Resistance level to an aphid potato pest varies between genotypes from the same Solanum accession

Plant resistance to aphids can be improved by introgressing resistant traits from wild Solanum species into the potato germplasm. Breeding parents are commonly selected from the different accessions of each species. Accessions originate from several seeds collected in a restricted area and are conserved as seeds in genebanks. Genetic heterogeneity may be expected between genotypes from the same accession and could influence resistance level. Working with the potato aphid, Macrosiphum euphorbiae (Thomas), and the accession PI243340 of Solanum chomatophilum (Bitter), which has been previously rated as resistant to M. euphorbiae, we genetically identified and assessed the resistance level of genotypes within the accession. A combination of two multilplex polymerase chain reactions (PCRs) discriminated the 13 plant genotypes assessed. Survival of M. euphorbiae, measured using clip cages, varied significantly between five genotypes, randomly selected among the 13 previously assessed, but did not differ between same-genotype plants. Survival among genotypes ranged from 0 to > 60% 12 d after adult molt, and the least resistant genotype exhibited survival close to the susceptible standard, Solanum tuberosum L. Our results support the use of PCR multiplex methods to assess genetic heterogeneity in wild Solanum, and suggest that within accession genetic heterogeneity is sufficient to influence resistance level to aphids. Fine screening at the genotype level is preferable when assessing resistance to aphids.     

Co‐occurrence of defensive traits in the potato aphid Macrosiphum euphorbiae

1. Insecticide usage selects strongly for resistance in aphid populations, but this could entail fitness costs in other resistance traits. The potato aphid Macrosiphum euphorbiae Thomas exhibits intraspecific variation in susceptibility to parasitism by braconid wasps and provides a suitable species to study the relation between the defensive traits of parasitism and insecticide resistance. 2. Clonal lines (23 in total) of M. euphorbiae were established from aphids collected in 2013 from geographically separate populations in the U.K. Clonal lines belonged to five aphid genotypes, but one genotype predominated (78% of samples), and the facultative endosymbiont Hamiltonella defensa was detected in c. 40% of lines. 3. Total esterase activity in aphid tissues varied significantly between aphid genotypes and collection areas, but there was no clear pattern in relation to H. defensa infection or between collection sites likely to differ in insecticide pressures. 4. Five clonal lines representing low to moderate levels of enzyme activity, which included different aphid genotypes and presence/absence of H. defensa infection, were assayed for their susceptibility to the parasitoid wasp Aphidius ervi Haliday. Aphid mummification varied significantly between aphid genotypes, with low values in one genotype of aphids irrespective of H. defensa presence. 5. The results revealed that aphid lines belonging to the parasitism‐resistant genotype exhibited moderate levels of total esterase activity, indicating a competitve advantage for this genotype of M. euphorbiae when exposed to chemical and biological control factors in agroecosystems.     

Spatial and temporal genetic variation in Tunisian field populations of Macrosiphum euphorbiae (Thomas)

The potato aphid Macrosiphum euphorbiae (Thomas) is a major pest of several economic crops in Tunisia. Using 10 microsatellites, we analyzed five populations of M. euphorbiae sampled during the 2004-2005 solanaceous and cucurbit season (April through September) from five geographic origins. From 235 aphids, 61 different multilocus genotypes were identified of which three genotypes MLG1, MLG2, and MLG42 were predominant on all host plants and regions. MLG1 and MLG2 genotypes were detected in 2004 and did not reappear in spring 2005, while the genotype MLG42 was detected only in 2005. All populations showed significant deviation from Hardy-Weinberg equilibrium even in data sets including one individual per genotype. χ(2) independence tests and analysis of molecular variance showed no significant differentiation among populations collected on different host plant and from different geographic origin, but differences between populations from two successive years were significant. Factorial component analysis corroborates these results. The probable causes of this seasonal variation were discussed.     

