Showing papers on "Aphid published in 1972"
TL;DR: The fascination of the aphid lies in part in its polymorphism, and their tremendous reproductive potential, salivary secretions, and ability to transmit virus diseases also gain them the dubious honor of being one of the most potent and world-wide enemies of agricultural crops.
Abstract: These small homopterans are one of the most varied, fascinating, and studied groups of insects, even though they are one of the "degenerates" of the modern insect world (lOS). The intense interest in aphids is exemplified by a recent review on the ecology of the green peach aphid, Myzus persicae, which cited 638 references (55). This is only a partial list of the available literature. The fascination of the aphid lies in part in its polymorphism (86). The variations of aphids are well known, for they alternate hosts with hosts, sexual with pathenogenetic forms, hibernating with aestivating forms, wingless with winged forms, and migrant with nonmigrant forms. And all of this variation may sometimes occur within the annual cycle of a single species as it does in the melon aphid, Aphis gossypii (117,203). The small size of aphids and their variability qualify them as excellent material for biological research. Their tremendous reproductive potential, salivary secretions, and ability to transmit virus diseases also gain them the dubious honor of being one of the most potent and world-wide enemies of agricultural crops. Since the infestations and virus diseases (20, 21, 33, 47, 139, 185, 201) are spread between geographical and political areas by the winged aphids, the behavior of flying aphids is of academic, economic, and review interest. Several excellent reviews are already available on aphids. These cover the biology (lOS), polymorphism (86), feeding and nutrition (7), the im pact of pathog�ns, parasites and predators on them (67), their role in the ecology of plant viruses (201), the ecology of the green peach aphid (55), and the ecological aspects of plant virus transmissions (23). Generalizations are difficult to make about aphids because, as such, they must encompass the behavior of countless individuals of a large number of diverse species. Over 430 aphid species are recorded from the state of New York (131, 132).831 species in Central Europe (l09). and. in 1953, an esti mated number of 2690 species for the world (109). Despite the warnings of other writers (14) against generalizations and oversimplification, this re view does both. Only the flight behavior of the black bean aphid (Aphis fabae) has been studied in detail on a world-wide basis. A considerable amount of informa-
188 citations
TL;DR: Segregation ratios in the F 1 and F 2 indicate that the androcyclic condition is induced by a recessive ‘ switch-gene ’ which completely suppresses the production of sexual females, and partially suppresses male production.
Abstract: The response to short photoperiod (10 h) of the F1 and F2 sexual generations of Myzus persicae (Sulz.) resulting from a cross between oviparae from a holocyclic clone and males from an androcyclic clone were examined and compared in experiments done at Imperial College Field Station, England. F1 and F2 progeny segregated into three distinct phenotypes; holocyclic, androcyclic and intermediate. Intermediate clones reared at 10 h photoperiod produced alatae which were physiologically intermediate between gynoparae and virginoparae, because their progeny consisted of oviparae, apterous virginoparae and intermorphs. Intermediacy was not affected by temperature and seems to be genetically determined. Segregation ratios in the F1 and F2 indicate that the androcyclic condition is induced by a recessive ‘ switch-gene ’ which completely suppresses the production of sexual females, and partially suppresses male production. This gene could be present in the heterozygous condition in a large proportion of parthenogenetic lines of the aphid, and thus confer a latent potentiality for anholocycly on populations even where conditions will not regularly permit this method of overwintering. Conversely where anholocycly is strongly favoured many aphids would be homozygous for the recessive, androcyclic character, but the potential for gamic reproduction could remain widespread.
98 citations
75 citations
TL;DR: Aphid performance was better on diets that contained both sterol and inorganic sulphur at the highest levels tested than on sterol-free diets with or without a supplement of in organic sulphur.
62 citations
TL;DR: Viruses, which multiply very much faster and attain larger populations than do aphids, have also become adapted efficiently to agricultural condi tions and have exploited different kinds of aphid behavior for their trans mission.
