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

(1)

Bionomics of

Aedes albopictus

(Skuse) vector

of chikungunya and dengue in the Indian

Ocean

(2)

Context

Chikungunya

tbr k 2005

tbr k 2005 2006

2006

Mayotte Dzaoudzi

outbreak 2005

outbreak 2005--2006

2006

Major vector:

Major vector: Ae.

Ae.

lb

Madagascar Mauritius Port Louis Saint Denis Antananarivo Mozambique

albopictus

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

L k f k

l d

Réunion Island Maputo Pretoria Johannesburg

Lack of knowledge

South Africa Durban Richards Bay Pietermaritzburg

.

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ENTOMOCHIK

Head of the project: Dr. Didier Fontenille (IRD, UR016, France Montpellier) Work packages 1-2: Dr. Hélène Delatte (IRD-CIRAD, Réunion)

(4)

Entomological factors of emergence of

Chik n n

di

nd th r h m n

Chik n n

di

nd th r h m n

Chikungunya disease and other human

arboviruses

Wkp 1: Population biology of Aedes albopictus

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

Ocean islands Ocean islands

Wkp 3: Relations between virus-vector (CHIKV & DENV) in Ae. albopictus & Ae.

aegypti populations aegypt popu at o s

Wkp 4: Modelisation of the p entomological riskg

Improve knowledge on vectors Forecasting entomological risks

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Introduction

Context

¾ 12 Culicidae sp.

p

_{0 - 3000 m}

¾ Ae. aegypti, indigenous

(Vassal, 1907)

¾ A

lb

i t

d

ib d i 1913

0 3000 m

¾ Ae. albopictus, described in 1913

(Edwards, 1920)

Summer samplings Summer samplings Winter upper limit

Isometre linesfrom 750 to 1250 m

Urbanized areas

¾ Highly abundant throughout the island (from urban to natural

habitat) up to 1200 m in dry winter season

(Delatte et al, 2008, VBZD)

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Introduction

Objective

¾ What are the life history traits of Ae. albopictus population

from la Réunion according to different temperatures ?

• Immature stages

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Material and Method

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

Immature stages

Daily records: ¾ Survival ¾ Survival ¾ Length of development Daily records:

Adult stage

¾ Longevity ¾ Fecundity

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RESULTS

Immature stages: development (L1 - adult)

Temps moyen de développement larvaire d' Aedes albopictus

35,0 a 35,0 40,0 e nt ( J ) ¾ Length of development e nt (day)

Average length of immatures development

12,3 14,4 b 10,4 c _{8,8 d} 10 0 15,0 20,0 25,0 30,0 e d é vel o p p e m e • Fastest development at 30°C (8.8 days) d evelopm e 0,0 5,0 10,0 15 20 25 30 35 Températures (°C) D u rée d e L ength of d Temperature (°C) ¾ Survival rate Températures ( C) L Temperature (°C) T T°°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 5 Survival 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

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RESULTS

Immature stages: development (L1 - adult)

pment ¾ Temperature threshold of development: 10.4°C of develo Rate ¾ Optimal development temperature: 29.7°C Temperature (°C)

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RESULTS Adult stage: longevity

Longévité moyenne estimée pour les femelles

Weibull model: females Ae. albopictus

T T°°CC 1515 2020 2525 3030 3535 Males (days) Males (days) 31.331.3 19.319.3 18.418.4 17.217.2 14.914.9 Males (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

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Results all stages: Intrinsinc rate of growth (r)

0,200 0,155 0,140 0,072 0 050 0,100 0,150 m e n t n a tu re l g rowth (r) -0,050 0,000 0,050 15 20 25 30 35 x d 'ac cr o isse m ic rate of g -0,103 -0,150 -0,100 Température (°C) Ta u x Intrins i Temperature (°C)p ( () )

¾ Optimum r between 25 and 30°C

¾ Negative value at 35°C: population decrease ¾ Negative value at 35°C: population decrease

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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

meal

Egg

laying

meal

y g

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Results adult stage:

Trophogonic cycle 3 1 b 3,9 b 3 5 4 4.5 m el le e male 1,7 a 3,1 b 1 3 a 2 2.5 3 3.5 m o yen /f e m o f cycles/f e 1,3 a 0.5 1 1.5 N b cycl es number o 0 20 25 30 35 Température (°C) A v erage 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

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Conclusion

¾ 20 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 )

¾ 20 to 30 C: the most favourable range for Ae. albopictus development of immatures 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

¾ Biological characteristics observed for the Ae. albopictus Reunionese population 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 for Partly explain the 2 explosive epidemics transmitted by Ae. albopictus for

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Thanks for you

attention !!

Bagny L Bastien F

attention !!

Bastien F Becker N Bouetard A Chiroleu F Dehecq JS Delatte H Delatte 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