Showing papers on "Myzus persicae published in 1995"

Expression of snowdrop lectin in transgenic tobacco plants results in added protection against aphids

Abstract: The range of sap-sucking insect pests to which GNA, (the mannose specific lectin from snowdrops (Galanthus nivalis) has been shown to be insecticidal in artificial diets has been extended to include the peach potato aphid (Myzus persicae). A gene construct for constitutive expression of GNA from the CaMV35S gene promoter has been introduced into tobacco plants. A transgenic tobacco line which expresses high levels of GNA has been shown to have enhanced resistance toM. persicae in leaf disc and whole plant bioassays,demonstrating the potential for extending transgenic plant technology to the control of sap-sucking insect pests.

Selection for resistance to azadirachtin in the green peach aphid, Myzus persicae

Abstract: Two lines ofMyzus persicae of the same origin were treated repeatedlywith pure azadirachtin (aza), or a refined neem seed extract (NSE), at the equivalent concentration of aza. After 40 generations, the aza-selected line had developed 9-fold resistance to aza compared to a non-selected control line, whereas the NSE-selected line did not. These results suggest that a blend of active constitutents in a botanical insecticide such as neem might diffuse the selection process, mitigating the development of resistance compared to that expected with a single active ingredient.

Aphid transmission of beet western yellows luteovirus requires the minor capsid read-through protein p74

Abstract: Beet western yellows luteovirus is obligately transmitted by the aphid Myzus persicae in a circulative, non-propagative fashion. Virus movement across the epithelial cells of the digestive tube into the hemocoel and from the hemocoel into the accessory salivary glands is believed to occur by receptor-mediated endocytosis and exocytosis. Virions contain two types of protein; the major 22 kDa capsid protein and the minor read-through protein, P74, which is composed of the major capsid protein fused by translational read-through to a long C-terminal extension called the read-through domain. Beet western yellows virus carrying various mutations in the read-through domain was tested for its ability to be transmitted to test plants by aphids fed on agro-infected plants and semi-purified or purified virus preparations. The results establish that the read-through domain carries determinants that are essential for aphid transmission. The findings also reveal that the read-through domain is important for accumulation of the virus in agro-infected plants.

Toxicity of lectins and processing of ingested proteins in the pea aphid Acyrthosiphon pisum

Abstract: Acute toxicity of thirty lectins was tested against the pea aphid Acyrthosiphon pisum (Harris) (Homoptera, Aphididae: Macrosiphini). Activity was measured on artificial diets containing moderate concentrations of lectins (10–250 μg/ml) by scoring mortality and growth inhibition over the whole nymphal period (7 days at 20°C). Most of the proteins tested exhibited low toxicity, but some induced significant mortality; these included the lectins from jackbean (Concanavalin A), amaranth, lentil and snowdrop. There was no direct correlation between toxicity and sugar specificity of the lectin; however, many mannose-binding lectins were toxic towards A. pisum. Concanavalin A was also tested on five other aphid species (Aphis gossypii, Aulacortum solani, Macrosiphum euphorbiae, Macrosiphum albifrons and Myzus persicae) at concentrations between 10–1500 μg/ml. Mortality was very variable from one species to another. Strong growth inhibition invariably occurred within this concentration range, although dose-response curves differed substantially between aphid species. The peptidase complement of A. pisum's digestive tract was also investigated, as well as the oral toxicity of some protease inhibitors (PIs) to this aphid. Most protein PIs were inactive, and no part of the digestive tract contained detectable amounts of endo-protease activity. This is in contrast to the strong amino-peptidase activity which was shown to occur predominantly in the midgut and crop portions of the digestive tract. The potential of lectins in transgenic crops to confer Host-Plant Resistance to aphids is discussed.

Habitat Manipulation to Enhance Biological Control of Brassica Pests by Hover Flies (Diptera: Syrphidae)

Abstract: Brassicas in New Zealand are attacked by the cabbage aphid, Brevicoryne brassicae (L.); the green peach aphid, Myzus persicae (Sulzer); and the larvae of Artogeia rapae (L.) and the diamondback moth, Plutella xylostella (L.). Use of prophylactic pesticides is the usual control strategy against such pests, but the invertebrate predatory community within fields can contribute to pest suppression. Larvae of New Zealand hover flies consume all of the above pests, but the requirement of the adult flies for pollen and nectar may limit their potential in fields where the non crop flora is impoverished. In this work, parts of the borders of three cabbage fields were drilled with the annual plant P. tanacetifolia tanacetifolia Benth. (Hydrophyllaceae) as a pollen source in the spring. Four strips were alternated with 4 control strips (naturally occurring vegetation). Aphid and A. rapae populations were assessed weekly in unsprayed plots adjacent to the 8 replicated areas, and hover fly eggs were counted simultaneously. Hover fly adults were trapped in yellow pan traps that were arranged across the field in transects from each of the eight sampling areas. Border planting with P. tanacetifolia clearly affected numbers of adult hover flies and aphid populations. The potential for this type of habitat manipulation to increase diversity as a component of integrated pest management is discussed with reference to comparable research in Europe.

