Jack D. DeAngelis

Bio: Jack D. DeAngelis is an academic researcher from Oregon State University. The author has contributed to research in topics: Spider mite & Thrips. The author has an hindex of 6, co-authored 10 publications receiving 174 citations.

Survival, Development, and Reproduction in Western Flower Thrips (Thysanoptera: Thripidae) Exposed to Impatiens Necrotic Spot Virus

Abstract: The effects of feeding on host plant tissue infected with a plant pathogenic virus on thrips survival, reproduction, and development was studied. Western flower thrips, Frankliniella occidentalis (Pergande), exposed through feeding as larvae to the impatiens necrotic spot virus (INSV, formerly tomato spotted wilt virus-impatiens serotype) had lowered survival and reproductive potential and slower development rate than did unexposed thrips under controlled environmental conditions. Virus-exposed thrips were 1.4 times as likely to die than unexposed thrips in a given day. The reproductive potential for the virus-exposed group was significantly lower, and preoviposition period was extended. Development time from second instar to adult was 15% longer for thrips exposed to virus-infected plant tissue as larvae compared with the development time for thrips not exposed to the virus.

Photosynthesis, Leaf Conductance, and Leaf Chlorophyll Content in Spider Mite (Acari: Tetranychidae)-Injured Peppermint Leaves

Abstract: Effects of feeding injury by the twospotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), on 14-CO2 assimilation (net photosynthesis), leaf conductance to gas exchange, and leaf chlorophyll in peppermint, Mentha piperita L., were investigated. Rates of 14-CO2, assimilation were reduced in proportion to degree of sustained injury and probably were the result of reduced leaf conductance to gas exchange, which inhibited influx of carbon dioxide to chloroplasts. Assimilation rates for both uninjured and variously injured leaves were correlated with leaf conductance. Inhibition of gas exchange in injured leaves was the predominant factor responsible for reduced photosynthesis. Extractable leaf chlorophyll was reduced in proportion to the degree of injury sustained. Leaf injury was estimated by using an injury index developed for these studies

Transmission of Impatiens Necrotic Spot Virus in Peppermint by Western Flower Thrips (Thysanoptera: Thripidae)

Abstract: Western flower thrips, Frankliniella occidentalis (Pergande), can transmit a begonia isolate of impatiens necrotic spot virus (INSV) to peppermint, Mentha piperita L. ‘Black Mitcham’. Transmission efficiency for adult thrips 2, 4, 6, 8, and 10 d after emergence varied from 0 to 60% for pairs of thrips and 0 to 20% for single thrips. However, 2-d-old adult thrips failed to transmit the virus. Symptoms of INSV infection of peppermint include stunting, downward curling and leaf tip dieback, and occasional growing tip necrosis. Older leaves are bronze-colored and exhibit sunken, brownish-grey lesions. Symptoms of the original INSV infection found in 1990 in greenhouse-grown ‘Black Mitcham’ cuttings included bright yellow mottling on newly mature leaves. The thripstransmitted isolate of INSV acquired from begonia produced only faint yellow mottling in peppermint leaves when exposed to cool temperatures (15°C). INSV infections were confirmed by symptomology and ELISA analysis. Spherical particles and granular arrays previously associated with INSV infection were observed in some tissue by examination with transmission electron microscopy. Virus was detected throughout the plant indicating a systemic infection. INSV was also detected in the vector thrips by ELISA.

Evidence for Spider Mite (Acari: Tetranychidae) Injury-Induced Leaf Water Deficits and Osmotic Adjustment in Peppermint

Abstract: Studies were conducted to examine the physiological response of peppermint, Mentha piperita L., to leaf water stress induced by feeding of the twospotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae). Levels of mite injury were estimated by a leaf injury index developed for these studies. Symptoms of water stress in mite-injured leaves were: a significant reduction in leaf fresh weight; reduced leaf specific weight (mg of fresh weight per cm2 of leaf area); and accumulation of soluble leaf carbohydrates. Soluble leaf carbohydrates of peppermint are sucrose (ca. 50%) and the galactosyl oligosaccharides raffinose and stachyose. Leaf starch content was unaffected by injury at all injury levels. Accumulation of soluble leaf carbohydrate in water-stressed leaves may help mite-injured leaves maintain cell turgor pressure through an osmotic adjustment (osmoregulation) mechanism. A new method for in situ starch hydrolysis for quantitative analysis of leaf starch also is presented.

Tospovirus-thrips interactions.

Abstract: The complex and specific interplay between thrips, tospoviruses, and their shared plant hosts leads to outbreaks of crop disease epidemics of economic and social importance. The precise details of the processes underpinning the vector-virus-host interaction and their coordinated evolution increase our understanding of the general principles underlying pathogen transmission by insects, which in turn can be exploited to develop sustainable strategies for controlling the spread of the virus through plant populations. In this review, we focus primarily on recent progress toward understanding the biological processes and molecular interactions involved in the acquisition and transmission of Tospoviruses by their thrips vectors.

