Host parasite interaction 03

Transcription

1 Measuring specificity and host range Host parasite interaction 03 Paulina Kramarz List of observed species - host range of mites (Unionicola sp.) Measuring specificity and host range Evolution of the host range Experimental infections - cross-infecting parasites. Ecological and physiological filters determine parasite host-range 1

2 Factors affecting host range Host range depends on parasite geographic distribution Host range depends on the phylogenetic age of the parasite group phylogenetic inertia Host range depends on the phylogenetic age of the parasite group Host range depends on transmission mode Host range depends on the complexity of the life-cycle Host range depends on the stage of the parasite s life-cycle Host range depends on the virulence of the parasite Host range depends on the variation in host availability Host range and geographical range in ectoparasites Host range depends on immune defences Biological control, BC Use of an organism to reduce the population density of another organism and thus includes the control of animals, weeds and diseases. Against animals - study and uses of parasites, predators and pathogens for the regulation of host (pest) densities. BC reduces rather than eradicates pests - natural enemy remain in the agroecosystem at low densities. BC Agents (BCA): Macrobial : insects, mites. Microbial : viruses, bacteria, fungi Host immune response and parasite host range 8 2

3 Three main techniques of BC Classical ( natural, inoculative ), ladybird Rodolia cardinalis against Icerya purchasi Parasitoid (wasp) Aphelinus mali angainst aphid Eriosoma lanigerum Augmentative (mass scale, comercial) Parasytoid (wasp) Trichogramma against Lepidoptera (cotton bollworm Heliothis virescens, sugar cane borer Diatraea saccharalis, European corn borer Ostrinia nubilalis) Other pests : whiteflies, leafminers, thrips, aphids and mites. Conservation control - use of indigenous predators and parasitoids, usually against native pests n.e. predatory ants in citrus orchards History 1880 ladybird Rodolia cardinalis against cottony-cushion scale Icerya purchasi Tachinid parasitoid Ptychomyia remota against coconut moth: Levuana iridescens Cassava (Manihot esculenta) - parasitoid Epidinocarsis lopezi against mealy bug Phenacoccus manihoti Predatory beetle Cryptolaemus montrouzieri against citrophilus mealy bug Pseudococcus calceolariae Cotesia parasitoids against sugar cane borer Diatraea saccharalis; Nucleopolyhedrovirus AgMNPV soya bean caterpillar (1 Mha) Egg parasitoids of the genus Trichogramma - ca. 10 Mha worldwide BC in greenhouses 10 Agains slow action Pro specificity Advantages and limitations of BC Bacteriophages

4 Mode of action Bacterial pathogens of crops Xanthomonas campestri infecting tomato Bacterial pathogens of crops Phage-propagating by nonpathogenic bacterial strains Erwinia amylovora, fire blight, (Rosaceae) 15 Closely-related epiphytic antagonist, Pantoea agglomerans 16 4

5 Viruses, family Baculoviridae Structure of Autographa californica (AgMNPV) Genus: Nucleopolyhedrovirus (PV), either single (SNPV) or mutliple (MNPV) nucleocapsid per envelope, eg. Autographa californica nucleopolyhedrovirus, AgMNPV; Enveloped virions are further occluded in polyhedrin matrix. AgMNPV in Brazil BC of soya beans Genus: Granulovirus, GV, one nucleocapsid per envelope, eg. Cydia pomonella granulovirus, CpGV. Enveloped virions are further occluded in granulin matrix Cycle of AcMNPV infection Production of CpGV, MADEX Cydia pomonella after infection with CpGV 20 5

6 Bacillus thuringiensis Sporulation of Bacillus thuringiensis Gram-positive soil bacterium. Saprophytic metabolism - digesting organic matter derived from dead organisms. Parasitic metabolism - colonization within living insects. Strains, six pathotypes: 1. lepidopteran-specific (e.g., var. berliner); 2. dipteran-specific (e.g., var. israelensis); 3. coleopteran-specific (e.g., var. tenebrionis); 4. both Lepidoptera and Diptera (e.g., var. aizawai); 5. Lepidoptera and Coleoptera (var. thuringiensis); 6. no known toxicity in insects (e.g., var. dakota). Glazier i Nikaido Glazier i Nikaido Mechanism of action of Bacillus thuringiensis Damage of midgut epithelium Endotoxin alkaline midgut Prototoxin proteases Active toxin Glazier i Nikaido 2007 healthy midgut epithelium white butterfly (Pieris brassicae) larva after endotoxin ingestion (disappearance of microvilli) Intact 10 min after endotoxin ingestion cells become permeable to the indicator stain 24 Glazier i Nikaido

7 Insects sensitive to Bt toxin Endosymbionts - Wolbachia Glazier i Nikaido Entomopathogenic fungi - Beauveria bassiana Entomopathogenic fungi Fungi (BC): Beauveria, Metarhizium, Nomuraea, Aspergillus, Verticillium, Paecilomyces, Isaria, Fusarium, Cordyceps, Entomophthora Hosts: Coleoptera, Lepidoptera, Hymenoptera, Hemiptera, Orthoptera, Homoptera, Diptera Infected Colorado beetles 27 Infected grasshoopers Beauveria bassiana 28 7

8 Application of Beauveria bassiana Metarhizium anisopliae 29 Locust Rice covered with fungi spores 30 Nematophagous fungi Herbivorous nematodes - eg. genus Meloidogyne Mode of infection: nematode-trapping, endoparasitic, egg and femaleparasitic, toxin-producing Structure of the traps (formed from vegetative hyphae ): adhesive nets, adhesive knobs, adhesive branches, and constricting rings; Endoparasites do not form trapping organs, but use their spores to infect. Little host specificity, can also live at varying degrees of saprophytism in soil. The largest group of antagonists against plant-parasitic nematodes

9 Constricting rings Adhesive hyphae Arthrobotrys dactyloides, A. brochopaga Arthrobotrys oligospora, Meria spp. Hirsutella rhossiliensis Infecting spores Parasitoids Cysts of Catenaria anguillulae in Xiphinema americanum Nematodes eggs infecetd with spores, eg.: Paecilomyces lilacinous, Dactylella oviparasitica Six holometabolous orders of insects: Hymenoptera, Diptera, Coleoptera, Lepidoptera, Trichoptera, and Neuroptera Eggs are laid directly into or on the host, sometimes near the host - ectoparasitoids or endoparasitoids Solitary or gregarious Hyperparasitism Koinobiont - host to continue to feed, grow, and function after parasitism, Idiobiont - host ceases development immediately upon being parasitized or shortly thereafter

10 Endoparasitoid, solitary Endoparasitoid, gregarious Lysiphlebus testaceipes Cotesia congregata soilcropandmore.info/crops/wheat/insects/bioinfo.htm 37 www4.ncsu.edu 38 Endoparasitoid, solitary Endoparasitoid, gregarious Trichogramma spp Voria ruralis

11 Ectoparasitoid, solitary Hyperparasitoid Spider wasp, Tachypompilus ignitus dragging an immobilized Palystes spider to her nest Hypopteromalus tabacum laying eggs in Cotesia congregata cocoons A parasitoid ovipositing in an aphid mummy lisaforehand.com/photos.html abbotlab.wordpress.com/2010/12/08/more-than-you-probably-wanted-to-know-about-aphid-hijacking-mummies-andsuper-powers/ 42 11