Behaviour modifying effects of low systemic concentrations of imidacloprid on Myzus persicae with special reference to an antifeeding response.

Abstract: With a combination of biological, analytical, electrophysiological, and video-optical methods, it was possible to show that low concentrations of the new chloronicotinyl insecticide, imidacloprid, strongly affect the behaviour of Myzus persicae (Sulz.), leading eventually to the death of the aphids. Tests to elucidate the biological properties were performed under laboratory conditions with cabbage leaf petioles placed in insecticidal solutions over different periods of time. LC15(24h) values were considered as low concentrations and calculated for imidacloprid and pirimicarb, respectively. Imidacloprid at low concentrations depressed the honeydew excretion of apterous adults of M. persicae by almost 95% within 24 h without affecting the vitality of the majority of aphids, whereas, at equitoxic concentrations, pirimicarb showed much weaker effects on honeydew excretion, which strongly coincided with mortality. In choice experiments with alate morphs of M. persicae over 48 h, their larvae almost always occurred on the untreated control leaf, and were not found on the leaf which was treated systemically with low concentrations of imidacloprid. Apterous aphids placed on cabbage leaves systemically treated with low concentrations of imidacloprid showed nearly the same decrease in weight as untreated starving aphids, suggesting that their death was caused by starvation. Aphids that were moved from imidacloprid-treated to untreated leaves after 24 h began feeding on the latter and showed a steady increase in weight and honeydew production. This suggests that the behavioural response is reversible. Aphids on pirimicarb-treated (equitoxic dose) leaves showed no decrease in weight. Electrical penetration graphs revealed that M. persicae on artificial membranes containing imidacloprid probed more often before feeding than aphids on control sachets. Time-lapse videofilming of apterous adults placed on cabbage leaves revealed a migration from the leaf treated with low concentrations of imidacloprid to an untreated leaf. From the results of these experiments and the observed symptomatology it is possible to postulate two different and dose-dependent modes of action of imidacloprid on M. persicae: (1) the well-known mode of action with visually obvious irreversible symptoms (paralysis, tremor, uncoordinated leg-movement) at field rates, and (2) the reversible starvation response as an antifeedant effect, which is not coupled with typical symptoms of neuronal disorder, at lower concentrations.

Effects of temperature on aphid phenology

Abstract: Daily samples between 1964 and 1991 from suction traps throughout Great Britain were used to study the migration phenologies of five aphid species: Brachycaudus helichrysi, Elatobium abietinum, Metopolophium dirhodum, Myzus persicae and Sitobion avenae, and their relationship with temperature. Regression relationships have been established between characteristics of aphid phenology and temperature, latitude and longitude for each species. There were differences between species in the period for which temperature was most strongly associated with aphid phenology. The study indicates that temperature, especially winter temperature, is the dominant factor affecting aphid phenology, for all five species. A 1 degrees C increase in average winter temperature advanced the migration phenology by 4-19 days depending on species. Effects of temperature on the aphid phenology are similar between holocyclic and anholocyclic species, unlike the effects of temperature on date of first flight record which have been previously shown to be important only in anholocyclic species.

Toxicity of neem to natural enemies of aphids.

Abstract: Neem [Azadirachta indica (A. Juss.)] seed oil (NSO) applied in three concentrations, 0.5%, 1% and 2%, to potted plants infested with green peach aphid,Myzus persicae (Sulzer), totally prevented adult eclosion of larval coccinellids,Coccinella undecimpunctata L., and reduced adult eclosion of syrphids,Eupeodes fumipennis (Thompson), to 11%, 7% and 0%, respectively, of the controls. Under the same conditions, NSO did not reduce the rate of parasitism ofM. persicae byDiaeretiella rapae (Mcintosh), but emergence of parasitoid adults from aphid mummies collected from treated plants was reduced to 35%, 24% and 0%, respectively, of the controls. Although topical treatment of predator larvae with NSO at concentrations of up to 5% did not affect survival, emergence of parasitoids from mummies dipped in aqueous emulsions of NSO at similar rates was reduced significantly. Under field conditions, sprays of NSO and neem seed extract to plants had no significant impact on the number of aphids parasitized. Although total numbers of predators were reduced, numbers of predators relative to aphid numbers were similar to those in controls. Neem insecticides may be suitable for use in integrated pest management programs, as under field use they appear to be relatively benign to aphid predators and parasitoids.

