Macrosiphum Euphorbiae Research Articles

Qualidade de diferentes espécies de pulgões como hospedeiros do parasitóide 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).

Larval Competition BetweenAphidius erviandPraon volucre(Hymenoptera: Braconidae: Aphidiinae) inMacrosiphum euphorbiae(Hemiptera: Aphididae)

Interspecific competition between parasitoid larvae may influence the size, structure, and stability of the population, leading to a reduction in total parasitism and thus restricting the pest control. Aphidius ervi (Haliday) and Praon volucre (Haliday) are endoparasitoids that possess a wide host range and present considerable potential for the biological control of the aphid Macrosiphum euphorbiae (Thomas). The larval competition between A. ervi and P. volucre, and the possible intrinsic competitive superiority of one of the parasitoids in M. euphorbiae, have been studied. In single parasitism experiments, mated parasitoid females (n=10) were maintained individually in contact with M. euphorbiae hosts (n=30) inside petri dishes containing lettuce leaf discs and maintained in environmental chamber at 22 ± 1°C, 70 ± 10% RH, and 12-h photophase. The multiple parasitism experiments consisted of exposing single parasitized aphids (n=120) to the second parasitoid species. Two oviposition events were performed with a 4-h interval between them, namely the following: sequence A (oviposition by A. ervi, followed by P. volucre) and sequence B (oviposition by P. volucre, followed by A. ervi). Oviposition sequence A generated 24 A. ervi and 55 P. volucre adults, whereas oviposition sequence B generated 23 and 49 adults. P. volucre is an intrinsically superior competitor compared with A. ervi, and the use of the two species simultaneously may result in competitive exclusion and influence the stability of the parasitoid population.

Developmental Times and Life Table Statistics ofAulacorthum solani(Hemiptera: Aphididae) at Six Constant Temperatures, With Recommendations on the Application of Temperature-Dependent Development Models

Aulacorthum solani (Kaltenbach) (known as foxglove aphid or glasshouse potato aphid) is a pest of increasing economic importance in several agricultural crops worldwide, including greenhouse vegetables and ornamentals. Developmental rates and age-specific life tables for a North American population of A. solani on pansy (Viola × wittrockiana) (Gams.) were determined at six constant temperatures, and comparisons were made to previous studies of A. solani from differing geographic regions and host crops. On pansy, A. solani developed fastest at 25°C, passing through the four nymphal instars in an average of 6.9 d. The highest intrinsic rates of population increase (0.410 and 0.445) and shortest population doubling times (1.69 and 1.56 d) were recorded at 20 and 25°C, respectively. Average total fecundity remained high from 10 to 20°C (74-68 nymphs/adult); a significant decrease to 39 nymphs/adult occurred at 25°C. For calculating developmental thresholds, we present here a method of adjusting the lower developmental threshold (t(min)) using estimates from nonlinear models to provide an improved estimate of the thermal constant (K, in degree-days). We also call attention to the necessity of using a simulation method to estimate the true upper developmental threshold (t(max)) and optimum developmental temperature (t(opt)) from the Lactin-2 model of temperature-dependent development.

Molecular, Biochemical, and Organismal Analyses of Tomato Plants Simultaneously Attacked by Herbivores from Two Feeding Guilds

