Showing papers on "Myzus persicae published in 1985"

Genetic variability in host plant adaptation of the green peach aphid, Myzus persicae

Abstract: The green peach aphid, Myzus persicae (Sulz.), is polyphagous on over 400 plant species in more than 50 families. Phenotypic plasticity of individuals and genetic variability in the population presumably contribute to this polyphagy. The genetic variability in field populations of M. persicae was assessed with respect to their adaptation to sugar beets and potatoes. An analysis of more than 1 000 clones, sampled during 1980, 1981 and 1982 from different host plants in the field, revealed a wide genetic variability in host plant adaptation to sugar beets as well as to potatoes. Both traits seem to be inherited independently from each other and do not correlate with clone-specific host plant preference of apterous adults. The aphid M. persicae can be characterized as a polyphagous insect species with a wide, continuously distributed variability and a broad phenotypic plasticity. A general differentiation of herbivorous species into generalists and specialists tends to ignore the genetic component in the complex of insect-plant relationships. Zusammenfassung Genetische Variabilitat in der Wirtspflanzenanpassung der Grunen Pfirsichblattlaus, Myzus persicae Die Grune Pfirsichblattlaus Myzus persicae (Sulz.) lebt polyphag an uber 400 Pflanzenarten in mehr als 50 Pflanzenfamilien. Ein breites Nahrungsspektrum einer Art ergibt sich jedoch aus der phanotypischen Plastizitat des Individuums oder einer Klonlinie und der genetischen Variabilitat der Population. Feldpopulationen der Grunen Pfirsichblattlaus wurden auf ihre genetische Variabilitat bezuglich der Wirtspflanzenanpassung an Rube und Kartoffel untersucht. Eine Analyse von mehr als 1 000 Klonen, die uber die Jahre 1980, 1981 und 1982 im Rheinland gesammelt wurden, lassen eine breite Variabilitat in der Wirtspflanzenanpassung der Population erkennen. Beide Merkmale scheinen unabhangig voneinander vererbt zu werden und zeigen keine Beziehung zum Wirtswahlverhalten adult apterer Lause der entsprechenden Klone. Die Art M. persicae kann daher charakterisiert werden als eine polyphage Insektenart mit einer breiten genetischen Variabilitat und einer grossen phanotypischen Plastizitat. Eine generelle Differenzierung von Herbivoren in Generalisten und Spezialisten vernachlassigt die genetische Komponente in der komplexen Beziehung zwischen Insekten und ihren Wirtspflanzen.

The role of flying aphid vectors in the transmission of cucumber mosaic virus and potato virus Y to peppers in Israel

Abstract: SUMMARY More than 44 species of aphids were trapped by suction during the spring seasons of 1981, 1982 and 1983 over a pepper field at Bet Dagan, Israel. Nineteen species transmitted cucumber mosaic virus (CMV), while seven transmitted potato virus Y (PVY) at least once. Over 80% of the CMV and of the PVY infection among test plants (Capsicum annuum cv. Weindale) exposed to trapped aphids was caused by Aphis citricola and two or three other Aphis species, Myzus persicae and Macrosiphum euphorbiae. Landing rate was determined by comparing the proportion of each species found on green tiles or pepper plants with that found in suction traps. A. citricola was the most common but was found in a much lower proportion on plants than either in flight or on green tiles. Aphis spp. and M. persicae were more than 2–5 times more frequent (relative to other species) on green tiles than in flight. M. persicae and M. euphorbiae, which colonise peppers, were found on peppers at a proportion several times higher than either on green tiles or in the air. The relative importance of the different vector species was calculated by multiplying abundance by the proportion of transmitters and the landing rate. A. citricola and Aphis spp. were responsible for more than 50% of the total transmission of either CMV in 1981 and 1982 and of PVY in 1981. Peaks of CMV infection of bait plants coincided with peaks of transmitters of A. citricola and Aphis spp. caught in suction traps. The significance of these findings in primary infection of peppers with CMV and PVY is discussed.