Chromosomal location of the amplified esterase genes conferring resistance to insecticides in Myzus persicae (Homoptera: Aphididae)

Abstract: Chromosomal location of the amplified esterase genes conferring resistance to insecticides in Myzus persicae (Homoptera: Aphididae)

Effects of plant age, leaf age and virus yellows infection on the population dynamics of Myzus persicae (Homoptera: Aphididae) on sugarbeet in field plots.

Abstract: Field experiments in which clip-caged apterae of Myzus persicae (Sulzer) (Homoptera: Aphididae) were monitored on sugarbeet revealed that leaf age, plant age and infection of the host with beet yellows closterovirus (BYV) had very large effects on aphid performance (development, reproduction and survival). On healthy plants performance was much better on young, expanding heart leaves than on older leaves. Performance on senescent leaves was poor. When apterae were kept on young heart leaves all their lives (by moving clip-cages to younger leaves every 4 days) there was a strong negative relationship between aphid performance and plant age (measured as plant leaf number at birth). On plants inoculated with BYV apterae showed large improvements in performance. These occurred so rapidly that nymphs born at the time of virus inoculation could benefit as much as those born later. The sizes and between-leaf distributions of M. persicae populations which developed from standard numbers of colonists on whole plants in cages were consistent with the results of the clip-cage experiments. Alatae were less sensitive than apterae to differences in plant and leaf age. Implications of the results for BYV epidemiology and control are discussed.

Transmission by aphids of a naturally non-transmissible plum pox virus isolate with the aid of potato virus Y helper component.

Abstract: Two Spanish plum pox virus (PPV) isolates, 5.15 and 3.3, were used in transmission experiments involving the aphid vector Myzus persicae, with woody and herbaceous host plants. These isolates differ in the size of their coat protein (CP) and sequence analysis revealed that isolate 3.3 has a 15 amino acid deletion near the N terminus of the CP, affecting the same positions as in a previously reported non-aphid-transmissible PPV isolate from Germany. Aphid transmission experiments showed that isolate 5.15 was transmitted from infected plants whereas isolate 3.3 was not. In contrast, both isolates were readily aphid-transmitted when acquired through artificial membranes from purified virus preparations supplemented with purified helper component (HC) obtained from potato virus Y-infected plants. This indicates that non-transmissibility of isolate 3.3 may be due to a defect in the HC rather than in the CP.

Pepper vein yellows virus, a novel luteovirus from bell pepper plants in Japan

Abstract: Bell pepper plants showing vein yellowing and leaf roll symptoms were observed in plastic houses at Kitanakagusuku, Okinawa Prefecture in 1981. The causal agent did not infect plants by mechanical inoculation or through seed but was transmitted by grafting and two species of aphids, Aphis gossypii Glover. collected from pepper and Myzus persicae Sulz. in a persistent manner. The causal agent has limited host range, only infect Capsicum species. In serological tests this agent did not react with antisera to potato leaf roll virus, tobacco necrotic dwarf virus, barley yellow dwarf virus and beet western yellows virus. Partially purified preparations contained spherical particles 25nm in diameter. In ultrathin sections virus-like particles were observed only in the phloem cells of infected pepper plants. Based on these results the causal agent was classified as a new member of the luteovirus group and named pepper vein yellows virus (PeVYV).

Biological factors influencing the transmission of potato leafroll virus by different aphid species

Abstract: Macrosiphum euphorbiae, collected in the field from potato plants infected with potato leafroll virus (PLRV), transmitted the virus to fewer potato plants in a field trial than did laboratory-rearedMyzus persicae. In the laboratory,M. persicae was the only efficient vector of PLRV fromPhysalis floridana seedlings, potato sprouts or excised leaves toP. floridana. Two clones ofM. euphorbiae and one clone ofAulacorthum solani transmitted PLRV from infected potato plants toNicotiana clevelandii as effeciently asM. persicae but a clone ofAphis gossypii was an inefficient PLRV vector. An isolate of PLRV, whichM. persicae transmitted inefficiently from potato toN. clevelandii, was also transmitted inefficiently byM. euphorbiae andA. solani.

