DOCSLIB.ORG

HOW INSECTS TRANSMIT VIRUSES 23 Plants Are Grown and Infect Healthy Such Loss and for Many Other Features Plants Subsequently Grown Therein

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
HOW INSECTS TRANSMIT VIRUSES 23 Plants Are Grown and Infect Healthy Such Loss and for Many Other Features Plants Subsequently Grown Therein 22 YEARBOOK OF AGRICULTURE 1953 carried through the winter for seed production. Ehmination of such sources of virus usually gives a high degree of control. The spread of X-disease on peach can be prevented by removing all infected chokecherries within 500 How Insects feet of peach orchards, and the virus diseases of raspberries can be con- trolled, in most instances, by destroy- Transmit ing all wild and escaped brambles in the immediate vicinity of plantings, provided the plandngs themselves are Viruses not already infected. Reducing the population of insect vectors by spraying or by other means L. M, Black has value in the control of some virus diseases. Usually it is not possible, Most viruses that cause plant disease however, to reduce the insect popu- are transmitted by insects, principally lations sufficiently or soon enough to those that have sucking mouth parts— obtain completely satisfactory results. aphids, leaflioppers, white flics, mealy- Some virus diseases can be partly con- bugs, and tingids. Leaf hoppers and trolled by destruction of the hosts of the aphids are the most important. insect vectors. Extensive reduction of Although many plant viruses are the weed hosts of the beet leaf hopper without known insect vectors, it is in the Western States would corre- generally expected that insect carriers spondingly reduce the amount of curly will eventually be discovered for most top virus carried from desert plants to of them. There are exceptions. To- cultivated fields. In much of this area, bacco mosaic virus and potato latent reduction in weed hosts comes about virus are two viruses that occur in naturally under systems of land man- high concentration in infected plants agement in which annual and peren- and are stable enough to be spread nial grasses and other nonhost plants readily from one plant to another by are allowed to replace the weed hosts almost any means that releases juice of the beet leafhopper. Fall spraying from a wound in an infected plant and to kill leaf hoppers on weeds in un- transfers the juice to a fresh wound in a cultivated areas has been resorted to healthy plant. Tobacco mosaic virus is also in the program to control curly thus transferred by the hands of men top. working with tobacco plants even Virus-free nursery stock is extrem.ely though the wounds may be only micro- important in the control of virus scopic in size. It can also be thus trans- diseases of straw^berry and raspberry. ferred by the mouth parts of grass- Natural virus spread often is not ex- hoppers. Potato latent virus can be tensive enough to cause serious dam- transferred from plant to plant when age during the life of plantings started the wind blows the leaves of diseased with virus-free nursery stock. That is plants against healthy ones so as to true also of some of the virus diseases injure both. The mystery about these of tree fruits. two viruses is not their transmission by such methods but why potato latent C. W. BENNETT is a pathologist of the virus is apparently not transmitted by division of sugar plant investigations^ sucking insects and why tobacco Bureau of Plant Industry, Soils, and Agri- mosaic virus is so poorly transmitted. cultural Engineering, who has had more A few viruses, such as wheat rosette than 50 years of experience in the study of virus and lettuce big-vein virus, con- plant viruses and virus diseases. taminate the soil in which diseased HOW INSECTS TRANSMIT VIRUSES 23 plants are grown and infect healthy such loss and for many other features plants subsequently grown therein. of aphid transmission. A virus trans- Just how inoculation takes place in mitted by aphids, particularly if it is such diseases is not known. Dodders of this nonpersistent type, is usually {Cuscuta species), parasitic flowering transmissible by several or, indeed, plants, can transmit plant viruses by many species. The virus of onion yel- means of the natural graft unions they low dwarf can be transmitted by more make with their hosts. Most plant vi- than 50 species of aphids, but not by ruses, however, dcpead on insects for thrips, mites, grasshoppers, beetles, their dispersal. caterpillars, or maggots. That kind of transmission is in con- APHIDS transmit more plant viruses trast to another type in which, follow- than any other group. Aphid-borne ing acquisition of virus, a latent period viruses induce in plants a great variety must elapse before the aphid is able of symptoms, the most important of to transmit. The aphid may then, do which are the mosaics. One of the so for many days without fresh access most efficient aphid vectors