Occurrence of Beet western yellows virus and its aphid vectors in over-summering broad-leafed weeds and volunteer crop plants in the grainbelt region of south-western Australia

2006 ◽  
Vol 57 (9) ◽  
pp. 975 ◽  
Author(s):  
B. A. Coutts ◽  
J. R. Hawkes ◽  
R. A. C. Jones
Keyword(s):  
Western Australia ◽  
Acyrthosiphon Pisum ◽  
Citrullus Lanatus ◽  
Aphid Species ◽  
Crop Plants ◽  
Lipaphis Erysimi ◽  
Raphanus Raphanistrum ◽  
Weed Species ◽  
Beet Western Yellows Virus ◽  
Volunteer Crop

During the summer periods of 2000, 2001, and 2002, presence of Beet western yellows virus (BWYV) was assessed in tests on samples from at least 12 broad-leafed weed species and 5 types of volunteer crop plants growing in the grainbelt region of south-western Australia. In 2000, BWYV was detected in 2 of 35 sites in 2% of 1437 samples, whereas in 2001 and 2002 the corresponding figures were 3 of 108 sites in 0.04% of 8782 samples, and 1 of 30 sites in 0.08% of 2524 samples, respectively. The sites with infection were in northern, central, and southern grainbelt districts, and in high and medium rainfall zones. The hosts in which BWYV was detected were the weeds Citrullus lanatus (Afghan or wild melon), Conzya spp. (fleabane), Navarretia squarrosa (stinkweed), and Solanum nigrum (blackberry nightshade), and the volunteer crop plant Brassica napus (canola). Small populations of aphids were found over-summering at 28% (2000), 4% (2001), and 17% (2002) of sites, mostly infesting volunteer canola and Raphanus raphanistrum (wild radish). They occurred in high, medium, and low rainfall zones, but were only found in central and southern grainbelt districts. The predominant aphid species found was Brevicoryne brassicae, with Acyrthosiphon pisum, Brachycaudus helichrysi, Hyperomyzus lactucae, Lipaphis erysimi, Myzus persicae, and Uroleucon sonchi present occasionally. The importance of these findings in relation to the epidemiology and control of BWYV in the grainbelt is discussed.

scholarly journals Genetic Diversity and Potential Vectors and Reservoirs of Cucurbit aphid-borne yellows virus in Southeastern Spain

2013 ◽  
Vol 103 (11) ◽  
pp. 1188-1197 ◽  
Author(s):  
Mona A. Kassem ◽  
Miguel Juarez ◽  
Pedro Gómez ◽  
Carmen M. Mengual ◽  
Raquel N. Sempere ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Aphis Gossypii ◽  
Purifying Selection ◽  
Aphid Species ◽  
Open Reading Frames ◽  
Weed Species ◽  
Nucleotide Substitutions ◽  
Multiple Introductions ◽  
Spatial And Temporal Scales ◽  
Southeastern Spain

The genetic variability of a Cucurbit aphid-borne yellows virus (CABYV) (genus Polerovirus, family Luteoviridae) population was evaluated by determining the nucleotide sequences of two genomic regions of CABYV isolates collected in open-field melon and squash crops during three consecutive years in Murcia (southeastern Spain). A phylogenetic analysis showed the existence of two major clades. The sequences did not cluster according to host, year, or locality of collection, and nucleotide similarities among isolates were 97 to 100 and 94 to 97% within and between clades, respectively. The ratio of nonsynonymous to synonymous nucleotide substitutions reflected that all open reading frames have been under purifying selection. Estimates of the population's genetic diversity were of the same magnitude as those previously reported for other plant virus populations sampled at larger spatial and temporal scales, suggesting either the presence of CABYV in the surveyed area long before it was first described, multiple introductions, or a particularly rapid diversification. We also determined the full-length sequences of three isolates, identifying the occurrence and location of recombination events along the CABYV genome. Furthermore, our field surveys indicated that Aphis gossypii was the major vector species of CABYV and the most abundant aphid species colonizing melon fields in the Murcia (Spain) region. Our surveys also suggested the importance of the weed species Ecballium elaterium as an alternative host and potential virus reservoir.

scholarly journals Intraspecific variation in immune gene expression and heritable symbiont density

