With recent national attention on mosquito-borne viruses such as the Zika virus, an Integrated Pest Management approach to mosquito control is more important than ever. Dr. Grayson Brown, professor at the University of Kentucky’s Department of Entomology, offers his expertise and insight on how to best manage mosquito populations on your customers’ properties.

1. KY
Entomology
Public Health

2. Barrier Applications for
Mosquito Suppression in
the Suburban Landscape
Dr. Grayson Brown
Public Health Entomology Laboratory
Department of Entomology
University of Kentucky
Lexington KY

3. Mosquitoes are top health
concern among Americans
62
38
30
26
11
14
Mosquitoes
Stinging Insects
Ticks
Spiders
Bed Bugs
Other
Source: NPMA 2013 Summer Survey reported in PCT Online, Sept. 2013

4. Of those concerned,
disease topped the list
Source: NPMA 2013 Summer Survey reported in PCT Online, Sept. 2013
54
43
35
11
5
Disease
Pain, sting/bite
Infestation in home
Allergy
Disease history

5. Recent mosquito-borne disease
outbreaks in N. America
— West Nile Virus: 1999 – 2006
— Dengue: 2005 – 20011
— Chikungunya: 2011 – 2015
— Zika: 2016 – Present
— More to come

7. Zika Symptoms
Eye Redness
Mild Viral
Conjunctivas
Flu-like symptoms
Joint aches,
particularly in wrists
and ankles
Mild rash
• Self-limiting, 3 days – week
• Not typically neuroinvasive, few complications, deaths extremely rare
and only in immune-compromised individuals

8. Most people don’t need to worry
about Zika
It’s only a serious threat to one
group

9. Result of decreased brain
size

10. Microcephalic Births in Brazil
0
500
1000
1500
2000
2500
3000
3500
4000
4500
2007 2008 2009 2010 2011 2012 2013 2014 2015 2016
AnnualCases
Year
Before Zika
April 2015
Post Zika

11. Extensive public concern at
all levels

12. How do mosquitoes
transmit disease?
— Mosquitoes are not “flying syringes”
— In order for a pathogen to be transmitted by a
mosquito:
— It has to infect the mosquito in a specific way
— The mosquito must have the biological, behavioral
and ecological traits to enable transmission
— The pathogen must have a pathogenic cycle inside its
human host that enables a return to the mosquito
(optional)
— We can’t do anything about the first & last of these.
Our mosquito control efforts are targeted at the 2nd
one.

13. Feeding
• Once the mosquito lands, the
labium slides back, exposing
mandibles & maxillae (stylets)
• Stylets pierce the skin and
probe until sensors on the tip
detect a capillary
• Saliva continues to be injected
during feeding as an
anticoagulant.
• Full blood meal is half to a
couple of microliters (0.001 ml).
Sensory Setae
Human
Hair
Blood
Capillary
Sensors
Lower
“Lip” (labium)
Palp
Mandibles
& Maxillae
Compound Eye

14. Choumet V, Attout T, Chartier L, Khun H, Sautereau J, et al. (2012) Visualizing Non Infectious and
Infectious Anopheles gambiae Blood Feedings in Naive and Saliva-Immunized Mice. PLoS ONE 7(12):
e50464. doi:10.1371/journal.pone.0050464

15. Mosquito Life Cycle
— Larvae are wigglers
— Pupae are tumblers
(quite active)
— Both breath air
— Eggs are laid on the
surface of water in rafts
(Culex) or singly
(Anopheles) or near water
(Aedes)

16. Eggs
Anopheles (note floats)
Culex egg raft
Aedes eggs are
laid near water

17. Mosquito Diet
— Most Larvae feed on
algae & bacteria but
a few are
predaceous and
feed on other
mosquito larvae
— Only females are
blood sucking
— Males and females
feed on nectar and
other plant juices

18. Mosquito Lifestyle
— Most mosquitoes do
not travel far from
the water from
which they emerged
— Adults are active at
night or twilight
— Many spend the day
in hollow trees,
culverts, and dense
shaded areas

19. Mosquitoes in the N. American
Suburban Landscape
— About 150 spp. of mosquitoes in N. America in 8
genera. Of these:
— < 10 are serious disease transmission threats
— About 10 more are less serious threats
— Another 20 or so are seasonal nuisance pests
— Most problems are confined to a few species in only
2 genera: Aedes and Culex.
— These two genera differ in very important ways.

