Showing papers on "Myzus persicae published in 2004"
TL;DR: Se can protect plants from feeding by aphids at leaf levels two orders of magnitude lower than those found in hyperaccumulators in the field, shed light on the possible functional significance of Se hyperaccUMulation.
Abstract: Summary
• Certain plant species hyperaccumulate selenium (Se) to 1000 mg kg−1 d. wt, even from low-Se soils. It is not known whether Se hyperaccumulation offers these plants any advantage. In this study the hypothesis was tested that Se can protect plants from phloem-feeding herbivores.
• Indian mustard (Brassica juncea) grown with or without Se was subjected to colonization by green peach aphids (Myzus persicae).
• In choice feeding experiments the aphids clearly avoided Se-containing plant material, and were able to detect and avoid Se-containing leaves with levels as low as 10 mg Se kg−1 d. wt. In nonchoice feeding experiments aphid population growth was inversely correlated with leaf Se concentration. The leaf Se concentration leading to a 50% reduction in aphid population growth was 1.5 mg kg−1 d. wt, and ≥ 10 mg Se kg−1 d. wt was lethal.
• In summary, Se can protect plants from feeding by aphids at leaf levels two orders of magnitude lower than those found in hyperaccumulators in the field. These results shed light on the possible functional significance of Se hyperaccumulation.
198 citations
TL;DR: The lack of behavioral response of the ladybird at short distance toward the cruciferous specialist aphid was related only to the absence of (E)-β-farnesene in the aphid prey volatile pattern.
Abstract: The volatiles released from several aphid and host plant species, alone or associated, were studied for their infochemical role in prey location. Using a four-arm olfactometer, the attraction of several combinations of three aphid (Myzus persicae, Acyrthosiphon pisum, and Brevicoryne brassicae) and three plant (Vicia faba, Brassica napus, and Sinapis alba) species toward Adalia bipunctata larvae and adults was observed. Both predatory larvae and adults were attracted only by A. pisum and M. persicae when they were crushed, whatever the host plant. (E)-beta-farnesene, the aphid alarm pheromone, was the effective kairomone for the ladybird. Plant leaves alone (V. faba, B. napus, and S. alba) or in association with nonstressed whole aphids (the three species) did not have any attraction for the predator. The B. brassicae specialist aphid is the only prey that was not attracted to A. bipunctata larvae and adults, even if they were crushed. Release of B. brassicae molecules similar to the host plant allelochemicals was demonstrated by GC-MS analysis. The lack of behavioral response of the ladybird at short distance toward the cruciferous specialist aphid was related only to the absence of (E)-beta-farnesene in the aphid prey volatile pattern.
186 citations
TL;DR: Two mutations in the ace1 gene of Aphis gossypii are associated with insensitivity of acetylcholinesterase (AChE) to carbamate and organophosphate insecticides, providing a molecular explanation of why pirimicarb has a specific aphicidal action.
Abstract: We have identified two mutations in the ace1 gene of Aphis gossypii that are associated with insensitivity of acetylcholinesterase (AChE) to carbamate and organophosphate insecticides. The first of these, S431F (equivalent to F331 in Torpedo californica), is associated with insensitivity to the carbamate insecticide pirimicarb in a range of A. gossypii clones. The S431F mutation is also found in the peach-potato aphid, Myzus persicae (Sulzer), and a rapid RFLP diagnostic allows the identification of individuals of both aphid species with a resistant genotype. This diagnostic further revealed the presence of S431 in several other pirimicarb-susceptible aphid species. The serine at this position in the wild-type enzyme has only been reported for aphids and provides a molecular explanation of why pirimicarb has a specific aphicidal action. A less specific insensitivity to a wide range of carbamates and organophosphates is associated with a second mutation, A302S (A201 in T. californica).
132 citations
TL;DR: The results suggest that a greenhouse integrated pest management (IPM) program using a botanical such as UDA-245 could effectively control infestations of major pests present while having a negligible effect on biological control agents.