Seasonal dynamics of cereal aphids on Russian wheat aphid (Homoptera: Aphididae) susceptible and resistant wheats

Field experiments were conducted in 1997 and 1998 to evaluate the impact of resistance to Russian wheat aphid, Diuraphis noxia (Mordvilko), on the cereal aphid complex in wheat. Two spring wheats were planted: the variety "Centennial" (Russian wheat aphid susceptible) and the advanced line IDO488 (Russian wheat aphid resistant). IDO488 incorporates the resistance found in PI 294994 into a Centennial background. Field plots were artificially infested with adult D. noxia and sampled weekly. The most abundant aphid species in 1997 were Metopolophium dirhodum (Walker), Sitobion avenae (F.), D. noxia, and Rhopalosiphum padi (L.). In 1998, the order of abundance was M. dirhodum, R. padi, S. avenae, and D. noxia. The resistant genotype had significantly fewer D. noxia than the susceptible one during both years. However, plant genotype had no significant effect on the other aphid species in either year. Both the initial density of D. noxia and plant growth stage, had a significant effect on D. noxia population development, but had no effect on the other aphid species. There was no interaction between D. noxia resistance and the population density of the other aphid species observed.     

Wild Solanum resistance to aphids: antixenosis or antibiosis?

The type (antixenosis or antibiosis) of resistance against the aphids Myzus persicae (Sulzer) and Macrosiphum euphorbiae (Thomas) was characterized for the wild tuber-bearing potatoes, Solanum chomatophilum Bitter and Solanum stoloniferum Schltdl. & Bouché through behavioral (olfactometry and electrical penetration graph) and physiological studies. In dual-choice assays, only S. stoloniferum exerted attraction to M. euphorbiae. This ruled out the possibility that plant volatiles of S. chomatophilum and S. stoloniferum may contribute to the high resistance expressed. In electrical penetration graph experiments, aphids feeding on S. stoloniferum showed increased salivation phases, whereas phloem ingestion was drastically reduced for both aphid species. Because reaching phloem elements was not delayed in both species, the resistance mechanism was phloem-located. The antixenosis exhibited by S. stoloniferum was similar on young and mature leaves. S. chomatophilum also showed phloem-located antixenosis against M. persicae. In contrast, M. euphorbiae had no difficulty to reach S. chomatophilum phloem tissues and to ingest sap. S. chomatophilum resistance against M. euphorbiae was antibiosis and only expressed in mature leaves, where a complete nymphal mortality was observed.     

Aphid parasitoid complex in potato in the context of IPM in Belgium

Parasitic hymenoptera of potato aphids were collected and identified in 2000 and 2001 in 11 potato fields in Belgium. Nine Aphidiidae species, parasiting seven aphid species, were found: Aphidius ervi, Aphidius matricariae, Aphidius picipes, Binodoxys angelicae, Diaeretiella rapae, Praon abjectum, Praon gallicium, Praon volucre and Toxares deltiger. A. ervi and A. picipes were the dominant and sub-dominant species, with 54% and 28% of the primary parasite collected, respectively. Both species and T. deltiger were found on Aphis nasturti, Aulacorthum solani, Macrosiphum euphorbiae and Myzus persicae, the four most important aphid potato in Belgium. Parasitism rate of A. nasturtii and, to a lesser extent, M. euphorbiae was low compared to A. solani and M. persicae. Parasitism of A. solani was particularly high, with 63.5% in 2000 and 89.2% in 2001, and this species was the preferred host of several Aphidiid species. The abundance of alternative hosts as other crops pest aphids or non-pest aphids on wild plants in agroecosystems could explains the efficacy of these species. The biological control of A. nasturtii and M. euphorbiae by parasitic hymenoptera was poorer, and several studies need to be undertaken to find suitable parasitic hymenoptera species effective on these aphids and agro-environmental measures able to promote them.     

Genotypic variation in induced resistance and induced susceptibility in the peach-Myzus persicae aphid system

In response to herbivore damage or stress, plants may express physiological or morphological changes known as induced responses. We tested whether previous herbivory by the aphid Myzus persicae differentially altered the expression of resistance and susceptibility among five genotypes of peach that differ in their resistance phenotype (avoidance resistance, antibiosis resistance or susceptibility). We measured behavioural and performance parameters of aphid success on plants previously infested by conspecifics as compared to uninfested controls. Significant variation was found both among genotypes and among resistance phenotype, including between genotypes showing a same resistance phenotype. Genotypes with avoidance resistance showed either induced resistance to aphid settling or no response. Genotypes with antibiosis resistance showed induced susceptibility to aphid settling, but the effects of previous herbivory on aphid development were either positive or negative depending on the genotype. In the susceptible genotype, most parameters of aphid settlement and performance, including reproduction, were positively influenced by previous herbivory. Using electronic recording, the aphid probing behaviour was examined to tentatively identify host plant tissues most likely to play a role in induced defenses. Probing behaviour was significantly affected by plant genotype, previous herbivory, and their interaction, indicating complex relations between the two factors. In the genotypes with avoidance resistance, aphids were deterred before they reach the phloem. In the genotypes expressing susceptibility or antibiosis resistance, previous herbivory triggered instead the induction of a phloem‐mediated response, that however diverged depending on the resistance status (facilitation or reduction of phloem sap uptake respectively). Genotypic variation in induction found in the peach‐M. persicae system establishes a useful framework to improve our knowledge of the ecological role of induced plant responses to aphids.     

