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Showing papers on "Aphididae published in 2013"


Journal Article
TL;DR: The flight behaviour of the aphid parasitoid Aphidius ervi Haliday has been studied in a wind tunnel, in response to the following natural odour sources: broad bean plants infested with Acyrthosiphon pisum, PHC and HDP, which both stimulated a similar high number of oriented straight flights.
Abstract: The flight behaviour of the aphid parasitoid Aphidius ervi Haliday (Hymenoptera: Braconidae) has been studied in a wind tunnel, in response to the following natural odour sources: broad bean plants infested with Acyrthosiphon pisum (Harris) (Homoptera: Aphididae) (PHC, plant-host complex), damaged broad bean plants from which the aphids were removed (HDP, host damaged plants), aphids (H, host) and uninfested broad bean plants (P, plant). The most attractive odour sources were PHC and HDP, which both stimulated a similar high number of oriented straight flights. In contrast, H and P were much less attractive and did not seem to be important in the long range attraction of the parasitoids.

92 citations


Journal ArticleDOI
TL;DR: Results suggest that use of aphid‐resistant soybean lines with Rag genes may be viable for managing soybean aphids, however, virulent biotypes of soy bean aphid were identified before release of Aphid‐ resistant soybean, and thus a strategy for optimal deployment of aphids‐resistant Soybean is needed to ensure sustainability of this technology.
Abstract: The soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), is an invasive insect pest of soybean [Glycine max (L.) Merr. (Fabaceae)] in North America, and it has led to extensive insecticide use in northern soybean-growing regions there. Host plant resistance is one potential alternative strategy for managing soybean aphid. Several Rag genes that show antibiosis and antixenosis to soybean aphid have been recently identified in soybean, and field-testing and commercial release of resistant soybean lines have followed. In this article, we review results of field tests with soybean lines containing Rag genes in North America, then present results from a coordinated regional test across several field sites in the north-central USA, and finally discuss prospects for use of Rag genes to manage soybean aphids. Field tests conducted independently at multiple sites showed that soybean aphid populations peaked in late summer on lines with Rag1 or Rag2 and reached economically injurious levels on susceptible lines, whereas lines with a pyramid of Rag1 + Rag2 held soybean aphid populations below economic levels. In the regional test, aphid populations were generally suppressed by lines containing one of the Rag genes. Aphids reached putative economic levels on Rag1 lines for some site years, but yield loss was moderated, indicating that Rag1 may confer tolerance to soybean aphid in addition to antibiosis and antixenosis. Moreover, no yield penalty has been found for lines with Rag1, Rag2, or pyramids. Results suggest that use of aphid-resistant soybean lines with Rag genes may be viable for managing soybean aphids. However, virulent biotypes of soybean aphid were identified before release of aphid-resistant soybean, and thus a strategy for optimal deployment of aphid-resistant soybean is needed to ensure sustainability of this technology.

87 citations


Journal ArticleDOI
TL;DR: Effects of natural enemies on aphid populations were strongest in assemblages that included specialist predators, either alone or with generalist predators, and a relationship between predator effects and temperature seasonality was only found for the USA.
Abstract: Aphids are among the most severe invertebrate pests of crops and cause high economic losses. The control of aphids by natural enemies is an essential ecosystem service with high relevance to management strategies applied in agricultural plant production and horticulture. However, the current knowledge on the effectiveness of specialist and generalist predators in aphid control with respect to host plants and climatic conditions has not yet been summarized in a meta-analytical approach. We collected 60 studies providing 168 independent cases of predator exclusion experiments to analyse how predator and host plant group and climatic conditions affect aphid control by natural enemies. Effects of natural enemies on aphid populations were strongest in assemblages that included specialist predators, either alone or with generalist predators. Generalists alone also reduced aphid numbers significantly, but not to the same extent as specialists. Effects of natural enemies were weaker on aphid populations feeding on legumes compared with aphids on grasses or herbs. The percentage reduction of aphids feeding on grasses, herbs or legumes was higher in treatments with assemblages or specialists alone compared with generalists with the largest difference on grasses. According to all field studies from the temperate zone, effects of natural enemies on aphid populations were strongest in areas with high precipitation seasonality. A relationship between predator effects and temperature seasonality was only found for the USA. Synthesis and applications. Specialist predators alone or assemblages of specialists and generalists had the strongest effect on aphid populations, especially when either feeding on grasses and herbs or when exposed to extreme weather events. The control of aphids by natural enemies is most promising in grass and herb crops, whereas it is less suited for controlling aphids in legume crops. Facing climate change, the effect of extreme weather events on aphid control by natural enemies will have further implications for developing management strategies for aphid control in the future. (Less)

77 citations


Journal ArticleDOI
17 Oct 2013-PLOS ONE
TL;DR: A complete 16,317 bp mitogenome of Cavariella salicicola and two nearly complete mitogenomes of Aphis glycines and Pterocomma pilosum are reported and a first comparative analysis of mitochondrial genomes of aphids is presented, showing that aphidMitogenomes share conserved genomic organization, nucleotide and amino acid composition, and codon usage features.
Abstract: Insect mitochondrial genomes (mitogenomes) are of great interest in exploring molecular evolution, phylogenetics and population genetics. Only two mitogenomes have been previously released in the insect group Aphididae, which consists of about 5,000 known species including some agricultural, forestry and horticultural pests. Here we report the complete 16,317 bp mitogenome of Cavariella salicicola and two nearly complete mitogenomes of Aphis glycines and Pterocomma pilosum. We also present a first comparative analysis of mitochondrial genomes of aphids. Results showed that aphid mitogenomes share conserved genomic organization, nucleotide and amino acid composition, and codon usage features. All 37 genes usually present in animal mitogenomes were sequenced and annotated. The analysis of gene evolutionary rate revealed the lowest and highest rates for COI and ATP8, respectively. A unique repeat region exclusively in aphid mitogenomes, which included variable numbers of tandem repeats in a lineage-specific manner, was highlighted for the first time. This region may have a function as another origin of replication. Phylogenetic reconstructions based on protein-coding genes and the stem-loop structures of control regions confirmed a sister relationship between Cavariella and pterocommatines. Current evidence suggest that pterocommatines could be formally transferred into Macrosiphini. Our paper also offers methodological instructions for obtaining other Aphididae mitochondrial genomes.

