Method for the Reduction of mosquitoes vectors of West Nile...
Transcript of Method for the Reduction of mosquitoes vectors of West Nile...
Method for the Reduction of mosquitoesvectors of West Nile virus and Dengue fever
Gerardo Ulíbarri, PhD
Sept. 2013
What are mosquitoes good for?
• Food for other animals/insects• As Larva or adulto mosquitoe
• Good virus/parasite wells• Vectors of viruses/ parasites
Some of the illnesses that mosquitoes can transmit to humans
• Yellow Fever (Aedes aegypti)• Dengue Fever (Aedes albopictus/aegypti)• Malaria (Anopheles gambiae)• West Nile virus (Culex pipiens)• Lymphatic filariasis (elephantiasis)• River blindness
Some of the illnesses that mosquitoes can transmit to animals
Encefalitis Equina del Este (Aedes vexans)Encefalitis Equina del Oeste (Culex/Culiseta)Malaria aviar (Culex quinquefasciatus)Virus del Oeste del Nilo (Culex spp)
3561 different species of mosquitoes around the world
http://www.mosquitocatalog.org/default.aspx
México 224 Continental United States 166 Canada 74
Walter Reed Biosystematics Unit (WRBU), Division of Entomology, Walter Reed Army Institute of Research (WRAIR), Silver Spring, Maryland, USA.
Anopheles spp. 478 Aedes / Ochlerotatus spp. 206 Culex spp. 789
México
Anopheles spp. 26 Aedes / Ochlerotatus spp. 25 Culex spp. 58
3561 different species of mosquitoes around the world
The mosquito reproductive cycle
• Mosquitoes undergo metamorphologicalchanges
• Only females need blood to develop their eggs
• Three days after biting, the female can lay from 3-300 eggs
• In 48 hours larva can emerge from the eggs
• Larva needs air to survive
• Adults emerge after 2 days in pupa state
http://commons.wikimedia.org/wiki/File:Culex_mosquito_life_cycle_es.svg
El ciclo de reproducción del mosco
• It needs from 4-6 days to go from egg to adult, dependent on Temperature
• Larva can survive in only 1 cm of water
• Eggs of some species can survive for years in drought
• Some eggs can support very low temperatures
• There are mosquitoes that prefer humans (antropophilic) to other animals for blood.
http://commons.wikimedia.org/wiki/File:Culex_mosquito_life_cycle_es.svg
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1) Biological
2) Physical
3) Chemical
Methods used to control or reduce mosquitoes
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1) Biological: Uses natural predators of the mosquito
Mosquito Fish (Gambusia affinis)
Bacteria: Bacillus thurigiensis israelensis (Bti)
Bacillus sphaericus
Dragon Fly
Genetically modified mosquitoes
Life history variation of invasive mosquitofish (Gambusia holbrooki) along a salinity gradient. C Alcaraz, E Garcıa-Berthou. BIOLOGICAL CONSERVATION 139 (2007) 83–92.Bacillus sphaericus as a mosquito pathogen: properties of the organism and its toxins. P Baumann, M A Clark, L Baumann, and A H Broadwell. Microbiol Rev. 1991 September; 55(3): 425–436.
Methods used to control or reduce mosquitoes
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Insects and animals that feed on mosquitoes
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1) Physical: Layer of oil in water surface
Water container coverts
Adult Traps
Carbon dioxide, water steam and heat
Photonic fence (micro laser)
Lethal Ovitraps (use insecticide)
Bed nets
Clean Patio
Methods used to control or reduce mosquitoes
13http://www.educasocial.com.uy/demo/mod/file/download.php?file_guid=1039
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1) Chemistry: pesticides Organochlorinated -DDT Organo-phosphates Carbamates Piretotroids
Neurotoxicity: prolonged activation of Sodium channels causing depolarization sustained depolarization in neurones, producing muscular spams.Teratogenicity: abnormal fetus developmentDDT: Inhibits shell formation in bird eggs.
Permetrine
Malathion
Carbaryldichlorodiphenyltrichloroethane
Methods used to control or reduce mosquitoes
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Methods used to monitor the presence of mosquitoes vectors of disease
How is it determined when is the right moment to spray pesticides
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CDC Light traps(Centers for Disease Control and Prevention)
(www.cdc.gov/)
CDC Light Traps
•Traps only adultmosquites and other inects
•Mainly females•Uses light and CO2 toattract the insects
•Problems•There is no selectivity
•High cost of operation•~$15 dollars per night /per trap
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Larval deep
www.keysmosquito.org/larvicides_treatments.html
www.ocvcd.org/mosquitoes2.php
•Problems•Every pond ahs to be verified independently
•High operative cost (labor)
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Human Bait
news.cals.wisc.edu/newsDisplay.asp?id=1771
www.trevorwilliams.info/Mosquitoes_blackflies...