Abstract: Although many new vectors of plant viruses have been discovered dur ing the past decade including nematodes and fungi, aphids stilI remain the taxon that transmits a greater number and variety of viruses than does any other group of organisms. This may partly be explained by their way of life, which is specialized to use food to the full when it is plentiful and suffer the least loss when it is lacking. They reproduce by parthenogenesis, viviparously, and rapidly on susceptible lush vegetation, and then have a short period of sexual activity sufficient to produce eggs that withstand long periods of adverse conditions, and for beneficial mutations to survive. Muta tions are many because of the very large populations aphids achieve, and these mutations help them to adapt to changing conditions of climate and host plants. Hence, they have been able to meet changes in agriculture and become ubiquitous in crops of the temperate region. Viruses, which multiply very much faster and attain larger populations than do aphids, have also become adapted efficiently to agricultural condi tions and have exploited different kinds of aphid behavior for their trans mission. These relationships seem to have evolved around three kinds of aphid behavior: 1. Host selection. Aphids make brief, shallow probes into a plant after migration or other movements between plants. 2. Colony estab lishment. Invading alatae of some species deposit a few larvae on each of several plants instead of establishing a single large colony on one plant. 3. Dispersal of population. After colonies of apterous alienicolae have be come dense alatae develop which move within and be. tween crops, establish ing new colonies. This insures against extinction of the race by overpopula tion and spreads viruses from the "parent plants" to new hosts. Watson & Roberts (178) and Sylvester (153) separated three categories of viruses which they call nonpersistent, semipersistent, and persistent, ac cording to the period during which feeding aphids remain infective after acquiring virus, respectively, one hour, one to three days, and an indefinite number of weeks.
57 citations
TL;DR: What factors in the sycamore aphid's environment regulate the appearance of the reddish and melanic forms are determined and the adaptive significance of these forms is discussed.
Abstract: In spring and summer alate virginoparae of the sycamore aphid are present but with the onset of autumn apterous oviparae and alate males appear. These mate, and the oviparae lay the overwintering eggs. This polymorphism is controlled by the aphid's response to changes in its environment (Dixon 1971). In addition to this polymorphism there are changes in the background colour of the aphid. Adult aphids of the spring and autumn generations have black bands on their abdomen and are generally darker in colour. In addition to this pigmentation of bands of the cuticle the body fluids and tissues range in colour from green to red. As the abdominal sclerites are transparent, except in the areas that are melanized, the aphid has a green or reddish ground colour. Aphids with a reddish ground colour are the rarer and they first appear in summer. The aim of this paper is to determine what factors in the sycamore aphid's environment regulate the appearance of the reddish and melanic forms and to discuss the adaptive significance of these forms.
50 citations
TL;DR: It was concluded that the long-distance transport of IAA from the apical bud of intact pea seedlings does not take place in the phloem sieve tubes involved in the transport of metabolites from foliage leaves, or in the non-living tissues of the xylem.
Abstract: When small colonies of the pea aphid [Acyrthosiphon pisum (Harris)] were established on the stem of Meteor Dwarf Pea seedlings (Pisum sativum L.), 14C was found in the honeydew 4.5 h after applying IAA-1-14C to a fully-expanded foliage leaf. In contrast, no activity was found in the honeydew or aphids 4.5 h after the application of IAA-1-14C to the intact apical bud even though the internode upon which the aphids were feeding contained high levels of 14C. The lack of radio-activity in aphids feeding on stems to which IAA-1-14C was applied via the apical bud was found not to be influenced by the internode position or by the transport interval allowed (up to 24 h).
48 citations
TL;DR: An analysis of and comparison with life tables of two other aphid species in addition to those produced here showed that the differences in rm were due almost entirely to differences in fecundity.