63 citations


Journal Article
TL;DR: Third and fourth instar larvae of Harmonia axyridis were released in spring into rose beds infested by the aphid Macrosiphum rosae and their efficiency is comparable with that of chemical treatments performed in neighbouring rose beds and the subsequent development of aphid populations was the same after these two types of treatments.
Abstract: Third and fourth instar larvae of Harmonia axyridis were released in spring into rose beds infested by the aphid Macrosiphum rosae. These biological treatments induced stabilization or a decrease of the aphid populations. Their efficiency is comparable with that of chemical treatments performed in neighbouring rose beds and the subsequent development of aphid populations was the same after these two types of treatments. The rearing condition of H. axyridis, particularly its feeding on a substitute prey (lepidopteran eggs), the climate, particularly the rainfall and low temperatures, sometimes near the development threshold of the coccinellid, and possibly the rose bush variety did not seem to affect its potential predatory efficiency. An aphid density of more than thirty aphids per rose bush appears to be necessary for the larvae to remain on the plants, when fifty larvae were released per four bushes.

61 citations


Journal ArticleDOI
TL;DR: The bioassays suggest that high levels of resistance to thiamethoxam occur in cotton aphid throughout the midsouthern United States, and flonicamid and sulfoxaflor need to be incorporated into a rotation strategy to preserve their efficacy against Cotton aphid.
Abstract: Cotton aphid, Aphis gossypii Glover, has a history of developing resistance to novel insecticides. A program is needed to monitor cotton aphid susceptibility to new insecticides. Concentration-mortality bioassays were conducted from 2008 to 2011 to monitor the susceptibility of cotton aphids from fields across the midsouthern United States to thiamethoxam and sulfoxaflor. Flonicamid was included in 2010 and 2011. Bioassays followed the procedures described by the Insecticide Resistance Action Committee for testing neonicotinoids against cotton aphid. Mortality was rated at 48 and 72 h. These bioassays suggest that high levels of resistance to thiamethoxam occur in cotton aphid throughout the midsouthern United States. Resistance ratios ranged from 0.9 to 562.6 at 48 h, and from 0.9 to 29.1 at 72 h. Aphid colonies tested were considered susceptible to flonicamid and sulfoxaflor. The LC50 values ranged from 1.43 to 6.60 ppm for flonicamid. The LC50 values for sulfoxaflor ranged from 1.01 to 5.85 ppm and 0.92–4.13 ppm at 48 and 72 h, respectively. These values represent the baseline variability of the susceptibility of cotton aphid to flonicamid and sulfoxaflor. The moderate level of variability observed combined with the high level of efficacy at low rates and the high reproductive rate of cotton aphid suggests that an effective resistance management plan needs to be devised for these insecticides. Flonicamid and sulfoxaflor should provide effective control of cotton aphid in areas where thiamethoxam resistance occurs. However, these insecticides need to be incorporated into a rotation strategy to preserve their efficacy against cotton aphid.

52 citations



Journal Article
TL;DR: Ten aphid species wcre used as prey for Adalia bipunctata and six of them (Euceraphis betulae, Cavariella konoi, Liosomaphis berberidis, Acyrthosiphon ignotum, Aphis farinosa and Macrosiphoniella artemisiae) are new essential preys for this coccinellid.
Abstract: Ten aphid species wcre used as prey for Adalia bipunctata and six of them (Euceraphis betulae, Cavariella konoi, Liosomaphis berberidis, Acyrthosiphon ignotum, Aphis farinosa and Macrosiphoniella artemisiae) are new essential preys for this coccinellid. Eucallipterus tiliae and E. betulae were the most suitable prey according to the rate of larval development, larval mortality, adult fresh weight and coccinellid abundance in the field. They are followed by L. berberidis, C. konoi and Tuberculatus annulatus. M. artemisiae and A. ignotum are also very profitable food in the laboratory, but they do not occur in the field together with A. bipunctata. A. farinosa from Salix caprea and Aphis fabae from Philadelphus coronarius were not very suitable as food due to the larval mortality (27% and 23%, respectively). A. fabae from Atriplex sagittata was an unsuitable prey: larval mortality was 67% and the adults that emerged as the survivors had the lowest weight recorded in this series of experiments. Aphis spiraephaga was also unsuitable prey: all 1st instar larvae of A. bipunctata died, even though slowly.

48 citations


Journal Article
TL;DR: It is concluded that the life cycles characteristic to most aphids in the temperate regions of the northern hemisphere are developed as an adaptation to the climatic conditions there.
Abstract: An answer to this question is proposed on the basis of the assumed evolutionary history of aphids based on palaeontological studies, zoogeographical data and estimated origin of each aphid genus in the world. An adaptive radiation of Aphididae and Lachnidae occurred rather late in the Tertiary on the northern hemisphere, and the tropics acted as a barrier. Most aphid genera endemic to the temperate regions of the southern hemisphere belong to other groups. The life cycles of aphids are discussed, and it is concluded, that the life cycles characteristic to most aphids in the temperate regions of the northern hemisphere are developed as an adaptation to the climatic conditions there.