Previous work identified aphids and caterpillars as having distinct effects on plant responses to herbivory. We sought to decipher these interactions across different levels of biological organization, i.e., molecular, biochemical, and organismal, with tomato plants either damaged by one 3rd-instar beet armyworm caterpillar (Spodoptera exigua), damaged by 40 adult potato aphids (Macrosiphum euphorbiae), simultaneous damaged by both herbivores, or left undamaged (controls). After placing insects on plants, plants were transferred to a growth chamber for 5 d to induce a systemic response. Subsequently, individual leaflets from non-damaged parts of plants were excised and used for gene expression analysis (microarrays and quantitative real-time PCR), C/N analysis, total protein analysis, proteinase inhibitor (PI) analysis, and for performance assays. At the molecular level, caterpillars up-regulated 56 and down-regulated 29 genes systemically, while aphids up-regulated 93 and down-regulated 146 genes, compared to controls. Although aphids induced more genes than caterpillars, the magnitude of caterpillar-induced gene accumulation, particularly for those associated with plant defenses, was often greater. In dual-damaged plants, aphids suppressed 27% of the genes regulated by caterpillars, while caterpillars suppressed 66% of the genes regulated by aphids. At the biochemical level, caterpillars induced three-fold higher PI activity compared to controls, while aphids had no effects on PIs either alone or when paired with caterpillars. Aphid feeding alone reduced the foliar C/N ratio, but not when caterpillars also fed on the plants. Aphid and caterpillar feeding alone had no effect on the amount of protein in systemic leaves; however, both herbivores feeding on the plant reduced the amount of protein compared to aphid-damaged plants. At the organismal level, S. exigua neonate performance was negatively affected by prior caterpillar feeding, regardless of whether aphids were present or absent. This study highlights areas of concordance and disjunction between molecular, biochemical, and organismal measures of induced plant resistance when plants are attacked by multiple herbivores. In general, our data produced consistent results when considering each herbivore separately but not when considering them together.

Role of host‐plant selection in resistance of wild Solanum species to Macrosiphum euphorbiae and Myzus persicae

AbstractDamage to potatoes by Macrosiphum euphorbiae (Thomas) and Myzus persicae (Sulzer) (both Hemiptera: Aphididae) can be controlled through plant resistance. We used ethological experiments and electric penetration graph (EPG) analysis to evaluate the role of host selection in the previously assessed resistance levels of Solanum accessions: Solanum circaeifolium Bitter subsp. capsicibaccatum (Cárdenas) (PI210036), S. chomatophilum Bitter (PI243340 and PI310990), S. okadae Hawkes & Hjert. (PI458367), S. oplocense Hawkes (PI473368), S. pinnatisectum Dunal (PI186553), S. polyadenium Greenm. (PI230463), S. tarijense Hawkes (PI414150), and S. trifidum Correll (PI255538), to M. euphorbiae and M. persicae. Through multivariate analysis, we grouped behavioural variables into factors, which we related to host selection behaviours, and then evaluated whether factors varied between each accession and the susceptible S. tuberosum. None of the factors obtained by ethological experiments differed among accessions. Four of six and three of five factors obtained through EPG varied among accessions for M. euphorbiae and M. persicae, respectively, and were used to suggest resistance characteristics. The resistance to M. persicae of both S. chomatophilum accessions was associated with pathway activity disturbance. Solanum tarijense and S. polyadenium resistance to M. persicae resulted from leaf surface characteristics, which may be trichomes. Solanum oplocense and S. trifidum resistance to M. euphorbiae resulted from the wound response system, whereas S. pinnatisectum resistance may stem from nutritionally unbalanced or toxic phloem sap. Solanum polyadenium resistance to M. euphorbiae was phloem‐based. Solanum circaeifolium ssp. capsicibaccatum resistance to M. persicae, and the resistance of PI243340 S. chomatophilum and S. tarijense to M. euphorbiae were not related to host selection and therefore were presumably due to physiologically active compounds.

Resistance of WildSolanumAccessions to Aphids and Other Potato Pests in Quebec Field Conditions

Two experiments were done to determine the susceptibility of six wild potato accessions to the aphids Macrosiphum euphorbiae (Thomas) (Hemiptera: Aphididae) and Myzus persicae (Sulzer). Densities of aphid colonies were compared between caged Solanum pinnatisectum Dunal (Solanales: Solanaceae), S. polyadenium Greenmam, S. tarijense Hawkes, S. infundibuliforme Philippi, S. oplocense Hawkes, and S. stoloniferum Schlechted and Bouché, and the commercially cultivated potato plant S. tuberosum L. cv. Désirée. Moreover the susceptibility of S. polyadenium and S. tarijense to the Colorado potato beetle Leptinotarsa decemlineata (Say) (Coleoptera: Chrlysomelidae), the potato flea beetle Epitrix cucumeris (Harris), and the potato leafhopper Empoasca fabae (Harris) (Hemiptera: Cicadellidae) was compared to that of S. tuberosum cv. Désirée in the field. Results indicated that S. polyadenium and S. tarijense were more resistant to M. persicae than S. pinnatisectum and the commercially cultivated S. tuberosum cv. Désirée. Solanum polyadenium was more resistant to aphids than S. tarijense in 2004, but not in 2005. Moreover, S. polyadenium and S. tarijense were more resistant than S. tuberosum cv. Désirée to L. decemlineata, E. cucumeris and E. fabae.