Abstract: Life tables were prepared from daily fecundity and survival data on 69 apterous black bean aphids, Aphis fabae Scopoli, and 47 apterous pea aphids, Acyrthosiphon pisum (Harris). Both were on broad beans in 20° ± 0.5 °C, 70–80% R.H., and 16 hr light per day. The intrinsic rates of natural increase (rm) computed from the life tables were 0.359 ♀/♀ day for the bean aphid and 0.404 ♀/♀ day for the pea aphid. Mortality was not important in determining the rates of increase because very few aphids died during their reproductive periods. Only 5 of 116 reproducing aphids died, all from inability to extrude nymphs which had died before bursting their embryonic membranes. These nymphs became covered with a discharge from the mother which cemented them in place and prevented the birth of succeeding nymphs. The resulting engorged females died in 3–4 days.An analysis of and comparison with life tables of two other aphid species in addition to those produced here showed that the differences in rm were due almost entirely to differences in fecundity. Two fecundity patterns, correlated with aphid phylogeny, were recognized.
42 citations
TL;DR: The results showed that biotypes of the aphid, with differing abilities to colonize respective sprout clones, existed in each area, and of the sevenSprout clones resistant to the Wellesbourne aphids, only one appeared never to be fully susceptible to one or more of the other biotype of B. brassicae.
Abstract: SUMMARY
Because they remained almost uncolonized by the cabbage aphid (Brevicoryne brassicae (L.)) throughout the growing season, plants of Brussels sprouts were singled out in each of 4 years, from plots heavily infested with the aphid, as possibly being resistant to attack. Clones of these plants were established from cuttings and tested in a controlled environment by inoculation with B. brassicae and later, in the field, by natural infestation. The tests confirmed that some of the plants were resistant to the aphid, and the most resistant of those from the first year of the work proved at least as resistant as any subsequently found. The resistance was expressed as antibiosis, but in the field host non-preference was also shown by incoming winged aphids.
The possibility that biotypes of B. brassicae might exist, to which the resistant sprout clones were not necessarily resistant, was investigated using B. brassicae collected from sprouts from each of several areas in England. Eight sprout clones, seven of which were known to be resistant, and the other susceptible, to B. brassicae from Wellesbourne were tested with these other B. brassicae. The results showed that biotypes of the aphid, with differing abilities to colonize respective sprout clones, existed in each area, and of the seven sprout clones resistant to the Wellesbourne aphid, only one appeared never to be fully susceptible to one or more of the other biotypes of B. brassicae.
40 citations
TL;DR: Five biotypes of the pea aphid, Acyrthosiphon pisum (Harris), from four hosts were recognized by their differential survival and rates of population increase on broom, white clover, alfalfa and broad beans, by body size, colour, and rate of natural increase on broad beans.
Abstract: Five biotypes of the pea aphid, Acyrthosiphon pisum (Harris), from four hosts were recognized by their differential survival and rates of population increase on broom, white clover, alfalfa and broad beans, by body size, colour, and rates of natural increase (r m ) on broad beans. A simple method is described which can verify that the differences between r m values measured by life table analysis are not due to chance. Four of the biotypes were sympatric. It is suggested that biotypes in the pea aphid result from annual adaptations to various species of leguminous host plants and therefore other characteristics of the biotypes may vary from year to year. For this reason, only fundatrices and their immediate offspring which have not been subjected to this selection should be used as test organisms in assaying plants for resistance to pea aphids. The use of a biotype of a single year for screening plant varieties may lead to the production of varieties which are highly acceptable to other biotypes.
39 citations
TL;DR: Nabids alone or in some combinations were superior to all other treatments in reducing the population of the noctuid species when these larvae were small.
Abstract: The efficiency of 3 predators, Geocoris bullatus (Say), Nabis americoferus Carayon, and Coccinella transversoguttata Faldermann, used singly and in combination, was evaluated against 3 prey species, the green peach aphid, Myzus persicae (Sulzer), the zebra caterpillar, Ceramica picta (Harris), and the bertha armyworm, Mamestra configurata Walker, on caged sugarbeet plants in the greenhouse. Coccinellids used alone or in combination with other predators were effective in reducing populations of green peach aphids. Also, nabids or geocorids alone were effective in reducing the population of aphids for about 1 week if the initial population averaged no more than 14 aphids per plant and if the predators were present at a rate of about 1 per plant; however, when the population of aphids was 34 per plant, nabids or geocorids alone were not effective. Nabids alone or in some combinations were superior to all other treatments in reducing the population of the noctuid species when these larvae were small.