45 citations


Journal ArticleDOI
TL;DR: The hypothesis that mineral oil physically inhibits the binding of the virus at the tip of the stylets is supported, as mineral oil was detected in the body of fewer aphids when they fed on plants 1 day after oil application, and a change in the aphid probing behaviour on mineral oil‐treated plants was deduced.
Abstract: Seed potato crops are currently sprayed weekly with mineral oil to prevent transmission of the Potato virus Y (PVY; Potyviridae: Potyvirus), one of the most prevalent and important non-persistent viruses affecting potato production. In spite of its wide usage as inhibitor of virus transmission, the mode of action for mineral oil is poorly known. The objective of this study was to quantify the effect of dosage and time from application of mineral oil on the inhibition of PVY acquisition. The bird cherry-oat aphid, Rhopalosiphum padi (L.) (Hemiptera: Aphididae), known as vector of PVY, was used in all the experiments. The results indicated that mineral oil efficiently decreased PVY acquisition by 75 and 70% 1 day after application of 5 and 10 l ha−1, respectively. The inhibition effect decreased with time from application; mineral oil inhibits acquisition for less than 4 days at 5 l ha−1 and between 8 and 12 days at 10 l ha−1. As mineral oil was detected in the body of fewer aphids when they fed on plants 1 day after oil application, a change in the aphid probing behaviour on mineral oil-treated plants was deduced. These results support the hypothesis that mineral oil physically inhibits the binding of the virus at the tip of the stylets.

42 citations


Journal Article
TL;DR: Females of the endophagous parasitoid Aphidius ervi Haliday respond positively to the cornicle secretion of the pea aphid, Acyrthosiphon pisum (Harris), and the behavioural response registered seems to be innate and not induced by associative learning.
Abstract: Females of the endophagous parasitoid Aphidius ervi Haliday (Hymenoptera: Braconidae) respond positively to the cornicle secretion of the pea aphid, Acyrthosiphon pisum (Harris) (Homoptera: Aphididae). The parasitoid response has been assessed in a Petri dish choice test by presenting an aphid dummy consisting of a glass bead coated with cornicle secretion along with an untreated bead, which acted as a control. Naive females responded similarly to the treated glass beads and aphids, while experienced females responded less to the treated beads than to aphids. The kairomonal activity of the cornicle secretion decreased as the wax dried. The behavioural response registered seems to be innate and not induced by associative learning.

Journal ArticleDOI
TL;DR: This study provides some evidence that winter A. rhopalosiphi populations are able to take advantage of an array of host types that vary in profitability, indicating that host selectivity may drop under winter's unfavourable conditions.
Abstract: Organisms can either evade winter's unfavourable conditions by migrating or diapausing, or endure them and maintain their activities. When it comes to foraging during winter, a period of scarce resources, there is strong selective pressure on resource exploitation strategy. Generalist parasitoids are particularly affected by this environmental constraint, as their fitness is deeply linked to the profitability of the available hosts. In this study, we considered a cereal aphid-parasitoid system and investigated (1) the host-parasitoid community structure, host availability, and parasitism rate in winter, (2) the influence of host quality in terms of species and instars on the fitness of the aphid parasitoid Aphidius rhopalosiphi De Stefani-Perez (Hymenoptera: Braconidae: Aphidiinae), and (3) whether there is a detectable impact of host fidelity on parasitism success of this parasitoid species. Host density was low during winter and the aphid community consisted of the species Rhopalosiphum padi L. and Sitobion avenae Fabricius (both Hemiptera: Aphididae), both parasitized by A. rhopalosiphi at non-negligible rates. Aphidius rhopalosiphi produced more offspring when parasitizing R. padi compared with S. avenae, whereas bigger offspring were produced when parasitizing S. avenae. Although aphid adults and old larvae were significantly larger hosts than young larvae, the latter resulted in higher emergence rates and larger parasitoids. No impact of host fidelity on emergence rates or offspring size was detected. This study provides some evidence that winter A. rhopalosiphi populations are able to take advantage of an array of host types that vary in profitability, indicating that host selectivity may drop under winter's unfavourable conditions.

Journal ArticleDOI
TL;DR: Both intercropping and application of volatile chemicals emitted by garlic could improve the population densities of natural enemies of cereal aphid, including ladybeetles and mummified aphids.

Journal ArticleDOI
16 Apr 2013-PLOS ONE
TL;DR: It is found that Arsenophonus infection is highly prevalent and genetically uniform and does not defend its soybean aphid host against these major parasitoid and fungal natural enemies.
Abstract: Aphids commonly harbor bacterial facultative symbionts that have a variety of effects upon their aphid hosts, including defense against hymenopteran parasitoids and fungal pathogens. The soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), is infected with the symbiont Arsenophonus sp., which has an unknown role in its aphid host. Our research goals were to document the infection frequency and diversity of the symbiont in field-collected soybean aphids, and to determine whether Arsenophonus is defending soybean aphid against natural enemies. We performed diagnostic PCR and sequenced four Arsenophonus genes in soybean aphids from their native and introduced range to estimate infection frequency and genetic diversity, and found that Arsenophonus infection is highly prevalent and genetically uniform. To evaluate the defensive role of Arsenophonus, we cured two aphid genotypes of their natural Arsenophonus infection through ampicillin microinjection, resulting in infected and uninfected isolines within the same genetic background. These isolines were subjected to parasitoid assays using a recently introduced biological control agent, Binodoxys communis [Braconidae], a naturally recruited parasitoid, Aphelinus certus [Aphelinidae], and a commercially available biological control agent, Aphidius colemani [Braconidae]. We also assayed the effect of the common aphid fungal pathogen, Pandora neoaphidis (Remaudiere & Hennebert) Humber (Entomophthorales: Entomophthoraceae), on the same aphid isolines. We did not find differences in successful parasitism for any of the parasitoid species, nor did we find differences in P. neoaphidis infection between our treatments. Our conclusion is that Arsenophonus does not defend its soybean aphid host against these major parasitoid and fungal natural enemies.