is the green to virus. A minority of viruses trans- peach aphid, Myzus persicae^ which mitted by aphids are spread in that transmits more than 50 different plant manner. One of them, the virus of po- viruses. tato leaf roll, is not transmitted by Much remains to be learned about the aphid until 24 to 48 hours have what actually occurs during trans- elapsed after acquisition. The virus mission by aphids. Many aphid vec- may then h^ retained by the insect for tors transmit virus after very brief 7 to 10 days, even through molts, with- feedings on diseased plants. Studies on out fresh access to virus from plants. this type of transmission have reached That an aphid may transmit one a point where the feeding intervals of virus in the persistent manner and individual aphids arc closely observed another in the non persistent from the and timed by a stop watch. For same host plant clearly indicates that example, the vector of beet mosaic persistence or nonpersistence is de- virus requires an acquisition feeding termined by the virus. of only 6 to 10 seconds. During subse- Why do we concern ourselves with quent consecutive inoculation feediiigs such minute details of transmission? of 10 seconds each on healthy plants, Simply because such knowledge may the virus is gradually lost by the aphids make the difl'ercnce between success and fewer than 2 percent of them can and failure in finding a vector of a transmit to more than four plants virus. For instance, no transmission without fresh access to virus. This virus of a certain mosaic virus could be o]> is said to be nonpersistent in the vector. tained after extensive trials with three Usually such a virus is lost more species of aphids when they were fed rapidly from feeding aphids than from one day on diseased plants and then fasting ones—the virus of cucumber transferred to healthy ones. When the mosaic disease, for instance, is lost by aphids were fasted for 30 minutes be- the aphid within 6 to 8 hours when fore an acquisition feeding of 5 to 10 fasting, but within 10 to 20 minutes minutes and were then allowed an when feeding on healthy plants. In inoculation feeding of 5 to 10 minutes, other instances this relation may be however, transmissions were obtained. reversed. The loss of virus from aphids during feeding may be due to a virus- LEAFHOPPERS, next to aphids, are inactivating enzyme secreted by the the most important vectors of plant aphids while feeding but not while viruses. Experiments by a Japanese fasting. Such a substance has not been grower in 1884 demonstrated a con- demonstrated, however, and in reality nection between rice stunt and leaf- we do not know the explanation for hoppers. That might be considered 24 YEARBOOK OF AGRICULTURE 1953 the first virus shown to be insect- viruses multiply to an infective con- transmitted, but actually it was not centration in their vectors. realized until more than 20 years later Although most leafhopper vectors do that the causal agent 01 the disease not transmit virus to their progeny was not the leafhopper but some au- through the egg, certain exceptions tonomous agent carried by the insect. exist. Rice stunt virus and clover club Viruses transmitted by leafhoppers leaf virus may be passed to 95 or 100 cause a variety of symptoms in plants, percent of young insects through the including chlorotic streaking of leaves eggs of the vectors. A single female (as in corn streak), necrosis or death of leafhopper carrying clover club leaf tissues (as in elm phloem necrosis), virus has originated at least 21 genera- tumors (as in wound-tumor disease), tions of infective progeny during a and yellows (as in aster yellows). All 5-year period without fresh access to known vectors for virus diseases with virus from plants. The virus in the a symptom picture like that of aster original female had been diluted yellows arc leafhoppers. at least 100,000,000,000,000,000,- Although many aphid-borne viruses 000,000,000 times. That would be can be transmitted by rubbing leaves impossible had not the virus multi- with juice from diseased plants, only plied in the leafhopper. two leafhopper-borne viruses have There may be, then, two main types been so transferred. In other cases of transmission of virus by leafhoppers. transmission has been accomplished One type, exemplified by curly top only by the use of insects, dodder, or virus, may be characterized by a very grafting. This has accordingly made short incubation period and no multi- the study of the viruses themselves plication in the vector; the other type very diihcult. For such researches it by a long period of incubation and has been necessary to permit the leaf- multiplication in the vector. hoppers to feed on virus solutions Once infective, leafhoppers tend to through membranes or to inject the remain so for many days without fresh virus solution into leafhoppers.
Load more

Recommended publications
  • Aphis Fabae Scop.) to Field Beans ( Vicia Faba L.