Restricted multiplication of potato leafroll virus in resistant potato genotypes

Abstract: SUMMARY Plants of a range of potato genotypes differing in rating for field resistance to potato leafroll virus (PLRV) were inoculated with the virus by grafting or by aphids (Myzus persicae). Plants of all genotypes tested became infected by each inoculation method and PLRV was detected by ELISA in the upper leaves of all genotypes within 26 days after grafting. Most genotypes with high resistance ratings developed only mild primary and secondary symptoms whereas those with low resistance ratings developed more pronounced symptoms. However, one genotype (G7461(4)) with a high resistance rating was very severely affected. The concentrations attained by PLRV in genotypes with high resistance ratings were only 1–10% of those in genotypes with low resistance ratings. These differences in virus concentration were found in young leaves of plants with primary or secondary infection, whether inoculated by grafting or by aphids and whether grown in the glasshouse or the field. In older leaves, differences in virus concentration between genotypes were at least as pronounced as those in younger leaves. In contrast, PLRV concentration in vascular tissue at the heel end of tubers of plants with primary infection was similar for all the genotypes tested. Although low PLRV concentration was consistently associated with high resistance rating it is not the only form of resistance to PLRV occurring in potato.

Transmission of potato virus Y by cereal aphids.

Abstract: The cereal aphidRhopalosiphum padi transmitted PVYO and PVYN from and to both tobacco and potato. However, it transmitted much less frequently thanMyzus persicae, even when aphids making single probes were compared.R. padi andM. persicae retained PVY for a similar duration. Both alatae and apterae ofR. padi transmitted infrequently, as also did progenies of individual aphids that had transmitted PVY.Metopolophium dirhodum also transmitted PVY infequently butSitobion avenae did not transmit.

Studies on beet western yellows virus in oilseed rape (Brassica napus ssp. oleifera) and sugar beet (Beta vulgaris)

Abstract: SUMMARY Oilseed rape (Brassica napus L. ssp. oleifera) was studied as a potential overwintering host for the sugar-beet yellowing viruses, beet yellows virus (BYV) and beet mild yellowing virus (BMYV), and their principal vector, Myzus persicae. In spring 1982, plants infected with a virus which reacted positively in enzyme-linked immunosorbent assay (ELISA) with BMYV antibody globulin were found in oilseed-rape crops; none of the plants contained virus which reacted with BYV antibody globulin. This virus was subsequently identified as beet western yellows virus (BWYV). No leaf symptoms could be consistently associated with infection of oilseed rape, but the virus was reliably detected by sampling any leaf on an infected oilseed-rape plant. Some isolates from oilseed rape did infect sugar beet in glasshouse tests, but the proportions of inoculated plants which became infected were low. Apparently there is therefore little danger of much direct transmission of BWYV by M. persicae from oilseed rape to sugar beet in spring. BWYV was introduced to and spread within oilseed-rape crops in autumn by M. persicae, and autumn-sown oilseed rape proved to be a potentially important overwintering host for M. persicae. In a survey of 80 autumn-sown crops of oilseed rape in East Anglia, northern England and Scotland in spring 1983, 78 were shown to be extensively infected with BWYV. Experimental plots of oilseed rape with 100% BWYV-infection yielded approximately 13.4% less oil than plots with 18% virus infection, the result of a decrease in both seed yield and oil content.

Evaluation of aphidoletes aphidimyza (dip. : cecidomyiidae) for control of myzus persicae (hom. : aphididae) in greenhouse and field experiments in the united states

Abstract: Greenhouse and field experiments were conducted to evaluate the potential of inoculative releases of the predatory midge,Aphidoletes aphidimyza (Rondani), on aphid populations on vegetables. The predator was collected from wild and cultivated plants in upstate New York and subsequently reared in the laboratory. Midges from the rearings were released, as pupae, into greenhouses and field plots where plants were infested with aphids, predominately the green peach aphid,Myzus persicae (Sulzer).

Measurement of aphid feeding rates on artificial diets using 3H‐inulin

Abstract: The radioactivity of the honeydew droplets excreted by young apterous adults of the green peach aphid, Myzus persicae, fed on an artificial diet containing 3H-inulin was a reliable measure of the volume of food ingested by the insects, since almost none of the ingested inulin was absorbed and retained by the insects. Zusammenfassung Quantitative Bestimmung der Nahrungsaufnahme von Aphiden auf kunstlicher Diat mit3H-Inulin Junge aptere Adulte von Myzus persicae wurden auf kunstlicher Diat mit oder ohne Zugabe von radioaktiv markiertem Inulin (3H, 100 μCi pro ml; 84.5 cpm pro nl) gehalten. Die Radioaktivitat der Blattlause und ihrer ausgeschiedenen Honigtautropfen wurde in Zeitintervallen nach der Futterung bestimmt. Die Ergebnisse zeigen, dass Inulin nur in geringer Menge von den Blattlausen absorbiert wird, und, dass die Radioaktivitat der ausge schiedenen Honigtautropfen nach Zugabe von 3H-Inulin zur kunstlichen Diat ein verlassliches Mass fur das Volumen der von ihnen aufgenommenen Nahrung ist.