Abstract: The emulsifiable concentrate UDA-245 based on an essential oil extract from Chenopodium ambrosioides variety near ambrosioides, a North American herbaceous plant, was compared with commercially available pesticides for their effectiveness to control green peach aphid, Myzus persicae (Sulzer) (Homoptera: Aphididae), western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), and greenhouse whitefly, Trialeurodes vaporariorium (Westwood) (Homoptera: Aleyrodidae). Side effects on the whitefly parasitoid Encarsia formosa Gahan (Hymenoptera: Aphelinidae) also were determined. With green peach aphid, UDA-245 at 0.5% concentration was significantly more effective than the control (water) treatment in a laboratory bioassay and significantly more effective than neem oil and the control treatment and as effective as insecticidal soap in a greenhouse assay. With the western flower thrips, UDA-245 at 0.5% was significantly more effective than neem oil, insecticidal soap and the control treatment in a laboratory bioassay, whereas in a greenhouse assay, UDA-245 at 1.0% was the only treatment that maintained control of the western flower thrips 2 wk after the last treatment period. UDA-245 at 0.5% (laboratory bioassay) was significantly more effective in managing greenhouse whitefly than neem oil, endosulfan, and the control treatment and as effective as insecticidal soap. Insecticidal soap proved to be toxic to the parasitoid E. formosa (71.9% mortality), whereas UDA-245 at 0.5% was not significantly more toxic than the control (11.2 and 4.6% mortality, respectively). Our results suggest that a greenhouse integrated pest management (IPM) program using a botanical such as UDA-245 could effectively control infestations of major pests present while having a negligible effect on biological control agents.
97 citations
TL;DR: It is hypothesize that three polypeptides, identified by mass spectrometry as Rack-1, GAPDH3, and actin, may be involved in the epithelial transcytosis of virus particles in the aphid vector.
90 citations
TL;DR: It appeared that the patch use of A. matricariae and D. rapae was not significantly affected by deltamethrin treatment, when compared with the controls, and the frequencies and sequences of behavioural items modified (e.g., frequency of sting).
Abstract: Neurotoxic insecticides are widely used for crop protection. One consequence is that changes in behaviour can be expected in surviving beneficial insects because of an impairment of host perception and motor abilities. Under laboratory conditions, we studied the impact of deltamethrin, a pyrethroid, on the oviposition behaviour of two hymenopterous parasitoids of aphids, Aphidius matricariae (Haliday) and Diaeretiella rapae (McIntosh) (Hymenoptera: Braconidae). They both para- sitize Myzus persicae (Sulzer) (Homoptera: Aphididae), which is the preferred host of A. matricariae, regardless of the host plant, whereas D. rapae is a major parasitoid of aphids on Cruciferae crops, including M. persicae. After exposure to deltamethrin, the different items of oviposition behaviour and the total time spent on the patch were recorded. The results showed that the patch time allocation by both parasitoid species was not significantly affected by deltamethrin treatment, when compared with the controls. Nor were the frequencies and sequences of behavioural items modified (e.g., frequency of sting). It therefore appeared that the patch use of A. matricariae and D. rapae on new colonies of M. persicae was not disturbed by deltamethrin at the three doses tested. The possibility that parasitoid strains are partially tolerant to deltamethrin is discussed.
81 citations
TL;DR: A diagnostic dose bioassay to detect kdr and provide preliminary information on the genotype present and two allelic discrimination PCR assays to determine precisely the genotypes of the two mutations in individual M. persicae using fluorescent Taqman MGB probes are developed.
73 citations
TL;DR: Adult weight and developmental rate of P. dissecta have a positive correlation, which suggests that if immature stages of ladybeetle developed faster, they should grow into heavier adults and female longevity and fecundity also have apositive correlation.
