Entomopathogenic nematodes in biological control: reality and prospective

1. GRIFA ETC Università degli studi Milano – Bicocca 16-17 Ottobre 2002 Entomopathogenic nematodes in biological control: reality and prospective Manuele Ricci e Adriano Ragni BioTecnologie B.T. S.r.l.

2. Entomopathogenic Nematodes

3. Taxonomy • PhylumNematoda • Class Secernentea • Order Rhabditida • Sub-order Rhabditina • Super-family Rhabditoidea • FamilySteinernematidae (25 species ) Heterorhabditidae (10 species)

4. MODE OF ACTIONNematodes seek for insect host

5. MODE OF ACTIONNematodes penetrate into the insect host

6. MODE OF ACTIONNematodes release their symbiotic bacteria

7. MODE OF ACTIONInsect dies due to the bacteria propagation

8. MODE OF ACTIONNematodes develop and reproduce in the host

9. MODE OF ACTIONNematodes leave the insect cadaver

10. Nematode: a syringe for bacteria? No, it is always a symbiosis

11. SYMBIOSIS BETWEEN NEMATODES AND BACTERIA NEMATODE ADVANTAGES BACTERIUM ADVANTAGES • Nematodes feed on bacteria that grow inside the insect body • Bacteria, without living inside the nematode intestine, cannot live by itself outside the insect host • Nematodes feed the insect tissues depleted by the bacterium growth • Bacteria can only reach the insect by means of the nematodes • Nematodes can overcome the insect immune-system by the immune-depression action that bacteria cause to the insect • Bacteria can overcome the insect immune-system by the immune-depression action that nematodes cause to the insect

12. NEMATODES AND THEIR SYMBIOTIC BACTERIA Nematode genus STEINERNEMA Nematode genus HETERORHABDITIS Symbiotic bacteria genus XENORHABDUS Symbiotic bacteria genus PHOTORHABDUS

13. Foraging Strategies and Insect Hosts Cruiser Ambusher Static Insects(es. Otiorhynchus sp.) Dinamic Insects (es. Sciarids)

14. Steinernematids J2 J3 Eggs J1 Dev. in stress J4 Normal Dev. J2D IJ Males Females J1-J4 IJ Hermaphrodites IJ Eggs Hermaphrodites Males Females Hermaphrodites Eggs Life Cycle of Entomopathogenic Nematodes Eterorhabditids

15. Otiorhynchus sulcatus Target:

16. Other Target Insects Insect Pests Crops Scarabeids: Popilia japonica, Maladera matrida Phyllopertha horticola, Aphodius spp. lawns, orchards, nurseries, sweet potatoes Curculionids: Otiorhynchus spp., Conorhychus mendicus, Balaninus elephas, Diaprepes abbreviatus, Cylas formicarius ornamentals, berries, citrus, sugar beet, chestnuts mushrooms, greenhouses Diptera: Sciarids, Forids, Scatopsids, Cecidomids vegetables Lepidoptera: Nottuids

17. Entomopathogenic Nematode Production In Vivo In solid In Vitro In liquid

18. Entomopathogenic Nematode Formulation Old In Sponge In Clays Actual Innovative under development In Granules

19. FIELD APPLICATION

20. PROSPECTIVES Market Needs: Low production costs Technology New strains Higher infectivity Higher production Extended shelf life Technology New strains Dry conditions New Target: Grillotalpa grillotalpa Melolontha melolontha Leaf miners Fruit flies Bactrocera sp. Ceratitis sp. Ragoletis sp. New applications: Extreme environmental conditions: cold warm dry Symbiotic Bacteria exploitation Extended applications: Foliar Indoor cockroach flies

21. NEW ENTOMOPATHOGENIC NEMATODE ACTIVE AT LOW TEMPERATURES • MARKET NEEDS • A product to control soil inhabiting insect pests • (weevil, grubs) at low temperatures (4-8°C). • (1996: Only Netherlands spent 2 Million US$ against • only 1 weevil species: Otiorhynchus sulcatus) • AVAILABLE PRODUCTS • CHEMICALS: few, not effective, not friendly • BIOLOGICAL: nematodes but at T°C above 12°C

22. NEW ENTOMOPATHOGENIC NEMATODE ACTIVE AT LOW TEMPERATURES • A nematode strain has been discovered and it is very active against O. sulcatus larvae even at 3°C • The strain is effective against larvae of B. elephas at 8°C • The strain belongs to Steinernema kraussei species • The strain can be reproduced in vivo at 15°C • The strain can be produced in liquid culture at 20°C without loosing its cold activity

23. ENTOMOPATHOGENIC NEMATODE SYMBIOTIC BACTERIA: A NOVEL SOURCE OF INSECTICIDAL TOXINS PHOTORHABDUS Before 1996 entomopathogenic nematodes symbiotic bacteria were know to act ONLY by means of nematodes Different laboratories in the word, found out that symbiotic bacteria may have direct (ingestion) activity against insect pests Symbiotic bacteria (or their metabolites) have been patented for their use as: - insecticide - fungicides - antibacterial activity - anti-tumor activity

24. ENTOMOPATHOGENIC NEMATODE SYMBIOTIC BACTERIA: A NOVEL SOURCE OF INSECTICIDAL TOXINS PHOTORHABDUS 1.Introduces a conceptual change in the mechanism of action of nematodes as bioinsecticides. 2. Might offer a cost efficient simplification over the use of the symbiotic complex nematode-bacterium for the control of certain insects. 3. Allows for the development of new bioinsecticide products for foliar application. 4. Might indicate the existence of a new group of microorganisms with insecticidal capabilities similar to the Bacillus thuringiensis. 5. Can generate a new battery of genes originated in Photorhabdus spp. for inducing insect resistance in transformed plants.

25. Due to their demonstrated safety, they are exempted from the registration, in most countries ENTOMOPATHOGENIC NEMATODESCONCLUSIONS • For the soil dwelling insect pests, there are few chemical insecticides available and with little efficacy • Nematodes seek for insects and kill them • Insects cannot easily develop resistance toward the nematode-bacterium complex • Entomopathogenic Nematodes are safe for the environment • Entomopathogenic Nematodes may be used for IPM programs