Host preference of plant genotypes is altered by intraspecific competition in a phytophagous insect

Variation among aphid genotypes leads them to preferentially colonize different host-plant genotypes. In a natural community, different genotypes within a species are expected to coexist on a single host plant, and these aphids can interact, potentially, altering host-plant preferences. Using a model aphid (Sitobion avenae) and barley (Hordeum vulgare) system, we compared aphid preference and performance in one- or two-genotype colonies in pots with genetically diverse host plants (6 genotypes) or genetically uniform host plants (1 genotype per pot). Aphid host preference was shown to differ when a second aphid genotype was present, with one aphid genotype exhibiting a preference change due to the genotypic identity of the second aphid. The population growth rate of the aphids was not influenced by the competitor, and thus, we conclude that these effects are due to aphid distribution (preference) rather than effects through performance. Our work demonstrates that within a complex ecological community, an individual’s behavior can be influenced by interactions with other genotypes within the same species, as well as interactions with genotypes of other species.     

Inheritance of partial resistance to the leaf aphids Macrosiphum euphorbiae and Uroleucon sonchi in lettuce

The genetics of partial resistance (PR) of lettuce to the leaf aphid species Macrosiphum euphorbiae and Uroleucon sonchi was studied in F₁ and F₂ generations of six crosses between four cultivars. Partial resistance inherited mainly additively. With M. euphorbiae the estimates of broad-sense F₂ heritability were low and non-significant in crosses between parents of the same resistance level (S x S and PR x PR), and high (0.69-0.76) in crosses between parents of different resistance level (PR x S). The level of resistance in lettuce cultivars ‘Charan’ and ‘Marbello’ led to a marked reduction in percentage of plants with colonies of M. euphorbiae in a field experiment. With U. sonchi the highest estimates of F₂ heritability were found in ‘Charan x ‘Avoncrisp’ (0.51) and ‘Charan’ x ‘Chou de Naples' (0.48). In the cross ‘Charan’ x ‘Marbello’ (PR x PR) no significant segregation for resistance to M. euphorbiae was found, indicating that these cultivars may have the same genetic constitution for resistance to M. euphorbiae.‘Charan’ has additional genes for resistance to U. sonchi, that are not, or only weakly linked to the gene(s) for resistance to M. euphorbiae. The heritability estimates for the partial resistance to M. euphorbiae and U. sonchi indicate that it is possible to effectively select for these traits in plant breeding programmes.     

Preinfestations of tomato plants by whiteflies (Bemisia tabaci) or aphids (Macrosiphum euphorbiae) induce variable resistance or susceptibility responses

In addition to constitutive plant resistance against pests or pathogens, plants can activate protective mechanisms upon contact with an invader or a chemical elicitor. Studies on induced plant resistance to herbivores, especially piercing-sucking insects, are less abundant than those devoted to pathogens. Several experiments under controlled conditions have been conducted to demonstrate that infestations by Macrosiphum euphorbiae induce plant resistance to Bemisia tabaci in susceptible tomato plants. After three days of exposure to 20 apterous adult aphids, the plants acquired a transiently induced resistance to B. tabaci when aphid removal occurred one or 18 hours prior to B. tabaci infestation; the effect disappeared when four days passed between aphid and whitefly infestations. The resistance observed was both locally and systemically induced. Other assays were performed to evaluate the effect of preinfestation with ten adults of B. tabaci during 48 h on the tomato responses to two different clones (Sp and Nt) of M. euphorbiae. The numbers of nymph and adult aphids were counted after the same time interval as the pre-reproductive period and 20 (Sp clone) or 22 (Nt clone) days after adult aphid removal. The tomato responses induced by whitefly feeding depend on the aphid clone. For the Sp clone, the number of aphid nymphs ten days after adult removal was significantly higher on whitefly preinfested plants than on uninfested plants. However, no significant differences were observed when the aphid clone Nt was tested. The duration of plant response to a previous infestation by B. tabaci is apparently limited.     