Abstract: Predation potential, development, immature survival and reproduction of an aphidophagous ladybeetle, Propylea dissecta (Mulsant) was studied when fed on seven aphid prey, viz Aphis gossypii, Aphis craccivora, Lipaphis erysimi, Uroleucon compositae, Brevicoryne brassicae, Rhopalosiphum maidis and Myzus persicae A gossypii was most suitable and consumed by the larvae and adults of P dissecta, while M persicae, the least Pre-imaginal development of P dissecta was fastest (0080 day−1) when A gossypii was used as prey, whilst slowest (0061 day−1) on M persicae The immature survival, adult emergence, adult male and female longevity of P dissecta was maximal (ie, 7710±004 and 9321±079%, 5710±162 and 6240±193 days, respectively) on A gossypii and minimal (ie, 6301±187 and 8173±179%, 4250±121 and 4940±232 days, respectively) when M persicae was provided as prey Oviposition period, fecundity, percent egg viability and mean reproductive rate was maximum (ie, 5030±203 days, 856
72 citations
TL;DR: There was a significant negative correlation between UV‐reflectance (320–400 nm) and log(N + 1)‐transformed number of individuals and five further aphid species, and high numbers of alate aphids were caught in traps with dark backgrounds, a result which was attributed to the high contrast between the background and target.
Abstract: To study the effect of background colour on aphid landing on green targets (water pan traps), two field experiments were set up in Hessen, Germany, in 2003. Traps were put onto coloured plastic sheets (13 colours, straw mulch, transparent foil, and uncovered soil, Experiment 1). In Experiment 2, green water pans were again put on coloured plastic sheets (red, white, green, and yellow), and the sheets were either sprayed with insect glue or not. Backgrounds and traps were spectrally characterised with a field radiometer (320 ‐950 nm). Aphid catches were highest in the traps on the uncovered background, and lowest in the traps on white or silver backgrounds. For Brevicoryne brassicae , Myzus persicae (Homoptera: Aphididae, Macrosiphini) and five further aphid species, there was a significant negative correlation between UV-reflectance (320 ‐ 400 nm) and log(N + 1)-transformed number of individuals. However, the effect of straw mulch (reduced aphid catches with straw compared to the uncovered background), could not be attributed to differences in UV-reflectance, as UV was almost identical in soil and straw. High numbers of alate aphids were caught in traps with dark backgrounds (e.g. black, dark green), a result which was attributed to the high contrast between the background and target. The substantially higher aphid numbers from targets with bare soil than from targets with spectrally similar black backgrounds were thought to be caused by the structure of the background surface: for alate aphids, landing close to the target on smooth surfaces may induce probing, and the lack of appropriate substrate will result in take-off, whereas soil will not induce probing, and aphids will continue to move towards the green targets.
72 citations
TL;DR: Aphid species counted on citrus trees in orchards in Valencia, Spain in the spring and autumn of 1997, 1998 and 1999 were consistent with the high prevalence and rapid spread of CTV in sweet orange, clementine, and satsuma mandarins in recent years in the region.
71 citations
TL;DR: Investigation of growth, development and reproduction of a ladybird beetle, Cheilomenes sexmaculata, found a linear relationship was found between development rate and weight of adult, daily prey consumption and relative growth rate, log weights of adult males and females, and female longevity and total fecundity.
Abstract: Growth, development and reproduction of a ladybird beetle, Cheilomenes sexmaculata (Fabricius) were investigated in relation to seven aphid species, viz. Aphis craccivora Koch, Aphis gossypii Glover, Rhopalosiphum maidis (Fitch), Myzus persicae (Sulzer), Uroleucon compositae (Theobald), Lipaphis erysimi (Kaltenbach) and Aphis nerii Boyer de Fonscolombe on specific hosts. Maximum prey consumption, percent larval survival, developmental rate, weight of different life stages, percent adult emergence, adult longevity and fecundity of C. sexmaculata were recorded on A. craccivora, and minimum on A. nerii. A linear relationship was found between development rate and weight of adult, daily prey consumption and relative growth rate, log weights of adult males and females, and female longevity and total fecundity. On the basis of overall performance of ladybird the order of suitability of prey species was A. craccivora>A. gossypii>R. maidis>M. persicae>U. compositae>L. erysimi>A. nerii.