    ANALYSIS OF THE DAMAGE CAUSED BY THE BLACK BEAN APHID ( APHIS FABAE SCOP.) TO FIELD BEANS ( VICIA FABA L.) BY JESUS ANTONIO SALAZAR, ING. AGR. ( VENEZUELA ) A THESIS SUBMITTED FOR THE DEGREE OF DOCTOR OF PHILOSOPHY IN THE UNIVERSITY OF LONDON OCTOBER 1976 IMPERIAL COLLEGE FIELD STATION, SILWOOD PARK, SUNNINGHILL, ASCOT, BERKSHIRE. 2 ABSTRACT The concept of the economic threshold and its importance in pest management programmes is analysed in Chapter I. The significance of plant responses or compensation in the insect-injury-yield relationship is also discussed. The amount of damage in terms of yield loss that results from aphid attack, is analysed by comparing the different components of yield in infested and uninfested plants. In the former, plants were infested at different stages of plant development. The results showed that seed weights, pod numbers and seed numbers in plants infested before the flowering period were significantly less than in plants infested during or after the period of flower setting. The growth pattern and growth analysis in infested and uninfested plants have shown that the rate of leaf production and dry matter production were also more affected when the infestations occurred at early stages of plant development. When field beans were infested during the flowering period and afterwards, the aphid feeding did not affect the rate of leaf and dry matter production. There is some evidence that the rate of leaf area production may increase following moderate aphid attack during this period. The relationship between timing of aphid migration from the wintering host and the stage of plant development are shown to be of considerable significance in determining the economic threshold for A.
    [Show full text]
  • (Pentatomidae) DISSERTATION Presented
    Genome Evolution During Development of Symbiosis in Extracellular Mutualists of Stink Bugs (Pentatomidae) DISSERTATION Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University By Alejandro Otero-Bravo Graduate Program in Evolution, Ecology and Organismal Biology The Ohio State University 2020 Dissertation Committee: Zakee L. Sabree, Advisor Rachelle Adams Norman Johnson Laura Kubatko Copyrighted by Alejandro Otero-Bravo 2020 Abstract Nutritional symbioses between bacteria and insects are prevalent, diverse, and have allowed insects to expand their feeding strategies and niches. It has been well characterized that long-term insect-bacterial mutualisms cause genome reduction resulting in extremely small genomes, some even approaching sizes more similar to organelles than bacteria. While several symbioses have been described, each provides a limited view of a single or few stages of the process of reduction and the minority of these are of extracellular symbionts. This dissertation aims to address the knowledge gap in the genome evolution of extracellular insect symbionts using the stink bug – Pantoea system. Specifically, how do these symbionts genomes evolve and differ from their free- living or intracellular counterparts? In the introduction, we review the literature on extracellular symbionts of stink bugs and explore the characteristics of this system that make it valuable for the study of symbiosis. We find that stink bug symbiont genomes are very valuable for the study of genome evolution due not only to their biphasic lifestyle, but also to the degree of coevolution with their hosts. i In Chapter 1 we investigate one of the traits associated with genome reduction, high mutation rates, for Candidatus ‘Pantoea carbekii’ the symbiont of the economically important pest insect Halyomorpha halys, the brown marmorated stink bug, and evaluate its potential for elucidating host distribution, an analysis which has been successfully used with other intracellular symbionts.
    [Show full text]
  • Correlation of Stylet Activities by the Glassy-Winged Sharpshooter, Homalodisca Coagulata (Say), with Electrical Penetration Graph (EPG) Waveforms
    ARTICLE IN PRESS Journal of Insect Physiology 52 (2006) 327–337 www.elsevier.com/locate/jinsphys Correlation of stylet activities by the glassy-winged sharpshooter, Homalodisca coagulata (Say), with electrical penetration graph (EPG) waveforms P. Houston Joosta, Elaine A. Backusb,Ã, David Morganc, Fengming Yand aDepartment of Entomology, University of Riverside, Riverside, CA 92521, USA bUSDA-ARS Crop Diseases, Pests and Genetics Research Unit, San Joaquin Valley Agricultural Sciences Center, 9611 South Riverbend Ave, Parlier, CA 93648, USA cCalifornia Department of Food and Agriculture, Mt. Rubidoux Field Station, 4500 Glenwood Dr., Bldg. E, Riverside, CA 92501, USA dCollege of Life Sciences, Peking Univerisity, Beijing, China Received 5 May 2005; received in revised form 29 November 2005; accepted 29 November 2005 Abstract Glassy-winged sharpshooter, Homalodisca coagulata (Say), is an efficient vector of Xylella fastidiosa (Xf), the causal bacterium of Pierce’s disease, and leaf scorch in almond and oleander. Acquisition and inoculation of Xf occur sometime during the process of stylet penetration into the plant. That process is most rigorously studied via electrical penetration graph (EPG) monitoring of insect feeding. This study provides part of the crucial biological meanings that define the waveforms of each new insect species recorded by EPG. By synchronizing AC EPG waveforms with high-magnification video of H. coagulata stylet penetration in artifical diet, we correlated stylet activities with three previously described EPG pathway waveforms, A1, B1 and B2, as well as one ingestion waveform, C. Waveform A1 occured at the beginning of stylet penetration. This waveform was correlated with salivary sheath trunk formation, repetitive stylet movements involving retraction of both maxillary stylets and one mandibular stylet, extension of the stylet fascicle, and the fluttering-like movements of the maxillary stylet tips.