Factors affecting the cold hardiness of the peach-potato aphid Myzus persicae

Abstract: SUMMARY Supercooling point studies were used to investigate the factors influencing the cold hardiness of the peach-potato aphid Myzus persicae, a freezing-susceptible insect. Overwintering adults lost cold hardiness as winter progressed, with a variable proportion showing a marked reduction in supercooling ability. Cold hardiness increased in spring so that all individuals demonstrated extensive supercooling ability typical of aphids reared in the laboratory at 20°C with a long photoperiod; these levels of cold hardiness were maintained in the field during summer and early autumn. First instar nymphs demonstrated considerable cold hardiness all year. Surface moisture caused inoculative freezing in some first instar nymphs and adults when supercooled, but the majority were unaffected. In the laboratory, adults starved for 7 days at 5°C showed distinct losses of supercooling potential equivalent to those observed in the field during mid to late winter. No loss of cold hardiness was found in first instar nymphs starved under the same conditions. The results demonstrate that the cold hardiness characteristics of M. persicae are atypical of those observed in other freezing-susceptible insects and it is suggested that continued feeding during mild winter conditions allows maintenance of cold hardiness particularly in adult aphids, and provides a possible explanation for the successful anholocyclic overwintering of M. persicae during such winters.

Lethal and Sublethal Effects of Aldicarh on Two Potato Aphids (Homoptera: Aphidae): Myzus persicae (Sulzer) and Macrosiphum euphorbiae (Thomas)

Abstract: Field tests conducted in 1982 and 1983 indicated that a minimum of 30 h was required to reach a 50% mortality level when winged green peach aphids, Myzus persicae (Sulzer), are exposed to aldicarb-treated potato plants. Surviving aphids are not expected to be efficient vectors of persistent viruses because of a significantly reduced ability to fly and to probe. Tests done with the common potato aphid, Macrosiphum euphorbiae (Thomas), yielded similar results.

Monitoring of inflights of green peach aphids,Myzus persicae (Sulzer), in New Brunswick potato fields by yellow pans from 1974 to 1983: Results and degree-day simulation

Abstract: Based on 10 years of trapping with yellow pan traps it was determined that on the average inflights of green peach aphids,Myzus persicae (Sulzer), start July 26 and cumulative catches of more than five aphids August 8. The lack of significant differences in the timing of first and cumulative catches of aphids between the northern and the southern section of the potato production area is additional evidence thatM. persicae does not usually overwinter in New Brunswick. Important yearly variations in the timing of the first cumulative catch of more than 5 aphids can be simulated by the thermal summation of 1188 DD and forecasted by regression on the timing of first inflights. The use of these results to improve the extension program is discussed.

Functional significance of the alarm pheromone composition in various morphs of the green peach aphid, Myzus persicae.

Abstract: Three isomers of farnesene occur in the siphon excretions of at least four aphid species: the siphon excretions of Myzus persicae contain (E)-β-farnesene, as well as (Z,E)-α, and (E,E)-α-farnesene The significance of (E)-β-farnesene as an alarm pheromone was evaluated by the investigation of the ratios and quantities of the above-mentioned farnesene isomers in various morphs of Myzus persicae (Sulz) It is suggested that a relationship exists between the production of farnesene isomers and the occurrence of morphs Zusammenfassung Die funktionelle Bedeutung der Zusammenstellung des Farnesens in verschiedenen Morphen von Myzus persicae Es ist bekannt, dass drei Isomere des Farnesens in der Siphonensekret von wenigstens vier Blattlausmorphen vorkommen So enthielt zum Beispiel das Siphonensekret bei Myzus persicae (E)-β-,(Z,E)-α- und (E,E)-α-Farnesen Um die Bedeutung des (E)-β-Farnesens zu ermitteln, haben wir die Mengen und Verhaltnisse der Farnesenisomere in verschiedenen Morphen von Myzus persicae bestimmt Die Ergebnisse deuten darauf hin, dass eine Beziehung zwischen der Produktion von Farnesenisomeren und der Bildung der Morphe in dieser Blattlaus besteht