TL;DR: This research sought to identify the aphid virus vector species associated with lettuce and broccoli crops in Spain, and to determine their population dynamics and ability to transmit Lettuce mosaic virus (LMV).
TL;DR: Results support the hypothesis of secondary PPV spread by indigenous aphids in Pennsylvania, and suggest that PPV-infected fruit has the potential to function as a virus source for long-distance dispersal.
Abstract: Thirteen aphid species were tested for their ability to transmit Pennsylvania isolates of Plum pox virus (PPV) collected in Columbia (PENN-3), Franklin (PENN-4), and York (PENN-7) Counties, PA. Four species, Aphis fabae, A. spiraecola, Brachycaudus persicae, and Myzus persicae, consistently transmitted PPV in preliminary transmission tests. Two species, Metopolophium dirhodum and Rhopalosiphum padi, were occasional inefficient vectors. Toxoptera citricida, from Florida, also was an effective vector but it does not occur in major stone-fruit-growing states. Species not transmitting PPV in parallel tests included Acyrthosiphon pisum, Aphis glycines, Aulacorthum solani, Macrosiphum euphorbiae, Rhopalosiphum maidis, and Sitobion avenae. When given a 3-day probing access period simultaneously on PPV-infected peach seedlings and healthy peach seedlings, Myzus persicae, Aphis spiraecola, A. fabae, and B. persicae transmitted PPV to 63, 31, 38, and 32% of the healthy peach seedlings, respectively. When given a similar probing period on PPV-infected peach fruit and healthy peach seedlings, the same aphid species transmitted PPV to 50, 35, 0, and 0% of seedlings, respectively. Results support the hypothesis of secondary PPV spread by indigenous aphids in Pennsylvania, and suggest that PPV-infected fruit has the potential to function as a virus source for long-distance dispersal.
TL;DR: The results suggest that P. neoaphidis can cross-infect aphid species which occur both in field crops and non-cropped areas, such as field margins, which is an important feature for the development of conservation biological control strategies.
TL;DR: Attack rate bioassays with leaf discs absent, using both satiated and starved aphids, revealed that background chemistry and internal aphid chemistry may have small effects on attack rate.
Abstract: Lipaphis erysimi (Kaltenbach) is a specialist crucifer feeding aphid and Myzus persicae (Sulzer) is a generalist feeding aphid. The foraging behavior of Diaeretiella rapae (McIntosh), a parasitoid with the ability to parasitize both of these species, was assessed using a series of attack rate and success bioassays, with turnip, Brassica rapa var rapifera, as the host plant. The attack rate of D. rapae was significantly greater on L. erysimi than on M. persicae when aphids were feeding on turnip leaf discs in Petri dishes, irrespective of the aphid species upon which the parasitoids were originally reared. Attack rate bioassays with leaf discs absent, using both satiated and starved aphids, revealed that background chemistry and internal aphid chemistry may have small effects on attack rate. Excision of D. rapae pupae from mummy cases and subsequent use of the fully developed adults in attack rate bioassays showed that cues received by D. rapae at the time of adult emergence provide cues that prime D. rapae to attack L. erysimi at a greater rate than M. persicae. However, the relative success of D. rapae on these two aphid species, in terms of the percentage of attacks resulting in a successful adult parasitoid, was not significantly different.
TL;DR: Esterase activity showed the level and variability expected for an R1 clone lacking mutations in the sodium channels (susceptible kdr), thus corresponding to a type slightly resistant to organophosphate and carbamate, and susceptible to pyrethroid insecticides.