Journal ArticleDOI
TL;DR: The nymphal mortality, the pre‐reproductive development time, and the probing behavior of M. euphorbiae on S. stoloniferum 96 hours post infestation by either aphid species are compared and probing behavior shows that aphids encounter more probing constrains on phloem activities–longer probing and salivation time– on S.
Abstract: Plants protect themselves against aphid attacks by species-specific de- fense mechanisms. Previously, we have shown that Solanum stoloniferum Schlechtd has resistance factors to Myzus persicae Sulzer (Homoptera: Aphididae) at the epidermal/mesophyll level that are not effective against Macrosiphum euphorbiae Thomas (Homoptera: Aphididae). Here, we compare the nymphal mortality, the pre-reproductive development time, and the probing behavior of M. persicae and M. euphorbiae on S. stoloniferum and Solanum tuberosum L. Furthermore, we analyze the changes in gene expression in S. stoloniferum 96 hours post infestation by either aphid species. Although the M. euphorbiae probing behavior shows that aphids encounter more probing constrains on phloem activities-longer probing and salivation time- on S. stoloniferum than on S. tuberosum, the aphids succeeded in reaching a sustained ingestion of phloem sap on both plants. Probing by M. persicae on S. stoloniferum plants resulted in limited feeding only. Survival of M. euphorbiae and M. persicae was affected on young leaves, but not on senescent leaves of S. stoloniferum. Infestation by M. euphorbiae changed the expression of more genes than M. persicae did. At the systemic level both aphids elicited a weak response. Infestation of S. stoloniferum plants with a large number of M. persicae induced morphological changes in the leaves, leading to the development of pustules that were caused by disrupted vascular parenchyma and surrounding tissue. In contrast, an infesta- tion by M. euphorbiae had no morphological effects. Both plant species can be regarded as good host for M. euphorbiae, whereas only S. tuberosum is a good host for M. persicae and S. stoloniferum is not. Infestation of S. stoloniferum by M. persicae or M. euphorbiae changed the expression of a set of plant genes specific for each of the aphids as well as a set of common genes.

Journal ArticleDOI
30 Jul 2013-ZooKeys
TL;DR: Investigation on the species composition and host range of aphids on ornamental greenhouse plants in Bulgaria was conducted over a period of five years, from 2008 to 2012, and Periphyllus californiensis and Aphis (Aphis) fabae mordvilkoi are reported for the first time for Bulgaria.
Abstract: Investigations on the species composition and host range of aphids on ornamental greenhouse plants in Bulgaria was conducted over a period of five years, from 2008 to 2012. Twenty greenhouses, growing ornamentals for landscaping, plant collections and other purposes were observed. They were located in the regions of Sofia, Plovdiv, Smolyan, Pavlikeni, Varna and Burgas. The total number of collected aphid samples was 279. Their composition included 33 aphid species and one subspecies from 13 genera and 5 subfamilies. Twenty-eight species were found to belong to subfamily Aphidinae. Almost 70 % of all recorded species were polyphagous. The most widespread aphid species was Myzus persicae, detected in 13 greenhouses all year round, followed by Aulacorthum solani (10 greenhouses) and Aphis gossypii (9 greenhouses). The widest host range was shown by Myzus persicae (43 hosts), Aulacorthum solani (32 hosts) and Aulacorthum circumflexum (23 hosts). The list of host plants includes 114 species from 95 genera and 58 families. The greatest variety of aphid species was detected on Hibiscus (9 species). Out of all aphid samples 12.9 % were collected on Hibiscus and 6.8 %, on Dendranthema. The greatest variety of aphid species was detected on Hibiscus (9 species). Periphyllus californiensis and Aphis (Aphis) fabae mordvilkoi are reported for the first time for Bulgaria. Furthermore, Aphis spiraecola has been found in new localities and has widened its host range in this country.

Journal ArticleDOI
TL;DR: DNA barcoding employing a 658 bp fragment of 5′ region of the mitochondrial cytochrome oxidase I (CO-I) gene is an efficient and accurate method for identification of aphid species (including cryptic species), an approach that potentially could play an important role in formulating viable pest management strategies, more especially biocontrol.
Abstract: Rapid, precise and timely identification of invasive pest insects such as aphids is important and a challenge worldwide due to their complex life cycles, parthenogenetic reproduction, sex and colour morphs. In this respect, DNA barcoding employing a 658 bp fragment of 5′ region of the mitochondrial cytochrome oxidase I (CO-I) gene is an effective tool in addressing the above. In the present study, we employed CO-I for discriminating 142 individuals representing 32 species of aphids from India. Sequence analyses revealed that the intraspecific and interspecific distances ranged from zero to 3.8% and 2.31 to 18.9%, respectively. In addition, the study also showed for the first time the prevalence of three cryptic species, namely Brevicoryne brassicae (Linnaeus), Hyperomyzus carduellinus (Theobald) and Brachycaudus helichrysi (Kaltenbach) from India. Our work has clearly demonstrated that DNA barcoding is an efficient and accurate method for identification of aphid species (including cryptic species), an approach that potentially could play an important role in formulating viable pest management strategies, more especially biocontrol.