2021 ◽  
Vol 17 (4) ◽  
pp. e1009552
Author(s):  
Holly L. Nichols ◽  
Elliott B. Goldstein ◽  
Omid Saleh Ziabari ◽  
Benjamin J. Parker
Keyword(s):  
Gene Expression ◽  
Acyrthosiphon Pisum ◽  
Aphid Species ◽  
F1 Hybrids ◽  
Immune Gene ◽  
Immune Genes ◽  
Immune Mechanisms ◽  
Immune Gene Expression ◽  
Host Microbe Interactions ◽  
And Function

Host genetic variation plays an important role in the structure and function of heritable microbial communities. Recent studies have shown that insects use immune mechanisms to regulate heritable symbionts. Here we test the hypothesis that variation in symbiont density among hosts is linked to intraspecific differences in the immune response to harboring symbionts. We show that pea aphids (Acyrthosiphon pisum) harboring the bacterial endosymbiontRegiella insecticola(but not all other species of symbionts) downregulate expression of key immune genes. We then functionally link immune expression with symbiont density using RNAi. The pea aphid species complex is comprised of multiple reproductively-isolated host plant-adapted populations. These ‘biotypes’ have distinct patterns of symbiont infections: for example, aphids from theTrifoliumbiotype are strongly associated withRegiella. Using RNAseq, we compare patterns of gene expression in response toRegiellain aphid genotypes from multiple biotypes, and we show thatTrifoliumaphids experience no downregulation of immune gene expression while hostingRegiellaand harbor symbionts at lower densities. Using F1 hybrids between two biotypes, we find that symbiont density and immune gene expression are both intermediate in hybrids. We propose that in this system,Regiellasymbionts are suppressing aphid immune mechanisms to increase their density, but that some hosts have adapted to prevent immune suppression in order to control symbiont numbers. This work therefore suggests that antagonistic coevolution can play a role in host-microbe interactions even when symbionts are transmitted vertically and provide a clear benefit to their hosts. The specific immune mechanisms that we find are downregulated in the presence ofRegiellahave been previously shown to combat pathogens in aphids, and thus this work also highlights the immune system’s complex dual role in interacting with both beneficial and harmful microbes.

scholarly journals WEEDS AS POTENTIAL HOSTS FOR FUNGAL ROOT PATHOGENS OF WATERMELON

2019 ◽  
Vol 32 (1) ◽  
pp. 1-6 ◽  
Author(s):  
Rui Sales Júnior ◽  
Ana Paula Medeiros dos Santos Rodrigues ◽  
Andreia Mitsa Paiva Negreiros ◽  
Márcia Michelle de Queiroz Ambrósio ◽  
Hailton da Silva Barboza ◽  
...  
Keyword(s):  
Root Rot ◽  
Citrullus Lanatus ◽  
Phytopathogenic Fungi ◽  
Soilborne Pathogens ◽  
Weed Species ◽  
Amaranthus Spinosus ◽  
Trianthema Portulacastrum ◽  
Different Types ◽  
Vine Decline ◽  
Boerhavia Diffusa

ABSTRACT Many watermelon (Citrullus lanatus) diseases are caused by soilborne pathogens in Brazil and worldwide. The goal of this study was to identify and quantify the frequency of phytopathogenic fungi associated with watermelon root rot and vine decline that were also present in the roots of weeds in the major watermelon production regions in the state of Rio Grande do Norte, Brazil. We collected root samples from 10 of the most prevalent weed species in 16 watermelon producing areas. The plants were identified and their frequencies in the fields were calculated. The fungi found in the weed roots were isolated and the main genera associated with watermelon vine decline were identified. We identified 13 weed species belonging to nine botanical families. The weed species with the highest frequencies found in the field were Amaranthus spinosus (25.0%), Trianthema portulacastrum (18.8%), Commelina sp. (18.8%), and Boerhavia diffusa (12.5%). The fungi Macrophomina, Rhizoctonia, and Monosporascus were isolated from the roots of the weed plants. While Macrophomina was isolated from 12 different types of plants, Rhizoctonia and Monosporascus were isolated from four and two different plant species, respectively.