Effects of plant protease inhibitors, oryzacystatin I and soybean Bowman-Birk inhibitor, on the aphid Macrosiphum euphorbiae (Homoptera, Aphididae) and its parasitoid Aphelinus abdominalis (Hymenoptera, Aphelinidae)

Transgenic plants expressing protease inhibitors (PIs) have emerged in recent years as an alternative strategy for pest control. Beneficial insects such as parasitoids may therefore be exposed to these entomotoxins either via the host or by direct exposure to the plant itself. With the objective of assessing the effects of PIs towards aphid parasitoids, bioassays using soybean Bowman-Birk inhibitor (SbBBI) or oryzacystatin I (OCI) on artificial diet were performed on Macrosiphum euphorbiae-Aphelinus abdominalis system. OCI significantly reduced nymphal survival of the potato aphid M. euphorbiae and prevented aphids from reproducing. This negative effect was much more pronounced than with other aphid species. On the contrary, SbBBI did not affect nymphal viability but significantly altered adult demographic parameters. Enzymatic inhibition assays showed that digestive proteolytic activity of larvae and adults of Aphelinus abdominalis predominantly relies on serine proteases and especially on chymotrypsin-like activity. Immunoassays suggested that OCI bound to aphid proteins and accumulated in aphid tissues, whereas SbBBI remained unbound in the gut. Bioassays using M. euphorbiae reared on artificial diets supplemented with both OCI and SbBBI showed a fitness impairment of Aphelinus abdominalis that developed on intoxicated aphids. However, only SbBBI was detected in parasitoid larvae, while no PI could be detected in adult parasitoids that emerged from PI-intoxicated aphids. The potential impact of PI-expressing plants on aphid parasitoids and their combined efficiency for aphid control are discussed.     

Inheritance of L1014F and M918T sodium channel mutations associated with pyrethroid resistance in Myzus persicae

Two amino acid substitutions (L1014F and M918T) in the voltage-gated sodium channel confer target-site resistance to pyrethroid insecticides in the peach potato aphid, Myzus persicae. Pyrethroid-resistant and -susceptible M. persicae clones with various combinations of these mutations were crossed under laboratory conditions, and the genotypes of aphid progeny were analysed by direct DNA sequencing of the IIS4-S6 region of the sodium channel gene. Segregation patterns showed that in aphids heterozygous for both L1014F and M918T, both mutations were present in the same resistance allele. Despite these mutations appearing largely recessive in other pest species, such aphids exhibited strong resistance to pyrethroids in leaf-dip bioassays. These results have important implications for the spread and management of pyrethroid resistance in field populations.     

Quality of different aphids species as hosts for the parasitoid Aphidius ervi Haliday (Hymenoptera: Braconidae: Aphidiinae)

The suitability of Macrosiphum euphorbiae (Thomas), Aulacorthum solani (Kaltenbach) and Acyrthosiphon kondoi Shinji (Hemiptera: Aphididae) as hosts for the aphid parasitoid Aphidius ervi Haliday was evaluated by assessing host size, host preference, and host quality. Tests were carried out in an environmental chamber at 22±1oC, 70±10% RH and 12h photophase. Replicates (11) consisted of one 24h-old mated female of A. ervi without a previous oviposition experience. Female was released into a Petri dish (5 cm) with 20 2nd and 3rd instars of one of each aphid species tested on a leaf disc of the host plant onto a 1% water-agar layer. Parasitoid emergency was lower in A. kondoi (78.7%) compared to M. euphorbiae (92.2%) and A. solani (91.7%). Acyrthosiphon kondoi (0.36 mm) was the smallest host. The parasitoid showed preference (74.0% parasitism) for M. euphorbiae, the largest host (hind tibia length=0.73 mm), which in turn yielded larger A. ervi females (0.75 mm).     