    [Show full text]
  • Twenty-Five Pests You Don't Want in Your Garden
    Twenty-five Pests You Don’t Want in Your Garden Prepared by the PA IPM Program J. Kenneth Long, Jr. PA IPM Program Assistant (717) 772-5227 [email protected] Pest Pest Sheet Aphid 1 Asparagus Beetle 2 Bean Leaf Beetle 3 Cabbage Looper 4 Cabbage Maggot 5 Colorado Potato Beetle 6 Corn Earworm (Tomato Fruitworm) 7 Cutworm 8 Diamondback Moth 9 European Corn Borer 10 Flea Beetle 11 Imported Cabbageworm 12 Japanese Beetle 13 Mexican Bean Beetle 14 Northern Corn Rootworm 15 Potato Leafhopper 16 Slug 17 Spotted Cucumber Beetle (Southern Corn Rootworm) 18 Squash Bug 19 Squash Vine Borer 20 Stink Bug 21 Striped Cucumber Beetle 22 Tarnished Plant Bug 23 Tomato Hornworm 24 Wireworm 25 PA IPM Program Pest Sheet 1 Aphids Many species (Homoptera: Aphididae) (Origin: Native) Insect Description: 1 Adults: About /8” long; soft-bodied; light to dark green; may be winged or wingless. Cornicles, paired tubular structures on abdomen, are helpful in identification. Nymph: Daughters are born alive contain- ing partly formed daughters inside their bodies. (See life history below). Soybean Aphids Eggs: Laid in protected places only near the end of the growing season. Primary Host: Many vegetable crops. Life History: Females lay eggs near the end Damage: Adults and immatures suck sap from of the growing season in protected places on plants, reducing vigor and growth of plant. host plants. In spring, plump “stem Produce “honeydew” (sticky liquid) on which a mothers” emerge from these eggs, and give black fungus can grow. live birth to daughters, and theygive birth Management: Hide under leaves.
    [Show full text]
  • Melon Aphid Or Cotton Aphid, Aphis Gossypii Glover (Insecta: Hemiptera: Aphididae)1 John L
    EENY-173 Melon Aphid or Cotton Aphid, Aphis gossypii Glover (Insecta: Hemiptera: Aphididae)1 John L. Capinera2 Distribution generation can be completed parthenogenetically in about seven days. Melon aphid occurs in tropical and temperate regions throughout the world except northernmost areas. In the In the south, and at least as far north as Arkansas, sexual United States, it is regularly a pest in the southeast and forms are not important. Females continue to produce southwest, but is occasionally damaging everywhere. Be- offspring without mating so long as weather allows feeding cause melon aphid sometimes overwinters in greenhouses, and growth. Unlike many aphid species, melon aphid is and may be introduced into the field with transplants in the not adversely affected by hot weather. Melon aphid can spring, it has potential to be damaging almost anywhere. complete its development and reproduce in as little as a week, so numerous generations are possible under suitable Life Cycle and Description environmental conditions. The life cycle differs greatly between north and south. In the north, female nymphs hatch from eggs in the spring on Egg the primary hosts. They may feed, mature, and reproduce When first deposited, the eggs are yellow, but they soon parthenogenetically (viviparously) on this host all summer, become shiny black in color. As noted previously, the eggs or they may produce winged females that disperse to normally are deposited on catalpa and rose of sharon. secondary hosts and form new colonies. The dispersants typically select new growth to feed upon, and may produce Nymph both winged (alate) and wingless (apterous) female The nymphs vary in color from tan to gray or green, and offspring.