Antixenosis phloem‐based resistance to aphids: is it the rule?

1. The concept of plant defence syndrome states that plant species growing in similar biotic or abiotic constraints should have convergent defensive traits. This article is a first step to test the prediction of this concept, by conducting experiments on wild Solanum species (or accessions) that originated from the Andes. The nature and the tissue localisation of the resistance of five wild Solanum species known to be resistant against the aphids Myzus persicae and Macrosiphum euphorbiae were determined by olfactometry and electrical penetration graph experiments.2. Volatile organic compounds may contribute to wild Solanum resistance, depending on Solanum accessions and aphid species. Volatiles of S. bukasovii and S. stoloniferum PI 275248 were not attractive to M. persicae, whereas S. bukasovii was repulsive to M. euphorbiae. In contrast, volatiles of S. stoloniferum PI 275248 were attractive for M. euphorbiae.3. Some wild Solanum species presented a generalised resistance in all plant tissues, so as for S. bukasovii and S. stoloniferum PI 275248 against M. persicae. However, except for S. bukasovii which was susceptible to M. euphorbiae, all tested Solanum species presented a phloem‐based antixenosis resistance against the two aphid species.4. A review of articles focused on the nature of resistance of wild Solanum species against aphids corroborated with our results, i.e. a phloem‐based antixenosis resistance against aphids is the rule concerning the system aphids–wild Solanum species.

Effects of systemic potato response to wounding and jasmonate on the aphid Macrosiphum euphorbiae (Sternorryncha: Aphididae)

AbstractPlant induced responses are activated by multiple biotic and abiotic stresses, and may affect the interactions between a plant and phytophagous insects. The objective of this work was to evaluate the effects of different stresses inflicted to potato plants (Solanum tuberosum) on the potato aphid (Macrosiphum euphorbiae). Abiotic wounding, biotic wounding by Leptinotarsa decemlineata and treatment with volatile methyl jasmonate (MeJA) were evaluated with regard to the orientation behaviour, the feeding behaviour and the development of the potato aphids. Dual‐choice olfactometry showed that plants treated with MeJA lost their attractiveness for the potato aphids, while both abiotic and biotic wounding did not alter the orientation of aphids. Electropenetrography revealed that the feeding behaviour of aphids was only slightly disturbed by a previous L. decemlineata wounding, while it was highly disturbed by mechanical wounding and MeJA treatment. Aphid nymph survival was reduced on mechanically wounded plants, the pre‐reproductive period was lengthened and the fecundity reduced on plants treated with MeJA. Our results bring new information about the effects of various stresses inflicted to S. tuberosum on M. euphorbiae. We showed that wounding and MeJA treatment induced an antixenosis resistance in potato plants against M. euphorbiae, which may influence aphid colonization processes.

PLoS Genetics Issue Image | Vol. 6(6) June 2010

The peach potato aphid Myzus persicae is the most economically important aphid pest in many regions of the world and has developed resistance to many classes of insecticide used for control. In this issue of PLoS Genetics, Puinean et al. made use of recent advances in genomics to quantify the expression of all genes encoding detoxification enzymes in an insecticide resistant strain of M. persicae. Resistance was associated with the over-expression of a single P450 gene, and the authors show, for the first time in an agriculturally important insect pest, that this is due to amplification of the gene. Image Credit: Photograph courtesy of Rothamsted Research

'BRS Tospodoro': a high lycopene processing tomato cultivar adapted to organic cropping systems and with multiple resistance to pathogens