20. Two
Generic
Biologies
Aedes/Ochlerotatus Culex
Dengue, EEE, LaCrosse West Nile, SLE, other
encephalitis
Attacks mammals Attacks birds, few human bites
Daytime – early evening Late night – early morning
Prefers cleaner water Prefers stagnant water
Few gens/year, OW as eggs Many gens/year, OW as adult
Daytime resting sites < 10 ft
(bushes)
Daytime resting sites > 10 ft
(trees)

21. Municipal Control Vs. Backyard Control
Municipal ULV Backyard Perimeter
AI Sumithrin Lambda cyhalothrin,
bifenthrin,
deltamethrin
Application Time Late PM/Early AM Daytime
Residual activity Hours Weeks/months
Spatial Scale Area Code Single Backyard
Most effective against Culex spp, some
Anopheles
Aedes, Ochlerotatus
Diseases Controlled West Nile, other
encephalitis
Zika, Dengue,
Chikungunya
The two are compatible and complementary

22. Suburban backyard as a
mosquito habitat
Need Aedes Culex
Water Clean Stagnant
Hosts Mammals Birds
Resting sites Low, dark,
humid sites
Trees
Air movement Minimal Minimal
Overwintering Areas that will
be covered with
water
Crevices in tree
bark, siding, etc.

23. How to they move about,
What are their stimuli
1. They have a simple stimulus response
2. First day or so post-eclosion, they just sit
3. Then they search for nectar (carbohydrate source) so they orient toward flowers
4. Next they search for a blood meal.
— If no olfactory stimuli, they move toward light
— CO2 is a long distance stimulus
— Body heat for short range
— Other volatile chemicals for individual selection
5. After a blood meal, they search for oviposition site
— Volatiles emitted by microfauna and other larvae are stimuli.
This completes a gonotropic cycle. Next cycle begins with a return to step 3.

24. How do they move toward people?
Direction of air movement
CO2 Plume

25. CO2 Plume
How do they move toward people?
Direction of air movement

26. This is the basis for how
perimeter applications for
mosquito control work.

27. Objective is to treat mosquito adults’ daytime
resting sites and work FROM the house

28. Start with vegetation near home

29. Then vegetation in the yard

30. Finally treat the perimeter

31. Objective is to flush the mosquitoes
from the yard

32. Technique and properties
are important
— Bad Things:
— Properties with little to no perimeter vegetation
— Properties whose predominate vegetation is grass
and flower/vegetable/herb gardens
— Treating grass/flowers/vegetables
— Treating in a haphazard pattern
— Failing to use proper PPE

33. Bad Property, Bad
Technique

34. Good Property, Good Technique

35. Dense non-flowering ground
vegetation

36. Dense Canopies

37. Underneath decks, crawlspaces or other
raised structures

38. Objective is to treat any location
that is dark, cool and moist.
Home’s Perimeter

39. Objective is to treat any location
that is dark, cool and moist.
Yard’s Perimeter

40. Use a vertical or circular motion to coat
the undersides of the leaves

41. What results should you
expect?

42. 0
3
6
9
12
-2 -1 0 1 2 3 4 5 6 7 8
Mosquitoes/Trap/Night
Weeks Post Treatment
Demand CS Water Placebo
Excellent control of Aedes
Avg. 75% reduction
after 1 week
Avg. 60% reduction over 6 weeks
96% Aedes
Before
Treatment
After Treatment
96% Aedes species