    [Show full text]
  • Alfalfa Aphid and Leafhopper Management for the Low Deserts
    ALFALFA APHID AND LEAFHOPPER MANAGEMENT FOR THE LOW DESERTS Eric T. Natwick U.C. Cooperative Extension Farm Advisor, Imperial County, California APHIDS Spotted Alfalfa ~ The spotted alfalfa aphid (Therioaphis maculata) was introduced into New Mexico in 1953 and by 1954 had spread westward into California. This aphid is small pale yellow or grayish in color with 4 to 6 rows of black spots bearing small spines on its back. The adults mayor may not have wings. Spotted alfalfa aphid is smaller than blue alfalfa aphid or pea aphid arid will readily drop from plants when disturbed. The aphids are common on the underside of leaves where colonies start on the lower part of the plants, but also infest stems and leaves ~s colonies expand. These aphids produce great Quantities of honeydew. Severe infestations can develop on non-resistant varieties of alfalfa and reduce yield, stunt growth and even kill plants. Feed Quality and palatability are also reduced by sooty molds which grow on the honeydew excrement. In most desert growing areas introduction of resistant varieties (e.g., CUF101) along with the activity of predacious bugs, lady beetles, lacewings, syrphid fly larvae and introduced parasites has reduced this aphid to the status of a minor pest. If susceptible varieties are planted and beneficial insect populations are disrupted, then severe infestations can occur from late July through September. Because spotted alfalfa aphid has developed resistance to organophosphorus compounds, the best way to avoid aphid problems is the planting of a resistant variety. In fields where a susceptible variety is planted the field should be checked 2 to 3 times per week during July through September.
    [Show full text]
  • Aphids and Their Control on Orchids
    APHIDS AND THEIR CONTROL ON ORCHIDS Paul J. Johnson, Ph.D. Insect Research Collection, South Dakota State University, Brookings, SD 57007 Aphids are among the most obnoxious of orchid pests. These insects are global and orchid feeding species are problematic in tropical growing areas as well as in commercial and hobby greenhouses in temperate regions. Rabasse and Wyatt (1985) ranked aphids as one of three most serious greenhouse pests, along with spider mites and whiteflies. These pernicious insects can show themselves on orchids year-around in warm climates, but seem to be mostly autumn and winter problems in temperate regions. Like most other orchid pests the most common routes into plant collections is through either the acquisition of an infested plant or the movement of plants from outdoors to indoors. However, certain reproductive stages of pest species do fly and they will move to orchids from other plants quite readily. Because of their propensity for rapid reproduction any action against aphids should be completed quickly while their populations are still small. An aphid infestation is often detected by an accumulation of pale-tan colored “skins” that fall beneath the developing colony. These “skins” are the shed integument from the growing and molting immature aphids. All of the common pest species of aphid also secrete honeydew, a feeding by-product exuded by the aphid and composed of concentrated plant fluids, and is rich in carbohydrates. This honeydew drips and accumulates beneath the aphid colony. Because of the carbohydrates honeydew is attractive to ants, flies, bees, other insects including beneficial species, and sooty mold.
    [Show full text]
  • 080052-12.042.Pdf
    -0€ - wlvJFllaMurB o sqss otoqdI rPl)au Jopaal P tu!,tofua I laoo vlapoutals aoaaqlar!^at aqJ .?yaBrI uPuqro,lurf - olorld 'Funo^ rraql.rojarpl ol stJasutMaJ aql Jo I auosr ArMreaalpua, aq1:1r761taooqy I t4t'lvJFllaMlrr8 sqs8- oloqd 'ds d' I DuuollsoJalaaq lamat aq1 I a6odsnonatd I auo pue 'slapaaluoulpf, {lureur are sallaaqa^ou sta^oJ tur&paua oqslraql ol anp sallaaqueql sarrueaalrt alout '(apprull{qdEs {ool uPl qtrq^ ^lruil) sallaaqa^or puno] aq osleIIr^ apMpl dUaql Fuourelng paalpue ur a^rl ol sloa3?u^U loJ luauruolr^ualuallaJxa ue apr^ordsd?aq lsodtuoJ pala^olun 'pllorv\ pasutaql Jo stasodruo3ap aql roj slErqeqralJo ritlnu pu€sdpaq lsoduof, 'luauruorr^ua l?lnl?uaql ur palJ^lal a.rpralleu f,ru?Alopup lalllt JealsV dVSHJSOdWOC 3HJ 'punojaq upt sdnol? paUrssplJtot?u.I aWJo lsoru ;urluasardal 'ruaql ,pue spasur ulqlro\ pllo,{ Ietnlpu aql Jo rxsof,orlllxp luasaldalsuaplpa rno sleurueupup spllq ,qsq,salrldal 'sFurrup turpnl3ur Jo a8uelapu e loj sa^lasuaqlpooJ tulaq ol usrlrs?lpdpue uorleparduo{ 's.la,1oU uaa4aq uallodJo Uodsuprlaql ol aspasrpJo uorssrursupll aql uro{ 'a^rsualxaosle alp sruals{so)a s,lau€ldsrql ulrlll,rsllasurJo alor aqJ :tellaupue sa^Pal 'poo/r lupld ol poolqpu?.rrpq Ieurup uro{ ',ldn3ro[aq] splrqeqaql sepaue^ puPasra^rp se sr pooJtraqJ .s.ra^upup lsoruIaqI'?tlp4snvol a^rleualp sarf,ads ,,(Ure3aur^ uoruruot ,d€aq 'spuod'sueal}s aql lsoduoJ sa{el Josralp/vr qsarJ aq} s.pFo/{aqlJo arxos (eraldeurac lsaSPI eJoluauodruof, ? srlrnlJ Eur{map JI papeur a^€qpu?suasap lsaup aql ur a^rl rapro) sarir€a aql ar€{.req asool lo xan€urEuritplap