Transmission mechanisms shape pathogen effects on host-vector interactions: Evidence from plant viruses

Abstract: Summary 1. Vector-borne pathogens and parasites can induce changes in the phenotypes of their hosts that influence the frequency and nature of host–vector interactions and hence transmission, as documented by both empirical and theoretical studies. To the extent that implications for transmission play a significant role in shaping the evolution of parasite effects on host phenotypes, we may hypothesize that parasites exhibiting similar transmission mechanisms – and thus profiting from similar patterns of interaction among hosts and vectors – will have correspondingly similar effects on relevant host traits. Here, we explore this hypothesis through a survey and synthesis of literature on interactions among plant viruses, their hosts, and insect vectors. 2. Insect-vectored plant viruses that differ in their modes of transmission benefit from different patterns of interaction among host plants and vectors. The transmission of persistently transmitted (PT) viruses requires that vectors feed on an infected host for a sustained period to acquire and circulate (and sometimes replicate) virions, then disperse to a new, healthy host. In contrast, non-persistently transmitted (NPT) viruses are effectively transmitted when vectors briefly probe infected hosts, acquiring virions, then rapidly disperse. 3. Based on these observations, and empirical evidence from our previous work, we hypothesized that PT and NPT viruses will exhibit different effects on aspects of host phenotypes that mediate vector attraction to, arrestment on and dispersal from infected plants. Specifically, we predicted that both PT and NPT viruses would tend to enhance vector attraction to infected hosts, but that they would have contrasting effects on vector settling and feeding preferences and on vector performance, with PT viruses tending to improve host quality for vectors and promote long-term feeding and NPT viruses tending to reduce plant quality and promote rapid dispersal. 4. We evaluated these hypotheses through an analysis of existing literature and found patterns broadly consistent with our expectations. This literature synthesis, together with evidence from other disease systems, suggests that transmission mechanisms may indeed be an important factor influencing the manipulative strategies of vector-borne pathogens, with significant implications for managing viral diseases in agriculture and understanding their impacts on natural plant communities.

Thrips Vectors of Tospoviruses

Abstract: Tospoviruses belong to the sole phytovirus genus, Tospovirus , in the family Bunyaviridae . Tospoviruses are known to be exclusively transmitted by thrips belonging to the family Thripidae and subfamily Thripinae. Of the known 1,710 species of Thripidae only 14 thrips species are currently reported to transmit tospoviruses. Thrips-transmitted tospoviruses cause severe yield losses to several economically important crops in the United States and worldwide. For instance, a single Tospovirus ( Tomato spotted wilt virus ) alone caused an estimated $1.4 billion in losses in the U.S. over 10 years. Global trade and associated movement of plant materials across borders have introduced tospoviruses and their vectors into newer areas. Advances in serological and molecular techniques have also led to identification of new tospoviruses. This scenario has also initiated new vector-pathogen interactions between introduced and native thrips species and tospoviruses. The goal of this manuscript is to provide a comprehensive and updated list of thrips species that serve as vectors of tospoviruses along with information pertaining to common names, key diagnostic characters, distribution, important crops economically affected, and thrips and Tospovirus -induced symptoms. The manuscript is prepared with special emphasis to the U.S., but information pertaining to other countries is also included.

Vector-Virus Mutualism Accelerates Population Increase of an Invasive Whitefly

Abstract: The relationships between plant viruses, their herbivore vectors and host plants can be beneficial, neutral, or antagonistic, depending on the species involved. This variation in relationships may affect the process of biological invasion and the displacement of indigenous species by invaders when the invasive and indigenous organisms occur with niche overlap but differ in the interactions. The notorious invasive B biotype of the whitefly complex Bemisia tabaci entered China in the late 1990s and is now the predominant or only biotype in many regions of the country. Tobacco curly shoot virus (TbCSV) and Tomato yellow leaf curl China virus (TYLCCNV) are two whitefly-transmitted begomoviruses that have become widespread recently in south China. We compared the performance of the invasive B and indigenous ZHJ1 whitefly biotypes on healthy, TbCSV-infected and TYLCCNV-infected tobacco plants. Compared to its performance on healthy plants, the invasive B biotype increased its fecundity and longevity by 12 and 6 fold when feeding on TbCSV-infected plants, and by 18 and 7 fold when feeding on TYLCCNV-infected plants. Population density of the B biotype on TbCSV- and TYLCCNV-infected plants reached 2 and 13 times that on healthy plants respectively in 56 days. In contrast, the indigenous ZHJ1 performed similarly on healthy and virus-infected plants. Virus-infection status of the whiteflies per se of both biotypes showed limited effects on performance of vectors on cotton, a nonhost plant of the viruses. The indirect mutualism between the B biotype whitefly and these viruses via their host plants, and the apparent lack of such mutualism for the indigenous whitefly, may contribute to the ability of the B whitefly biotype to invade, the displacement of indigenous whiteflies, and the disease pandemics of the viruses associated with this vector.

Plant viruses transmitted by thrips

Abstract: All thrips (order Thysanoptera) that are known to be vectors of plant viruses are identified and described. Thrips transmit plant viruses in the Tospovirus, Ilarvirus, Carmovirus, Sobemovirus and Machlomovirus genera. Tospoviruses are the cause of a number of significant emerging diseases, such as capsicum chlorosis and scape blight of onion. They infect thrips as well as plant hosts and the relationship between pathogen and vector is intimate. Once infected at the larval stage, adult thrips usually transmit tospovirsuses for life. Transmission to plant hosts occurs when thrips feed. Information on the distribution and hosts of all recognised thrips vectors is provided. Fourteen tospovirus species are described with information provided on other tospoviruses that have not yet been designated as species. The history of the research that has led to present knowledge is reviewed in chronological order for each tospovirus. The possible origin of tospoviruses is discussed. Information is presented on viruses, which are thrips-transmitted by mechanical processes, in other genera. Pathways of spread of thrips vectors in relation to the threat of tospoviruses to European agriculture are discussed.