Upload
others
View
5
Download
0
Embed Size (px)
Citation preview
Coby Schal <[email protected]>
Department of Entomology
W. M. Keck Center for Behavioral Biology
North Carolina State University
Importance of Basic and Translational
Approaches in Bed Bug Research
BB Summit, DC 2011
Presentation Outline
• Trends of scientific publishing on BB
• Research approaches
• 3 Examples of translational research
1.Chemical ecology: Pheromones, other
semiochemicals
2.Population genetics
3.Gene expression & transcriptomes
• Perspective: Fundamental & translational
research
Lite
ratu
re t
ren
ds
0 100 200 300 400 500
1860-1870
1871-1880
1881-1890
1891-1900
1901-1910
1911-1920
1921-1930
1931-1940
1941-1950
1951-1960
1961-1970
1971-1980
1981-1990
1991-2000
2001-2010
Bed bug papers, patents
all databases
N = 1,407
0 5000 10000 15000 20000 25000 30000
1860-1870
1871-1880
1881-1890
1891-1900
1901-1910
1911-1920
1921-1930
1931-1940
1941-1950
1951-1960
1961-1970
1971-1980
1981-1990
1991-2000
2001-2010
Mosquito papers, patents
all databases
N = 68,388
• “flat” productivity for
60 yrs – 1940 – 2000
• upsurge in information
in the last decade
• mosquito : BB = 50 :1
Lite
ratu
re t
ren
ds
0 1 2 3 4 5 6
BRITISH MEDICAL JOURNAL
CANADIAN JOURNAL OF ZOOLOGY-REVUE …
GIDROBIOLOGICHESKII ZHURNAL
JOURNAL OF MEDICAL ENTOMOLOGY
LANCET
MEDITSINSKAYA PARAZITOLOGIYA I PARAZITARNYE …
NEW SCIENTIST
MEDICAL AND VETERINARY ENTOMOLOGY
SOUTH AFRICAN JOURNAL OF SCIENCE
TRANSACTIONS OF THE ROYAL SOCIETY OF …
1981 – 1990
N = 31 of 136
0 5 10 15 20 25 30
AMERICAN JOURNAL OF TROPICAL MEDICINE AND …
JOURNAL OF ENVIRONMENTAL HEALTH
PARASITOLOGY RESEARCH
PROCEEDINGS OF THE NATIONAL ACADEMY OF …
AMERICAN ENTOMOLOGIST
MEDICAL AND VETERINARY ENTOMOLOGY
JOURNAL OF INSECT PHYSIOLOGY
JOURNAL OF ECONOMIC ENTOMOLOGY
MEDICAL ENTOMOLOGY AND ZOOLOGY
JOURNAL OF MEDICAL ENTOMOLOGY
2001 – 2010
N = 81 of 468
Bed bugs: all databases, top 10 journals
Government invests in
“hands-off”
Basic research
Basic research, inspired by
curiosity,…adds to
„pool of knowledge‟
Applied research
and development...
stem from basic
research spin-offs
Society benefits with
information and cool
technologies and
sometimes…information
for practitioners and
decision makers
Linear Model
• Applied research poorly funded
• Compartmentalization: Different
teams engaged in basic & applied
• Basic researcher may be off on
another project before application
21st Century Approach: Integrating Research, Extension, Outreach and Teaching
Translational research
mission-oriented, multidisciplinary, incentivized
shorter time-frame to practical applications
• Disease vectors, bite allergies, asthma
• Abiotic interactions: temp, humidity
• Biological control agents: viruses, fungi, bacteria
• New pesticides, modes of action, resistance
• Novel non-chemical targets: cuticle, midgut, ovaries
1. BB behavior, communication, aggregation
2. Population biology
3. Unique genes and interactions of gene products,
BB genome
• More topics later…… Dr. Kells
A (partial) ‘Laundry’ List of Needs
Example 1: Host finding, chemicalsHost seeking Host location Host
rejection/acceptance;
engorgement
Host cues
CO2
Host odors
Temperature
Sensory ecology associated with host-seeking behavior
Optimal host:• human• chicken• rat• rabbit
Optimal source:• dynamic headspace
collection• SPME
Behavioral assaysolfactometers
Chemical IDGC-EAD, HPLC, GC-MS,
prep-GC, NMR, synthesis
Heat:• Dose-response
Moisture:• Dose-response
CO2:• Dose-response
New chemicals:• Dose-response
GC-EADA
dd
itiv
e &
syn
ergi
stic
in
tera
ctio
ns
Bioassay-guided fractionation
• Host-attractants for traps
• Sex pheromones
• Aggregation pheromones
Detection
Monitoring
Dissemination of
biological control
agents
Attract-and-Kill
• Repellents
• Attractants for baits?