•Problems•Only anthropophagic mosquitoes are trapped
•Dilemma with the ethic of using humans as bait
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Gravid y Ovitraps
www.ocvcd.org/mosquitoes2.php
www.fehd.gov.hk/.../2002/calendar-photo5.html
•Problems•Very selective. Attraction depends on solution used•Only attracts gravid females
•Problems•Very selective, Attraction depends on the solution used•Only collects eggs/larvae
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West Nile virus-The North America Problem
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Culex spp – Main vectors of the West Nile virus
http://www.madrimasd.org/blogs/virusemergentes/2012/10/el-avance-de-los-flavivirus-emergentes-y-reemergentes/
22www.usgs.gov/125/articles/images/wnv_map.jpg
http://www.cdc.gov/westnile/resources/pdfs/cummulative/99_2012_CasesAndDeathsClinicalPresentationHumanCases.pdf
West Nile virus infections
1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012US 62 21 66 4156 9862 2539 3000 4269 3630 1356 720 1021 712 1590Canada 414 1481 25 225 151 2215 36 13 5 101 62
0100020003000400050006000700080009000
10000
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Mosquito BehaviourMosquito behaviour is mainly influenced by a series of olfactory stimuli.
W Takken, and B G Knols. (1999). Annu. Rev. Entomol. 44, 131-157.
Odorant Binding Proteins (OBP)
• Water-soluble globular proteins with exposed hydrophilic groups
• Located in the lymphatic space surrounding the sensory neurons
• Transport the hydrophobic odorant molecules through the aqueous lymph to the odorant receptors.
Proteina tipo-G acoplada a receptores (G-PCR)
• Seven transmembranehelical proteins
• Residing on the dendritic membrane of the olfactory sensory neurons
• Activated when bound to OBP which in turn activates the olfaction signal
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Receptor del olor 7 (Or‐7)• Identificado y caracterizado en varias especies de
mosquitos: Anopheles gambiae (AgOr7), Aedes aegypti (AaOr7), Culex quinquefasciatus (CqOr7)
• CqOr7 fue identificado en Marzo de 2006 por el equipo del Dr. Zwiebel, el mismo grupo que secuencio el genoma del mosco Anofeles. (Xia and Zwiebel, 2006).
Xia, Y. & Zwiebel, L. J. Insect Biochem Mol Biol 36, 169‐76 (2006)
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Modified Ovitrap
http://www.youtube.com/watch?v=VwIqGbhq4T8Mosquito laying eggs, eggs hatching (#311) nature1upclose·
Bacteral fermentation
H2O
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Culex egg rafts on modified ovitrap
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www.qac.org
Egg Raft
Larva
Pupa
Modified Ovitrap
Field studies
We have found up to 89 rafts in one night study(~26,000 eggs)
What is the secret?
The apical part (superior) of each egg contains a chemical compound which serves a signaling to oviposition to new comers (attractant) for the Culex spp.
Initially, the mosquitoes are attracted to the ovitrap by the natural concoction.
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Sudbury
Ovitrap
Day Temperature (oC) Relative Humidity (%) # of Egg Raft / Day
Max. Mean Min.
1 24.4 18.45 12.5 87.42 41
2 27.9 22.15 16.4 73.96 146
3 30.3 24 17.7 70.88 52
4 31.6 25.05 18.5 59.54 67
5 31.4 24.85 18.3 66.21 33
6 31.4 25.05 18.7 62.08 30
14 29.4 22.9 16.4 90.25 47
15 22.8 19.7 16.6 70.58 30
16 25.5 21.7 17.9 91.38 103
17 29.3 23.2 17.1 77.29 116
18 21.7 18.3 14.9 70.21 165
19 22.2 17.85 13.5 80.33 65
20 27.5 22.8 18.1 89.88 52
21 33.2 27.2 21.2 81.38 119
Total 2007
Average 91
Sudbury
Ovitrap
Average eggs in a raft (Sudbury)= 270 (Culex pipiens/restuans)
In the first field study 2007 rafts werecollected in 21 days = 541,890 eggs
An average of 25,804 eggs per day
Using only 3 modified ovitraps
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2007 Field study150 modified ovitraps were used in 12 different sitesField study was run from 1st of June to the 30 of August
• 11196 rafts were colected in 90 days• 870 rafts per week• 3,358,800 eggs destroyed!
If one estiamtes a 20% of the eggs hatching producing females capable of laying eggs;
In the first two weeks they will produce:(870)(2)(270)=469,800 x 0.2= 93,960 females
If each lays eggs once; 25,369,200 eggs potentially produced
In Only Two weeks
But, does this really cause a reduction of mosquitoes?
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NCDC Light Trap
Artificial Breeding Pools4
CDC Light Trap
Ovitrampa modificada4 1
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1 2 3 4 5 6 7 8 9 10Sudbury control 1 9 4 24 10 78 74 89 52 44Long Lake 2 1 3 5 1 2 2 0 0 0
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mos
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ntComparative study between a test site using modified ovitraps and two
control sites without ovitraps, in Sudbury
Collection of adult mosquitoes was done using the standard CDC light traps on each site
Ovitrap
ABP
Bacterialfermentation
Rafts
Dumpsolution
Bacterialfermentation
Rafts
Filtersolution
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fehd.gov.hk
OOH
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erythro‐6‐Acetoxy‐5‐hexadecanolideB.R. Laurence and J.A. Pickett J. Chem. Soc, Chem. Commun. 1982 p. 59-60
Do the modified ovitraps work as well with other species?
