Evaluation of Three Strategies for Control of Aedes aegypti and Ae. albopictus Populations

Transcription

1 Evaluation of Three Strategies for Control of Aedes aegypti and Ae. albopictus Populations Christopher R. Lesser/Mark D. Latham Manatee County Mosquito Control District

2 The Problem: Aedes albopictus and aegypti -- A very significant nuisance/quality of life problem Aedes albopictus and aegypti as Disease Vectors What Control Strategies? Traditional ULV Adulticiding: Very problematic Source Reduction & Public Education is largely a wasted effort Hand-applying larvicides to small containers is too labor intensive for large scale population control/reduction. Currently, there is no good or proven method for control of these populations due to human sanitary and social behaviors and mosquito behaviors.

3 Purpose & Objective Develop an effective IPM strategy for control of Ae aegypti and albopictus independent of source reduction and/or public education Question: Can large geographic areas be treated with any combination of ULV larvicides and/or adulticides to control domestic mosquitoes? Employed a testing protocol that evaluates area-wide population level mosquito reductions in 3 separate weekly treatment schemes: 1) ground ULV larviciding 2) time-sensitive adulticide applications, and 3) a combination of larvicide/adulticide applications. Previous Research: Based upon previous research, we know that ULV applied larvicides can be a highly effective killing agent in controlled tests (Manatee County 2010, Delaware 2008, 2009; Virginia 2006, 2009; et. al) but can the extension be made that population level reductions can be made with the same technologies and methodologies?

4 % Mortality Aedes albopictus Larvicide Efficacy Trial Altosid Concentrate, 1.0 fl oz/ac 8/19/ Day Measure 16 Day Measure Yard #1 Yard #2 Yard #3 Yard #4 Yard #5

5 Methodologies 2010 Manatee County MCD Test Four study sites selected (range 145 to 413 acres); all within older residential neighborhoods in/near Bradenton, FL with history of high domestic mosquito problems Larvicide Only Adulticide Only Larvicide & Adulticide Control Each test area treated once per week Larvicide = Altosid 5% (undiluted) through a VecTec Grizzly at 3psi yielding a VMD of ca. 42microns as measured on MgO slide at an application rate of 4.0 fl oz/ac and an assumed 300ft swath Adulticide = Omega Mist Mac (30:30 permethrin/pbo) through a London Fog at 6psi and ca. 15 microns at an application rate of 0.007# ai/ac and an 300 ft swath Larvicide applications generally made when favorable winds and low thermals existed simultaneously generally 1 hour prior to sunset. Adulticide applications made during periods of high aegypti/albopictus activity and low thermal activity - generally within 1hr of twilight

6 Methodologies (cont.) Measured Ae. aegypti and albopictus population dynamics via 30 ovitraps located within each of the 4 study sites; eggs were collected and counted weekly (ie; 120 ovi-traps over 4 sites) Two different ovi-trap designs set at each of the 15 sampling sites

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8 Study Location

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12 Picture of Truck Spraying

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17 Germination Paper

18 Eggs on Paper

19 Larvicide Adulticide Larvicide + Adulticide Control Efficacy of 3 Techniques For Ae. aegypti/albopictus Control (Values Indicate Average # of Eggs & Larvae at 15 Sampling Sites within each group) Weekly adulticiding & larviciding activities started on 7/ /29 7/7 7/13 7/20 7/28 8/3 8/11 8/17 8/24 9/1 9/8 9/14 9/21 9/28 10/5 10/12 Date of Collection Larviciding Stopped

20 Relative Population Growth Efficacy of 3 Techniques for Ae. aegypti and Ae albopictus Control; Data Normalized by Location to 7/20/ Larvicide Adulticide Larvicide and Adulticide Control /20 7/28 8/3 8/11 8/17 8/24 9/1 9/8 9/14 9/21 9/28 10/5 10/12

21 Percent Population Change 400 Efficacy of 3 Techniques for Ae. aegypti and Ae. albopictus Control; Data Normalized by Location and Corrected for Control Variation Larvicide Adulticide Larvicide and Adulticide Control /20 7/28 8/3 8/11 8/17 8/24 9/1 9/8 9/14 9/21 9/28 10/5 10/12 Date of Ovitrap Collection

22 Results The practices of larviciding (only) and adulticiding (only) appears to have no effect upon reducing population size of Ae. aegypti and albopictus The combination of larviciding and adulticiding appears to be synergistic, significantly reducing the domestic mosquito populations and keeping them at low levels

23 Additional Points of Interest We observed a +45.0% preference for oviposition upon germination paper over masonite paddles Preliminary studies with sentinel larvae placed in shallow Petri-dishes and within the study site found that adulticides had some larvicidal properties Where to from here? Repeat this study in 2011 Aerial application of Vectobac WDG guided by WingMan/Aimms20

24 QUESTIONS?