The effect of insecticides and a plant barrier row on aphid populations and the spread of bean yellow mosaic potyvirus and subterranean clover red leaf luteovirus in Vicia faba in South Australia

Abstract: SUMMARY The effect of the insecticides malathion, demeton-S-methyl and disulfoton, and a barley barrier row on the rate and pattern of spread of bean yellow mosaic potyvirus (BYMV) and subterranean clover red leaf luteovirus (SCRLV) in Vicia faba was investigated in field plots with artificially introduced sources of viruses and vectors. The systemic insecticide treatments reduced aphid populations in the plots and this was associated with reduced spread of SCRLV, but not of BYMV. The barley barrier did not affect aphid populations in plots; however, it reduced the spread of BYMV to rows 1 · 1 m from the source but had only a minor effect on the spread of SCRLV. Apterae rather than alates of Aulacorthum solani were implicated in the spread of SCRLV. Spread of BYMV was attributed mainly to alate migrants of Myzus persicae and Macrosiphum euphorbiae, but other aphid species and morphs which occurred in high populations at the times of most rapid virus spread may also have had an active role as vectors of BYMV.

The effect of sub-lethal dosages of the synthetic pyrethroid fenvalerate on the reproductive rate of the aphid Myzus persicae

Abstract: A series of experiments in the laboratory and greenhouse, were designed to test the possible causes of the field resurgence of the aphid Myzus persicae. Stimulation of reproduction occurred at topical dosages of around the LD5 value. Residual film tests indicated a significant depression in fecundity when aphids were held on sub-lethal deposits of fenvalerate, even at dosages below the LD5 value. Trends in the population build-up experiments in the greenhouse suggested there may be some stimulation when aphids are confined to aged deposits of fenvalerate 7 days after treatment, but the slight increase was not significant.

Influence of Potato Plant Phenology on the Population Dynamics of the Green Peach Aphid, Myzus persicae (Homoptera: Aphididae)

Abstract: The population dynamics of the green peach aphid (GPA), Myzus persicae (Sulzer), were examined on four commercial potato cultivars, Solanum tuberosum tuberosum (L.) cv. Katahdin, Norchip, Superior, and 8NW-8, with differing maturation rates and on one wild potato, S. canasense PI 283074. GPA abundance, population growth rate, alate abundance, and within-plant distribution were compared among cultivars. Results showed that GPA numbers were similar among commercial cultivars during most of the growing season. However, GPA population dynamics were influenced by potato plant phenology. GPA were more abundant earlier, populations peaked sooner, and declined earlier on the short-season cultivar, ‘Superior’. Populations on longer-season cultivars reached highest levels later. At 1,167 degree-days, GPA numbers were ca. 50% smaller on ‘Superior’ than on the mid-season cultivar, ‘Norchip’. Fewer GPA were observed on S. canasense than on the commercial cultivars. GPA populations reached one-half their highest level from 6 to 8 days sooner in the growing season on ‘Superior’ than on later-maturing cultivars. Alate numbers were greatest on ‘Superior’, followed by ‘Norchip’, ‘Katahdin’, and 8NW-8. GPA were found predominantly on the lower leaves of each cultivar. GPA population growth rates were greatest on the lower leaves and slowest on the upper leaves of each cultivar. GPA populations increased more rapidly on the upper, middle, and lower leaves of ‘Superior’ than on longer-season cultivars.

Nonstable Parathion and Endosulfan Resistance in Green Peach Aphids (Homoptera: Aphididae)

Abstract: Parathion and endosulfan insecticide resistant colonies of green peach aphids, Myzus persicae (Sulzer), collected from various potato fields in Wisconsin, reverted to susceptible conditions after being maintained in greenhouse insecticide-free enviroments. The amounts of time which field-collected aphids remained as insecticide-resistant colonies varied from as few as 10 to as many as 27 generations after their collection from the fuield. Stability of resistance varied in splinter colonies which were derived from aphid colonies in different phases of transition from resistant to susceptible conditions. Reversions to parathion susceptibility were paralleled by near-simultaneous reversions to endosulfan susceptibility. Once begun, the reversion process proceeded rapidly and was completed within approximately four generations.