Potato leafroll virus spread in differentially resistant potato cultivars under varying aphid densities

Abstract: An action threshold of 3-10 green peach aphid,Myzus persicae (Sulzer), apterae per 100 lower leaves is recommended for use in Minnesota to prevent further spread of potato leafroll virus (PLRV) in potato,Solarium tuberosum L. This threshold was first developed and validated using the PLRV susceptible cultivar Russet Burbank. Here we report experiments to determine if higher aphid densities could be tolerated in PLRV resistant cultivars,i.e., Kennebec (moderately resistant) or Cascade (highly resistant), without an increase in PLRV infection. Insecticidal sprays were applied to plots when predetermined target aphid densities, based on number of apterae per 100 leaves, were reached: 3, 10, 30, and 100 (Russet Burbank); 10, 30, 100, and 300 (Kennebec); and 30, 100, 300, and 1000 (Cascade). The response variable was the average percentage of PLRV infected plants. Overall mean cumulative aphid-days and percent PLRV infection were 617 and 23.5% for Russet Burbank, 1,296 and 10.2% for Kennebec, and 4,816 and 9.5% for Cascade. For each cultivar, the highest target aphid density tolerated without an increase in PLRV spread was determined by comparing PLRV infection in plots sprayed on predetermined thresholds to PLRV infection in plots where aphids were rigorously controlled. This maximum density was 10 apterae per 100 leaves for Russet Burbank and 300 apterae per 100 leaves for Cascade. Results using Kennebec were ambiguous, but Kennebec was always more resistant to PLRV than Russet Burbank. Excised leaflet tests showed that the cultivars did not differ in resistance to green peach aphid. It appears that action thresholds based on green peach aphid apterae can be different depending upon the inherent PLRV-resistance of the cultivar.

Responses of Myzus persicae to the repellent polygodial in choice and no-choice video assays with young and mature leaf tissue.

Abstract: Polygodial is a plant-derived drimane sesquiterpenoid which shows antifeedant activity against aphids, and has been applied successfully in field trials, reducing cereal aphid numbers and consequently spread of barley yellow dwarf virus (Dawson etal., 1986). When the compound was painted onto leaf halves for laboratory choice assays, significantly fewer numbers of aphids settled on these areas (Pickett et al., 1987; Asakawa et al., 1988). Polygodial can have a long term contact effect, affecting aphid behaviour after 24 h exposure on leaves or other green surfaces (Hardie et al., 1992; Powell et al., 1993). However, aphids can apparently detect the compound very rapidly, within 2 min of plant access, and video recordings of behaviour suggested that the repellency involves antennal tip contact with the polygodial-treated leaf area (Powell et al., 1993). Despite such clear demonstrations of repellency, when whole mature leaves (Griffiths et al., 1982) or seedlings (Hardie et al., 1992; Powell et al., 1993) were treated with polygodial, allowing no choice of a less deterrent substrate, aphids showed no differences in behaviour from those on control plants. No direct comparisons have been made of aphid responses to polygodial applied in choice and no-choice tests, with other experimental conditions held constant; such an approach may help interpret previous findings and contribute to a better understanding of the repellent effect. In this study, the behaviour of Myzus persicae (Sulzer) was video-recorded on polygodialand solvent-treated leaf discs, in both choice and no-choice situations. As previous experiments have indicated that the aphidrepellent properties of polygodial may depend on leaf age, being more effective on mature leaves than on young cotyledons (Powell et al.. 1993), the experimental treatments were tested on discs cut from both young and mature leaves.

A new viral ringspot disease of citrus (Citrus species) in India

Abstract: An experiment was conducted during 1990--1993 to study ringspot disease of citrus (Citrus spp), its distribution, host range, etiological agent and economic importance. A disease with ringspot symptoms was found widely distributed in most commercial citrus cultivars, viz. 'Malta', 'Mosambi' and 'Satgudi' of sweet orange [Citrus sinensis (L.) Pers.] 'Nagpur Orange' and 'Kinnow Mandarin' of mandarin (C. reticulata Blanco); and 'Kagzi Lime' and 'Kagzi Kalan' of lime [C. auran tifolia (Christen.) Swingle]. The disease was found transmitted by grafting and dodder (Cuscula reflexa Roxb.) from citrus to citrus but not by sap, seed, soil and 4 aphid species, viz cotton aphid (Aphis gossypii Glover), green citrus aphid (A. citricola van der Goot), groundnut aphid (A. craccivora Koch) and green peach aphid [Myzus persicae (Sluz.)]. Three types of filamentous particles of 640 nm X 15 nm, 690 nm X 9 nm and 2 250 nm x 40 nm were found associated with the disease in purified as well as in leaf-dip preparations. Particles of 2250 nm x 40 nm were in the form of tubules and were recorded for the first time with viral infection in citrus and helped in diagnosis of the disease. Host range, virion morphology and presence of tubules indicated that the citrus-ringspot disease in India is different from the ringspot and psorosis diseases reported earlier from other parts of the world. In 'Kinnow Mandarin' the disease caused 20.54-98.38% loss in yield.

