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Control of Disease Vectors

Consortium for the Barcode of Life Regional Meeting Nairobi, Kenya 18-19 October 2006. Control of Disease Vectors. Dr Yvonne-Marie Linton Natural History Museum, London. Correct species identification is critical for effective control of insect-borne pathogens and agricultural pests.

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Control of Disease Vectors

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  1. Consortium for the Barcode of Life Regional Meeting Nairobi, Kenya 18-19 October 2006 Control of Disease Vectors Dr Yvonne-Marie Linton Natural History Museum, London

  2. Correct species identification is critical foreffective control of insect-borne pathogens and agricultural pests

  3. Uses of DNA Barcodes As a diagnostic tool: • for identifying regulated species: • disease vectors, agricultural pests, invasive species • protected species, CITES listed, trade-sensitive • for general scientific research • ecological studies, inventories As a “Triage” tool • for flagging potential new species (undescribed and cryptic) To assist in taxonomic research

  4. New DNA Barcoding Schemes Mosquitoes (c. 3500 spp) – vectors of malaria, filariasis, dengue, yellow fever, JE, West Nile virus etc Fruit flies (Tephritids) (c. 3000 spp) – economically devastating pests of fruit crops worldwide Both have been accepted by CBOL as ‘demonstrator’ projects

  5. MBI inceptive meeting, NHM, London 21-22 Nov 2005

  6. Can DNA barcoding work in mosquitoes? Can a short region of DNA (720bp of COI) really enable us to identify all known species? Can it help identify unknown species?

  7. Why barcode mosquitoes? • Relatively small but diverse group • Relatively well known • Actively researched worldwide • Huge potential impact on parasitic and arboviral disease control

  8. Overcoming the global taxonomic impediment DNA characters are easier to obtain and compare, making the discovery of new species more rapid BUT sequence data is effectively useless unless meshed with a strong taxonomic framework based on morphology Integrated systematic studies are “the new taxonomy”

  9. An. (C.) christyi An. (N.) oswaldoi atropos sacharovi persiensis 98 martinius GB Palaearctic atroparvus 94 100 95 labranchiae GB messeae 79 64 daciae 67 maculipennis 70 melanoon 96 beklemishevi quadrimaculatus 75 maverlius 66 smaragdinus 95 inundatus 87 95 100 Nearctic diluvialis occidentalis 95 freeborni hermsi 92 earlei 87 ITS2 phylogeny Maculipennis Group (745 seqs)(GB GenBank) New species identified on basis of DNA data and formally described using integrated description

  10. Annularis Group 1000 600 500 400 300 200 96 ITS2 100 100 96 nivipes philippinensis annularis 99 Wide geographical sampling reveals new species 0.02 annularis India* annularis Viet/Korea/Laos/Camb annularis Philippines* philippinensis Vietnam/Laos nivipes Vietnam/Cambodia/Laos jamesi Vietnam maculatus Vietnam

  11. Voucher specimens

  12. Outcome of the MBI inceptive meeting MBI objectives: To generate DNA barcodes for at least 5 specimens of each species of 80% of the World Culicidae within two years

  13. Major obstacles to objectives • How many Culicid species are there? • Where will we find them? • Where would the specimens come from? • Frozen DNA collections? • Field collected samples? • Museum specimens? We realised that for the project to be a success in such a short time frame, museum specimens would have to play a major role

  14. To meet our objectives • A pilot study to assess the feasibility of getting usable DNA from Museum specimens must be undertaken - If success rate was higher than 50% we could go ahead with the project! • An up-to-date taxon list was needed! • Species distributions needed to be established

  15. Smithsonian Institution, USAMay 11-12 2006 • Update meeting of 5 members of the MBI steering committee to assess success of pilot study

  16. CPV1-1 An. philippinensis Luksang Kampong, Preah Vihear Province, Cambodia. Human Bait. Linton et al., 2004 Sigma Qiagen GenBank AF546338 mtDNA COI GenBank AJ674540 nDNA ITS2 500 bp Museum specimens from 2000 COI: LCO1490F/HCO1490R

  17. A. LCO1490F/HCO2198R B. LCO1490F/C1J1718MODR An. gambiae – 1938 An. minimus – 1998 An. gambiae – 1936 St. aegypti – 1973 St. aegypti – 1954 St. aegypti – 1916 C. quinquefasciatus -1969 Neg. extraction An. gambiae – 2001 Neg. PCR Archive mosquitoes (QIAmp micro kit, QIAgen)

  18. Optimal DNA extraction from Museum specimens Minimum of 12-24hrs in shaking incubator @ 55oC 100μl GB 10μl Prot K 2 min QIAgen Blood kit and magnetic bead DNA transfer QIAgen Biosprint, 50μl

  19. Priority order of sequencing? • Field collected samples less than 10 years old (silica gel or pinned) • Mosquitoes stored individually in >80% ETOH and less than 10 years old • Mosquito specimens from pinned collections >10 years old • Slide mounted larvae/pupae Specimens from as wide a geographical range as possible will be used

  20. Culicidae species list • 3,449 formally recognised species as at July 1 2006 • Quantitative counts of museum holdings • 2930/3449 in 9 collections • 85% of all currently known taxa are available to MBI

  21. Zoogeographic Distribution of CulicidaeGenera (approx number of species) per region 14 (200) 14 (190) 23 (880) 18 (560) 24 (820) 20 (520)

  22. MBI Co-ordinators: Y. Linton & R. Lane NHM Co-ordinators: R. Harbach (morph) & Y. Linton (mol) SMITHSONIAN Co-ordinators: R. Wilkerson (morph) & D. Foley (mol) ITM W. Van Bortel UND N. Besansky India Co-ordinator: P. Kumar SE Asia Co-ordinator: P. Somboon Africa Co-ordinator: M. Coetzee Latin America Co-ordinators: M. A. Sallum & M. Quinones Australasia Co-ordinator: D. Foley World mosquito workers

  23. MBI strategy summary • Primarily reliant on museum specimens but fresh is better! • To actively include global members of the mosquito community as collaborators • Donations of specimens will be acknowledged in the BOLD database • All specimens will be identified and voucher specimens stored where possible • Access to the data will be immediate and free.

  24. Current status of MBI • We have a updated species list • We have knowledge of species distribution • We can get good quality sequenceable DNA from museum specimens • We have tested the utility of the barcoding primers across many Culicidae genera • We have access to 85% of all the known taxa • We need your help! BUT WE ARE READY TO GO!

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