Effect of undersowing potatoes with grass on potato aphid numbers

Abstract: SUMMARY The numbers of the potato aphids, Macrosiphum euphorbiae and Myzus persicae, were counted on potatoes undersown and not undersown with perennial ryegrass in field experiments during 1980 and 1981. The numbers of aphids on potatoes undersown with grass were found generally to be smaller than the aphid numbers on potatoes not undersown with grass. Tuber yields were not significantly reduced by the undersowing of potatoes. The agronomic feasibility of undersowing potatoes for aphid control is discussed.

Development and reproduction of the green peach aphid, myzus persicae (homoptera: aphididae), on upper and lower leaves of three potato cultivars

Abstract: The influence of potato cultivar ( Solanum tuberosum tuberosum (L.) cvs. Katahdin (long-season), Norchip (mid-season), and Superior (short-season)) and vertical leaf position on certain life statistics of the green peach aphid, Myzus persicae (Sulzer), were assessed in a glasshouse environment. Aphids were caged on upper and lower leaves of each cultivar. Developmental time requirements for pre-reproductive life stages were similar among cultivars and between leaf positions. Longevity was similar among cultivars within leaf position. However, aphids survived 62.3, 53.6, and longer on lower leaves than on upper leaves of Superior, Norchip, and Katahdin ( p shorter on Superior than on Katahdin. MGT was 15.2, 6.9, and shorter on lower leaves than on upper leaves of Superior, Norchip, and Katahdin, respectively ( p

Aphid Transmission of Turnip Mosaic Virus and Cucumber Mosaic Virus

Abstract: An investigation was undertaken to obtain further information on aphid transmission of turnip mosaic virus (TuMV) and cucumber mosaic virus (CMV) from doubly infected turnip plants (Brassica campestris cv Yorii) to healthy ones. Both winged and wingless forms of Myzus persicae (SULZER) transmitted TuMV alone at a higher rate, but failed to transmit or seldom transmitted CMV alone. Both forms of Aphis gossypii GLOVER, showed three types transmission, TuMV alone, CMV alone and both viruses simultaneously, but they transmitted CMV alone more effectively. In the transmission test with successive transfers at 10-minute intervals, most of the M. persicae individuals transmitted TuMV alone to only the first plant of the series. And A. gossypii also commonly transmitted TuMV alone or CMV alone to the first plant only. When M. persicae and A. gossypii had fed first on infected leaves and then fed on anti-TuMV γ-globulin through a stretched parafilm membrane, the transmission of TuMV was prevented completely or decreased remarkably. And A. gossypii treated with anti-CMV γ-globulin after feeding on the infected leaves, transmitted TuMV regularly, but seldom transmitted CMV.

Aphidivorous Activity of a Coccinellid Beetle, Harmonia axyridis Pallas(Coleoptera: Coccinellidae)

Abstract: Some experiments were conducted to evaluate the aphidivorous activity of coccinellid beetle, Harmania axyridis Pallas. Experiments were carried out using with laboratory reared beetles and two aphid species(Aphis gossypii and Myzus persicae). Factors referred in the study of aphidivorous activity were the age of beetle, aphid species, temperatreu and illumination time. The aphidivorous activity was greatly different in relation to aphid species, developmental stages of the beetle, and the temperature. The 3rd and 4th instar larvae consumed more aphids than the 1st and 2nd instar larvae. Though the beetles consumed more number of cotton aphid, total weight of aphids consumed the more or less the same. Aphidivorous activity of the 1st to 4th instar larvae increased with a rise in temperature and adult activity was relativel high at and low at . The aphidivorous activity of the beetles was not influenced by the illumination period under the conditions given in this experiments, however, seem to require further study.

Glasshouse tests and field selection for heritable resistance to Myzus persicae in sugar beet

Abstract: SUMMARY A technique is described to assess and select in the field for resistance to Myzus persicae in sugar beet. Lines developed by this method were aphid resistant when compared with commercial cultivars. The resistance was inherited by progeny lines. Variation between beet lines in glasshouse tests suggested segregation of a number of resistance genes with varying effects. Integration of selection for aphid-resistance and agronomic performance during beet breeding is discussed.