The effect of short-term aphid feeding on the partitioning of 14CO2 photoassimilate in three legume species

1987 ◽  
Vol 65 (4) ◽  
pp. 666-672 ◽  
Author(s):  
C. D. B. Hawkins ◽  
M. I. Whitecross ◽  
M. J. Aston
Keyword(s):  
Acyrthosiphon Pisum ◽  
Aphid Species ◽  
Unit Weight ◽  
Short Term ◽  
Garden Pea ◽  
Aphis Craccivora Koch ◽  
Aphid Feeding ◽  
Lateral Branches ◽  
Species Specific ◽  
Partitioning Pattern

The short-term effects of the feeding of cowpea aphids (Aphis craccivora Koch) and pea aphids (Acyrthosiphon pisum (Harris)), both Homoptera: Aphididae, on 14C translocation and plant growth of broadbean (Vicia faba L. cv. Aquadulce), cowpea (Vigna unguiculata (L.) Walp. cv. Caloona), and garden pea (Pisum sativum L. cv. Victory Freezer) seedlings were investigated, but not all plant–aphid combinations were utilized. Within 10 days of infestation, aphid feeding reduced the flux of translocate to the roots, changed the assimilate partitioning pattern in affected shoots, and apparently induced assimilate sources to become assimilate sinks. Cowpea aphid feeding also caused more lateral branches to be formed in broadbean. Some of these effects may be related to the imbibing of translocate by aphids, while other effects may result from a series of interactions involving substances in the saliva of aphids, plant hormones, and the assimilate ratio of sources–sinks. The amount of radioactivity found per unit weight of aphid tissue increased between days 5 and 10 in all four plant–aphid combinations. This may indicate that the nymphs were incapable of feeding on the larger phloem elements. Except for the decreased rate of translocation to the roots, the effect of aphid feeding on translocation is plant–aphid species specific.

scholarly journals Relative toxicity of some insecticides and azadirachtin against four crop infesting aphid species

1970 ◽  
Vol 27 ◽  
pp. 31-34
Author(s):  
M Khalequzzaman ◽  
Jesmun Nahar
Keyword(s):  
Myzus Persicae ◽  
Aphis Gossypii ◽  
Aphid Species ◽  
Aphis Craccivora ◽  
Lipaphis Erysimi ◽  
Relative Toxicity ◽  
Plant Origin ◽  
Residual Film ◽  
Aphis Gossypii Glover ◽  
Aphis Craccivora Koch

Indirect application was used to assay the toxicity of five insecticides; viz. malathion, carbosulfan, cymbush, imidacloprid and azadirachtin against four important crop infesting aphid species, Aphis craccivora Koch, Aphis gossypii Glover, Myzus persicae (Sulzer) and Lipaphis erysimi (Kaltenbach), reared on bean, brinjal, potato and cauliflower plants respectively. Residual film technique was applied by bringing leaves with tested aphids of the vegetable plants in the laboratory. Malathion was the least toxic to all aphids having LC50 as 327.97, 333.92, 305.26 and 313.77 μg cm-2 for A. craccivora, A. gossypii, M. persicae and M. persicae respectively. Cypermethrin was the most toxic showing LC50 as 12.55, 12.29, 12.55 and 12.10 μg cm-2 in the above mentioned species of aphid respectively. Carbosulfan and imidacloprid showed moderate toxicity. Azadirachtin as a natural plant origin insecticide proved to be the most toxic having LC50 as 0.41 μg cm-2 for A. craccivora, 0.34 μg cm-2 for A. gossypii and 0.44 μg cm-2 for both M. persicae and L. erysimi. Key words: Insecticide, toxicity, azadirachtin, Aphis craccivora, Aphis gossypii, Myzus persicae, Lipaphis erysimi   doi:10.3329/ujzru.v27i0.1950 Univ. j. zool. Rajshahi Univ. Vol. 27, 2008 pp. 31-34

scholarly journals SELECTIVITY OF SAFLUFENACIL APPLIED SINGLY AND IN COMBINATION WITH GLYPHOSATE ON COFFEE AND CITRUS CROPS

2016 ◽  
Vol 29 (1) ◽  
pp. 45-53 ◽  
Author(s):  
CLEBSON GOMES GONÇALVES ◽  
ANTONIO CARLOS DA SILVA JUNIOR ◽  
MARIA RENATA ROCHA PEREIRA ◽  
SIDNEI ROBERTO MARCHI ◽  
DAGOBERTO MARTINS
Keyword(s):  
Sandy Soil ◽  
Chemical Treatment ◽  
Crop Plants ◽  
Plant Leaves ◽  
Weed Species ◽  
Chemical Treatments ◽  
Randomized Design ◽  
Completely Randomized Design ◽  
Leaves And Roots