Detection of the luteoviruses, beet mild yellowing virus and beet western yellows virus, in aphids caught in sugar‐beet and oilseed rape crops, 1990–1993

Abstract: Summary The incidence of beet mild yellowing luteovirus (BMYV) and non-beet-infecting strains of beet western yellows luteovirus (BWYV) in individual winged aphids, caught in yellow water-traps, in sugar beet during the spring and early summer, and in oilseed rape plots in the autumn, was monitored using monoclonal antibodies in ELISA tests from 1990 to 1993. Between 0% and 8% of the Myzus persicae trapped in sugar beet each year carried BMYV, whereas 0% to 4% caught in oilseed rape in the autumn contained this virus. In 1990, 6.5% of Macrosiphum euphorbiae trapped in sugar beet contained BMYV, but in subsequent years less than 1% were carrying virus. Much higher proportions (26–67%) of the M. persicae tested from sugar beet contained BWYV, and similar proportions tested from oilseed rape (24–45%) also carried this virus in the autumn. In contrast only 3–19% of the M. euphorbiae caught in sugar beet contained BWYV, and none in oilseed rape. In 1991 and 1992 large numbers of Breuicoryne brassicae were caught in the plot of oilseed rape, of which over 50% contained BWYV; none were carrying BMYV. In transmission studies between 1990 and 1992, 1% and 27% of M. persicae transmitted BMYV and BWYV respectively to indicator plants; subsequent ELISA tests on the same aphids showed that 3% and 33% respectively contained the two viruses. One percent of M. euphorbiae transmitted BMYV, but none were found to contain BMYV using ELISA; 15% transmitted BWYV whilst only 5% were found to carry the virus. In 1992 and 1993 the incidence of BMYV-infection in the sugar-beet fields in which aphids had been trapped ranged from 1.2%, in a field which had received granular pesticide (aldicarb) at drilling plus three foliar aphicidal sprays, to 39.5% in a field which had received only one foliar spray. In 1992 in a sugar-beet crop which had received no aphicidal treatments, and where 2.8% of immigrant M. persicae and 2.5% of M. euphorbiae contained BMYV, 11.6% of plants developed BMYV infection. Lowest levels of infection were associated with the use of granular pesticides at drilling. In 1990, 80% of oilseed rape plants in a field plot were infested with a mean of seven wingless M. persicae per plant by mid-December; 37% of these plants were infected with BWYV. The studies show that M. persicae is the principal vector of BWYV, and large proportions of winged M. persicae carry the virus, in contrast to BMYV, which is consistent with the common occurrence of BWYV in brassica crops such as oilseed rape.

Within-plant accumulation of potato leafroll virus by aggregated green peach aphid feeding

Abstract: Aggregates of 20 green peach aphids placed on noninoculated leaves of plants previously inoculated with potato leafroll virus (PLRV) caused significantly more accumulation of PLRV at their feeding sites than in aphid-free leaves in both potato and Physalis floridana. Based on comparable periods of postinoculation, six times more viral antigen was detected by enzyme-linked immunosorbent assay in inoculated leaves of P floridana than of potato. The amount of PLRV detected in inoculated leaves was significantly correlated with the amount of PLRV that accumulated in aggregate feeding leaves, indicating that systemic spread of PLRV was titer-dependent. The movement of PLRV to aggregated aphid feeding sites probably followed the path of metabolites directed to the site of aphid damage and/or nutrient withdrawal. The accumulation of PLRV was not specific to the area of aggregated feeding but was evident throughout the leaf supporting the aphid colony. Aphids feeding in aggregates provided a mechanism that optimized virus acquisition from infected plants in which the pathogen was not uniformly distributed.

Muestreo de poblaciones y actividad de vuelo de Aphis frangulae gossypii Glover (Homoptera, Aphididae) y otros pulgones sobre cítricos en Castellón

Abstract: MELIA, A., 1995: Sampling populations and flight activity of Aphis frangulae gossypii Glover (Homoptera, Aphididae) and others aphids on citrics in Castellon. Bol. San. Veg. Plagas, 21(4): 601-610. The evolution of the population and the activity of flight of the four main species of aphids in citrics, Aphis frangulae gossypii Glover, Aphis spiraecola Patch, Toxoptera aurantii (Boyer de Fonscolombe) y Myzus persicae (Sulzer), have been studied on Clementine Clemenules and Oroval since 1985 to 1994, both included. The aphid that has had a denser population is the A. fr. gossypii and only one that has come over the threshold for intervention. On the fields these populations have been correlated with the captures of winged in yellow traps, settled on the ground, having established thresholds of usage of these traps.