TL;DR: Field studies on menazon-sprayed and unsprayed plants closely or widely spaced showed that aphid numbers increased rapidly on the groundnut crop 31–45 days from emergence but declined rapidly as the plants matured, and spraying with menazon prevented breeding by incoming alates.
Abstract: Observations on Aphis craccivora Koch at Serere, Uganda, in 1964–68 showed that dry season carry-over of aphids could occur on the common weeds Euphorbia hirta and E. prostrata; at other times aphids were seen on Gliricidia sepium, Cassia tora, Centrosema pubescens and Macroptilium atropurpureum, the last two being increasingly used as pasture legumes. In pot tests, attempts to transfer the virus through G. sepium, Cassia tora, Stylosanthes guianensis and Centrosema pubescens were unsuccessful. Volunteer groundnuts growing in open situations were an important source of virus and vector. Field studies on menazon-sprayed and unsprayed plants closely or widely spaced showed that aphid numbers increased rapidly on the groundnut crop 31–45 days from emergence but declined rapidly as the plants matured. Superficially the plants appeared to be free of aphids but large populations were often found on hypanthia, flowers and gynophores. Coccinellids, especially Cheilomenes sulphurea (Ol), were important predators. Aphid numbers were far higher on groundnuts with low plant densities, possibly because the number of favoured feeding sites is increased, but the number of plants infested was not significantly different at high and low densities. Yellow panels had little effect on aphid numbers. Spraying with menazon (294 g active ingredient/ha, 5 times) prevented breeding by incoming alates.
TL;DR: Aphids of one species or another are always present in cereal crops in sufficient numbers during the summer months to provide copious quantities of honey dew, and this is unlikely to be a limiting factor in the biology of the wheat bulb fly, Leptohylemyia coarctata.
Abstract: SUMMARY
The trapping of alate aphids in emergence cages each 1 yd2 (0–83 m2) over cereal crops from mid-June to the end of July, 1964 to 1971, always revealed colonies of cereal aphids within the crop.
Four species, Sitobion avenae, S. fragariae, Metopolophium dirhodum and Rhopalosiphum padi occurred every year in different proportions. Alate aphids from winter wheat were most numerous in 1968 and fewest in 1967. Alatae developed slightly earlier in cages than in the field and peak catches were a few days earlier than in a nearby 12-2 m suction trap.
Cereal aphid colonies were adversely affected by bad weather in May, e.g. in 1969, and by predators. Coccinellidae (chiefly Propylea 14-punctata) were the dominant predators in 1971 and 1968, Syrphidae in 1966, 1971 and 1968 and Chrysopidae in 1970. Parasites belonging mainly to the genus Aphidius were numerous every year. When hyperparasites such as Asaphes vulgaris, Lygocerus sp., Conostigmus sp. and Phaenoglyphis sp. were abundant as in 1967, they affected numbers of aphids in the current year and increased them in the following year (1968), possibly by hindering early, heavy parasitism. Hyperparasites could have an important influence in fluctuations of cereal aphid populations from year to year. Aphids of one species or another are always present in cereal crops in sufficient numbers during the summer months to provide copious quantities of honey dew, and this is unlikely to be a limiting factor in the biology of the wheat bulb fly, Leptohylemyia coarctata.
TL;DR: Six phytosterols are present in radish seedlings and in the excreta of the aphid, Myzus persicae fed on the seedlings, and the possiblity that these compounds are transported in the phloem and utilized by the aphids is discussed.