'BRS Tospodoro' is a high lycopene tomato cultivar, which combines multiple disease resistance genes and desirable processing traits. This cultivar was found to be suitable for both conventional and organic crop systems. 'BRS Tospodoro' was obtained via backcross breeding using 'Viradoro' as recurrent parent and the inbred line 'CNPH 1306' as the donor of the Pto gene (resistance to Pseudomonas syringae pv. tomato race 0). 'BRS Tospodoro' has the Mi1-2 gene that controls resistance to root-knot nematodes (Meloidogyne incognita, M. javanica, and M. arenaria) as well as tolerance to populations of the aphid Macrosiphum euphorbiae (vector of Potyvirus species), and to whiteflies (Bemisia tabaci). 'BRS Tospodoro' has also the Sw-5b gene, which controls resistance to major Tospovirus species (Groundnut ringspotirus, Tomato chlorotic spot virus, Chrysanthemum stem necrosis virus, and Tomato spotted wilt virus). This cultivar is also resistant to Stemphylium solani and S. lycopersici (Sm gene), Fusarium oxysporum f. sp. lycopersici race 1 (I-1 gene) and Verticillium dahlie race 1 (Ve gene). 'BRS Tospodoro' presents uniform fruit ripening, with the first harvest being done around 110 to 120 days after plant emergence. The fruits are firm, square-shaped, with an average weight of 46 g (in organic cropping) to above 70 g (in conventional cropping). The soluble solids content is in the range between 4.6 and 4.8 ºBrix. The external fruit color is uniform (gene u) and bright red (L* = 44.1; a* = 33.9; b* = 20.4). The average lycopene content of mature fruits is 104 µg/g. This cultivar has the jointless locus (j2), which facilitates both manual and mechanical harvesting. 'BRS Tospodoro' has determinate growth habit (locus sp) with vigorous foliage, which provides good fruit protection from sunscald. 'BRS Tospodoro' can be cultivated in all the traditional processing tomato-producing areas of Brazil without the need of any technical adjustment. 'BRS Tospodoro' displayed very good adaptation to the South Brazilian Region and South Cone of South America (Argentina and Uruguay), where P. syringae pv. tomato and Tospovirus are serious economic problems for the crop. 'BRS Tospodoro' might also be cultivated in traditional processing tomato-producing areas (South-East, North-East and Central Brazil), if geminivirus control measures are adopted. Due to its vigorous foliage, 'BRS Tospodoro' requires careful monitoring of the environmental conditions that favors late blight (Phytophthora infestans) epidemics. 'BRS Tospodoro' has been evaluated under organic crop systems with excellent performance in field assays conducted in Brasilia-DF, Brazil.

Mi-mediated aphid resistance in tomato: tissue localization and impact on the feeding behavior of two potato aphid clones with differing levels of virulence

The Mi-1.2 gene in tomato, Solanum lycopersicum L. (Solanaceae), confers resistance against several herbivores, including the potato aphid, Macrosiphum euphorbiae (Thomas) (Hemiptera: Sternorrhyncha: Aphididae) and the sweetpotato whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Sternorrhyncha: Aleyrodidae). Previous studies on the tissue localization of resistance have given varying results; whitefly resistance was attributed to factors localized in the mesophyll or epidermis, whereas aphid resistance was attributed to factors localized in the phloem. Our study utilizes the direct current electrical penetration graph (DC-EPG) technique to compare aphid feeding behavior on resistant (Mi-1.2+) and susceptible (Mi-1.2-) tomato plants. This study also compares the impact of resistance on the feeding behavior of two aphid clones that vary in their virulence, or their ability to survive and reproduce on resistant plants. Previous work had shown that the avirulent WU11 clone is almost completely inhibited by resistance, whereas the semi-virulent WU12 clone can colonize resistant hosts. Here, DC-EPG analysis shows that both aphid clones take longer to initiate cell sampling and to establish a confirmed sieve element phase on resistant plants than on susceptible hosts, and have shorter ingestion periods on resistant plants. However, the magnitude of these deterrent effects is far less for the semi-virulent clone than for the avirulent aphids. In particular, the WU12 clone is less sensitive to factors that limit sieve element ingestion, showing shorter non-probe duration and rapidly establishing sustained phloem ingestion on resistant plants when compared to the WU11 clone. We conclude that, in addition to previously described factors in the phloem that inhibit ingestion, Mi-mediated aphid resistance also involves factors (possibly in the mesophyll and/or epidermis) that delay initiation of phloem salivation, and that act in the intercellular spaces to deter the first cell sampling. Furthermore, the relative effectiveness of these components of resistance differs among insect populations.