RAPD PCR confirms absence of genetic variation between insecticide resistant variants of the green peach aphid, Myzus persicae (Homoptera: Aphididae)

Abstract: Previous allozyme analysis has revealed an apparent absence of enzyme variability in the green peach aphid, Myzus persicae (Sulzer). We are inter­ ested in determining the genetic relatedness of individual M persicae clones carrying different numbers of esterase 4 (E4) gene copies conferring resis­ tance to insecticides, in order to determine how many times and in what geo­ graphic locations resistance via gene duplication may have evolved. We have therefore extended th analysis of genetic variability in M. persicae to the DNA level using random amplification of polymorphic DNA (RAPD) with sin­ gle 10 mer oligonucleotide primers. Here we report a lack of variability be­ tween resistant clones in Wisconsin populations even at th DNA leveL Fur­ ther, 'fast' E4 (FE4) variants appear to be absent from Wisconsin populations, despite FE4 variants of moderate resistance (Rl) being the most common clones in the United Kingdom. These results suggest that resistance in M. per­ sicae may have evolved a very few times and that North American populations may differ from those in Europe by founder effects. Previous reports on the levels of allozyme variation n the green peach aphid, Myzus persicae (Sulzer), have revealed a striking absence of enzyme variability. Thus in surveys conducted in the United Kingdom (Wool et aL 1978; Brookes and Loxdale 1987) , Germany (Tomiuk and Wohrmann 1983) and North America (May and Holbrook 1978) all enzymes were found to be monomorphic except for two esterase loci (El/2 and E4). This means that the predominant reported genetic variability for this ph d is associated with gene duplication of the esterase 4 (E4) gene (Field et al. 1988), which can se­ quester (Devonshire and Moores 1982) and hydrolyze (Devonshire 1977) a wide range of insecticidal esters. E4 variants can be classified as E4 or FE4 depending on their mobility on polya rylamide gels (FE4 or 'fast'E4 shows higher mobility) and S, Rl' R., or Ra in relation to the apparent level of activity observed using artificial napihyl ester substrates (Devonshire 1989) . Clones of Rl activity appear to carry he FE4 enzyme, whilst Rand Ra clones carry E4 (although there is some over­ lap of E4 and FE4 aclivities within the resistance classification). Interest­ ingly, recently reported sequence data from these two genes has shown t at the DNA flanking this gene is the same within E4 and FE4 clones and differs only between E4IFE4 types (Field et al. 1993). However, the precise number of amplified copies of each of the E4IFE4 genes and the number oflocations at IDepartment of Entomology, University of Wisconsin-Madison, Madison, WI 53706. 2To whom correspondence should be addressed. 1 Al-Aboodi and Ffrench-Constant: RAPD PCR Confirms Absence of Genetic Variation Between Insecticid Published by ValpoScholar, 1995 128 THE GREAT LAKES ENTOMOLOGIST Vol. 28, No.2 which they have been amplified in the genome of individual clones remains unpublished. Therefore it is not currently possible to exactly correlate the number of amplified E4IFE4 genes with the levels of resistance (S, R 1, R2 or R3)· Temperate populations of M. persicae, away from their woody h st (peach), ppear to be largely anholocyclic (asexual reproduction) overwinter­ ing as nymphs or adults instead of eggs (Blackman 1971) . These observations therefore raise the fascinating possibility that resistance via duplication ofE4 (or FE4) may have arisen a limited number of times and has been driven through asexually reproducing populations within a few clonal variants. We are therefore interested in documenting the number of individual clones car­ rying E4IFE4 mediated resistance. Despite the high level of controversy gen­ erated over the reproducibility of random amplified DNA (RAPD) markers (Hederick 1992; Riedy et al. 1992; Ellsworth et al. 1993), previous studies have shown that if care is taken over DNA to primer ratios (Ellsworth et al. 1993) , that these arbitrary DNA markers can be reproducible. RAPD mark­ ers have thus been used to address questions in population ecology in a range of insects (Hadrys et aL 1992) and to detect polymorphisms within (Black et aL 1992), and distinguish between (Cenis et aL 1993), aphid species. RAPD markers have also been successfully used to trace clonal lineages within var­ ious protozoa (Tibayrenc et l. 1993). W w re therefore interested in using RAPD markers to understand the genetic relationships between resistant clonal variants of M. persicae in temperate North American populati s, in order to address the two related questions. 1) How many me and in what locations has resistance arise ? 2) Do North American and European popula­ tions show genetic differences? RAPD PCR markers were chosen in order to represent a random sampling of genetic variation in the Myzus genome. Here we report, following analysis of 35 clones of differing E4 activity with 27 random 10 mer oligonucleotides, that no reproducible variability in RAPD banding patterns was observed between any of the clones. Further, elec­ trophoretic analysis of the E4 variants in Wisconsin shows an apparent ab­ sence of FE4 variants, d spite the fact that Rl clones of FE4 mobility are the most common clones found in crop populations in the United Kingdom. This suggests that resistance caused by gene duplication ofE4 has arisen in a very limited number of genetically similar clones. MATERIALS AND METHODS Aphid clones. Aphids were collected from crop plants, predominantly potatoes, in July and August of 1992 and 1993 in Wisconsin USA. The num­ bers of clones collected from different counties (Dane, Oneida, Langdale, Waushara, Columbia, Oconto, Juneau and Adams) are shown in Table 1. Clones were established from individual females on excised potato leaflets kept in small plastic cages at room temperature in the laboratory. Three ref­ erence Rl FE4 clones were collected in S ptember 1992 in the United King­ dom from autumn sown rape ear Cambridge, England. Electrophoresis and RAPD peR. crylamide gel electrophoresis was performed as described elsewhere ( sand Loxdale 1987). Fiv in­ dividuals from the same aphid clones were al o used to make genomic DNA for RAPD PCR. DNA preparation was as for individual Drosophila and has been described elsewhere (ffrench-Constant et al. 1993). DNA was resus­ pended in sterile distilled water to a concentration of 1 ng/JlL 1 ng of DNA was added to a PCR reaction containing; 0.4 mM magnesium chloride, 0.1 mM dNTPs, 0.2 J1M of a single random 10 mer primer (purchased from J. Carlson, 2 The Great Lakes Entomologist, Vol. 28, No. 2 [1995], Art. 2 https://scholar.valpo.edu/tgle/vol28/iss2/2 1995 129 THE GREAT LAKES ENTOMOLOGIST Table L Number and location of Myzus persicae clones collected in counties within Wis­ consin, USA and East Anglia, UK. Their E4 activity as scored by polyacrylamide gel electrophoresis is shown,

