Control of Aedes aegypti and Ae. albopictus. Christopher Lesser and Mark Latham Manatee County MCD Palmetto, FL

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1 Control of Aedes aegypti and Ae. albopictus Christopher Lesser and Mark Latham Manatee County MCD Palmetto, FL

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3 Background: * Most MCD s originally established to deal with nuisance and disease vectors species Majority created to control -- Aedes taeniorhynchus and Ae. sollicitans

4 Background: * Most MCD s originally established to deal with nuisance and disease vectors species Majority created to control -- Aedes taeniorhynchus and Ae. sollicitans *Historically efforts against Aedes aegypti and albopictus by mosquito control programs in Florida been focused upon public education (media, schools, public events, etc.), very focal premise sanitation in response to resident s service requests and some night time truck spraying (ULV adulticiding) admittedly more public relations than effective wide area mosquito control

5 Background (cont.) Little if any authority to enter onto private properties without permission of resident Code Enforcement laws generally do not include mosquito breeding containers Because of the very strong privacy rights in the U.S., there is reluctance of political bodies to support strong sanitation ordinances (Fred Soper s approach in Brazil was strong-handed and forced his will upon the citizens but successful!!) Resistance to pyrethroids very common in Aedes aegypti populations

6 Background (cont.) Dengue, once a common epidemic occurrence, was eradicated from Florida in the late 1940 s; From the 1980 s onward.. increasing number of imported cases but no documented local transmission until reemergence in Key West outbreak in 2009 (22 local cases) and 2010 (66 local cases); Zika: approx. 300 locally acquired cases in 2016-current (most in SE Florida); (Sidebar 36,000 in P.R.) Majority of Florida residences, even those in lower income areas, have screens and air conditioning which provide significant protection by restricting Aedes aegypti to exophilic behavior (unlike much of South America and the Caribbean) Key West and many areas of SE Florida are more island lifestyle, making it higher risk, particularly with large number of visitors/tourism Since reemergence of Dengue in Florida in 2009 and appearance of Chikungunya in the Caribbean in 2013 and now Zika in Florida programs re-evaluating available methods and efficacy on Aedes aegypti and albopictus populations Yes we know that premise sanitation is the best form of domestic mosquito control. But.

7 Domestic Complaints received by Manatee County MCD June, July, August 2011

8 25,000 acre block Scope of Problem: 2-person teams; 20min/home; 6hr field day = 18homes per day = 6 acres/day Need 11.5 years for 2 people to make a complete sanitation operation Or need 140 employees to make the complete inspection every 30-days Cost - $7.0 million in direct/indirect employee costs

9 Re-Evaluation of Existing Strategies Manatee County Mosquito Control District (Southwest FL) has an operating budget of $4.0 million and a workforce of 30 (10 field inspectors) to cover a 750 square mile county (50+ square miles urban) with 350,000 residents Considered all control methods that might provide wide area coverage without the need to access private properties and utilizing existing equipment and techniques Small droplet larviciding from our truck-mounted cold aerosol equipment Ground adulticiding (space spraying) using our truck-mounted cold aerosol equipment Small droplet aerial larviciding (helicopter) Aerial adulticiding (helicopter) Not considering any hand-application (backpack sprayers) platforms or ATSB, GMO, Wolbachia, or trap-and-kill stations since these techniques are labor intensive, slow developing, expensive and generally aren t applicable to widearea population control nor can be rapidly employed in a disease response

10 Truck applications of Larvicides.

11 Evaluation: Small droplet truck larviciding (2010) Equipment calibrated to deliver Altosid 5% (methoprene - IGR) at 4 oz/ac and droplet size of approximately microns (Dv0.5) Spray applications performed post sunset (avoid traffic, public outdoor activities) Results: Good/acceptable level of larval mortality in sentinel larvae placed in the treatment area but observed no overall population-level reduction as compared to control populations Why? Poor chemical coverage due to low/negligible winds at night, particularly in wooded neighborhoods; too many cryptic breeding habitats

12 Truck-based adulticiding (2013) Very common technique used throughout Florida mosquito control programs for general mosquito control million acres treated annually in Florida Primarily targeting mosquitoes with crepuscular & nocturnal activity periods. Not aegypti/albopictus Most programs use pyrethroid formulation High pyrethroid resistance in local Aedes aegypti led to use of Fyfanon ULV (96.5% malathion) at 0.75 oz/ac (maximum labeled rate) and a droplet size of 15 microns

13 2013: Efficacy of Weekly Daytime-Ground ULV Adulticide - Fyfanon 97% upon Ae. aegypti/albopictus Populations (Values Indicate Average # of Eggs & Larvae at 15 Sampling Sites within each group) Start of Weekly ULV Applications % Reduction during treatment period per Henderson-Tilton (control variation corrected) Spraying at Dusk!! Treatment Control 1 Control /16 4/23 4/30 5/7 5/14 5/21 5/30 6/4 6/11 6/18 6/25 7/2 7/9 7/16 7/23 7/30 8/6 8/13 8/20 8/27 9/3 Date of Collection