Abstract: The tobacco-feeding race of Myzus persicae (Sulzer), formerly known as M nicotianae Blackman, was introduced into Chile during the last decade In order to evaluate the genetic diversity and insecticide resistance status of Chilean tobacco aphid populations, a field survey was conducted in 35 tobacco fields covering a 300 km latitudinal survey The populations sampled were characterized using microsatellite markers and morphometric multivariate analysis Insecticide resistance levels were assessed through a microplate esterase assay and the mutation status of the kdr gene All samples collected corresponded to the same anholocyclic aphid genotype, and showed morphological variation within the range expected for the tobacco-feeding race of M persicae Esterase activity showed the level and variability expected for an R1 clone lacking mutations in the sodium channels (susceptible kdr), thus corresponding to a type slightly resistant to organophosphate and carbamate, and susceptible to pyrethroid insecticides
TL;DR: This work examined whether consumption rates of several predator species on focal (GPA) prey was reduced in the presence of alternative (CPB egg) prey, and found that two predator species, Nabis spp.
TL;DR: Results from the study show that parasitioids differentiated between odour of the three cultivars in dependence of their rearing history when the plant is uninfested.
Abstract: :
The olfactory response of the parasitoid Aphidius colemani (Viereck) (Hymenoptera: Braconidae) to odours in a tritrophic system involving three cultivars of common cabbage, Brassica oleracea var capitata, characterized by different levels of susceptibility to Myzus persicae (Sulzer) (Hemiptera: Aphididae) was studied in a four-way olfactometer. Odours influenced A. colemani response in the olfactometer to varying degrees. The magnitude of parasitoid response to odours of uninfested cabbage depended on cultivar, with Derby Day [green-leaved, susceptible to M. persicae and the crucifer specialist, Brevicoryne brassicae (Linnaeus) (Hemiptera: Aphididae)] and Minicole (green-leaved, partially resistant with known antibiosis factors for B. brassicae) preferred over Ruby Ball (red-leaved with antixenosis factors for M. persicae and B. brassicae). The odour of the cabbage cultivar on which the parasitoid had been reared was preferred over the other cultivars. However, when provided with a choice between odours of infested plants, parasitoids did not show a significant preference for the cultivar on which they were reared. Results from the study show that parasitioids differentiated between odour of the three cultivars in dependence of their rearing history when the plant is uninfested.
TL;DR: Nymphs of both aphid species parasitized in the 1 st and 2 nd instars were mummified when reached the 4 th instar or adult stage, whereas those parasi- tized in the 3 rd and 4 thinstars wereMummified in the adult stage.
Abstract: The instar preference and parasitization (expressed as mummification rate) of Aphis gossypii Glover and Myzus persicae (Sulzer) (Hemiptera: Aphididae) by the parasitoid Aphidius colemani Viereck (Hymenoptera: Aphidiidae) were studied at 25±0.5°C, 65±5% r.h. and a 16L : 8D photoperiod. The female parasitoids were 24-36 h old and were left to forage for 1 h on an eggplant leaf on which 10 nymphs of each instar of A. gossypii or M. persicae were placed. The percentage of A. gossypii nymphs mummified was higher than that of M. persicae (43.2 and 25.2%, respectively). The parasitoid parasitized nymphs of all instars of both aphid species, but it showed a preference for 1st and 2nd instars of A. gossypii and 1st instar of M. persicae. Nymphs of both aphid species parasitized in the 1st and 2nd instars were mummified when reached the 4th instar or adult stage, whereas those parasitized in the 3rd and 4th instars were mummified in the adult stage. The importance of these results in the effectiveness of A. colemani in biological control of A. gossypii and M. persicae is discussed.
TL;DR: The results indicate that M. pygmaeus performs very well when it feeds on the aphid M. persicae on pepper plants, and can increase its numbers at all temperatures tested.