Untersuchungen zur biologischen Bekämpfung von Blattläusen (Hom., Aphididae) an Kopfsalat im Unterglasanbau

Abstract: Studies on the biological control of aphids (Hom., Aphididae) on lettuce in greenhouses: From March to September, 1992, the efficiency of Aphidius matricariae Haliday, Aphidoletes aphidimyza (Rondani) and Chrysoperla carnea (Stephens) in controlling aphids on lettuce in glasshouses was tested. The following aphid species, entering through the ventilation apertures, occurred in the greenhouse chambers: Aulacorthum solani (Kaltenbach) (75%), Macrosiphum euphorbiae (Thomas) (12%), Nasonovia ribis-nigri (Mosley) (2%), and — late in the season only — Myzus persicae (Sulzer) (11%). Aphidius matricariae proved to be useless for controlling aphids on lettuce; A. solani and N. ribis-nigri were not shown to be host species for this parasitoid, and oviposition of A. matricariae into specimens of M. euphorbiae was very rare. Indeed, A. matricariae is an excellent parasitoid of M. persicae, but, in these experiments, this aphid was of minor importance as a lettuce pest. Aphidoletes aphidimyza did not control the aphids under the climatic conditions common in greenhouses for growing lettuce, even if pupae of the predatory midge had been applied three times. Of the species tested, only the application of Chrysoperla carnea (eggs) resulted in reasonable aphid control. The best effects from this predator were achieved when eggs were first added to the young lettuce plants before transplanting, subsequently followed by three sprayings of Chrysoperla eggs at weekly intervals (25–30 eggs per m2). A method of spraying stem-less Chrysoperla eggs, suspended in water plus detergent, on 500 to 1000 m2 by compressed air are developed. Zusammenfassung Von Marz bis September 1992 wurde in Gewachshauskabinen die Leistungsfahigkeit von Aphidius matricariae Haliday, Aphidoletes aphidimyza (Rondani) und Chrysoperla carnea (Stephens) bei der biologischen Bekampfung von Blattlausen an Kopfsalat im Unterglasanbau verglichen. Durch naturlichen Zuflug traten in den Gewachshauskabinen folgende Blattlausarten auf: Aulacorthum solani (Kaltenbach), Macrosiphum euphorbiae (Thomas), Nasonovia ribis-nigri (Mosley) und Myzus persicae (Sulzer). Aphidius matricariae ist fur die biologische Bekampfung von Blattlausen an Kopfsalat nicht geeignet. Die aufgetretenen Blattlausarten Aulacorthum solani und Nasonovia ribis-nigri werden uberhaupt nicht parasitiert und Individuen der Art Macrosiphum euphorbiae nur auserst selten mit Eiern belegt. Die Blattlausart Myzus persicae wird zwar von A. matricariae hervorragend parasitiert, sie machte aber in den Versuchen nur einen Anteil von 11% der aufgetretenen Individuen aus. Aphidoletes aphidimyza erwies sich fur die biologische Blattlausbekampfung an Kopfsalat im Unterglasanbau als ungeeignet. Selbst bei dreimaliger Ausbringung von Puppen wurde der Blattlausbefall nicht significant vermindert. Beim Einsatz von Chrysoperla carnea wurde eine signifikante Reduktion des Blattlausbefalls erreicht. Der groste Erfolg stellte sich ein, wenn Florfliegen-Eier bereits wahrend der Anzucht der Salatjungpflanzen in den Pflanzenbestand ausgebracht wurden. Die bislang bekannten Ausbringungs-methoden erwiesen sich auf den groseren Flachen im Erwebsgartenbau als nicht praktikabel. Die Ausbringung ungestielter Eier aus einem Flussigmedium mit Hilfe eines Zerstaubers wurde verbessert. Eine muhelose, grosflachige Ausbringung von Florfliegen-Eiern mittels Druckluft auf einer Flache von 500–1000 m2 wurde entwickelt.