01 Jan 1972
TL;DR: The host range of the aphidiine parasite Monoctonus paulensis was determined through numerous field collections of many aphid species found in central and coastal California.
Abstract: The host range of the aphidiine parasite Monoctonus paulensis (Ashmead) was determined through numerous field collections of many aphid species found in central and coastal California. The species Acyrthosiphon pisum (Harris), Amphorophora rubitoxica Knowlton, Macrosiphum californicum (Clarke), M. cuphorbiae (Thomas), Masonaphis grindeliae Williams, Myzus ornatus Laing, M. persicae (Sulzer), and Sitobion fragariae (Walker) are reported in this paper as hosts of the parasite. The ecology of M. paulensis is reported from a study of aphid populations occurring in a cultivated alfalfa field and an area of uncultivated floral associations. Field data indicate that S. fragariae is the principal host of this parasite in central lowland California.
TL;DR: Marked progress has been achieved in developing commercially useful host-resistance to this group of insects with the exception of the cotton bollworm and boll weevil.
Abstract: The development of host resistance to insect pests offers promise of reducing yield losses as well as a material reduction in the use of insecticides. A review of progress and the current situation is presented for selected insect pests, Hessian fly (Mayetiola destructor), European corn borer (Ostrinia nubilalis), boll weevil (Anthonomus grandis), corn earworm and cotton bollworm (Heliothis zea), pea aphid (Acyrthosiphon pisum), spotted alfalfa aphid (Therioaphis maculata), potato leaf hopper (Empoasea fabae), and the alfalfa weevil (Hypera postica). With the exception of the Hessian fly the only feasible control for this group of insects, prior to the development of resistant types, has been through use of chemicals. Marked progress has been achieved in developing commercially useful host-resistance to this group of insects with the exception of the cotton bollworm and boll weevil. Even here types differing in various components of resistance have been identified but the combination of these characteristics into an acceptable commercial variety remains to be accomplished. Increased emphasis is being placed on host-plant resistance. Success in such efforts requires the close cooperation of entomologists, geneticists, and breeders.
TL;DR: Control of the aphid population on potatoes in small plots was obtained by manually placing small numbers of eggs or newly hatched larvae of Coccneilla septempunctaia L., or of eggs of Chrysopa spp.
Abstract: In northeastern Maine, from 30 to 56% all-season control of the aphid population on potatoes in small plots was obtained by manually placing small numbers of eggs or newly hatched larvae of Coccneilla septempunctaia L., or of eggs of Chrysopa spp. on the plants during several weeks in early summer. Although differences between treated and untreated plots for total aphid infestation were significant over a 3-week period, lack of many significant differences among the predator treatments may have been due in part to interplot movement of the introduced predators. The placement of chrysopid eggs in the plots resulted in better control of the green peach aphid, Myxus persicae (Sulzer), than of the potato aphid, Macrosiphum euphorbiae (Thomas). The reverse occurred from that of eggs or larvae of the coccinellid. Protein hydrolysate spray exerted no appreciable effect upon populations of aphids, coccinellids, or of chrysopid larvae on treated plants.
TL;DR: Yield of tubers was related somewhat positively to numbers of predaceous larvae introduced, and somewhat negatively to all-season abundance of aphids on the plants, which was related more to physiological condition of the plants in late summer than to effectiveness of predators in controlling the aphids.
Abstract: Evaluations were made in 1968 and 1969 of the effectiveness of Chrysopa spp., Coccinella septempunctata L., and C. transversoguttata Faldermann as predators when introduced as eggs on potato plants in large field cages infested with Myzus persicae (Sulzer) and Macrosiphum euphorbiae (Thomas). In 1968, 5 early-season weekly applications of eggs resulting in 513,300 hatching larvae of Chrysopa spp. per acre gave 48% better control of aphids than did 128,300 hatching larvae per acre applied at the same times. Likewise, 6 similar applications of C. septempunctata for a total rate of 317,600 hatching larvae per acre, gave 70% better aphid control than did 79,300 hatching larvae applied at the same times.
