Cuáles son las mejores prácticas para la aplicación de insecticidas en el control del Aedes aegypti?

Transcription

1 Cuáles son las mejores prácticas para la aplicación de insecticidas en el control del Aedes aegypti? What are the best practices for insecticide application to control Aedes aegypti? Eduardo Zerba Centro de Investigaciones de Plagas e Insecticidas (CIPEIN) (Research Center of Pest and Insecticides) Buenos Aires (1603); ARGENTINA. WHO/PAHO collaborating centre "II Encuentro Internacional para el Control de Aedes aegypti Por qué no podemos controlar el Aedes aegypti?". Ciudad de Panamá, Panamá November 18-22, 2011 ezerba@citefa.gov.ar ezerba@live.com.ar

2 DENGUE: Aedes infested areas and recent epidemic situations

3 Number of dengue fever (DF) and dengue hemorrhagic fever (DHF) cases, Region of the Americas, Source: The Epidemiology of Dengue in the Americas Over the Last Three Decades: A Worrisome Reality José Luis San Martín, Olivia Brathwaite, Betzana Zambrano, José Orlando Solórzano,Alain Bouckenooghe, Gustavo H. Dayan, and María G. Guzmán Am. J. Trop. Med. Hyg., 82(1), 2010, pp

4 Chemical control of insect vectors is actually the principal action to interrupt the vectorial tranmission Chemical control is still valid as the principal tool of Integrated Vector Management

5 Aedes aegypti Yellow fever transmissor In 1881, it was Cuban doctor Carlos J. Finlay who first theorized, that yellow fever was actually transmitted by mosquitoes. Dr. Carlos Finlay ( )

6 Yellow fever and Aedes aegypti in Cuba Spanish-American War (1898) Walter Reed, a physician of the American army, confirmed Finlay s theory and proceeded, along with US Army physician William Gorgas to lead the efforts to eradicate the disease in the city of Havana and the interior of the country (1900). Walter Reed ( ) Fewer than 400 American soldiers were killed in combat during the war. But more than 2,000 contracted yellow fever during the campaign. William Gorgas ( )

7 La Habana holds the distinction of being first city in the world to have successfully eradicated yellow fever. Gorgas s sanitary workers used various methods to eliminate or reduce mosquito infestation: they drained or covered with kerosene all sources of standing water, fumigated areas infested with adult mosquitoes, and isolated disease-stricken patients with screening and netting. Spatial treatment with pyrethrins fumes in Havana (1901) As a result of the genius of Finlay and the Reed and Gorgas effort, La Habana was the first city in the world to have successfully eradicated yellow fever.

8 Are we using a novel strategy to the control of dengue vector?

9 Current principal strategy of Ae. Aegypti control Environmental management Gorgas s sanitary workers drained sources of standing water and used nets Gorgas s sanitary workers fumigated (pyrethrum fumes) areas infested with adult mosquitoes Spacial (Adulticides) Chemical Control Gorgas s sanitary workers drained or covered with kerosene all sources of standing water Focal (Larvicides)

10 Our Center works with the concept of new control tools characterized by: Able to be used at critical sites in the vectorial transmission, With lower application costs and With the possibility to be used by the community at risk.

11 Larvae and pupa control An important target to improve the Aedes aegypti control

12 Pyriproxyfen: a very selective larvicide Insect growth regulator mimic of Juvenile Hormone Oral toxicity: Dermal toxicity: LD50 rat: > 5000 mg/kg LD50 rat: > 2000 mg/kg Inhalation toxicity: LC50 (4 h) rat: > 1300 Skin irritation: Eye irritation: Sensitisation: Not irritating rabbit Not irritation rabbit Not sensitising Guinea pig Noncarcinogenic, nonteratogenic, nonmutagenic, rapid environmental degradation Excelent toxicological profile! WHO has assessed pyriproxyfen for use as a mosquito larvicide in drinking-water in containers, particularly to control dengue fever

13 New applications of pyriproxyfen for Aedes control Pyriproxyfen in new formulations for spatial treatments Pyriproxyfen diluted in solid materials constitutive of lethal ovitraps

14 Toxicity of active principles used in solid larvicide formulations to inmature forms of Aedes aegypti Larvicide EC 50 * (ppb) (Confidence intervals) PYRIPROXYFEN** ( ) TEMEPHOS*** 3.60 ( ) * EC 50 Effective Concentration 50 % ** Effect = inhibition of adult emergence *** Effect = larvae mortality Seccacini et al J.Am.Mosq.Control Assoc. 24(3) (2008).