Journal ArticleDOI
TL;DR: Findings indicate that aphid preference is influenced by VOC release from PLRV‐ or sham‐inoculated potato plants and that VOC emissions and Aphid preference depend upon the age at inoculation and leaf position within the potato plants.
Abstract: Green peach aphid, Myzus persicae (Sulzer) (Hemiptera: Aphididae), an important pest of potato (Solanum tuberosum L.) (Solanaceae), preferentially settles on Potato leafroll virus (PLRV)-infected potato plants as compared with non-infected ones, primarily in response to volatile organic compounds (VOCs) released by the plants. In this study, we examined the dynamics of these effects, measuring arrestment of apterous M. persicae in response to VOC from upper, middle, and lower leaflets of PLRV-infected potato plants at the same stage in disease progression (4 weeks after inoculation), but inoculated at 1, 3, or 5 weeks after transplanting (WAT). Sham-inoculated plants were used as controls and VOC were collected and quantified. Aphid arrestment was greater on PLRV-infected plants inoculated at 1 and 3 WAT as compared with sham-inoculated plants, but this preference was reversed in plants inoculated at 5 WAT. Relative arrestment of M. persicae by infected plants and VOC release was greater for lower and middle leaflets than for upper leaflets at 1 and 3 WAT compared to sham-inoculated plants. The reverse was observed in plants inoculated at 5 WAT. Findings indicate that aphid preference is influenced by VOC release from PLRV- or sham-inoculated potato plants and that VOC emissions and aphid preference depend upon the age at inoculation and leaf position within the potato plants. The implications of these dynamics in vector behavior for spread of PLRV in the field in natural and managed systems are discussed.

Journal ArticleDOI
TL;DR: Three species in particular (Illinoia liriodendri, Obolodiplosis robiniae and Phytoliriomyza jacarandae) were not previously found in the Iberian Peninsula.
Abstract: SummaryThe spread of invasive pests is an important topic in pest control and early detection is crucial for containment of invasive aliens. In this study the results of recent surveys on alien insects of ornamental urban plants in Portugal are reported. Overall, 13 alien species associated with allochthonous ornamental plants were recorded. Seven of these pests are new to the Portuguese fauna: Tinocallis kahawaluokalani (Kirkaldy); Illinoia liriodendri (Monell); Appendiseta robiniae (Gillette) (Hemiptera: Aphididae); Acizzia jamatonica (Kuwayama) (Hemiptera: Psyllidae); Dasineura gleditchiae (Osten Sacken); Obolodiplosis robiniae (Haldeman) (Diptera: Cecidomyiidae); and Phytoliriomyza jacarandae Steyskal & Spencer (Diptera: Agromyzidae). Additional distribution data are also provided for other recently introduced alien pests in Portugal: Myzocallis (Lineomyzocallis) walshii (Monell) (Hemiptera: Aphididae); Platycorypha nigrivirga Burckhardt; Glycaspis brimblecombei Moore (Hemiptera: Psyllidae); Calophya ...

Journal ArticleDOI
TL;DR: It is found no evidence that habitat diversification enhanced the biological control of green apple aphids compared to the control treatments, but the greater plant cover in FLOWER resulted in increased woolly apple aphid infestations compared to BAREgr or GRASS.
Abstract: Effects of habitat diversification through ground cover management on green apple aphids (Aphis spp.) (Hemiptera: Aphididae), woolly apple aphid (Eriosoma lanigerum [Haussmann]) (Hemiptera: Aphididae), their insect natural enemies and the most abundant canopy insects (in the Neuroptera, Fulgoromorpha, Cicadomorpha, Heteroptera, Coleoptera and Formicidae) were studied in an apple orchard over 6 years. The composition and diversity of the main functional groups of canopy insects was also compared. Habitat diversification was achieved by changing ground cover conditions within the orchard. In the treatment termed FLOWER, annual and/or perennial flowering plants were sown in the alleys of an apple orchard. Other ground cover treatments were weed-free bare ground (termed BAREgr) and orchard plots with alleys of mowed grass (termed GRASS), which served as control treatments. We found no evidence that habitat diversification enhanced the biological control of green apple aphids compared to the control t...

Journal ArticleDOI
TL;DR: The results from 2007 to 2011 indicate that KS4202 can support aphid populations with minimal yield loss at levels where significant yield loss would be expected in most other genotypes.
Abstract: The soybean aphid,Aphisglycines Matsumura, has become the most signiÞcant soybean (Glycine max (L.) Merrill) insect pest in the north central soybean production region of North America. The objectives of this research were to measure selected genotypes for resistance to the soybean aphid in the later vegetative and reproductive stages under Þeld conditions, and conÞrm the presence of tolerance in KS4202. The results from 2007 to 2011 indicate that KS4202 can support aphid populations with minimal yield loss at levels where signiÞcant yield loss would be expected in most other genotypes. The common Nebraska cultivar, OAsgrow 2703, appears to show signs of tolerance as well. None of the yield parameters were signiÞcantly different between the aphid infested and noninfested treatments. Based on our results, genotypes may compensate for aphid feeding in different ways. Asgrow 2703 appears to produce a similar number of seeds as its noninfested counterpart, although the seeds produced are slightly smaller. Field evaluation of tolerance in KS4202 indicated a yield loss of only 13% at 34,585Ð53,508 cumulative aphid-days, when 24 Ð36% yield loss would have been expected.