Abstract: Life table parameters and other biological characteristics were estimated for the predator Macrolophus pygmaeus Rambur (Hemiptera: Miridae) when fed on pepper plant/leaves with or without prey Myzus persicae (Sulzer) (Homoptera: Aphididae). The experiments were conducted at 15, 20, 25, and 30°C, under a photoperiod of 16:8 (L:D) h and at 65 ± 5% RH. Egg incubation was shortest at 30°C (10.5 d), egg hatch percentage reached 90% at 20°C, sex ratio was 78% at 25°C, and preoviposition period was shortest at 25°C (6.1 d). Only females with access to prey were able to reproduce. Fecundity was highest at 20°C (203.9 eggs). Females and males survived longer at 15°C (120.7 and 132.9 d, respectively). When provided with prey, M. pygmaeus can increase its numbers at all temperatures tested. Its intrinsic rate of increase and doubling time were highest at 25°C (0.0958 d−1 and 7.2 d, respectively). The lowest temperature threshold for population increase was 9.06°C. In the absence of prey, the predator did not oviposit, but females and males survived for a relatively long time at 15°C (26.5 and 28.7 d, respectively) and for a shorter time as temperature increased. The results indicate that M. pygmaeus performs very well when it feeds on the aphid M. persicae on pepper plants. Although the pepper plant can support adults, it does not permit population increase when prey is not available. However, these results are discussed with other findings in the context of a better and more effective use of this predator for biological control of M. persicae on pepper plant.
TL;DR: Although there were no differences in the numbers of predated aphids, with the majority predated for all accessions, the compatibility of trichome‐based host plant resistance of Lycopersicon species and the biocontrol of aphids by lacewings is questionable.
Abstract: Trichome-based host plant resistance of Lycopersicon (Solanaceae) species offers the potential to reduce pesticide use in tomato production, but its compatibility with biocontrol agents is largely unknown. The effect of trichome-based host plant resistance on the lacewing biocontrol agent, Mallada signata, was assessed for five accessions of L. cheesmanii, four accessions of Lycopersicon hirsutum, two accessions of Lycopersicon pennellii, and one Lycopersicon esculentum cultivar. An intact leaf was isolated from the whole plant using Tangletrap to coat the petiole and 20 green peach aphids [Myzus persicae (Sulzer) (Homoptera: Aphididae)] were placed on the leaf surface. After 24 h, 10 lacewings were placed on the leaf. The numbers of dead, trapped by exudates, untrapped and predated lacewings and aphids, and the numbers that had left the leaf were recorded a further 24 h later. Differences in insect designations between accessions were analysed using ANOVA. A General Linear Model (GLM), consisting of the densities of each trichome type and leaf area, was fitted to the data to determine the role of trichomes on the observed effects on lacewings and aphids. Lacewing mortality was greater on one accession of L. pennellii and one accession of L. hirsutum than on L. esculentum. The GLM indicated that type IV trichomes decreased the numbers of aphids predated, and increased cannibalism and, along with type III trichomes, increased entrapment-related predator mortality. Although there were no differences in the numbers of predated aphids, with the majority predated for all accessions, the compatibility of trichome-based host plant resistance of Lycopersicon species and the biocontrol of aphids by lacewings is questionable.
TL;DR: A higher proportion of plants developed SPVD symptoms in the inner square than plants located further away from the infected plot, and number of infected plants correlated with trap catches of whiteflies only for the first season.
12 Jan 2004
TL;DR: This poster presents a probabilistic procedure to identify the fruit flies of eight fruit flies found in the fruit fly sac of the hoverfly, a type of hoverfly commonly found in arid regions.
Abstract: Laboratory of Agricultural Entomology, Department of Entomology and Agricultural Zoology, Benaki Phytopathological Institute, 8 Stefanou Delta str., 145 61 Kifissia, Attica, Greece; tel.: +3
TL;DR: Female adults of the aphidopagous gall midge, Aphidoletes aphidimyza (Rondani) (Diptera: Cecidomyiidae), showed an olfactory response to honeydew excreted by the green peach aphid, Myzus persicae (Sulzer) (Hemiptera): Aphididae under laboratory conditions.
