Evaluation of Three Strategies for Control
of Aedes aegypti and Ae. albopictus Populations
Christopher R. Lesser/Mark D. Latham
Manatee County Mosquito Control District
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.
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?
100.00
Aedes albopictus Larvicide Efficacy Trial
Altosid Concentrate, 1.0 fl oz/ac
8/19/2008
96.43
96.43
96.03
90.00
8 Day Measure
80.00
73.33
70.00
% Mortality
60.00
66.67
60.00
54.44
50.63
50.00
40.00
30.00
20.00
10.00
0.00
Yard #1
Yard #2
Yard #3
Yard #4
Yard #5
16 Day Measure
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 18-20 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
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
Study Location
Study Location
Picture of Truck Spraying
Germination Paper
Eggs on Paper
Efficacy of 3 Techniques For Ae. aegypti/albopictus Control
(Values Indicate Average # of Eggs & Larvae at 15 Sampling Sites within each group)
300
Weekly adulticiding &
larviciding activities
started on 7/21.
Larvicide
Adulticide
250
Larvicide +
Adulticide
Control
240.0
239.3
210.1
200
168.6
183.1
158.4
166.1
142.7
135.9
143.3
131.3
126.4
82.2
82.5
105.0
77.9
70.1
69.1
61.7
7.7
3.9
3.2
0
6/29
45.7
46.7
20.1
24.0
46.4
46.4
115.5
105.5
87.2
81.1
77.3
79.6
74.1
57.5
52.1
53.1
51.5
43.3
42.1
33.8
102.5
97.5
85.3
40.7
50
25.4
34.7
32.6
31.4
21.1
Larviciding Stopped
7.7
6.3
7/7
100
97.7
51.3
30.6
150
147.2 158.9
127.9
132.1
90.7
153.8
34.5
0
7/13
7/20
7/28
8/3
8/11
8/17
8/24
Date of Collection
9/1
9/8
9/14
9/21
9/28
10/5
10/12
Efficacy of 3 Techniques for Ae. aegypti and Ae albopictus Control;
Data Normalized by Location to 7/20/2010
3.0
Larvicide
Relative Population Growth
2.5
2.63
2.43
Adulticide
2.09
Larvicide and Adulticide
2.0
Control
1.49
1.5
1.26
0.84
1.0
0.82
0.83
0.74
0.00
-0.5
0.26
-0.58
-0.34
-0.55
-0.62
-0.56
-0.59
0.79
0.21
0.19
0.06
-0.05
0.17
0.01
-0.04
-0.44
0.60
0.49
0.51
0.5
0.0
1.21
1.10
-0.30
-0.31
-0.72
-0.20
-0.03
-0.30
-0.60
-1.0
-0.35
-0.39
-0.51
-0.74
-0.77
-0.76
-0.72
-0.81
-0.72
9/1
9/8
9/14
9/21
9/28
-0.86
-0.81
-1.5
7/20
7/28
8/3
8/11
8/17
8/24
10/5
10/12
Efficacy of 3 Techniques for Ae. aegypti and Ae. albopictus Control;
Data Normalized by Location and Corrected for Control Variation
400
377.06
Larvicide
350
Adulticide
Percent Population Change
Larvicide and Adulticide
300
Control
262.00
250
200
207.51
167.51
159.99
150
135.74
100
70.50
73.23
72.32
72.64
50
18.02
0
30.32
0.00
-50
62.42
2.05
-25.83
-25.16
-27.12
-42.06
-8.17
-46.03
-70.44
-100
7/20
34.62
7.78
81.17
7/28
8/3
8/11
8/17
-76.70
8/24
-78.30
-80.08
9/1
9/8
Date of Ovitrap Collection
-84.12
-72.94
9/14
9/21
-56.51
9/28
-61.94
10/5
10/12
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
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
QUESTIONS?