Effect of mixed viral infections (potato virus Y-potato leafroll virus) on biology and preference of vectors Myzus persicae and Macrosiphum euphorbiae (Hemiptera: Aphididae)

Mixed viral infections of heterologous viruses such as Potato virus Y (family Potyviridae, genus Potyvirus, PVY) and Potato leafroll virus (family Luteoviridae, genus Polerovirus, PLRV) are a regular occurrence in Idaho's potato, Solanum tuberosum (L.), cropping systems. An increased number of plant samples from Idaho's potato fields over the past 2 yr has serologically tested positive for both PVY and PLRV via double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) and exhibited more severe symptoms than singly-infected plants (PVY or PLRV). Several studies have extensively examined the mixed infection phenomenon but to the best of our knowledge, none have examined the effect of such infections on vector biology and preference. Laboratory studies were conducted to examine the effect of mixed viral (PVY-PLRV) infection on the fecundity and preference of two of the most efficient PVY and PLRV vectors, the green peach aphid, Myzus persicae (Sulzer), and the potato aphid, Macrosiphum euphorbiae (Thomas) (Hemiptera: Aphididae). M. persicae and M. euphorbiae adults were clip-caged (one adult per cage) to leaflets of PVY, PLRV, PVY-PLRV-infected, and noninfected potato plants. The number of nymphs produced in all four treatments was recorded after 96 h. M. persicae and M. euphorbiae fecundity was significantly higher on mixed infected plants than on singly infected plants or noninfected plants. Preference of alatae and apterae of M. persicae and M. euphorbiae was determined with the use of settling bioassays. Both alatae and apterae of M. persicae and M. euphorbiae preferentially settled on PVY-PLRV-infected plants than on singly infected plants (PVY or PLRV) or noninfected plants.     

Potato aphid, Macrosiphum euphorbiae (Thomas), in tomatoes: plant canopy distribution and binomial sampling on processing tomatoes in California

A binomial sampling method for the potato aphid, Macrosiphum euphorbiae (Thomas), on processing tomato plants, Lycopersicon esculentum (Mill), is proposed. Relationships between mean number of M. euphorbiae per leaf and proportion of leaves infested [P(I)] with M. euphorbiae for both upper and interior leaves of the processing tomato varieties 'Alta' and 'Halley' are presented. A split-plot design was used with variety, position in the plant canopy, and block as the factors examined through linear regression and analysis of variance (ANOVA). Results supported the hypotheses that M. euphorbiae densities on upper canopy leaves are predictive of densities on inner canopy leaves and that proportion of M. euphorbiae infested leaves are predictive of mean densities per leaf. Mean M. euphorbiae density was greater on 'Alta' than 'Halley' tomato plants, supporting the assumption that 'Alta' is the more susceptible variety. Taylor's Power Law coefficients, a and b, were similar for proportion of M. euphorbiae-infested upper and inner leaves of both 'Alta' and 'Halley'. Taylor's b coefficients ranged from 1.57 to 1.74, indicating a highly clumped distribution for M. euphorbiae.     

Genetic interactions influence host preference and performance in a plant-insect system

Phytophagous insects generally feed on a restricted range of host plants, using a number of different sensory and behavioural mechanisms to locate and recognize their host plants. Phloem-feeding aphids have been shown to exhibit genetic variation for host preference of different plant species and genetic variation within a plant species can also have an effect on aphid preference and acceptance. It is known that genotypic interactions between barley genotypes and Sitobion avenae aphid genotypes influence aphid fitness, but it is unknown if these different aphid genotypes exhibit active host choice (preference) for the different barley genotypes. Active host choice by aphid genotypes for particular plant genotypes would lead to assortative association (non-random association) between the different aphid and plant genotypes. The performance of each aphid genotype on the plant genotypes also has the ability to enhance these interactions, especially if the aphid genotypes choose the plant genotype that also infers the greatest fitness. In this study, we demonstrate that different aphid genotypes exhibit differential preference and performance for different barley genotypes. Three out of four aphid genotypes exhibited preference for (or against) particular barley genotypes that were not concordant with differences in their reproductive rate on the specific barley genotype. This suggests active host choice of aphids is the primary mechanism for the observed pattern of non-random associations between aphid and barley genotypes. In a community context, such genetic associations between the aphids and barley can lead to population-level changes within the aphid species. These interactions may also have evolutionary effects on the surrounding interacting community, especially in ecosystems of limited species and genetic diversity.     

How nutritionally imbalanced is phloem sap for aphids?