Abstract: Female adults of the aphidopagous gall midge, Aphidoletes aphidimyza (Rondani) (Diptera: Cecidomyiidae), showed an olfactory response to honeydew excreted by the green peach aphid, Myzus persicae (Sulzer) (Hemiptera: Aphididae) under laboratory conditions. The response was only elicited by treatments with honeydew, whereas aphids, aphids with pepper plants or leaves, and pepper plants or leaves were not attractive to the midges. Dose-dependent responses were observed from whole honeydew, honeydew volatiles extracted in pentane, and honeydew volatiles captured on Porapak Q®. When honeydew was eluted with three sequential pentane washes, a positive response was only observed from the midges for the first wash. Female midges laid more eggs on pepper plants infested with higher densities of M. persicae. The olfactory response of midges to honeydew is discussed with respect to prey location.
TL;DR: Responses of female Dicyphus hesperus Knight (Heteroptera: Miridae) to the odours of plants and prey were tested in the laboratory using a Y‐tube olfactometer and the results are discussed as they relate to the evolution of infochemical use in generalist omnivorous predators.
Abstract: Responses of female Dicyphus hesperus Knight (Heteroptera: Miridae) to the odours of plants and prey were tested in the laboratory using a Y-tube olfactometer. Females were attracted to the odour of tomato leaves infested with nymphs of the greenhouse whitefly, Trialeurodes vaporariorum West-wood (Homoptera: Aleyrodidae), compared to uninfested leaves. No such attraction occurred to tomato leaves infested with two-spotted spider mites, Tetranychus urticae Koch (Acari: Tetranychidae). When females were simultaneously presented with the odours of whitefly and mite-infested leaves, no preference for either odour was recorded. Similarly, females were attracted to the odour of pepper leaves infested with green peach aphids [Myzus persicae (Sulzer) (Homoptera: Aphididae)] compared to uninfested leaves, but were not attracted to the odour of pepper leaves infested with eggs of cabbage loopers, Trichoplusia ni (Hubner) (Lepidoptera: Noctuidae). When aphid-infested and looper-egg-infested pepper leaves were presented simultaneously, no preference for either odour was detected. The results are discussed as they relate to the evolution of infochemical use in generalist omnivorous predators.
TL;DR: Although no accessions provided strong resistance to aphid coloniza- tion evident by signifi cantly reduced numbers of aphids, several commercial varieties and sources of virus resistance exhibited strong tolerance to GPA, evident as reduced damage.
Abstract: A greenhouse screen for resistance to green peach aphid (GPA) (Myzus persicae (Sulzer)) was done using 50 pepper (Capsicum spp.) accessions. There were signifi cant differences among accessions for damage rating, number of aphids per plant and num- ber of aphids per leaf. Leaf pubescence, the basis of a reported nonpreference resistance mechanism to green peach aphid infestation, failed to protect pepper accessions from GPA colonization and damage. Sources of resistance and tolerance to cotton aphid (Aphis gossypi (Glover)) supported high levels of green peach aphid infestation and exhibited considerable damage. Although no accessions provided strong resistance to aphid coloniza- tion evident by signifi cantly reduced numbers of aphids, several commercial varieties and sources of virus resistance exhibited strong tolerance to GPA, evident as reduced damage. Tolerant varieties could be an important component in integrated pest management of green peach aphid. The green peach aphid (GPA) is an impor- tant pest of peppers in the northeastern U.S. As a direct pest of pepper plants, high populations of GPA can cause chlorosis, necrosis, wilt- ing, stunting, fl ower and fruit abortion, leaf distortion and defoliation. In addition, aphid honeydew excretions can be accompanied by the growth of sooty mold, contaminating fruit and reducing the photosynthetic capability of plants. GPA is even more important as an indirect pest, vectoring plant viruses such as cucumber mosaic virus (CMV), tobacco etch virus (TEV), pepper mottle virus (PepMoV) and potato virus Y (PVY). In New York, an- nual infestation of GPA affects ≥75% of the pepper acreage, with yield losses as high as 50% when combined with losses due to virus damage.
TL;DR: The number of eggs laid by A. gifuensis peaked on the first days after the emergence at the two temperatures tested, indicating their proovigenic status and suggesting its great potential for use as a biological control agent for M. persicae.
