Management of ticks and Lyme disease in 

protected natural areas

USGS Patuxent Wildlife Research Center

Coastal Field Station, Woodward Hall – PLS

University of Rhode Island

Kingston, RI 02881 USA

Howard S. Ginsberg, Ph.D.
Lyme disease

RMSF

Other tick-borne

WNV

Other mosquito-borne

Plague

Human cases of vector-borne diseases, United States, 2002
Lyme disease

vector

pathogen reservoirs
Life cycle of Ixodes scapularis

adults larvae nymphs adults

POPULATION 1

POPULATION 2

nymphs adults larvae

SPRING SUMMER FALL WINTER SPRING SUMMER FALL

hosts hosts

YEAR 1 YEAR 2
Approaches to managing ticks and Lyme disease

- Self-protection precautions

- Habitat manipulation

- Manipulation of host populations

- Biological control

- Pesticide applications

- broadcast

- host-targeted
Integrate techniques so as to efficiently lower 

probability of exposure to pathogen

Pe = 1 – (1 – kv)

n

Pe = probability of being bitten by at least one infected vector

kv = proportion of vectors infected with pathogen (=prevalence)

n = number of vector bites

IPM for tick-borne diseases of humans
0

0.2

0.4

0.6

0.8

1

0 5 10 15 20

kv=0.10

kv=0.01

kv=0.25

kv=0.5

Probability of exposure to pathogen

NUMBER OF TICK BITES

PROBABILITY

OF

EXPOSURE
from: Ginsberg. 1993. American Journal Of Epidemiology 138:65-73.
0

0.2

0.4

0.6

0.8

1

0 5 10 15 20

kv=0.10

kv=0.01

kv=0.25

kv=0.5

Probability of exposure to pathogen

NUMBER OF TICK BITES

PROBABILITY

OF

EXPOSURE
Approaches to managing ticks and Lyme disease

- Self-protection precautions n Minimal effect

- Habitat manipulation n Substantial effect ( )

- Manipulation of host populations n and/or kv Substantial effect ( )

- Biological control n Nontarget effects (-)

- Pesticide applications Nontarget effects (-)

- broadcast n broad

- host-targeted kv narrow

Management technique Lowers n or kv Environmental effects 
Habitat requirements of Ixodes scapularis nymphs

poor habitat good habitat
0

1

2

3

4

WOODS SHRUB MEADOW

ADULTS 

PER 

SAMPLE

Habitat distribution of Ixodes scapularis

0

0.2

0.4

0.6

0.8

WOODS SHRUB/MEADOW

NYMPHS

PER

SAMPLE
Environmental factors affecting nymphal distribution

0

0.5

1

1.5

2

2.5

3

3.5

0.9 0.95 1 1.05

Standardized RH

Standardized NYMPHS

0

0.5

1

1.5

2

2.5

3

3.5

0.9 0.95 1 1.05 1.1

Standardized Canopy Cover

Standardized NYMPHS
0

10

20

30

40

50

60

70

80

90

100

1993 1994 1995 1996 1997 1998 1999

YEAR PERCENT IN DECIDUOUS HABITAT

LARVAE

NYMPHS

Habitat shifts from the larval to the nymphal stage,

Fire Island, NY

From Ginsberg et al. 2004.Environ. Entomol.33:1266-1273. 
0

1

2

3

4

1994 1995 1996 1997 1998 1999 2000

INSIDE

OUTSIDE

MEAN NO.

TICKS

PER

SAMPLE

** * *

Nymphal Ixodes scapularis inside and outside of deer 

exclosures, Fire Island National Seashore, NY

From Ginsberg et al. 2004.Environ. Entomol.33:1266-1273. 
Landscape design works at three levels

1) Landscape design affects tick population size

- likelihood of tick encounter

- transmission dynamics of pathogen

2) Landscape design affects host abundance

- reservoir competence of alternative host species

- diversity of host species

3) Landscape design affects human encounter with ticks

- probability of human exposure to pathogen
Habitat requirements for Ixodes scapularis nymphs

• moist leaf litter

• typically with forest canopy cover

• appropriate hosts present

Landscape features that lower tick abundance/number 

of tick bites

• dry at ground level

• open forest canopy 

• appropriate hosts excluded (local? area-wide?)

• people discouraged or excluded from tick 

habitat
Lyme disease risk map – United States

Centers for Disease Control and Prevention
Barriers – various functions

Paths – separate people from tick habitat
Useful references

Bowman, AS & P Nuttall (eds.) 2008. Ticks: Biology, Disease and Control. 

Cambridge University Press, Cambridge, UK.

Ginsberg, HS & KC Stafford, III. 2005. Management of ticks and tick-borne 

diseases, pp. 65-86 In Goodman, JL, DT Dennis, & DE Sonenshine (eds.)

Tick-Borne Diseases of Humans. ASM Press, Washington, DC.

Gray, JS, O Kahl, RS Lane, & G Stanek (eds.) 2002. Lyme Borreliosis,

Biology, Epidemiology and Control. CABI Publishing, Wallingford,

Oxon, UK.

Mullen, G & L Durden (eds.) 2009. Medical and Veterinary Entomology, 2nd ed.,

Academic Press, Elsevier Science, San Diego, CA.

Stafford, KC, III. 2007. Tick Management Handbook, revised ed., 

The Connecticut Agricultural Experiment Station, New Haven, CT. 

(available online at: www.caes.state.ct.us - phone: (203) 974-8440)