Aphids harbour intracellular symbionts (Buchnera) that provide their host with amino acids present in low amounts in their diet, phloem sap. To find out the extent to which aphids depend on their symbionts for synthesis of individual essential amino acids, we have evaluated how well phloem sap amino acid composition matches the aphids' needs. Amino acid compositions of the ingested phloem sap were compared to amino acids in aphid body proteins and also to available information about optimal diet composition for other plant feeding insects. Phloem sap data from severed stylets of two aphid species, Rhopalosiphum padi (L.) (Homoptera: Aphididae) feeding on wheat, and Uroleucon sonchi (L.) (Homoptera: Aphididae) feeding on Sonchus oleraceus (L.), together with published information on phloem sap compositions from other plant species were used.Phloem sap has in general only around 20% essential amino acids, with a range from 15–48%. Aphid body proteins and optimal diets for two other plant feeding insects have around 50%. The phloem sap of early flowering S. oleraceus ingested by U. sonchi contained 48%, which seems to be exceptional. Aphids feeding on different plants appear to be very differently dependent on their symbionts for their overall essential amino acid synthesis, due to the large variation in proportion of essential amino acids in phloem sap from different plants.The profile of the essential amino acids in phloem sap from different plant species corresponds rather well to profiles of both aphid body proteins and optimal diets determined for plant feeding insects. However, methionine and leucine in phloem sap are in general low in these comparisons, suggesting a higher dependence on the symbiont for synthesis of these amino acids. Concentrations of several essential amino acids in phloem from different plant species seem to vary together, suggesting that levels of symbiont provisioning of different amino acids are adjusted in parallel.     

Characterization of pea aphid resistance in Medicago truncatula

To achieve a thorough understanding of plant-aphid interactions, it is necessary to investigate in detail both the plant and insect side of the interaction. The pea aphid (PA; Acyrthosiphon pisum) has been selected by an international consortium as the model species for genetics and genomics studies, and the model legume Medicago truncatula is a host of this aphid. In this study, we identified resistance to PA in a M. truncatula line, 'Jester', with well-characterized resistance to a closely related aphid, the bluegreen aphid (BGA; Acyrthosiphon kondoi). The biology of resistance to the two aphid species shared similarity, with resistance in both cases occurring at the level of the phloem, requiring an intact plant and involving a combination of antixenosis, antibiosis, and plant tolerance. In addition, PA resistance cosegregated in 'Jester' with a single dominant gene for BGA resistance. These results raised the possibility that both resistances may be mediated by the same mechanism. This was not supported by the results of gene induction studies, and resistance induced by BGA had no effect on PA feeding. Moreover, different genetic backgrounds containing a BGA resistance gene from the same resistance donor differ in resistance to PA. These results suggest that distinct mechanisms are involved in resistance to these two aphid species. Resistance to PA and BGA in the same genetic background in M. truncatula makes this plant an attractive model for the study of both plant and aphid components of resistant and susceptible plant-aphid interactions.     

Effect of an alternate weed host, hairy nightshade, Solanum sarrachoides, on the biology of the two most important potato leafroll virus (Luteoviridae: Polerovirus) vectors, Myzus persicae and Macrosiphum euphorbiae (Aphididae: Homoptera)

Hairy nightshade, Solanum sarrachoides (Sendtner), is a ubiquitous weed in potato agro-ecosystems and nonagricultural lands of southeastern Idaho and the Pacific Northwest. This weed increases the complexity of the Potato leafroll virus (PLRV) (Luteoviridae: Polervirus)-potato pathosystem by serving as aphid and virus reservoir. Previous field studies showed higher densities of green peach aphid, Myzus persicae (Sulzer), and potato aphid, Macrosiphum euphorbiae (Thomas), the two most important vectors of PLRV, on S. sarrachoides compared with potato plants in the same fields. Some of the S. sarrachoides plants sampled in these surveys tested positive for PLRV. Viral infections can alter the physiology of plant hosts and aphid performance on such plants. To understand better the potential effects of S. sarrachoides on the PLRV-potato-aphid pathosystem, the life histories of M. persicae and M. euphorbiae were compared on virus-free and PLRV-infected S. sarrachoides and potato. Individual nymphs of each aphid species were held in clip cages on plants from each treatment to monitor their development, survival, and reproductive output. Nymphal survival for both aphids across plant species was higher on S. sarrachoides than on potato, and, within plant species, it was higher on PLRV-infected plants than on noninfected plants. With a few exceptions, similar patterns occurred for fecundity, reproductive periods, adult longevity, and intrinsic rate of increase. The enhanced performance of aphids on S. sarrachoides and on PLRV-infected plants could alter the vector population dynamics and thus the PLRV-disease epidemiology in fields infested with this weed.