Domyzus (nectarosiphon) species other thanm persicae pose a threat to the idaho potato crop

Abstract: Green peach aphids (Myzus persicae (Sulzer) ) pose a threat to the Idaho potato (Solanum tuberosum L.) crop primarily because they transmit potato leafroll virus (PLRV). Only colonizing vectors are epidemiologically significant because PLRV is persistently transmitted. Additionally, Idaho winters are severe enough that most permanently anholocyclic aphid species do not establish. It is now accepted that the taxon that has been known asMyzus (Nectarosiphon)persicae (Sulzer) is in fact at least three species (M. persicae, Myzus nicotianae Blackman andMyzus antirrhinii (Macchiati) ). It was not known whether the newly designated species had the potential to damage the Idaho potato crop. The objectives of our research were to determine whetherMyzus (Nectarosiphon) spp. other thanM. persicae occurred naturally in Idaho, whether they could colonize potato and transmit PLRV, and whether they were potentially holocyclic. NoMyzus (Nectarosiphon) spp. other thanM. persicae were found in Idaho in trap nurseries; howeverMyzus ascalonicus Doncaster recently has been found on stored bulbs and in suction trap collections in north Idaho. Laboratory bioassays for PLRV vector potential usingPhysalis floridana Rydb. indicator plants show thatM. nicotianae can transmit PLRV as efficiently asM. persicae. Similarly,M. nicotianae colonized potato as well asM. persicae in a replicated laboratory experiment comparing two clones ofM. nicotianae and one clone ofM. persicae. Our observations indicate that North AmericanM. nicotianae may be capable of a limited facultative holocycle. Thus, in laboratory experiments,M. nicotianae is as damaging asM. persicae with respect to PLRV vector potential; however,M. nicotianae may not occur naturally in areas like Idaho that have no tobacco production. A summary of allMyzus (Nectarosiphon) spp. with respect to PLRV epidemiology is provided.

Effects of dietary amino acids on the production of sexual morph by the green peach aphid, Myzus persicae

Abstract: In order to complete a holocycle of the green peach aphid, Myzus persicae, on a synthetic diet, the effects of dietary amino acid contents on development of sexuals were investigated. For this purpose, the aphids were reared on holidic diets for two to three generations at 20°C under a scotophase of 15 h per diem. Under these conditions, the production of males by the aphids on a synthetic diet was very much poorer than those reared on radish seedling. On reducing the amino acid concentration of the diet, the proportion of males produced was comparable to that produced by aphids fed on radish seedlings. The obtained males were smaller and survived longer than those reared on radish seedling. Under the long night photoperiod and on the synthetic diet with reduced amino acids, gynoparae and then oviparae were also obtained. The oviparae were mated with the males grown on the synthetic diet, and laid eggs. The eggs, however, did not turn dark in color, and perished. © 1995 Wiley-Liss, Inc.