Journal ArticleDOI
TL;DR: Results suggested that the nylon net technique could be used to screen sorghum genotypes for resistance to M. sacchari, and some of the genotypes that exhibited resistance to aphid damage under field conditions showed comparatively higher rates of aphid increase than the susceptible check, Swarna in the clip cage assay, indicating that antixenosis could be one of the components of resistance to the pest.
Abstract: The sugarcane aphid Melanaphis sacchari (Zehnt.) has become a serious pest of sorghum, particularly during the post-rainy season in India and East and Southern Africa. Therefore, we tested a number of techniques to screen sorghum genotypes for their resistance to M. sacchari. Infesting the plants with aphid-infested leaf cuttings and covering with a nylon net was effective in screening sorghum genotypes for their resistance to M. sacchari. Sprinkling the plants with aphids (filled in an 0.5 ml eppendorf tube) in the greenhouse was also used to confirm whether the resistance of genotypes selected is less susceptible to the aphids under natural infestation. Nine genotypes (Line 61510, ICSV 12001, ICSV 12002, ICSV 12003, ICSV 12004, ICSV 12005, SLR 41, PU 10-1 and DJ 6514) exhibited moderate levels of resistance to M. sacchari. These genotypes also exhibited a lower rate of aphid multiplication in the clip cage and leaf disc assays. The rates of aphid multiplication were lower on the genotypes IS 21807, IS 40615, IS 40616 and IS 40618 than on the susceptible check, Swarna in the clip cage assay under the field conditions. Also, lower rates of aphid increase were also recorded on IS 21807 and IS 40615 in the leaf disc assay under laboratory conditions. Some of the genotypes that exhibited resistance to aphid damage under field conditions showed comparatively higher rates of aphid increase than the susceptible check, Swarna in the clip cage assay, indicating that antixenosis could be one of the components of resistance to M. sacchari in these genotypes. Therefore, the clip cage assay could be used to gain further understanding of the mechanisms of resistance to M. sacchari. There is a need to assess the role of antixenosis and colonization in genotypic reaction against M. sacchari to identify the lines with different mechanisms of resistance to this pest. The results suggested that the nylon net technique could be used to screen sorghum genotypes for resistance to M. sacchari. The genotypes exhibiting resistance to M. sacchari can be used to develop aphid-resistant sorghums for sustainable crop production.

Journal ArticleDOI
TL;DR: Results point towards a phloem‐localized factor for aphid resistance in H. bulbosum, i.e., on A17 plants the phloen salivation time is too short for a successful infection by BYDV leading to vector resistance.
Abstract: A Hordeum bulbosum L. (Poaceae) clone A17 was identified, which showed complete resistance to Barley yellow dwarf virus (BYDV) and Cereal yellow dwarf virus (CYDV). It was not possible to infect plants of A17 with BYDV-PAV, -MAV, or with CYDV-RPV by the aphid vectors Rhopalosiphum padi (L.) or Sitobion avenae (Fabricius) (both Hemiptera: Aphididae). Plants of the A17 clone and of the BYDV-susceptible H. bulbosum clone A21 revealed some resistance to R. padi compared to the susceptible winter barley cultivar Rubina [Hordeum vulgare L. (Poaceae)]. The development time to the imago was longer and the number of nymphs was reduced on both clones compared with cv. Rubina. The probing and feeding behaviour of R. padi on plants of the H. bulbosum clones was studied over 12 h and compared with that on plants of the barley cv. Rubina. Principal component analysis of the results of the feeding behaviour revealed a clear separation of the H. bulbosum genotypes from Rubina. On H. bulbosum the number of penetrations was higher but total feeding time was shorter. Significant differences were mainly found in the phloem feeding parameters for plants of both clones in comparison to Rubina, with the virus resistant A17 clone having the strongest effect and the susceptible A21 clone being intermediate. Most significant differences were found in parameters of the phloem salivation phase. On A17, an average of less than one (0.9) E1 phase per plant was observed (3.3 on A21 and 5.7 on Rubina) and its duration was reduced to less than 1 min (0.9 min) in comparison to 2.4 min on A21 and 5.7 min on Rubina. Also, the phloem feeding (E2) phase was clearly reduced on A17 plants with 0.5 E2 phases per test and a mean duration of 1.1 min in contrast with 2.9 and 3.5 E2 phases per test and 34.1 and 421.3 min for A21 and Rubina, respectively. These results point towards a phloem-localized factor for aphid resistance in H. bulbosum, i.e., on A17 plants the phloem salivation time is too short for a successful infection by BYDV leading to vector resistance.