Studies on the cold hardiness of the peach-potato aphid Myzus persicae (Sulzer)

Abstract: A system incorporating a prototype automatic thermoelectric cooling method with computer-based recording of aphid supercooling points was developed and formed the basis of cold hardiness assessment. Under laboratory culture all developmental stages of Myzus persicae had a mean inherent supercooling potential below -20°C, with first instar nymphs the most cold hardy. When maintained at 5°C, younger instars demonstrated acclimation ability unlike adult aphids, and in an insecticide resistant strain, adults lost cold hardiness. When in contact with surface moisture, the majority of aphids did not experience inoculative nucleation. Sexual morphs of M. persicae possessed supercooling ability comparable with laboratory maintained parthenogenetic morphs; eggs supercooled to below -30°C. Seasonal studies of supercooling ability demonstrated that all aphid stages were most cold hardy in summer. Younger instars showed natural acclimatisation and were cold hardy throughout the year. Overall adults lost cold hardiness as winter progressed, exhibiting bimodal supercooling point distributions in two winters, with distinct high (HG) and low (LG) groups and mean supercooling points of approximately -20°C and -10 oe respectively. Clonal differences and adult age did not account for this pattern. Following experimental starvation at 5°C, first instars of M. persicae maintained extensive supercooling potential but adults exhibited losses of cold hardiness comparable with those in natural overwintering populations, suggesting that feeding may be necessary to maintain adult cold hardiness levels during winter. Subsequent starvation experiments did not reproduce the dramatic losses of cold hardiness implying that the feeding influence was more complex than the availability of food per se. In a series of host transfer experiments the mean supercooling point of Aphis fabae adults could be shifted by over 10°C, increasing when they fed on beans and reduced when transferred back to spindle; the LG (spindle/poor supercoolers) to HG (bean/good supercoolers) shift was more difficult to achieve and suggested a nucleating agent in spindle sap. Trimethylsilyl derivatised carbohydrate extracts of M. persicae and A. fabae were analysed by capillary gas-liquid chromatography. Glucose, glycerol, fructose, mannitol, sucrose, and trehalose were detected in samples of both species, together with trace amounts of unidentified carbohydrates in M. persicae samples. Dulcitol was present in spindle-fed A. fabae only. There was no obvious correlation between carbohydrate content and supercooling ability but high total percentage body carbohydrate levels were revealed and may have a solute effect, enhancing inherent supercooling potential and dependent on carbohydrate-rich sap intake. Laboratory cultured A. fabae were capable of extensive supercooling, as were individuals collected from summer herbaceous hosts; first instars were the most cold hardy. When associated with the primary host, spindle, all aphids showed poor supercooling potential, less than -15°C; overwintering eggs were capable of supercooling to below -30°C and acclimatised in winter. Eggs and oviparae were not subject to inoculative nucleation. Preliminary experiments to relate supercooling ability to mortality at sub-zero temperatures proved inconclusive and were terminated when temperature shock and/or desiccation were thought to have induced premature mortality. The results demonstrate that the cold hardiness characteristics of M. persicae are atypical of those observed in other freezing-susceptible arthropods. It is proposed that continued feeding during mild winters maintains cold hardiness levels in adult M. persicae and this influence may provide a possible explanation for the successful anholocyclic overwintering of this aphid during such winters. Avenues of research to further investigate this proposal are suggested.

Host specificity and speciation

Abstract: Most aphids are autoecious (Figure 3.1), living on one or a few species of a particular genus of plants (Eastop, 1973). About 10% are heteroecious (Figure 3.1), spending autumn, winter and spring on a primary host plant, and the summer on a secondary host plant(s), which is rarely closely related to the primary host. For example the primary host of the rosy apple aphid, Dysaphis plataginea, is apple (Rosaceae) and its secondary host is plantain (Plantago lanceolata, Plantaginaceae); for the currant-yellow rattle aphid, Hyperomyzus rhinanthi, it is red currant (Ribes rubrum, Grossulariaceae) and greater yellow rattle (Rhinanthus major, Scrophulariaceae), respectively. Although heteroecious species are classified as polyphagous it is noteworthy that most of them live on one species of plant at a time, i.e. they are sequentially monophagous. The type of heteroecious life cycle shown by the black bean aphid, Aphis fabae, and the peach-potato aphid, Myzus persicae (Figure 3.1), in which there is a wide range of secondary host plants, is very rare. Even in these highly polyphagous species it is possible that particular genotypes do best on certain species of plant (Takada, 1979; Weber, 1985a-c), i.e. most aphids show a very high degree of host specificity, even the heteroecious species.