Biological performance of Myzus persicae and Macrosiphum euphorbiae (Homoptera: Aphididae) on seven wild Solanum species

Resistance level of seven accessions of wild Solanum species (Solanaceae) to Myzus persicae and Macrosiphum euphorbiae (Homoptera: Aphididae) was evaluated by measuring survival and fecundity during sleeve cage experiments and population growth on whole plants in a controlled environment. The survival was lowest on the Solanum circaeifolium spp. capsicibaccatum, Solanum pinnatisectum and Solanum trifidum accessions for M. persicae and on the S. circaeifolium spp. capsicibaccatum, Solanum okadae and S. trifidum, accessions with M. euphorbiae. Plant species significantly influenced the fecundity of both aphid species. Aphid population growth on whole plants was negatively affected by the age of the plant, but generally followed the levels of net reproductive rate on different plant species observed during the sleeve cage experiment. The population of M. persicae varied among the seven wild potato accessions with the lowest growth rates on S. circaeifolium spp. capsicibaccatum, Solanum polyadenium, Solanum tarijense and S. trifidum. The number of M. euphorbiae also varied among accessions but the smallest population was collected from S. polyadenium. The results can be used to identify sources of resistance to aphids within those accessions already known to be resistant to the Colorado potato beetle. This study highlights the difficulties involved in developing a high‐throughput screening test for aphid resistance compatible with a potato breeding programme.

Aphids and associated natural enemies on Ile Amsterdam and Ile Saint-Paul, Southern Indian Ocean

AbstractIle Amsterdam (37°50′S, 77°30′E, 55 km2) and Ile Saint-Paul (38°43′S, 77°31′E, 7 km2) are very isolated volcanic islands which were originally colonized by a few invertebrate fauna and flora. Invasive species richness has then increased along with human activity. A three-year monitoring programme (1997, 2000, 2001) and a summer campaign (2007) allowed species diversity, host plants, abundance and phenology of introduced aphids and natural enemies to be described. Seven cosmopolitan aphid species have been found on Ile Amsterdam (Aulacorthum solani,A. circumflexum,Macrosiphum euphorbiae,Myzus ascalonicus,M. cymbalariae,M. ornatusandRhopalosiphum padi) and three on Ile Saint-Paul (A. solani,M. cymbalariaeandR. padi). On Ile Amsterdam, these aphids were found on 28 host plants (out of 57 sampled plants), mainly introduced species.Phylica arboreawas the only native plant much colonized by one aphid species,A. circumflexum. Aphids were mainly present on the base or in this vicinity. One Hymenopteran parasitoid,Aphidius matricariae, and two hyperparasites (Dendrocerus aphidumandPhaenoglyphis villosa), probably introduced along with their host, were collected. Aphid activity is very low during the autumn (March–May) and at a maximum in spring and summer. Their density and diversity decrease with distance from the research station. From these results, the possible impact of aphids on native plants is discussed.

WRKY72-type transcription factors contribute to basal immunity in tomato and Arabidopsis as well as gene-for-gene resistance mediated by the tomato R gene Mi-1.

WRKY transcription factors play a central role in transcriptional reprogramming associated with plant immune responses. However, due to functional redundancy, typically the contribution of individual members of this family to immunity is only subtle. Using microarray analysis, we found that the paralogous tomato WRKY genes SlWRKY72a and b are transcriptionally up-regulated during disease resistance mediated by the R gene Mi-1. Virus-induced gene silencing of these two genes in tomato resulted in a clear reduction of Mi-1-mediated resistance as well as basal defense against root-knot nematodes (RKN) and potato aphids. Using Arabidopsis T-DNA insertion mutants, we found that their Arabidopsis ortholog, AtWRKY72, is also required for full basal defense against RKN as well as to the oomycete Hyaloperonospora arabidopsidis. Despite their similar roles in basal defense against RKN in both tested plant species, WRKY72-type transcription factors in tomato, but not in Arabidopsis, clearly contributed to basal defense against the bacterial pathogen Pseudomonas syringae. Of the five R genes that we tested in tomato and Arabidopsis, only Mi-1 appeared to be dependent on WRKY72-type transcription factors. Interestingly, AtWRKY72 target genes, identified by microarray analysis of H. arabidopsidis-triggered transcriptional changes, appear to be largely non-responsive to analogs of the defense hormone salicylic acid (SA). Thus, similarly to Mi-1, which in part acts independently of SA, AtWRKY72 appears to utilize SA-independent defense mechanisms. We propose that WRKY72-type transcription factors play a partially conserved role in basal defense in tomato and Arabidopsis, a function that has been recruited to serve Mi-1-dependent immunity.