In 1969, 4 early-season, weekly applications of C. septempunctata , for a total per acre rate of 409,000 hatching larvae, resulted in 63% better control of the aphids than did 3 semiweekly applications for a total of 122,700 hatching larvae per acre, when started July 22. The aphid control was 26% better when the 3 semiweekly applications were started on June 27 than on July 22. Similar results were obtained from identical introductions of C. transversoguttata , except that the semiweekly treatment resulted in better aphid control when started on July 22 rather than on June 27.
Mobile stages of introduced coccinellids on the potatoes in 1969 had a negative relationship to abundance of aphids on the potato plants. Yield of tubers was related somewhat positively to numbers of predaceous larvae introduced, and somewhat negatively to all-season abundance of aphids on the plants. Spread of leaf-roll virus was related more to physiological condition of the plants in late summer than to effectiveness of predators in controlling the aphids.
TL;DR: The reactions of sycamore aphid nymphs and adults to attacks by different instars of the predatory bug Anthocoris nemorum (L.) were observed, and walking and kicking were by far the most frequent responses observed in each aphid instar.
Abstract: The reactions of sycamore aphid Drepanosiphum platanoides (Schr.) nymphs and adults to attacks by different instars of the predatory bug Anthocoris nemorum (L.) were observed. Aphids which avoided capture did so either by moving away from the predator by walking, swivelling, or dropping, or by actively defending themselves by kicking. Large aphids were much better at avoiding capture than small aphids, and were seldom captured even by large anthocorids. Walking and kicking were by far the most frequent responses observed in each aphid instar and bore an inverse relationship to each other, walking becoming increasingly common as a response to successive anthocorid instars. Kicking at predators became more effective as the size of the aphid relative to the anthocorid increased. The mode of capture of prey by anthocorids is poorly suited to prey such as sycamore aphids, which employ their defensive responses with increasing success as they become older. The most certain way for an aphid of any instar to avoid capture is to walk away, but this can affect growth by interrupting feeding.
TL;DR: Field tests in which the color responses of aphids have been used for control have been limited, and it is found that aphids may be repelled from plants surrounded by aluminum foil (strongly light-reflective).
Abstract: Studies of the biology of aphids (Aphididae) have shown that in the migrating (alate) form, many species react to color. Cartier (1965, 1966) found that the pea aphid, Acyrthosiphon pisum (Harris), and the potato aphid, Macrosiphum euphorbiae (Thomas), preferred emitted yellow and orange light to blue, green, and red light. Also, these same species showed consistently better growth when they were reared with 24 hr of light of these particular wavelengths. Other workers reported the attraction of several species of alate aphids to yellow or orange surfaces (Broadbent 1948, Moericke 1951, Kennedy and Stroyan 1959, Kring 1967), and Moericke (1955, 1969) found that some may be attracted by yellow-white surfaces with strong UV radiation. Nevertheless, actual field tests in which the color responses of aphids have been used for control have been limited. Smith et al. (1964) and Kring (1964, 1970) found that aphids may be repelled from plants surrounded by aluminum foil (strongly light-reflective).
TL;DR: Experiments are described in which the green peach aphid, Myzus persicae Sulz.
Abstract: It is well known that many plant viruses can be transmitted by aphids, but the highly infectious tobacco mosaic virus (TMV) seems to have no aphid vector. Only Hoggan (1934) reported a very low level of transmission which, however, has not been substantiated (Orlob, 1963; Pirone, 1969). Some progress on this problem was made when Teakle & Sylvester (1962) showed that TMV could be inoculated by aphids placed on virus-covered leaves. More recently we demonstrated that aphids can transmit TMV from a virus-covered leaf to a healthy leaf (Lojek & Orlob, 1969). Now we wish to describe experiments in which the green peach aphid, Myzus persicae Sulz., transmitted TMV from tomato and doubly infected tobacco. The following plants were used as virus sources: Nicotiana tabacum L. var. Havana or Lycopersicon esculentum L. var. Potentate for TMV or TMV/cucumber mosaic virus (CMV); N. tabacum var. Xanthi n.c. for CMV and potato virus Y (PVY).
