Field evaluation of the establishment potential of wMelPop Wolbachia in Australia and Vietnam for dengue control.
BACKGROUND
Introduced Wolbachia bacteria can influence the susceptibility of Aedes aegypti mosquitoes to arboviral infections as well as having detrimental effects on host fitness. Previous field trials demonstrated that the wMel strain of Wolbachia effectively and durably invades Ae. aegypti populations. Here we report on trials of a second strain, wMelPop-PGYP Wolbachia, in field sites in northern Australia (Machans Beach and Babinda) and central Vietnam (Tri Nguyen, Hon Mieu Island), each with contrasting natural Ae. aegypti densities.


METHODS
Mosquitoes were released at the adult or pupal stages for different lengths of time at the sites depending on changes in Wolbachia frequency as assessed through PCR assays of material collected through Biogents-Sentinel (BG-S) traps and ovitraps. Adult numbers were also monitored through BG-S traps. Changes in Wolbachia frequency were compared across hamlets or house blocks.


RESULTS
Releases of adult wMelPop-Ae. aegypti resulted in the transient invasion of wMelPop in all three field sites. Invasion at the Australian sites was heterogeneous, reflecting a slower rate of invasion in locations where background mosquito numbers were high. In contrast, invasion across Tri Nguyen was relatively uniform. After cessation of releases, the frequency of wMelPop declined in all sites, most rapidly in Babinda and Tri Nguyen. Within Machans Beach the rate of decrease varied among areas, and wMelPop was detected for several months in an area with a relatively low mosquito density.


CONCLUSIONS
These findings highlight challenges associated with releasing Wolbachia-Ae. aegypti combinations with low fitness, albeit strong virus interference properties, as a means of sustainable control of dengue virus transmission.
National Institute of Hygiene and Epidemiology, Hanoi, Viet Nam. ngtrhien@yahoo.com.
Tran Hien
TH
Nguyen
National Institute of Hygiene and Epidemiology, Hanoi, Viet Nam. le.nguyen@nihe.org.vn.
H Le
HL
Nguyen
National Institute of Hygiene and Epidemiology, Hanoi, Viet Nam. yenanihe@yahoo.com.
Thu Yen
TY
Nguyen
National Institute of Hygiene and Epidemiology, Hanoi, Viet Nam. vusinhnam@gmail.com.
Sinh Nam
SN
Vu
National Institute of Hygiene and Epidemiology, Hanoi, Viet Nam. trannhuduong@gmail.com.
Nhu Duong
ND
Tran
Institute Pasteur, Nha Trang, Viet Nam. nghiavbc@gmail.com.
T N
TN
Le
Institute Pasteur, Nha Trang, Viet Nam. vienquangmai@gmail.com.
Quang Mai
QM
Vien
Institute Pasteur, Nha Trang, Viet Nam. chienpasteurnt@gmail.com.
T C
TC
Bui
Khanh Hoa Health Department, Nha Trang, Viet Nam. lehuutho3@gmail.com.
Huu Tho
HT
Le
Australian Foundation for Peoples of Asia and the Pacific Limited, Hanoi, Viet Nam. simon.kutcher@afapvn.org.
Simon
S
Kutcher
Australian Foundation for Peoples of Asia and the Pacific Limited, Hanoi, Viet Nam. tim.hurst@afapvn.org.
Tim P
TP
Hurst
Australian Foundation for Peoples of Asia and the Pacific Limited, Hanoi, Viet Nam. duonghuong_xhh@yahoo.com.
T T H
TT
Duong
QIMR Berghofer Medical Research Institute, Herston, Australia. jasonjeffery77@hotmail.com.
Jason A L
JA
Jeffery
QIMR Berghofer Medical Research Institute, Herston, Australia. Jonathan.Darbro@qimrberghofer.edu.au.
Jonathan M
JM
Darbro
QIMR Berghofer Medical Research Institute, Herston, Australia. bigjean@optusnet.com.au.
B H
BH
Kay
School of Biological Sciences, Monash University, Melbourne, Australia. inaki.iturbe@monash.edu.
Iñaki
I
Iturbe-Ormaetxe
School of Biological Sciences, Monash University, Melbourne, Australia. jean.o.popovici@gmail.com.
Jean
J
Popovici
School of Biological Sciences, Monash University, Melbourne, Australia. Brian.Montgomery@health.qld.gov.au.
Brian L
BL
Montgomery
School of Biological Sciences, Monash University, Melbourne, Australia. andrew.turley@monash.edu.
Andrew P
AP
Turley
School of Biological Sciences, Monash University, Melbourne, Australia. flora.zigterman@monash.edu.
Flora
F
Zigterman
School of Biological Sciences, Monash University, Melbourne, Australia. helen.cook@monash.edu.
Helen
H
Cook
School of Biological Sciences, Monash University, Melbourne, Australia. petercook80@gmail.com.
Peter E
PE
Cook
School of Biological Sciences, Monash University, Melbourne, Australia. petrina.johnson@monash.edu.
Petrina H
PH
Johnson
School of Biological Sciences, Monash University, Melbourne, Australia. peter.a.ryan@monash.edu.
Peter A
PA
Ryan
School of Public Health, Tropical Medicine and Rehabilitation Sciences, James Cook University, Smithfield, Australia. chris.paton@jcu.edu.au.
Chris J
CJ
Paton
School of Public Health, Tropical Medicine and Rehabilitation Sciences, James Cook University, Smithfield, Australia. scott.ritchie@jcu.edu.au.
Scott A
SA
Ritchie
Oxford University Clinical Research Unit, Hospital for Tropical Diseases, Ho Chi Minh City, Viet Nam. csimmons@oucru.org.|Centre for Tropical Medicine, University of Oxford, Churchill Hospital, Oxford, UK. csimmons@oucru.org.|Department of Microbiology and Immunology, University of Melbourne, Parkville, Australia. csimmons@oucru.org.
Cameron P
CP
Simmons
School of Biological Sciences, Monash University, Melbourne, Australia. scott.oneill@monash.edu.
Scott L
SL
O'Neill
Bio21 Institute and School of BioSciences, University of Melbourne, Parkville, Australia. ary@unimelb.edu.au.
Ary A
AA
Hoffmann
D000330:Aedes / Q000382:microbiology* / Q000502:physiology; D000818:Animals; D001315:Australia / Q000453:epidemiology; D003715:Dengue / Q000517:prevention & control* / Q000635:transmission; D004777:Environment; D005260:Female; D006801:Humans; D007303:Insect Vectors / Q000382:microbiology*; D008297:Male; D010572:Pest Control, Biological / Q000379:methods*; D011679:Pupa; D014744:Vietnam / Q000453:epidemiology; D020577:Wolbachia / Q000502:physiology*