The production of different morphs by alate viviparae of the aphid Myzus persicae temporarily exposed to long scotophases

Abstract: The development of alatae of the green peach aphid, Myzus persicae, as gynoparae rather than as virginoparae was investigated with regard to the number of exposures to a long-night (LN) regime of 15 h darkness per diem which the aphids experienced before and/or after their birth. The minimum number of exposures to LN that resulted in all of the alatae developing into gynoparae was two prenatal plus one postnatal or one prenatal plus two postnatal, provided the scotophases in these treatments were at least 12 h long. A cumulative effect of several successive exposures to LN was also evident when the presumptive alatae were exposed to LN either from birth or not until several days after birth. Fewer exposures to LN were needed in the former case. Zusammenfassung Die Produktion verschiedener Morphen der Blattlaus Myzus persicae aus alaten Viviparae, die zeitweise langen Dunkelphasen ausgesetzt waren Die Entwicklung von Alatae der grunen Pfirsichblattlaus, Myzus persicae, hauptsachlich zu Gynoparae, eher als zu Virginoparae, wurde im Hinblick auf den Einfluss der Anzahl an Langnachten (LN: 15 Stunden Dunkelheit pro Tag), denen die Aphiden vor und/oder nach der Geburt ausgesetzt waren, untersucht. Zur ausschliesslichen Entwicklung aller Alatae zu Gynoparae waren mindestens 2 prenatale und eine postnatale LN-Exposition oder eine prenatale und 2 postnatale LN-Expositionen notwendig, vorausgesetzt die Dunkelphasen betrugen mindestens 12 Stunden. Ausserdem zeigte sich ein kumulativer Effect durch mehrere, aufeinanderfolgende LN-Expositionen, wenn die Alatae diesen von Geburt an, oder einige Tage nach der Geburt, ausgesetzt waren. Im ersten Fall waren weniger LN-Expositionen notwendig.

Insecticidal Activity and Properties of TIA-230 (Pyraclofos)

Abstract: TIA-230 (pyraclofos*), O-[1(4-chlorophenyl)-4-pyrazolyl]o-ethyl S-propyl phosphorothiolate showed high insecticidal activity against the Lepidopterous, Coleopterous, Hemipterous, and Dipterous insect pests, such as Spodoptera litura, Mamestra brassiase, Pseudaletia separata, Plutella xylostella, Pieris rapae, Adoxophyes orana, Chilo suppressalis, Aulacophora femoralis, Phyllotreta striolata, Phaedon brassicae, Henosepilachna vigintioctopunctata, Lissorhoptrus orizophilus, Aphis gossypii, Aphis glycines, Myzus persicae, Hyalopterus pruni, Musca domestica and Culex pipiens molestus. The compound also showed a high acaricidal activity against Tetranychus urticae, Tetranychus kanzawai and Rhizoglyphus echinopus and showed a high nematicidal activity against Meloidogyne incognita. Residual activity by foliar spray of TIA-230 was shown to be higher than those of prothiophos, acephate, methomyl, demethylvinphos, chlorpyrifos-methl, dicofol, fenbutatin oxide and cyhexatin. In field tests, the sprays of 0.017% and 0.035% solution of TIA-230 (wettable powder) were highly effective in controlling the damage to cabbage by Spodoptera litura, Mamestra Brassiase, Plutella xylostella, Pieris rapae and Myzus persicae.

Survival and the relationship between fecundity and longevity in Myzus persicae (Homoptera: Aphididae)

Abstract: In a previous report (Jansson and Smilowitz 1985), several life statistics of Myzus persicae (Sulzer) were compared on upper and lower leaves of three potato cultivars (Solanum tuberosum tuberosum cvs. Katahdin, Norchip, and Superior). In general, life statistics were similar (p > 0.05) between cultivars. However, certain life statistics (fecundity and intrinsic rate of increase) consistently were greater (p < 0.05) on lower leaves than on upper leaves of each cultivar. In the previous study, we did not include data on age-specific survival or the relationship between fecundity and longevity to support the premise that the population dynamics of M. persicae on potato are related to the physiological age of leaves (i.e. nutritional quality of leaves) (see Jansson and Smilowitz 1985). This information would be useful for developing a model describing the population dynamics of M. persicae. For this reason, we present here data on age-specific survival and the relationship between fecundity and longevity of M. persicae on upper and lower leaves of three Dotato cultivars.