14 2013: Efficacy of Weekly Night-Ground ULV Adulticide - Fyfanon 97% upon Ae. aegypti/albopictus Populations (Values Indicate Average # of Eggs & Larvae at 15 Sampling Sites within each group) Spraying Post- Sunset!! Start of Weekly ULV Applications Treatment Control Control 2 68% Reduction during treatment period per Henderson-Tilton (control variation corrected) /16 4/23 4/30 5/7 5/14 5/21 5/30 6/4 6/11 6/18 6/25 7/2 7/9 7/16 7/23 7/30 8/6 8/13 8/20 8/27 9/3 Date of Collection 0

15 Truck Applied Adulticides Disadvantages: Slow (only treat a few hundred acres per evening) Relies upon ambient winds (at the ground-level) to carry spray cloud (little in nocturnal periods) Often need multiple spray events in a short window to be effective (1-2x per week) Higher public exposure to the spray operations; more complaints (as compared to aerial applications)

16 Aerial Applications of Larvicides

17 Typical Aerial Larviciding at MCMCD Routinely utilized method in treating coastal swamp habitats of our major pest species, Aedes taeniorhynchus, the Black Salt Marsh Mosquito Daytime applications; low level and using a liquid formulation with large droplets in the micron range (1mm range..that deposit very close to the aircraft flight line Applied to concentrated mosquito breeding Utilize environmentally friendly actives: Bti, Spinosad, methoprene

18 Aerial Larviciding for Aegypti? ( ) But could this method be adapted to treat scattered/cryptic container habitats of Aedes aegypti in an urban environment? From a public acceptance standpoint. YES.we are already using night-time aerial adulticiding over many urban/suburban/rural areas from an altitude of 150 feet utilizing both NVG s and specialized flight guidance systems for accuracy and safety. But We want larger droplets than aerial adulticides that will deposit but small enough that that could move with prevailing air currents and deposit into containers in both open and sheltered areas. After much trial/error research, we compromised on a droplet size of approximately microns (Dv0.5)

19 2011: Efficacy of Aerial Larviciding upon Ae. aegypti/albopictus Populations (Values Indicate Average # of Eggs & Larvae at 15 Sampling Sites within each group) Aerial Larvicide - Methoprene on 8/16, 8/31 and 9/14; Midnight - 2am 128-acres Control Treatment Number of Eggs and Larvae 5/2 5/9 5/16 5/23 5/31 6/6 6/13 6/20 6/27 7/5 7/11 7/18 7/25 8/1 8/8 8/15 8/22 8/29 9/6 9/12 9/19 9/26 10/3 10/10 Date of Collection 9.6 0

20 2011: Efficacy of Aerial Larviciding upon Ae. aegypti/albopictus Populations (Values Indicate Average # of Eggs & Larvae at 15 Sampling Sites within each group) Aerial Larvicide - Methoprene on 8/16, 8/31 and 9/14; Midnight - 2am 128-acres Control Treatment Number of Eggs and Larvae /2 5/9 5/16 5/23 5/31 6/6 6/13 6/20 6/27 7/5 7/11 7/18 7/25 8/1 8/8 8/15 8/22 8/29 9/6 9/12 9/19 9/26 10/3 10/10 Date of Collection 9.6 0

21 Efficacy of Aerial Adulticide Applications on Aedes aegypti Populations

22 Aerial Daytime Adulticiding in Cortez Village 97% Reduction Average Mortality = 89.7% 78% Reduction 94% Reduction

23 Night-Aerial Adulticiding for Ae. aegypti/albopictus??? Will it work on a day-active mosquito? And why switch from a day-spray activity previously shown to be successful?

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25 2013: Efficacy of Night-Aerial ULV Applications on Aedes aegypti populations - Night Applications Aerial applications; 6/20, 7/3, 7/15, and 7/30 Spray-On: min after astronomical sunset Population Reduction: 6/ % 7/3-86.5% 7/ % 7/ % Avg: 91.2% Landing Rate Counts Jun 20-Jun 27-Jun 4-Jul 11-Jul 18-Jul 25-Jul 1-Aug 8-Aug 15-Aug 22-Aug 29-Aug 5-Sep

26 Discussion The practices of nocturnal aerial adulticiding appears to have a significant population level impact upon exophilic mosquitoes when appropriate droplet sizes and spray techniques are used. Not a great deal of observed difference between evening (presunset) and night (post-sunset) aerial spray events. Would this be enough to truncate a Dengue epidemic or local transmission?