TL;DR: The relative importance of the aphids Aphis craccivora, Macrosiphum euphorbiae, Myzus persicae and Aphis gosypii as vectors of subterranean clover stunt virus (SCSV) and bean yellow mosaic virus (BYMV) was obscured by the overwhelming incidence of A, craccivo, and spraying with fenitrothion reduced aphid populations in control plots but had little effect on virus incidence.
Abstract: Field Studies were made of aphid infestation, population behaviour and virus incidence on Pisum sativum, Vicia faba and Phaseolus vulgaris at Bathurst, New South Wales, from November 1969 to June 1970. The relative importance of the aphids Aphis craccivora, Macrosiphum euphorbiae, Myzus persicae and Aphis gosypii as vectors of subterranean clover stunt virus (SCSV) and bean yellow mosaic virus (BYMV) was obscured by the overwhelming incidence of A, craccivora. On the first two plantings, virus incidence exceeded 90 per cent and yields were almost nil. Virus incidence was low on peas and canning beans on the third planting. Late infection on broad beans was 82-96 per cent. BYMV incidence, negligible on the first two plantings, was 16 per cent on the third planting of broad beans. Migrating alate aphids were trapped and tested on subterranean clover; c. 10 per cent of A. craccivora carried SCSV, and about 10 per cent of M. eybhorbiae, late in the season, carried BYMV. Three species of coccinellids attacked A. craccivora but did not control aphids until plants matured. Spraying with fenitrothion reduced aphid populations in control plots but had little effect on virus incidence and greatly reduced coccinellids. Aphidiid parasites were few and had little effect on aphid populations.
TL;DR: In a field study conducted in Louisiana during 1962 and 1963 to determine the seasonal abundance of flying aphid populations in sugarcane fields and to relate this to the seasonal spread of the cane mosaic virus (SCMV) as discussed by the authors, the incidence of SCMV symptoms was determined periodically in experimental plots.
Abstract: Field studies were conducted in Louisiana during 1962 and 1963 to determine the seasonal abundance of flying aphid populations in sugarcane fields and to relate this to the seasonal spread of sugarcane mosaic virus (SCMV). Winged aphids were caught on sticky traps and also collected from sugarcane plants. The incidence of SCMV symptoms was determined periodically in experimental plots.
Of the 9 known vectors of SCMV, only Acyrthosiphon piston (Harris), Hysteroneura selariae (Thomas), Myzus persicae (Sulzer), Rhopalosiphum maidis (Fitch), and Schizaphis grammum (Rondani) occurred during periods of virus spread in sufficient numbers to be considered of probable importance in the spread of SCMV. These five species plus Aphis gossypii Glover, A. maidiradicis Forbes, A. craccivora Koch, Rhopalosiphum paid (L.) complex, R. Pseudobrassicae (Davis). R. rufiabdominalis (Sasaki), Tetrancura hirsula (Baker) and Therioaphis maculata (Buckton) constituted 90% of 5231 aphids representing 69 species which were caught on sticky traps during these studies.
Populations of alatae of all species mentioned above, except T. maculata , were found to be significantly correlated with periodic increases of SCMV symptoms. There was also a significant correlation between periodic increases in Disease symptoms and the total numbers of aphids trapped 4 weeks earlier.
Except for R. pseudobrassicae , alatae of all aphids mentioned above, plus Sipha flava (Forbes), Dactynotus ambrosiae (Thomas), Chailophorus vimnalis Monel, and Aphis sp., were caught on plants. Only H. setariae and R. maidis were found colonizing on sugarcane.