A female mosquito (Anopheles gambiae) feedingPhoto courtesy Centers for Disease Control & Prevention, photographer Jim Gathany(http://home.howstuffworks.com/mosquito-magnet1.htm)
Aedes aegypti
(http://en.wikipedia.org/wiki/Aedes)
http://www.paho.org/hq/index.php?option=com_content&view=article&id=264&Itemid=363&lang=en
Dengue Regional Information: Number of Cases-2013
Estado del estudio en Pentatlán, Gro, México.Inicio : primera semana de Febrero hasta Ultima semana de Agosto 2013
(30 semanas de estudio)
Modified Ovitrampa
Aedes eggs on a paper pellon
Photo of Aedes mosquitoe eggs on paper pellon
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Atrayente
Control
Total number of Aedes mosquito eggs collected during the field study in Petatlán, Gro
Semana 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16Atrayente 4575 6643 7076 6515 5617 4502 4001 5744 8870 7570 4769 2622 2425 3887 4653 4664Control 1048 481 785 665 776 896 503 602 704 1180 494 368 553 668 430 606
Huevo destruido 5623 7124 7861 7180 6393 5398 4504 6346 9574 8750 5263 2990 2978 4555 5083 527017 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32
3763 3005 2695 3552 2802 4799 4134 4640 4921 5217 4599 4184 4763 3959 7304 7119723 621 690 713 624 806 820 876 910 1151 1094 808 855 889 1013 12204486 3626 3385 4265 3426 5605 4954 5516 5831 6368 5693 4992 5618 4848 8317 8339
Atractant= 40 ovitrampasControl = 10 ovitrampas
Total 155,58924,572180,161
Week
Total eggs collected
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Control/ovitrap
Attractant/ovitrap
Semana 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
Atrayente/ovitrampa 131 190 202 186 160 129 108 144 222 189 119 66 61 97 116 117
Control/ovitrampa 70 32 52 44 52 60 75 105 70 118 49 37 55 67 43 61
Semana 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32
Atrayente/ovitrampa 94 75 67 89 70 120 103 116 123 130 115 105 119 99 183 178
Control/ovitrampa 72 62 69 71 62 81 82 88 91 115 109 81 86 89 101 122
Average eggs collected per ovirapduring the study (32 weeks)
Attractant 126
Control 74
Eggs collected
per ovitrap
Week
Total number of Aedes mosquito eggs collected during the field study in Petatlán, Gro
In Red-Egg couunt using traditional ovitraps with attractant solution (Downtown Petatlan) In Blue-egg count using traditional ovitraps, where the modified ovitraps were located.
Semana/mesTerceraJunio
CuartaJunio
PrimeraJulio
SegundaJulio
TerceraJulio
CuartaJulio
PrimeraAgosto
SegundaAgosto
TerceraAgosto
CuartaAgosto
Quinta Agosto
Control / ovitrampaEn lugar del estudio 18 3 0 20 13 17 11 2 8 18 12Atrayente / ovitrampa
En lugar ajeno al estudio 29 79 104 97 71 63 37
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Control / ovitrampa en lugar del estudio
Atrayente / ovitrampa en lugar ajeno al estudio
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Eggs collected
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Comparative Field studies between Petatlán, Gro, México in 2013 (Green)and a field study in Zayaxche, Guatemala en 2010 (Blue). Observe that the count does not go up during the rainy season in Mexico (July-Sept).
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Atrayente/ovitrampa‐Gua Control/ovitrampa‐Gua Atrayente/ovitrampa‐Pet Control/ovitrampa‐Pet
E F M A M J J A S O N D
Atrayente/ovitrampa‐Gua 71 273 308 877 744 1135 1555 371 350 300 256 240Control/ovitrampa‐Gua 37 109 172 276 137 245 407 164 205 206 113 103Atrayente/ovitrampa‐Pet 709 568 596 485 231 462 568Control/ovitrampa‐Pet 199 291 60 298 202 341 480
Conclusion: • The modified ovitraps reduce the presence of the adult Culex spp. mosquito vector of the
West Nile virus in above 80% when a Culex-specific attractant solution is used. The solution that has been used is based on a known bacterial/yeast fermentation of natural plants and a few other attractant ingredients.
• The modified ovitraps maintain low the population of the Aedes spp. mosquitoes, vectors of the dengue virus, even during the rainy season. The difference of adult mosquitoes between the site with modified ovitraps and a site with no ovitraps is approx. of 60-70% (to be verified). The attractant solution has been develop exclusively for the Aedes type of mosquitoes.
• Modified ovitraps are being studied with different attractant solution in Zayaxche, Peten, Guatemala against the malaria mosquitoes by the team of Jacobo Rojas y ValentínSalazar from the local Health Unit.