27 Back to the Real World: If we had a Local case of Dengue or Chik.. What Would We Do? What Technique Would be Most Efficacious? 2014 Evaluated Efficacy of: Surveillance-based Aerial Adulticide, vs Surveillance-based Aerial Adulticides + Aerial Larvicide Applications (think. IPM for domestic mosquitoes) Malathion Altosid 5%

28 Effects of Aerial Larviciding and Adulticiding on Ae. aegypti/albopictus Populations (IPM - approach) A & L A L L A L POPULATION SIZE - AVG LANDING RATE COUNT 8.0 Larvicide + Adulticide Control May 24-May 31-May 7-Jun 14-Jun 21-Jun 28-Jun 5-Jul 12-Jul 19-Jul 26-Jul 2-Aug 9-Aug 16-Aug 23-Aug 30-Aug 6-Sep DATE

29 10.0 Effects of Aerial Larviciding and Adulticiding on Ae. aegypti/albopictus Populations (IPM - approach) POPULATION SIZE - LANDING RATE COUNT Larvicide + Adulticide Control A & L A L L A L % Overall Population Reduction May 24-May 31-May 7-Jun 14-Jun 21-Jun 28-Jun 5-Jul 12-Jul 19-Jul 26-Jul 2-Aug 9-Aug 16-Aug 23-Aug 30-Aug 6-Sep DATE

30 Cost: $34.57/acre (Chemical Costs) 89.3% Seasonal Population Reduction

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33 10.0 Effects of Aerial Larviciding and Adulticiding on Ae. aegypti/albopictus Populations (IPM - approach) POPULATION SIZE - LANDING RATE COUNT Larvicide + Adulticide Control A & L A L L A L % Overall Population Reduction May 24-May 31-May 7-Jun 14-Jun 21-Jun 28-Jun 5-Jul 12-Jul 19-Jul 26-Jul 2-Aug 9-Aug 16-Aug 23-Aug 30-Aug 6-Sep DATE

34 Effects of Aerial Larviciding and Adulticiding on Ae. aegypti Populations (Myakka, FL) POPULATION SIZE - AVERAGE LRC /16/13 8/14/13 11/12/13 2/10/14 5/11/14 8/9/14 11/7/14 2/5/15 5/6/15 8/4/15 11/2/15 1/31/16 4/30/16 7/29/16 10/27/16 DATE

35 Effects of Aerial Larviciding and Adulticiding on Ae. aegypti Populations (Myakka, FL) POPULATION SIZE - AVERAGE LRC Avg % reduction % reduction 2 0 5/16/13 8/14/13 11/12/13 2/10/14 5/11/14 8/9/14 11/7/14 2/5/15 5/6/15 8/4/15 11/2/15 1/31/16 4/30/16 7/29/16 10/27/16 DATE

36 Concerns & Criticisms Small study area only 150 acres Vegetative habitats not similar to urban cores where Zika vectors would typically be found No tall buildings or marine/water influences to spray operations Treating a rural agricultural community with dis-similar attitudes towards aerial spraying as may be found in an urban core

37 2017: Large Scale Evaluation of Domestic Mosquito Control Anna Maria Island, FL Tourist destination with all of the typical issues for an aerial mosquito control operation in an urban-core. a largely naive human population with spray mission influenced by marine winds & thermal currents off ocean Very high Ae. aegypti population (amongst the highest in the County) Population sizes evaluated several times per week Before/After within Control/Treatment areas Applied Fyfanon and Altosid 5%

38 Map of Treatment area

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40 2017: Effects of Aerial Larviciding and Adulticiding on Ae. aegypti Populations on Anna Maria Is. (FL) 15.0 A &L L A L A L 13.0 POPULATION SIZE - LRC'S Larvicide + Adulticide Control Jun 10-Jun 17-Jun 24-Jun 1-Jul 8-Jul 15-Jul 22-Jul 29-Jul 5-Aug 12-Aug 19-Aug 26-Aug 2-Sep 9-Sep 16-Sep -1.0 DATE

41 2017: Effects of Aerial Larviciding and Adulticiding on Ae. aegypti Populations on Anna Maria Is. (FL) A & L L A L A L POPULATION SIZE - LRC'S Jun 10-Jun 17-Jun 24-Jun 1-Jul 8-Jul 15-Jul 22-Jul 29-Jul 5-Aug 12-Aug 19-Aug 26-Aug 2-Sep 9-Sep 16-Sep -1.0 DATE Larvicide + Adulticide Control

42 Altosid Field Bioassay 10 dry Petri dishes placed in treatment area Flooded with habitat water and wild-strain A.A. larvae in the laboratory 7/13/17 aerial larvicide event: 80.0% emergence inhibition 7/27/17 aerial larvicide event: 97.8% emergence inhibition

43 Summary Sanitation Best theoretical approach but doesn t work in practice due to poor access and poor public participation (Optimized) Truck adulticiding may be effective in small geographic areas but limited to small scale mosquito control approaches; may have poor acceptability in many residential areas Aerial larviciding is effective but costly and doesn t target active vectors Aerial adulticiding is very effective but gains are short-lived IPM approaches (ie active surveillance + aerial larvicides + aerial adulticide) yield excellent long-term control