• Phagostimulants
• More…… Dr. FeldlauferAlvaro Romero: NSF Post-Doctoral Fellow
Blood Test material
15 min feeding period
37o C37o C
What’s in blood that bed bugs like?
Individual bugs weighed before and after feeding
Blood Test
material
0
10
20
30
40
50
60
70
Blood Water
Weig
ht in
cre
ase (
%)
Adult males
n = 20
Blood contains phagostimulants
P < 0.05
Water + ATP = Blood!
0
20
40
60
80
100%
En
go
rge
d
a
Blood Water 10-8 10-7 10-6 10-5 10-4
ATP (M)
aba
b
aab
b
• Blood contains phagostimulants
• ATP is a highly effective phagostimulant
• All life stages displayed similar gorging responses to ATP
• ATP is a more effective phagostimulant than other
adenosine nucleotides
ATP > ADP > AMP
• Other phagostimulants?
Richard Naylor
Alvaro Romero
Example 2: Population genetics
Where have bed bugs resurged from?
3 Major hypotheses:
Local “home grown” bed bug populations
1. Residential, urban reservoirs
2. Agricultural (e.g., poultry farms) reservoirs
Global “immigrant” bed bugs
3. Outside USA: travel, globalization
A single, or few, invasion(s): Low diversity
Allele Diversity: immigrant population(s) << global populations
Multiple, independent invasions: High diversity
Allele Diversity: immigrant populations ~ source populations
• Microsatellite markers: Genetic diversity
Genetic differentiation
• 21 populations from 9 states
Broad-scale BB population genetics(Vargo, Booth, Saenz, Schal)
Virna Saenz
Across populations
• Very high genetic diversity
– 3 to 17 alleles/locus (mean = 8.4)
– But, need comparisons to “candidate” source
populations
– Suggests multiple sources
Within populations
• Very low genetic diversity
– 1 to 4 alleles/locus
– Mean relatedness of individuals
• r = 0.75 (0.5 = sibs)
– Very high levels of inbreeding
– Suggests single/few sources per infestation
Genetic diversity
Genetic differentiation of populations
Completely
similar
Completely
different
strong genetic differentiation!
but, no “Isolation-by-Distance”
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
1 3 5 7 9
F ST
8100 km
ln distance
2 km 20 km 150 km 1100 km
Winston-Salem
NC
invasion & spread
local spread
Y = 0.0257X + 0.5127
R² = 0.0675
• Within populations: Very low genetic
diversity & high inbreeding
– Populations appear to be founded by a singly
mated female
yet,
• Across populations: Very high genetic
diversity & high genetic differentiation
– Multiple introductions
– “Jump”, human-mediated transport
Broad-scale BB population genetics(Vargo, Booth, Saenz, Schal)
May 2003 May 2004 June 2005
How do bed bugs spread within a building?
Doggett and Russell. 2008.
May 2003
Doggett and Russell. 2008.
May 2004 June 2005
How do bed bugs spread within a building?
Single introduction?
May 2003 June 2005
How do bed bugs spread within a building?
Doggett and Russell. 2008.
Multiple
introductions?