43. Greatly reduced mosquito bites
0
2
4
6
8
-2 -1 0 1 2 3 4 5 6 7 8
MosquitoBites/10min
Weeks Post Treatment
Demand CS Water Placebo
85% reduction
after 1 week
73% reduction over 6
weeks
98% Aedes
98% Aedes species

44. No effect on Culex mosquitoes
0
15
30
45
60
-1 0 1 2 3 4 5 6 7 8
Mosquitoes/Trap/Night
Weeks Post Treatment
Demand CS Water Placebo
No Effect
96% Culex (Principal WNV vector)

45. Season-­‐long
Summary
(Totals
7/7/14
–
9/10/14)
Post-­‐
Treatment
Totals
Demand
CS
Demand
+
Archer
Control
CDC
Mosquitoes
102 68 763
Gravid
Trap
Mosquitoes
133 96 489
HLR
Counts
59 84 224
Larvae
in
Egg
Traps
89 35 1,788

46. 2014
Season-­‐Long
Summary
%
ReducNon
of
Selected
Species
RelaNve
to
Control
Species
Demand
CS
Demand
+
Archer
Aedes
albopictus
87 % 78
Culex
pipiens
34 61
Aedes
vexans
72 79
Anopheles
spp.
16 44

47. 2014 Aedes Trap Results
0
10
20
30
40
50
60
70
1
2
3
4
5
6
7
8
9
10
11
12
Total
mosquitoes/trap/night
Week
Demand
+
Archer
Demand
Alone
Control

48. Most recent work is showing significant
suppression for 2 months (2015 data)
0
10
20
30
40
50
60
70
1
2
3
4
5
6
7
8
9
Mosquitoes
Weeks
Post-­‐Treatment
Mean
(±SE)
-­‐
CDC
Trap
Demand
Demand
+
Archer
Control

49. Mosquito bites on humans (2015 data)
0
2
4
6
8
10
12
14
16
18
2
3
4
5
6
7
8
9
Average
#
Mosquitoes/5
minutes
Weeks
Post-­‐Treatment
Mean
(±SE)
-­‐
Human
Landing
Rate
Count
Demand
Demand
+
Archer
Control

50. Barrier treatments are only
one part of a
comprehensive
management program

51. Homeowners
— They have responsibility too
— Source Reduction
— Avoiding pruning/removal of treated foliage
— Ideally removing harborage sites prior to treatment
— Gutter repair
— Expectations
— Suppression is not elimination
— May reduce some disease risk but not all

52. Problems
— Problems that can arise with these management
programs and how to avoid/resolve them.
— Non-target effects
— Chemical trespass
— Resistance management and its importance
— Mosquito species not well controlled by these
programs and their significance (Culex)

53. Non-Target Effects
— Some can be
avoided
— Pollinators
— Aquatic
organisms
— Plants
— Other beneficials
— Some cannot
— Lady beetles
— Fireflies
— Some spiders
Chemical Trespass

54. Main method of avoiding chemical
trespass is to keep the spray low on low
wind days
Insecticide
layer & Aedes
resting sites
Culex
resting
sites
8 – 10 feet

55. Resistance Management
— Growing problem with resistance to synthetic
pyrethroids in mosquitoes
— Greatest problem is with sumithrin
— Great variability between species
— Residuals have relatively little problem right now
— Typical neighborhoods have ~ 10% of homes
treated so 90% of mosquitoes are not exposed
— We need to keep an eye on this and use resistance
management strategies as much as possible.

56. — Backyard perimeter applications will provide effective
suppression of Zika vectors
— They should be used as part of a comprehensive
program
— Consider printing a homeowner pamphlet on what
they can do (cf. CDC, your Pub. Health Dept. sites)
— Consider products that minimize treatment
frequency.
— Don’t forget that you are part of an overall mosquito
management effort
Tips for this coming year

57. KY
Entomology
Public Health
Thank You