Abstract: Reproductive potentials of an indigenous aphid parasitoid, Aphidius gifuensis, on Myzus persicae were measured in a laboratory at two constant temperatures, 20°C and 25°C. Single female parasitoids produced 529.0 progeny at 20°C and 536.7 at 25°C during their life spans. Longevities were 12.8 days and 12.3 days at 20°C and 25°C, respectively. The number of eggs laid by A. gifuensis peaked on the first days after the emergence at the two temperatures tested, indicating their proovigenic status. Intrinsic rates of natural increase for A. gifuensis were calculated as 0.350 at 20°C and 0.462 at 25°C. These values are higher than those for M. persicae, suggesting a significant character of A. gifuensis that indicates its great potential for use as a biological control agent for M. persicae.
TL;DR: Comparison of the capsid protein and 3’ UTR sequences of SPV2 with those of other potyviruses demonstrated that it is a distinct member of the genus Potyvirus (family Potyviridae).
Abstract: An incompletely described potyvirus isolate from sweet potato in Taiwan, referred to as 'sweet potato virus 2' (SPV2), was further characterised. Electron microscopy revealed that SPV2 has filamentous particles of 850 nm in length and induces cytoplasmic cylindrical inclusions consisting of pinwheels and scrolls. The virus was mechanically transmitted to several species of the genera Chenopodium, Datura, Nicotiana, and Ipomoea. Two biotypes of Myzus persicae transmitted SPV2 in a non-persistent manner. Decoration titer experiments revealed a distant serological relationship between SPV2 and other potyviruses infecting sweet potato. The 3'-terminal 2006 nucleotides of the viral RNA were determined and shown to be a potyviral genome fragment comprising the coding region for the C-terminal half of the NIb protein, the entire coat protein cistron, and the 3' untranslated region (UTR). Comparison of the capsid protein and 3' UTR sequences of SPV2 with those of other potyviruses demonstrated that it is a distinct member of the genus Potyvirus (family Potyviridae). We propose that SPV2 is named Sweet potato virus Y.
TL;DR: The magnitude of intraguild predation by adult females of the predator Anthocoris nemorum on immature larvae of the aphid parasitoid Aphidius colemani inside mummies of peach-potato aphids Myzus persicae was investigated under laboratory conditions in a preference experiment and did not exhibit prey preference between mummies and unparasitised aphids.
Abstract: The magnitude of intraguild predation by adult females of the predator Anthocoris nemorum on immature larvae of the aphid parasitoid Aphidius colemani inside mummies of peach-potato aphids Myzus persicae was investigated under laboratory conditions in a preference experiment. Each predator consumed a mean (95% confidence limits) of 2.8 (2.1; 3.8) immature parasitoids within mummies and 3.6 (2.7; 4.6) unparasitised aphid nymphs. Thereby A. nemorum engaged in intraguild predation with A. colemani and did not exhibit prey preference between mummies and unparasitised aphids.
TL;DR: Control of virus yellows disease is focused on the study and control of this aphid species, and its application offers potential to optimise the rational use of aphicides such as imidacloprid so as to benefit beet growers and the environment by reducing prophylactic use of seed treatment.
Abstract: Virus yellows is an important disease affecting yield in sugar beet in the UK. Myzus persicae (Sulzer) is the most effective and efficient aphid vector of the three viruses causing the disease: beet yellows virus, beet mild yellowing virus and beet chlorosis virus. Control of virus yellows disease is thus focused on the study and control of this aphid species. UK national surveys of virus yellows began in 1946 and these data helped to formulate disease forecasting schemes to optimise control. Over the years, in addition to improvements in farm hygiene, periodic changes and developments in control of the disease have occurred. To accommodate these important developments, virus yellows forecasting schemes have evolved accordingly. The most recent version has been adapted to take account of the current widespread use of imidacloprid seed treatment. Its application offers potential to optimise the rational use of aphicides such as imidacloprid so as to benefit beet growers and the environment by reducing prophylactic use of seed treatment.