Journal ArticleDOI
TL;DR: The aphids' responses to the two plant pathogens individually is consistent with the alteration in plant nutrient content by infection and also the induction of different plant defence pathways and the possible cross‐talk between them.
Abstract: Phytophagous insects have to contend with a wide variation in food quality brought about by a variety of factors intrinsic and extrinsic to the plant. One of the most important factors is infection by plant pathogenic fungi. Necrotrophic and biotrophic plant pathogenic fungi may have contrasting effects on insect herbivores due to their different infection mechanisms and induction of different resistance pathways, although this has been little studied and there has been no study of their combined effect. We studied the effect of the biotrophic rust fungus Uromyces viciae-fabae (Pers.) Schroet (Basidiomycota: Uredinales: Pucciniaceae) and the necrotrophic fungus Botrytis cinerea Pers. (Ascomycota: Helotiales: Sclerotiniaceae) singly and together on the performance of the aphid Aphis fabae Scop. (Hemiptera: Aphididae) on Vicia faba (L.) (Fabaceae). Alone, botrytis had an inhibitory effect on individual A. fabae development, survival and fecundity, while rust infection consistently enhanced individual aphids’ performance. These effects varied in linear relation to lesion or pustule density. However, whole-plant infection by either pathogen resulted in a smaller aphid population of smaller aphids than on uninfected plants, indicating a lowering of aphid carrying capacity with infection. When both fungi were applied simultaneously to a leaf they generally cancelled the effect of each other out, resulting in most performance parameters being similar to the controls, although fecundity was reduced. However, sequential plant infection (pathogens applied five days apart) led to a 70% decrease in fecundity and 50% reduction in intrinsic rate of increase. The application of rust before botrytis had a greater inhibitory effect on aphids than applying botrytis before rust. Rust infection increased leaf total nitrogen concentration by 30% while infection by botrytis with or without rust led to a 38% decrease. The aphids’ responses to the two plant pathogens individually is consistent with the alteration in plant nutrient content by infection and also the induction of different plant defence pathways and the possible cross-talk between them. This is the first demonstration of the complex effects of the dual infection of a plant by contrasting pathogens on insect herbivores. Key words: Vicia faba, Botrytis cinerea, Uromyces viciae-fabae, tripartite interactions, induced resistance

Journal ArticleDOI
TL;DR: It is demonstrated that any strategy to control A. gossypii and manage pirimicarb resistance should target A. tournaisianii strains of all MLG types residing on any plant species and not just cotton.
Abstract: Background Aphis gossypii is an important pest of cotton that has developed resistance to many chemicals used for its control. Any lack of understanding of its genetic structure, resistance status and host plant specialisation hampers effective management. Rsults Eight microsatellite markers were genotyped for a collection of Australian A. gossypii field isolates from 55 plant species from major Australian cotton-producing regions. The aphid's pirimicarb resistance status linked to the ACE1 (acetylcholinesterase) S431F mutation was determined by PCR-RFLP. Overall, the genetic diversity was low and there were only 13 multilocus genotype (MLG) groups found in a total of 936 aphids, suggesting asexual reproduction. Three MLGs (Aust-01, Aust-02 and Aust-04) represented 78% of all aphids tested. MLGs Aust-01 (41%) and Aust-02 (18%) were linked to the ACE1 S431F mutation and found on cotton and a range of hosts. Aust-04 (19%) hosted mainly on cotton (but also Asteraceae and Malvaceae) was predominantly susceptible to pirimicarb. Given their abundance and widespread occurrence, these three clones were considered to be superclones. Conclusion The study demonstrated that any strategy to control A. gossypii and manage pirimicarb resistance should target A. gossypii strains of all MLG types residing on any plant species and not just cotton.© 2012 Society of Chemical Industry

Journal ArticleDOI
TL;DR: The results pointed Jaen, Almuden, and Raza cultivars as the least suitable host plants, indicating that they were the most resistant to M. persicae among the cultivars the authors tested.
Abstract: Green peach aphids, Myzus persicae (Sulz.) (Hemiptera: Aphididae), obtained from pepper fields, were colonized on susceptible pepper plants in a growth chamber. The development, survivorship, and life table parameters of the green peach aphid were evaluated on nine peppers cultivars as follows: Almuden, Bilano, Bird, Cabezo, de la Sierra, Eppo, Jaen, Raza, and Yatasto at controlled conditions (20 ± 1°C; about 70% RH; 14h photophase). The development times of immatures ranged from 6.1 days on Yatasto to 11.4 days on Jaen, whereas immature survival was close to 100% on all cultivars. The intrinsic rate of increase (r m ) for green peach aphid on Bilano and Yatasto were the highest. Jackknife estimates of r m varied from 0.281 to 0.174 females/female/day on Yatasto and Jaen, respectively. The mean population generation times (T) on these hosts ranged from 13.7 to 22.7 days. The highest net reproductive rates (R 0 ) were on Bird and Bilano (63.8 and 62.89 females/female/generation, respectively) and the lowest on De la Sierra and Almuden (34.1 and 38.7, respectively). Because of the high coefficient of determination (R 2) values in Gompertz and Weibul models, survival data from different cultivars had a good fit to both models. The results pointed Jaen, Almuden, and Raza cultivars as the least suitable host plants, indicating that they were the most resistant to M. persicae among the cultivars we tested.

Journal ArticleDOI
TL;DR: This study shows that being able to feed on a plant not automatically implies that a population can successfully develop on that plant, because aphids showed phloem ingestion during the 8‐h recording period on resistant lettuce, but were not able to survive and reproduce on the same lettuce line.
Abstract: When crops are bred for resistance to herbivores, these herbivores are under strong selection pressure to overcome this resistance, which may result in the emergence of virulent biotypes. This is a growing problem for crop species attacked by aphids. The Nr-gene in lettuce confers near-complete resistance against the black currant-lettuce aphid, Nasonovia ribisnigri (Mosely) (Hemiptera: Aphididae). Since 2007, populations of N.ribisnigri have been reported in several locations in Europe to infest resistant lettuce varieties that possess the Nr-gene. The objective of this study was to analyse the behaviour and level of virulence of several N.ribisnigri populations observed to have colonized Nr-locus-containing lettuce lines. We analysed the stylet penetration and feeding behaviour, and the performance of these N.ribisnigri populations on resistant and susceptible lettuce lines. Large variation in the degree of virulence to the Nr-locus-containing lettuce lines was found among populations of the Nr:1 biotype. The German population was highly virulent on the Nr-containing resistant lettuce lines, and showed similar feeding behaviour and performance on both the susceptible and resistant lettuces. The French population from Paris was the second most virulent, though reproduction on the resistant lines was reduced. The French population from Perpignan and a population from Belgium, however, showed reduced performance and feeding rate on the resistant compared to the susceptible lettuces. The lettuce background in which the Nr-gene is expressed influences the level of resistance to the various Nr:1 aphid populations, because the performance and feeding behaviour differed between the aphids on the cultivars (romaine lettuce) compared to the near-isogenic lines (butterhead/iceberg lettuce). This study also shows that being able to feed on a plant not automatically implies that a population can successfully develop on that plant, because aphids showed phloem ingestion during the 8-h recording period on resistant lettuce, but were not able to survive and reproduce on the same lettuce line.