    [Show full text]
  • Download PDF (Inglês)
    Biota Neotropica 20(4): e20201045, 2020 www.scielo.br/bn ISSN 1676-0611 (online edition) Article Anatomy of male and female reproductive organs of stink bugs pests (Pentatomidae: Heteroptera) from soybean and rice crops Vinícius Albano Araújo1* , Tito Bacca2 & Lucimar Gomes Dias3,4 1Universidade Federal do Rio de Janeiro, Instituto de Biodiversidade e Sustentabilidade, Macaé, RJ, Brasil. 2Universidad del Tolima, Facultad de Ingeniería Agronómica, Ibagué, Tolima, Colombia. 3Universidad de Caldas, Caldas, Facultad de Ciencias Exactas y Naturales, Departamento de Ciencias Biológicas, Colombia. 4Universidad de Caldas, Grupo de investigación Bionat, Caldas, Colombia. *Corresponding author: Vinícius Albano Araújo, e-mail: [email protected] ARAÚJO, V., BACCA, T., DIAS, L. Anatomy of male and female reproductive organs of stink bugs pests (Pentatomidae: Heteroptera) from soybean and rice crops. Biota Neotropica 20(4): e20201045. https://doi.org/10.1590/1676-0611-BN-2020-1045 Abstract: Pentatomidae comprises a diverse group of stink bugs widely distributed in the Neotropical region. Many species are phytophagous and cause injuries to plants, and can thus be defined as agricultural pests. In this study, the anatomy of the female and male reproductive tracts of three important agricultural pests in Colombia is described: Piezodorus guildinii Westwood, 1837 and Chinavia ubica Rolston 1983, found on soybeans, and Oebalus insularis Stål, 1872, found in rice crops. For that, light microscopy techniques were used. The anatomy of the reproductive tract of sexually mature males of the three species studied consisted of a pair of testes, vas deferens, seminal vesicles, ejaculatory bulb, an ejaculatory duct that opens into an aedeagus, and paired accessory glands.
    [Show full text]
  • Aphid and Whitefly Management in Alfalfa in Imperial Valley, California
    APHID AND WHITEFLY MANAGEMENT IN ALFALFA IN IMPERIAL VALLEY, CALIFORNIA Eric T. Natwick and M. Lopez1 ABSTRACT In the low desert region of southern California and Arizona, spotted alfalfa aphid, Therioaphis maculata, pea aphid, Acyrthosiphon pisum, blue alfalfa aphid, Acyrthosiphon kondoi, and cowpea aphid, Aphis craccivora must be managed for successful alfalfa hay production. Considerable progress has been made toward the control of the aphid pests via host plant resistance, but insecticide applications are commonly needed to maintain population densities of aphids below damaging levels. Experiments were conducted at the University of California Desert Research and Extension Center in 1999, 2000 and 2004 to compare efficacy of registered and unregistered materials and combinations of materials for aphid control in alfalfa. The results of these three insecticide efficacy experiments indicate that cowpea aphid is susceptible to control by several different aphicides. Currently there are no cowpea aphid resistant alfalfa varieties. Therefore, cowpea aphid should be controlled using an insecticide registered for use on alfalfa when a damaging population builds up in an alfalfa stand. INTRODUCTION Although several resistant varieties have been developed and released, resistance levels have been low and variable (Lehman 1978). Insecticides still have a major role in the alfalfa insect pest management (Natwick 1987). The blue alfalfa aphid, cowpea aphid, pea aphid and spotted alfalfa aphid are commonly controlled in low desert alfalfa with chlorpyrifos or dimethoate when aphid populations reach damaging levels (Anonymous 2003, Anonymous 1985). Other insecticides used in alfalfa that provide aphid control include: carbofuran, several pyrethroid insecticides or malathion. Insecticides are applied to a large portion of the alfalfa acreage in the low desert region of the Southwestern United States each year for aphid control.