Probably more than three-fourths of the total virus spread during one crop year occurred during late winter and spring. Aphids were trapped in greatest abundance during March, April, and May of 1962 and 1963. Approximately 80% of the total aphids which migrated over sugarcane fields during a month period (while some tying portions of sugarcane plants were exposed above the soil surface) did so between March 1 and May 31, 1963, Flying aphid populations were much lower during (all than in spring, hut higher than in summer.
There appeared to be no significant difference in the rate of spread of SCMV among sugarcane plants of different ages.
TL;DR: In 1966, 8-in, aluminum flashing standing on edge proved effective as a barrier to interplot movement of the larvae of Coccinella septempunctata L. when introduced sequentially into 0.014-acre plots of potatoes; notwithstanding, the small plots proved unsatisfactory for evaluating effectiveness of the introduced predators, chiefly because of the habits of the predators.
Abstract: In 1966, 8-in, aluminum flashing standing on edge proved effective as a barrier to interplot movement of the larvae of Coccinella septempunctata L. when introduced sequentially into 0.014-acre plots of potatoes; notwithstanding, the small plots proved unsatisfactory for evaluating effectiveness of the introduced predators, chiefly because of the habits of the predators. The flashing had a 1-1½-in, band at the top on each side coated with Fluoro Glide®, technical grade.
Approximately square ¼-acre fields were superior to 12x50 ft plots for evaluating effectiveness of manual introductions of 2nd and 3rd instars of C. septempunctata or 2nd instars of Chrysopa spp. against aphids on potatoes. In small fields having light-to-moderate aphid infestations, better control was obtained from sequential introductions of Chrysopa spp. at 88,100 larvae/acre than from 4 applications of C. septempunctata at 30,500 larvae/acre. However, the best all-season control was achieved where introductions of both predators at these rates were made in the same field. Best all-season control ranged from 33 to 97%, depending upon species of aphid; for all species of aphids combined, it was 58.
The abundance of predaceous stages of coccinellids and chrysopids during the summer on sample aphid count leaves in the fields or plots was not well correlated with the numbers of C. septempunctata or Chrysopa spp. introduced into the plantings.
TL;DR: Selecting uninjured ‘Cody’ alfalfa plants in the field following a heavy infestation of Acyrthosiphon pisum (Harris) expediently obtained resistant plants that appeared comparable to that obtained by selection in the greenhouse.
Abstract: Selecting uninjured ‘Cody’ alfalfa plants in the field following a heavy infestation of Acyrthosiphon pisum (Harris) expediently obtained resistant plants. Resistance appeared comparable to that obtained by selection in the greenhouse. Progeny testing facilitated selection of highly resistant plants.
TL;DR: When offered increasing numbers daily, pairs of adults of Coccinella septempunctata L. containing nondiapausing females consumed the largest percentage of green peach aphids, Myzus persicae (Sulzer), when the number offered was 170 or 200, as compared with 154 or 174 for those containing diapauses females.
Abstract: When offered increasing numbers daily, pairs of adults of Coccinella septempunctata L. containing nondiapausing females consumed the largest percentage of green peach aphids, Myzus persicae (Sulzer), when the number offered was 170 or 200, as compared with 154 or 174 for those containing diapausing females, As the number of aphids per beetle introduced daily was increased from 58 to 115, the estimated daily consumption of nondiapausing females increased from 56 to 99, whereas that of diapausing females increased from 50 to 87, Daily aphid consumption by nondiapausing females was greater when they were fed aphids only or aphids daily along with a liquid food supplement every 4th day than when fed aphids daily plus the liquid supplement every 2nd day, Under similar conditions, daily aphid consumption by diapausing females was increased by including the liquid food supplement in the diet, whether offered every 4th or every 2nd day.
The larvae of C. septempunctata consumed from 619 to 750 green peach aphids (of all sizes), on average, between hatching and pupation, depending on time of year. The comparable range in numbers for C. transversoguttata Faldermann was 699 to 756, Differences between coccinellid lid species in numbers of aphids caten per larva were not significant ( P = 0.05).