Bionomics of Aedes albopictus (Skuse) vector of chikungunya and dengue in the Indianof chikungunya and dengue in the Indian

Ocean

Delatte H, Gimonneau G, Triboire A & Fontenille D

Context Context

Chikungunya Chikungunya tbr k 2005tbr k 2005 20062006

MayotteDzaoudzi

outbreak 2005outbreak 2005--20062006Major vector: Major vector: Ae. Ae. lblb

Madagascar

MauritiusPort Louis

Saint Denis

AntananarivoMozambique

albopictus albopictus (Reiter et al., 2007)(Reiter et al., 2007)

L k f k l d

Réunion Island

MaputoPretoria

Johannesburg

Lack of knowledgeSouth Africa

Durban

Richards BayPietermaritzburg .

ENTOMOCHIKENTOMOCHIKENTOMOCHIKENTOMOCHIK

Head of the project: Dr. Didier Fontenille (IRD, UR016, France Montpellier)

Work packages 1-2: Dr. Hélène Delatte (IRD-CIRAD, Réunion)

Entomological factors of emergence of Entomological factors of emergence of Chik n n di nd th r h m nChik n n di nd th r h m nChikungunya disease and other human Chikungunya disease and other human

arbovirusesarboviruses

Wkp 1: Population biology of Aedes albopictus

Wkp 2: Phylogeography & population genetics of Ae. albopictus in the Indian Ocean islandsOcean islands

Wkp 3: Relations between virus-vector (CHIKV & DENV) in Ae. albopictus & Ae. aegypti populationsaegypt popu at o s

Wkp 4: Modelisation of the entomological riskp g

Improve knowledge on vectorsForecasting entomological risks Develop new strategies of vector control

IntroductionContextContext

12 Culicidae sp. 0 - 3000 mp

Ae. aegypti, indigenous (Vassal, 1907)

A lb i t d ib d i 1913

0 3000 m

Ae. albopictus, described in 1913 (Edwards, 1920)

Summer samplingsSummer samplingsWinter upper limitIsometre lines from 750 to 1250 mUrbanized areas

Highly abundant throughout the island (from urban to naturalhabitat) up to 1200 m in dry winter season (Delatte et al, 2008, VBZD)

Vector of DENV (1977-78 & 2004) & CHIKV (2005-2006)

Introduction

Objective

What are the life history traits of Ae. albopictus population

from la Réunion according to different temperatures ?

• Immature stages

• Adult stagedu s age

Material and Method

Lab studies on F2 field populations at 8different constant temperatures (5 to 40°C)

Immature stagesDaily records:

SurvivalSurvival

Length of development

Daily records:

Adult stage

Longevity

Fecundity

Blood feeding activity

RESULTS Immature stages: development (L1 - adult)

Temps moyen de développement larvaire d' Aedes albopictus

35,0 a35,040,0

ent (

J)

Length of development

ent (

day) Average length of immatures development

12,314,4 b

10,4 c 8,8 d10 015,020,025,030,0

e dé

velo

ppem

e

• Fastest development at 30°C (8.8 days)

deve

lopm

e

0,05,0

10,0

15 20 25 30 35

Températures (°C)

Dur

ée d

eLe

ngth

of d

Temperature (°C)Survival rate

Températures ( C)L Temperature (°C)

TT°°CC 1515 2020 2525 3030 3535

S i l t (%)S i l t (%) 50 050 0 77 577 5 bb 76 376 3 bb 67 567 5 bb 2 52 5Survival rate (%)Survival rate (%) 50.0 a50.0 a 77.577.5 bb 76.376.3 bb 67.567.5 bb 2.5 c2.5 c

• Best survival rates from 20°C to 30°C

RESULTS Immature stages: development (L1 - adult)

pmen

tTemperature threshold of development: 10.4°C

of d

evel

oR

ate Optimal development

temperature: 29.7°C

Temperature (°C)Model of Logan (1976) corrected by Lactin (1995)

RESULTS Adult stage: longevity

Longévité moyenne estimée pour les femelles

Weibull model: females Ae. albopictus

TT°°CC 1515 2020 2525 3030 3535Males (days)Males (days) 31.331.3 19.319.3 18.418.4 17.217.2 14.914.9Males (days)Males (days) 31.3 31.3 19.3 19.3 18.4 18.4 17.2 17.2 14.9 14.9 Females (days)Females (days) 38.6 38.6 28.7 28.7 29.9 29.9 32.1 32.1 19.9 19.9

Results all stages: Intrinsinc rate of growth (r)

0,200

0,1550,140

0,0720 050

0,100

0,150m

ent n

atur

elgr

owth

(r)

-0,050

0,000

0,050

15 20 25 30 35

x d'

accr

oiss

emic

rate

of g

-0,103-0,150

-0,100

Température (°C)

Taux

Intri

nsi

Temperature (°C)( )p ( )

Optimum r between 25 and 30°C

Negative value at 35°C: population decreaseNegative value at 35°C: population decrease

Results adult stage: Trophogonic cycle

The trophogonic cycle was considered as starting with a blood meal including the succession of physiological phenomena of g p y g p

oocytes maturation and ending by oviposition (Clements 1992).

Trophogonic cycle

Blood

mealEgg layingmeal y g

Results adult stage: Trophogonic cycle

3 1 b

3,9 b

3 54

4.5

mel

leem

ale

1,7 a

3,1 b

1 3 a22.5

33.5

moy

en/fe

mof

cyc

les/

fe

1,3 a

0.51

1.5

Nb

cycl

es

num

ber o

020 25 30 35

Température (°C)Aver

age

Temperature (°C)

Fecundity & average duration / trophogonic cycle

Temperature 20°C 25°C 30°C 35°C

Eggs (number) 50.8 a 65.3 a 74.2 a 48.7 a

Length of cycles (d) 4.3 a 3.1 a 3.9 a 2.9 a

Min. pre-blood meal p. (d) 2 2 2 2

Conclusion20 to 30°C: the most favourable range for Ae albopictus development of

Short trophogonic cycles

+Sh t P bl d l i d (2 d )

20 to 30 C: the most favourable range for Ae. albopictus development ofimmatures and adults, with the optimum in a range between 25 to 30°C

Short Pre-blood meal period (2 days)+

High (ideal) temperatures of subtropical summers

Biological characteristics observed for the Ae. albopictus Reunionesepopulation are closer to the asian populations

High (ideal) temperatures of subtropical summers

+

G d t i l t f CHIKV & DENV (V ill t l 2008)Good vectorial competence for CHIKV & DENV (Vazeille et al., 2008)

+

Enough viremic travellers carrying an arbovirus

=Partly explain the 2 explosive epidemics transmitted by Ae albopictus forPartly explain the 2 explosive epidemics transmitted by Ae. albopictus for

DENV & CHIKV in the Indian Ocean in 1977-8 and 2005-6

Thanks for you attention !!

Bagny L

Bastien F attention !!Bastien F

Becker N

Bouetard A

Chiroleu F

Dehecq JS

Delatte HDelatte H

Dumont Y

Failloux AB

Fontenille D

Lacroix R

Martin E

Paupy C

Quilici S

« ENTOMOCHIK DREAM TEAM »

FROM THE 4 WORKPACKAGES

Reiter P

Reynaud B

Vazeille M FROM THE 4 WORKPACKAGES