    [Show full text]
  • Aphids: Those Sucking Insects
    Aphids: those sucking insects Erin W. Hodgson Extension Entomologist Utah State University Utah Green Conference Sandy, Utah; 24 January 2007 Outline • Background and key characters • Host-plant relationships • Aphid biology and life cycle • Geographical distribution • Most common aphid pests • Control options • Where to get more information Definitions • Heteroecious – alternating between hosts • Monoecious – remains on one host • Holocyclic – Complete life cycle, goes through sexual reproduction • Anholocyclic – always remains asexual More definitions • Alatae – winged insect • Apterae – wingless insect • Parthenogenesis – reproduction from unfertilized eggs by unmated females • Viviparous – giving birth to live young • Oviviparous – giving birth by laying eggs Aphid background • More than 4,400 species of aphids • Related to scales, cicadas, hoppers – Hemiptera: Sternorrhyncha: Aphididae • Aphids can feed on all plant parts • Most aphids use trees or woody hosts – Trees slow to develop resistance • Most aphid pests are exotic Key aphid characters • Aphids are soft-bodied, “weak” •Most are <3mm long • Head is pointed downward for feeding • Antennae are 5- or 6-segmented • Compound and simple eyes • Walking legs, “skinny” More aphid characters • Thorax and abdomen appear fused • Most aphids have cornicles (tail pipes) – Excrete alarm pheromones • Most aphids have a cauda –“flick”honeydew Host-plant relationships • Most aphids feed within 1 plant family • Some aphids are host-alternating (10%) – Primary woody plants in the fall/winter/spring
    [Show full text]
  • Spring Dispersal of Some Leafhoppers and Aphids
    Journal of the Minnesota Academy of Science Volume 35 Number 2 Article 11 1968 Spring Dispersal of Some Leafhoppers and Aphids A. G. Peterson University of Minnesota J. D. Bates Northern High School, Pontiac, Michigan R. S. Saini Alabama Agricultural and Mechanical College Follow this and additional works at: https://digitalcommons.morris.umn.edu/jmas Part of the Entomology Commons Recommended Citation Peterson, A. G., Bates, J. D., & Saini, R. S. (1968). Spring Dispersal of Some Leafhoppers and Aphids. Journal of the Minnesota Academy of Science, Vol. 35 No.2, 98-102. Retrieved from https://digitalcommons.morris.umn.edu/jmas/vol35/iss2/11 This Article is brought to you for free and open access by the Journals at University of Minnesota Morris Digital Well. It has been accepted for inclusion in Journal of the Minnesota Academy of Science by an authorized editor of University of Minnesota Morris Digital Well. For more information, please contact [email protected]. ENTOMOLOGY Spring Dispersal of Some Leafhoppers and Aphids 1 A.G. PETERSON,* J. D. BATES,** and R. S. SAINI*** ABSTRACT - Two species of leafhoppers and four species of cereal aphids appear to be trans­ ported to Minnesota each spring on strong winds from the south or southwest. The aster leaf­ hopper, Macrosle/es fascifrons (Stall; the English grain aphid, Macrosiphum avenae (Fabr.l; the apple grain aphid, Rhopalosiphum fitchii (Sand.); and the greenbug, Schizaphis graminum (Rend.), usually arrive in Minnesota during late April or early May. Weather conditions favor­ able for northward movement of these insects consist of a high pressure area over the eastern states, a low pressure area over the western plains, and the resulting strong, persistent, south wind which is often called a low-level jet.
    [Show full text]