field in case of the more resistant cultivar and certainly later in relation to the main time of planting had an impact on limiting the PVY and PVM infection of potato tubers. Hence multiplication of microtubers and in vitro plantlets in field conditions could be very economical using cultivars which are relatively resistant to viruses. However, adopting a later than usual planting period (end of June) and applying an additional protective cover (such as non-woven agricultural fabric) in the first period of a plant’s growth, promotes multiplication of microtubers and in vitro plantlets in field conditions for cultivars with low resistance levels.
Robert J. Lamb - One of the best experts on this subject based on the ideXlab platform.
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Population Variability and Persistence of Three Aphid Pests of Potatoes Over 60 Years
Canadian Entomologist, 2020Co-Authors: Robert J. Lamb, P.a. Mackay, Andrei AlyokhinAbstract:Abstract Abundance, persistence, and variability of populations of Macrosiphum euphorbiae (Thomas), Myzus persicae (Sulzer), and Aphis nasturtii Kaltenbach (Hemiptera: Aphididae) in potato plots for intervals of 58 years (n = 1), 29 years (n = 2), 19–20 years (n = 3), and 9–10 years (n = 6) were compared. The abundance of M. euphorbiae showed no trend among decades and varied 2.4-fold, whereas that of M. persicae and A. nasturtii declined and showed 54-fold and 3700-fold variation, respectively. All three aphid species persisted through the first five decades and M. euphorbiae also persisted through the sixth (last) decade, but M. persicae and A. nasturtii failed to persist for 1 and 3 years of the last decade, respectively. Population variability (a proportion between 0 and 1) measured over a 58-year interval was high: 0.585 for M. euphorbiae, 0.771 for M. persicae, and 0.830 for A. nasturtii. During the first three but not the last three decades, population variability increased with sampling interval, ...
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Estimating population variability of aphids (Hemiptera: Aphididae): how many years are required?
Canadian Entomologist, 2016Co-Authors: Robert J. Lamb, Patricia A. Mackay, Andrei AlyokhinAbstract:AbstractVariability is an important characteristic of population dynamics, but the length of the time series required to estimate population variability is poorly understood. To this end, population variability of Macrosiphum euphorbiae (Thomas), Myzus persicae (Sulzer), and Aphis nasturtii (Kaltenbach) (Hemiptera: Aphididae) was investigated. Population variability (measured as PV, a proportion between 0 and 1) was estimated for time series of 3–62 years, giving replicate estimates for time series of 3–20 years that were normally distributed. Mean values for PV were more uniform for a time series of 12 years or longer than for shorter ones. The standard deviation of PV declined to a minimum at 12–15 years, as the length of the time series increased. Discrimination of estimates of PV was reliable for 15-year time series and longer, but not necessarily for shorter ones. Although M. euphorbiae had a relatively low PV, the coefficient of variation of that PV (12.5), was higher than for the other two species (3.5, 4.5). For robust estimates of PV, a time series of 15 years is recommended, because it minimises the standard deviation of PV, and discriminates values of PV that differ by 0.06 on a 0–1 scale.
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Seasonal dynamics of three coexisting aphid species: implications for estimating population variability
The Canadian Entomologist, 2013Co-Authors: Robert J. Lamb, Patricia A. Mackay, Andrei AlyokhinAbstract:AbstractSeasonal patterns of abundance and population variability were determined for Macrosiphum euphorbiae (Thomas), Myzus persicae (Sulzer), and Aphis nasturtii (Kaltenbach) (Hemiptera: Aphididae) in potato plots from weekly samples for 28 years. All species showed a single annual peak, but arrived and reached peak abundance at different times. Population variability (PV, a proportion between 0 and 1) for the week of peak abundance was close to that of other sample weeks and mean seasonal abundance. Based on mid-season abundance, PV of 0.76 for M. persicae differed significantly from 0.80 for A. nasturtii, as well as from 0.59 for M. euphorbiae. A weekly time scale for abundance, initiated at an early stage of plant growth, produced slightly different estimates of PV early and late in the season than a scale centred on peak abundance for each species. PV at the time of invasion differed from estimates for the rest of the summer. The annual abundance used to estimate PV was best determined in the context of aphid life history. Nevertheless, PV provided a robust and precise metric for comparing population variability among the three species, regardless of their seasonal patterns of abundance.
Rudra P. Singh - One of the best experts on this subject based on the ideXlab platform.
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Potato leafroll virus detection by RT-PCR in field-collected aphids
American Potato Journal, 1997Co-Authors: Rudra P. Singh, J. Kurz, G. Boiteau, Lynn M. MooreAbstract:A reverse transcription polymerase chain reaction (RT-PCR) assay was applied to analyze green peach aphids ( Myzus persicae Sulzer) collected from yellow-pan traps between 1988 and 1994, from New Brunswick commercial potato fields, for potato leafroll virus (PLRV). The RT-PCR technique was also used to assess the PLRV content of Myzus persicae Sulzer, Aphis nasturtii Kaltenbach, and Macrosiphum euphorbiae Thomas caught in yellow-pan traps from selected fields in 1995. RT-PCR bands specific for PLRV were detected in all three species, indicating that they all can acquire the virus. The usefulness of the RT-PCR procedure in determining the PLRV content of aphid catches and thus assisting in disease management recommendations is discussed.
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Detection of stylet-borne and circulative potato viruses in aphids by duplex reverse transcription polymerase chain reaction.
Journal of Virological Methods, 1996Co-Authors: Rudra P. Singh, J. Kurz, Gilles BoiteauAbstract:Abstract A reverse transcription polymerase chain reaction (RT-PCR) assay was designed to amplify stylet-borne potato virus Yo (PVYo) in aphids using primers located in the viral capsid gene. A 480 bp long product was detected in aphids exposed to PVYo-infected potato plants. Approximately 40% of Myzus persicae and 15% of Aphis nasturtii exposed briefly to PVYo-infected plants acquired the virus. This rate of acquisition by both species of aphids was typical of our earlier observation of the virus transmission tests. No significant difference in virus detection was observed whether the aphids were tested immediately after exposure to virus sources or stored for up to 45 days in ethanol at room temperature. The addition of a second pair of primers located in the capsid gene of circulative potato leafroll virus (PLRV) allowed simultaneous amplification of two viruses (duplex RT-PCR) in single aphids. Acquisition of PVYo by the aphids already viruliferous with PLRV was significantly reduced, compared to aphids not carrying PLRV. Duplex RT-PCR for PVYo and PLRV could be applied to analyze aphids collected from the field to ascertain the relative presence of both viruses in a single test.