15 ULV spatial treatment with permethrin + pyriproxyfen fumigant tablet Fumigant formulation improve the mosquito population control by the addition of a very effective larvicide Adulticide effect X Larvicide effect X

16 Fumigant tablet containing permethrin and pyriproxyfen A 50 g fumigant tablet containing 10% permethrin and 2% pyriproxyfen Eficiency of pyriproxyfen delivery in fumes: more than 95 % Thermal behaviour and biological activity of a new smoke generating formulation against larvae and adults of Aedes aegypti (Diptera: Culicidae), Harburguer et al, Pest. Science Management 65(11) (2009)

17 Indoors treatment with fumigant tablet containing permethrin and pyriproxyfen Treatment Adult index (mean number of adults captured per house during 10 minutes of search by one person) for all treated areas and the control area Letter a indicates that adult index in each treated area is significant different from the control area (p 0.05). Letter b indicates that at least one treatment is significant different from control area (in this case treatment FT + ULV). Letter c indicates that there are no significant differences between treatments (p > 0.05). A new strategy for Aedes aegypti (Diptera: Culicidae) control with community participation through the use of a newly fumigant formulation. Hraburguer et al, J. Med. Entomology, accepted for publication, 2011

18 Community attitude with respect to the use of the fumigant tablet after an instructive meeting with community members Community response to the use of the fumigant tablet Community response to who applies the fumigant tablet A new strategy for Aedes aegypti (Diptera: Culicidae) control with community participation through the use of a newly fumigant formulation. Hraburguer et al, J. Med. Entomology, accepted for publication, 2011

19 New project: Solid materials containing pyriproxyfen as constituents of lethal ovitraps Containers of Stearine, bee wax or paraffin with 0.1 or 0.5 % pyriproxyfen Disposable container with 0.1 or 0.5 % bee wax in pyriproxyfen as bottom

20 SOLID MATERIALS CONTAINING PYRIPROXYFEN AS COMPONENTS OF LETHAL OVITRAPS Residual larvicide effect %AEI %AEI % Pyri 0.5 % Pyri 1.0 % Pyri % Pyri Control 30 Control days 0 days 240 days days days days days Disposable containers which bottom is a polyethylene disk containing pyriproxyfen Paraffin plus pyriproxyfen containers Juan, Laura; Seccacini, Emilia; Zerba, Eduardo; Licastro, Susana, Joournal of Medical Entomology, Volume 50, Number 4, pp (4)

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23 Adult emergence inhibition Inhibición de Emergencia (%) Larvicide ovitraps: extrapolation of the results obtained in an accelerating ageing test Equivalence = 2 years in natural conditions Ctrol Positivo Envejecimiento Ctrol Negativo Nov 04-Nov 05-Nov 06-Nov 07-Nov 08-Nov 11-Nov 12-Nov 13-Nov Días Positive control (Ovitrap at T=0) Días Ovitrap with accelerated ageing test

24 Larvae attractant A new form of a more efficient larvicide action Larvicide bait

25 Mortality Sinergism of larvicide effect of Bti by addition of a larvae attractant 0,01% p/p 10-4 % p/p Average Control Time Cipein, 2013, unpublished results

26 Sinergism of larvicide effect by attractant addition Larvae Attractant Concentration (Y-PG) 0 Larvicide MT50% (min.) ( )* 2gr solid Bti 10-2 % p/p formulation 83.5 ( )* 10-4 % p/p 99.9 ( )*

27 Novel formulations containing pyriproxyfen are new alternatives with excellent larvicide effect to improve the control of Ae. aegypti in different situations, including with community participation The possibility to use larvae attractants open the possibility to develop larvicide baits as novel tools for mosquito control

28 Gracias a todos ustedes y a mis compañeros del Centro de Investigaciones de Plagas e Insecticidas, Buenos Aires, Argentina