May 2004
Single
introduction
Within apartments
• Low genetic diversity 1 to 4 alleles/locus
• High relatedness r = 0.54
Among apartments
• Low genetic diversity 2 to 5 alleles/locus
Flo
ors
3rd
9th
Single!
Few!
Empirical test: BB spread within a building
How many individuals start an infestation?
How many introductions?
Raleigh, NCIsolated building, recent infestation
Within apartments
• Low genetic diversity 1 to 4 alleles/locus
• High relatedness r = 0.65
Among apartments
• High genetic diversity 2 to 11 alleles/locus Multiple!
Few!
Empirical test: BB spread within a building
How many individuals start an infestation?
How many introductions?
Jersey City, NJBuilding complex, old infestation
12 1211 1212 1213 1201 1202 1203 1204 1205
1210 ST 1209 EV EV 1208 1207 ST Cust 1206
10 1011 1012 1013 1001 1002 1003 1004 1005
1010 ST 1009 EV EV 1008 1007 ST 1006
9 911 912 913 901 902 903 904 905
910 ST 909 EV EV 908 907 ST 906
8 811 812 813 801 802 803 804 805
810 ST 809 EV EV 808 807 ST 806
7 711 712 713 701 702 703 704 705
710 ST 709 EV EV 708 707 ST 706
6 611 612 613 601 602 603 604 605
610 ST 609 EV EV 608 607 ST 606
5 511 512 513 501 502 503 504 505
510 ST 509 EV EV 508 507 ST 506
4 411 412 413 401 402 403 404 405
410 ST 409 EV EV 408 407 ST 406
1 111 112 113 101 102 103 104 105
110 ST 109 EV EV 108 107 ST 106
collections by Changlu Wang
1st
12th
Empirical test: BB spread within a building
1
2
3
4
Apt 1 Apt 2 Apt 3 Apt 4
Empirical test: BB spread within a building
Jersey City, NJ: 17 populations
3 genetic clusters
software: STRUCTURE
Warren Booth
Large scale (continental, East Coast)
• Bed bug populations come from multiple geographic
sources
• Extensive human-mediated movement of bed bugs
across large geographic areas
Interception important at transportation hubs
Fine scale (within buildings)
• Infestations often start with a single introduction, and
then spread; but also multiple introductions
Early detection critical
Forensic applications: sources of bed bug infestations
Implications of Population Genetics
Example 3: Genome, Transcriptome
• Genes common to BB and other insects?
• Genes common to hematophagous arthropods
• Genes and gene products unique to BB
• Why do BB not vector diseases?
• When and where genes are turned on or off
(transcripts specific to tissue-, time-, instar-,
feeding-, resistance-, etc.)
• Gene networks:
immunity, heat/cold response, feeding behavior,
sexual behavior, host-finding………
Example 3: Genome, Transcriptome
“Nearly 85.9% of the C.
lectularius sequences showed
similarity to insect sequences,
but 44.8% of the deduced
proteins of C. lectularius did
not show similarity with
sequences in the GenBank”
Quantitative PCR
mRNA levels for a cytochrome
P450 (CYP9) in:
pesticide-resistant (blue bars)
pesticide-susceptible (red bars)
Perspective: Fundamental and Translational research
• Government & private sector investments
• Innovative, medium- and long-term
• Accountable to stakeholder input
• Spawns ideas for novel tactics, products
• Research Pest control
• Apply discoveries from research in the
lab to “clinical” studies
• Break down compartmentalization
Collaborators & co-workers: Ed Vargo
Warren Booth, Alvaro Romero, Virna Saenz, Rick Santangelo
Changlu Wang
Blanton J. Whitmire Endowment NC State University
USDA-NIFA-AFRI
Pest management companies:
Orkin
Cooper
Rentokil/JC Ehrlich
TerminixNSF Postdoctoral Research
Fellowship in Biology
Life cycleEgg to Adult = 45 days at 26o C
Department of Medical Entomology, ICPMR, Westmead Hospital, Australia
bedbuginfo.dondodd.com/
sciencedude.ocregister.com