ABSTRACT: Saflufenacil is absorbed by the plant leaves and roots, thus the residual permanence of this herbicide can cause losses to the crop plants. Therefore, the objective of this study was to evaluate the selectivity of the saflufenacil herbicide, applied singly and in combination with glyphosate, on coffee and citrus plants grown in a sandy soil. Two experiments were implemented and conducted in completely randomized design with four replications. The chemical treatments consisted of three sequential applications, with directed spraying of saflufenacil at rates of 0.035, 0.07 and 0.105 kg a.i. ha-1, glyphosate at rate of 2.160 kg a.e. ha-1, the two herbicides combined at the same rates, and a control without chemical treatment. The saflufenacil applied singly and in combination with glyphosate was selective for coffee and citrus plants, which presented no visual toxicity symptoms. The sequential application of saflufenacil, singly and in combination with glyphosate did not affect the growth of coffee and citrus plants. The saflufenacil has potential for use, in combination with glyphosate on controlling many weed species in coffee and citrus areas without any interference on the development of these species.

scholarly journals Diversity of aphids (Hemiptera: Aphididae) associated with potato crop in Tizi-Ouzou (North of Algeria), with new records

2021 ◽  
Vol 117 (1) ◽  
pp. 1
Author(s):  
Samia AIT AMAR ◽  
Karima BENOUFELLA-KITOUS
Keyword(s):  
Myzus Persicae ◽  
New Records ◽  
Potato Crop ◽  
Abundant Species ◽  
Aphid Species ◽  
Crop Plants ◽  
Yellow Traps ◽  
First Time ◽  
Sampling Season ◽  
Brachycaudus Helichrysi

<p>Aphids are among the phytophagous pests that cause serious damage to crop plants. In Northern Algeria, we have little information on their diversity. In this context, the study of the diversity of aphids was carried out in three regions of Tizi-Ouzou (North of Algeria) namely Tizi-Ouzou center, Tizi-Rached and Aghribs on the potato crop using yellow traps. The results showed a total richness of 65 aphid species, divided into 36 genera, 9 tribes and 8 sub-families, of which 11 species were identified for the first time in Algeria. These are <em>Aphis coreopsidis</em> (Thomas, 1878), <em>Capitophorus hippophae</em> (Walker, 1852), <em>Cavariella theobaldi </em>(Gillette &amp; Bragg, 1918), <em>Hyadaphis coriandri </em>(B. Das, 1918), <em>Macrosiphoniella linariae </em>(Koch, 1855),<em>Monelliopsis pecanis </em>Bissell, 1983, <em>Myzus hemerocallis</em> Takahashi, 1921, <em>Pseudoregma panicola </em>(Takahashi, 1921), <em>Rhopalosiphoninus staphyleae</em> (Koch, 1854), <em>Schizaphis eastopi</em> Van Harten &amp; Ilharco, 1971 and <em>Ovatus inulae </em>(Walker, 1849)<em>. </em>The field located in the center of Tizi-Ouzou is the richest with 55 species, followed by the field of Tizi-Rached with 30 species, and 24 species have been recorded in Aghribs. During the sampling season, <em>Hyperomyzus lactucae</em> (Linnaeus, 1758) and <em>Brachycaudus helichrysi</em> (Kaltenbach, 1843)  are the most abundant species with 24.44 % and 21.8 % respectively. Three aphid species have been observed on potato leaves, namely <em>Macrosiphum</em> <em>euphorbiae</em> (Thomas, 1878), <em>Aphis</em> <em>gossypii</em> Glover, 1877  and <em>Myzus persicae</em> (Sulzer, 1776). The latter species was observed in all three study regions.</p>

scholarly journals Epiphytic strains of Pseudomonas syringae kill diverse aphid species.