Characterization of Solanum chomatophilum resistance to 2 aphid potato pests, Macrosiphum euphorbiae (Thomas) and Myzus persicae (Sulzer)

The aphids Macrosiphum euphorbiae (Thomas) and Myzus persicae (Sulzer) (Hemiptera: Aphididae) are responsible for yield reduction in potato ( Solanum tuberosum) production by direct phloem feeding and by spreading viruses. Breeding resistant traits from Solanum chomatophilum into the potato germplasm provides alternative means to control aphid infestations. Integrated pest management strategy, using plant resistance, benefits from the characterization of the resistance and of its impact on aphid biology. Our objective was to characterize the resistance of S. chomatophilum by assessing the effects of accessions, plant parts on aphid performance, and by assessing the impact of the resistance factors on different aphid developmental stages and on alate morph production. Detailed aphid performance was obtained by measuring fecundity, survival, percentage of nymphs that reached adult moult, and population growth using whole plant and clip cage experimental designs. Accession and plant physiological age, but not aphid developmental stage, influenced all life-history parameters, except for alate morph production which was not induced on the resistant accessions. Plant part influence was independent of plant species and accession. Both experimental designs resulted in congruent resistance levels at the accession level for each of the two aphid species, supporting the use of any of them in S. chomatophilum resistance screening. PI243340 was resistant to both aphid species, while PI365324 and PI310990 were also resistant to M. euphorbiae and M. persicae, respectively.

Differential Consumption of Four Aphid Species by Four Lady Beetle Species

The acceptability of four different aphid species Macrosiphum albifrons (Essig), Macrosiphum euphorbiae (Thomas), Macrosiphum pseudorosae Patch, and Myzus persicae (Sulzer) (Hemiptera: Aphididae), as prey for four lady beetle species, one native species Coccinella trifasciata L, and three non-native Coccinella septempunctata L, Harmonia axyridis Pallas, Propylea quatuordecimpunctata L (Coleoptera: Coccinellidae) were tested in the laboratory. The relative field abundance of adults of the same lady beetle species on host vegetation, Lupinus polyphyllus Lindley (Fabales: Fabaceae), Solanum tuberosum L (Solanales: Solanaceae), and Rosa multiflora Thunberg (Rosales: Rosaceae), both with and without aphids present was also observed. In the laboratory, H. axyridis generally consumed the most aphids, while P. quatuordecimpunctata consumed the fewest. The exception was P. quatuordecimpunctata, which consumed a greater number of M. albifrons nymphs, and C. trifasciata, which consumed a greater number of M. albifrons nymphs and adults, compared with the other two beetle species. Lady beetles consumed fewer M. albifrons compared with the other three aphid species, likely because of deterrent compounds sequestered by this species from its host plant. In the field, P. quatuordecimpunctata was the most abundant species found on L. polyphyllus and S. tuberosum.

C.V. Riley's Lost Aphids:Siphonophora fragariaevar.ImmaculataandAphis rapaevar.Laevigata(Hemiptera: Aphididae)

The syntypes of Siphonophora fragariae var. Immaculata Riley were rediscovered in the aphid collection of the United States of America National Museum of Natural History. The name (S. fragariae Immaculata) previously being largely lost and forgotten, we here establish it as the senior synonym of Macrosiphum euphorbiae (Thomas). Reversal of precedence can be validated, however, and we establish S. fragariae Immaculata as a nomen oblitum and M. euphorbiae a nomen protectum with respect to each other. In uncovering the original description of the Riley species, we also found a description of Aphis rapae var. laevigata Riley. We have not found A. rapae laevigata anywhere else in the literature nor have we found any type specimens. Based on Riley's succinct description and host plant identity, we consider it a nomen dubium synonym of Myzus persicae (Sulzer). Because the short articles publishing the two aphid names have been missing from taxonomists' libraries, they are transcribed in their entirety.