Journal ArticleDOI
TL;DR: Important events in aphids included fungal penetration of the integument of the less-resistant leg intersegmental membrane and invasion of natural openings, formation of hyphal bodies in live aphids by three days post-inoculation (PI), and extensive hyphal colonization of the two leg segments closest to the insect body at death of the aphids.
Abstract: Histopathogenesis of living insects of Myzus persicae Sulzer (Hemiptera: Aphididae) and Phenacoccus manihoti Matile‐Ferrero (Hemiptera: Pseudococcidae) by Beauveria bassiana (Balsamo) Vuillemin (Ascomycota: Hypocreales) was monitored from penetration through insect death. Important events in aphids included fungal penetration of the integument of the less-resistant leg intersegmental membrane and invasion of natural openings, formation of hyphal bodies in live aphids by three days post-inoculation (PI), and extensive hyphal colonization of the two leg segments closest to the insect body at death of the aphids. Confocal microscopy of green fluorescent protein-labeled B. bassiana in live mealybugs indicated the fungus penetrated the host through the legs and mouthparts. The fungus was scarce in live mealybugs at 1–5 days PI, formed hyphal bodies by six days PI, and growth was limited to parts of dead hosts at 6–7 days PI. In dead mealybugs, hyphal bodies were near solid tissue. Blastospores were in the hemolymph.

Journal ArticleDOI
TL;DR: Although infestation caused a reduction in the grain yield of the three cultivars, this effect was lower for BRS Timbaúva, and the cultivar Embrapa 16 supported higher infestations and was more tolerant to damage than the BRS Guabiju.
Abstract: Among the aphids associated with wheat and other winter cereals, Rhopalosiphum padi (L.) is currently the predominant species in the wheat growing region of southern Brazil. The damage caused by this aphid occurs by direct feeding and/or by the transmission of pathogenic viruses, such as the Barley/Cereal yellow dwarf virus. In order to estimate the direct damage caused by R. padi on wheat, we evaluated the population growth of this aphid during the tillering and elongation stages and its effects on grain yield components. The experiment was conducted in a screenhouse with three wheat cultivars (BRS Guabiju, BRS Timbauva, and Embrapa 16). The effect of a period of 16 days, starting from an infestation of 40 aviruliferous aphids/plant, was evaluated and compared to non-infested plants. In both stages, the population growth of R. padi was lower on the BRS Timbauva. Although infestation caused a reduction in the grain yield of the three cultivars, this effect was lower for BRS Timbauva. The cultivar Embrapa 16 supported higher infestations and was more tolerant to damage than the BRS Guabiju.

Journal ArticleDOI
TL;DR: A ‘generalist’ population obtained from cucumber, sweet pepper, citrus, eggplant and okra which exhibited statistically better development on cotton; versus a population from cotton which, by comparison on reciprocal hosts, developed poorly on non-natal hosts except on eggplant.
Abstract: The aphid, Aphis gossypii, is a primary pest of citrus, cotton, cucurbits and greenhouse-grown vegetables in Turkey and throughout Europe. There is some previous empirical data suggesting that host-adapted genotypes of this aphid exist which may in fact be host-races. To determine if host races of A. gossypii are indeed present in the eastern Mediterranean region of Turkey, reciprocal host transfer experiments and life table analyses were performed with multiple asexual lineages (= clones) of the aphid collected from different hosts. The collection hosts included citrus, cucumber, eggplant, okra, sweet pepper and cotton. Aphid developmental times on the host from which the aphid was originally collected (= collection or natal host) were shorter (5.2–6.0 days) and had a higher intrinsic rate of population growth (rm = 0.25–0.44) than the 6.6–7.3 days required when the aphid was reared on a non-original collection host (= non-collection host or non-natal host) and had rm = 0.03–0.30. Total immature mortality of the cotton clone, especially in the first nymphal stage, was high (51–100%) with low rm (0–0.03) on cucumber, citrus and sweet pepper. Aphid populations transferred from citrus, eggplant and okra to cotton (rm = 0.29–0.30) did not differ significantly in their performance from that of the cotton population on cotton (rm = 0.34), whereas that from sweet pepper and cucumber populations (rm = 0.22–0.24) were significantly lower. These data have allowed us to separate A. gossypii into two distinct biological groups: (a) a ‘generalist’ population obtained from cucumber, sweet pepper, citrus, eggplant and okra which exhibited statistically better development on cotton; versus (b) a population from cotton which, by comparison on reciprocal hosts, developed poorly on non-natal hosts except on eggplant. Development of the cotton clone on cucumber and okra was not improved after four successive generations on the non-natal host. The good development of A. gossypii from eggplant and cotton on these reciprocal hosts suggests that these particular clones were similar, if not identical, host races.