2021 ◽  
Author(s):  
Melanie R. Smee ◽  
Imperio Real-Ramirez ◽  
Catalina Zuluaga Arias ◽  
Tory A. Hendry
Keyword(s):  
Biological Control ◽  
Pseudomonas Syringae ◽  
Plant Pathogens ◽  
Acyrthosiphon Pisum ◽  
Rhopalosiphum Padi ◽  
Aphid Species ◽  
Pea Aphid ◽  
Oral Exposure ◽  
Pest Species ◽  
Epiphytic Bacteria

Interactions between epiphytic bacteria and herbivorous insects are ubiquitous on plants, but little is known about their ecological implications. Aphids are devastating crop pests worldwide, and so understanding how epiphytic bacteria impact aphid populations is critically important. Recent evidence demonstrates that plant-associated bacteria, such as Pseudomonas syringae, can be highly virulent to one species of aphid, the pea aphid (Acyrthosiphon pisum). Yet currently we have no knowledge on how broad this phenomenon is across diverse aphid species that are of high agricultural concern. In controlled experiments using oral exposure in artificial diet, we challenged five aphid species of agricultural importance with three strains of P. syringae that vary in virulence to the pea aphid. These strains also vary in epiphytic ability and comprise two phytopathogens and one non-plant pathogenic strain. In general, differences in virulence to aphids remained relatively constant across strains regardless of the aphid species, except for the bird cherry-oat aphid (Rhopalosiphum padi) which is significantly less susceptible to two P. syringae strains. We demonstrate that lower infection incidence likely plays a role in the reduced susceptibility. Importantly, these data support previous results showing that interactions with epiphytic bacteria are important for aphids and may play a large, but underappreciated, role in insect population dynamics. Our study illustrates a potential role of epiphytic bacteria in the biological control of aphid pests broadly, but suggests the need for more research encompassing a greater diversity of pest species. Importance Sap-sucking aphids are insects of huge agricultural concern, not only because of direct damage caused by feeding, but also because of their ability to transmit various plant pathogens. Some bacteria that grow on leaf surfaces, such as Pseudomonas syringae, can infect and kill aphids, making them potentially useful in biological control of pest aphids. However, only one aphid species, the pea aphid (Acyrthosiphon pisum) has been tested for infection by P. syringae. Here we challenged five aphid species of agricultural importance with three strains of P. syringae that vary in virulence to the pea aphid. We found that four of these aphid species were susceptible to infection and death, suggesting that these bacteria could be broadly useful for biological control. However, one aphid species was much more resistant to infection, indicating that more testing on diverse aphid species is needed.

scholarly journals Seed Shattering: A Trait of Evolutionary Importance in Plants

2021 ◽  
Vol 12 ◽  
Author(s):  
Aniruddha Maity ◽  
Amrit Lamichaney ◽  
Dinesh Chandra Joshi ◽  
Ali Bajwa ◽  
Nithya Subramanian ◽  
...  
Keyword(s):  
Plant Species ◽  
Management Practices ◽  
Future Research ◽  
Raphanus Raphanistrum ◽  
Weed Species ◽  
Management Options ◽  
Seed Shattering ◽  
Seed Retention ◽  
Management Regimes ◽  
Crop Harvest

Seed shattering refers to the natural shedding of seeds when they ripe, a phenomenon typically observed in wild and weedy plant species. The timing and extent of this phenomenon varies considerably among plant species. Seed shattering is primarily a genetically controlled trait; however, it is significantly influenced by environmental conditions, management practices and their interactions, especially in agro-ecosystems. This trait is undesirable in domesticated crops where consistent efforts have been made to minimize it through conventional and molecular breeding approaches. However, this evolutionary trait serves as an important fitness and survival mechanism for most weeds that utilize it to ensure efficient dispersal of their seeds, paving the way for persistent soil seedbank development and sustained future populations. Weeds have continuously evolved variations in seed shattering as an adaptation under changing management regimes. High seed retention is common in many cropping weeds where weed maturity coincides with crop harvest, facilitating seed dispersal through harvesting operations, though some weeds have notoriously high seed shattering before crop harvest. However, high seed retention in some of the most problematic agricultural weed species such as annual ryegrass (Lolium rigidum), wild radish (Raphanus raphanistrum), and weedy amaranths (Amaranthus spp.) provides an opportunity to implement innovative weed management approaches such as harvest weed seed control, which aims at capturing and destroying weed seeds retained at crop harvest. The integration of such management options with other practices is important to avoid the rapid evolution of high seed shattering in target weed species. Advances in genetics and molecular biology have shown promise for reducing seed shattering in important crops, which could be exploited for manipulating seed shattering in weed species. Future research should focus on developing a better understanding of various seed shattering mechanisms in plants in relation to changing climatic and management regimes.

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