Modification of Macrosiphum euphorbiae colonisation behaviour and reproduction on potato plants treated by mineral oil

AbstractAlthough mineral oil spray is one of the most effective ways to control the transmission of non‐persistent aphid‐borne viruses in the field, its mode of action is poorly understood. In this study, the effects of mineral oil treatment of potato plants on host selection behaviour, growth, and reproduction of potato aphids, Macrosiphum euphorbiae (Thomas) (Hemiptera: Aphididae), were investigated. The effects were assessed 30 min, 1 day, and 7 days after treatment, (1) on aphid orientation behaviour by using a Y‐tube olfactometer, and (2) on aphid feeding behaviour by using the electrical penetration graph (EPG) technique. Olfactory experiments showed that the oil had a repulsive effect only 30 min after spraying. EPG experiments showed a slight modification of the aphid feeding behaviour mainly 7 days after treatment. The number of both salivation and sap ingestion events during the phloem phases were increased 7 days after treatment. In addition, irrespective of the time after treatment, xylem ingestion time was increased. Clip cage experiments were set up to assess potential effects of the oil treatment on aphid survival and population parameters. Nymphal mortality was increased on treated plants, whereas fecundity of surviving insects was enhanced. The antagonistic effects of oil treatment on aphids are discussed in a plant protection context.

Presence of the Aphid,Chaetosiphon fragaefolii, on Strawberry in Argentina

Seasonal abundance of the strawberry aphid complex under different agronomic practices in the outskirts of La Plata, Argentina was studied on strawberry, Fragaria x ananassa Duchesne (Rosales: Rosaceae). Aphid densities were low in strawberry fields in which insecticides and fungicides were used. In addition to Aphis gossypii, Aphis fabae, Mysus persicae and Macrosiphum euphorbiae, the aphid, Chaetosiphon fragaefolii (Cockerell) (Homoptera: Aphididae), was recorded for the first time in this horticultural area. Life history and some demographic parameters were calculated for C. fragaefolii. The mean duration of nymphal stages was 10.44 days, the oviposition period was 11.8 days, and the mean number of nymph/female/day was 2.4 ± 0.3. Demographic parameters analyzed included the net reproductive rate Ro = 14.55 ± 0.096 nymph/female, generation time T=16.91 ± 0.035 days, and the intrinsic rate of increase rm = 0.158 ± (0.004). No parasites were found associated with C. fragaefolli. The pathogenic fungus, Entomophthora planchoniana Cornu (Zygomycetes: Entomophthorales) was the main mortality factor. Although aphids are not the main pests in strawberry fields, C. fragaefolii can be a serious problem because it can transmit several virus diseases of strawberry. Greater knowledge of life history traits and mortality factors of this species is needed in order to design appropriate control strategies.

Relevance of the Mi23 Marker and the Potato Aphid Biology as Indicators of Tomato Plant (Solanum lycopersicum L.) Resistance to Some Pests

Relevance of the Mi23 Marker and the Potato Aphid Biology as Indicators of Tomato Plant (Solanum lycopersicum L.) Resistance to Some Pests Mi-1.2 gene, expressed in tomato plants, contributes to endogenous resistance against nematodes and some Hemiptera insects. The aim of this study was to screen the presence of dominant/recessive locus of the Mi-1.2 gene in tomato cultivars with different allelic combination using Mi23 SCAR method and to assess the capacity of the local potato aphid (Macrosiphum euphorbiae Thomas) population to develop on different tomato cultivars (dominant and recessive homozygotes in Mi-1.2 locus). The results showed that both Mi23 marker and potato aphid performance are relevant methods in screening tomato cultivars with a different allelic combination of Mi-1.2 gene. The assessment of biological potential of M. euphorbiae proved that, in comparison with control (tomato plants with recessive alleles of Mi-1.2 gene), the aphid mortality increased 9- and 4 - fold (in the first and second experimental series, respectively) and the female longevity decreased 3 - fold when fed on tomato cvs with dominant alleles of Mi-1.2 gene. Furthermore, the resistance against aphids manifests as an antibiosis mechanism in tomato plants carrying dominant alleles.