Larval temperature and nutrition alter the susceptibility of Aedes aegypti mosquitoes to chikungunya virus Catherine J. Westbrook and L. Philip Lounibos Florida Medical Entomology Laboratory, University of Florida, Vero Beach, FL, USA SUMMARY We report how variations in larval temperature and food quantity influence Ae. aegypti larval development time (Table 1) and mortality (Fig. A) and adult female size (Table 1) and susceptibility for CHIKV. We found that larval temperature, but not food quantity, nor the temperature X food level interaction, had a significant effect on chikungunya infection (Fig. C), but that temperature, food quantity, and the interaction had a significant effect on dissemination (Fig. D). We also measured wing length and CHIKV body titer from a subset of freshly engorged mosquitoes (Fig. B) from each temperature-food level treatment to determine if the amount of virus ingested from the infectious blood meal was correlated with mosquito body size. We found that wing length was positively correlated with the initial quantity of virus ingested, but significant wing length - infection correlations disappeared after the extrinsic incubation period. This study suggests that larval environmental variables are important in shaping vector-viral interactions and that mosquito size alone may not be a good predictor of viral susceptibility.

BACKGROUND

In the last five years chikungunya virus (CHIKV) has emerged as an important agent of human arboviral epidemics and one of the principle vectors in the outbreaks was Aedes aegypti, the yellow fever mosquito. Fluctuating temperatures and limited food are common features in the aquatic container habitats occupied by immature Ae. aegypti and have a strong influence on adult body size and may also influence vector-virus interactions.

PROCEDURE action A extr l® RN Trizo qRT-PCR

Aedes aegypti

2

1 Individually reared South Florida F1 Aedes aegypti

Larvae fed: 3.0 mg or 10.5 mg 1:1 yeast:albumin and Reared at: 20ºC, 27ºC or 34ºC

10 Day Extrinsic incubation period

4

3

Trizol® RNA ex tr qRT-PC action R

Mosquitoes given CHIKV blood meal (6.3 Log10 PFU/mL)

•development time •adult size

1.0

♀ Days egg to adult * (n) ♀ wing length (mm)# (n)

27°C

34°C

Low

High

Low

High

Low

High

12a (487) 3.34±0.02a (116)

13b (467) 3.67±0.02b (60)

6.5c (391) 3.03±0.02c (90)

6.5c (477) 3.28±0.01d (91)

5.5d (492) 2.7±0.02e (33)

6.0e (449) 2.87±0.02f (58)

Proportion infected

20°C

*H= 2322.46; df = 5; P <0.0001 , # F = 261.56; df = 5; P<0.0001

Proportion of dead larvae among six treatments (N = 6, temperature-food combinations)

7

Positive leg = dissemination % disseminated =# pos. legs /# pos. bodies

Proportion of mosquitoes positive for CHIKV in body by larval temperature

Temperature and food treatment medians and means for female development time to adulthood and wing length. Within a measured variable different letters denote significance. Temperature Food level

Positive body = infection % infected= # pos. bodies /# engorged

5

Measured:

• larval mortality

6

Correlation analysis of natural log of CHIKV whole mosquito titers and wing lengths for freshly engorges females

χ2=26.0248, df = 2, P<0.0001 χ2=26.0248, df = 2, P<0.0001

*

0.8 0.6 0.4 0.2 0.0 20°C

27°C

34°C

Larval rearing temperature * 27°C significantly different from other two temperatures

10

0.04

0.02

Low 20°C

High 20°C

Low 27°C

High 27°C

Low 34°C

High 34°C

Food Level Temperature

*Treatment 6 significantly different from 1-5 (χ2 = 39.67, df = 5, P<0.0001)

9.5

0.8

9

Proportion disseminated

0.06

0.00

Proportion of mosquitoes with disseminated CHIKV infections by larval temperature and food level

* Natural Log (whole m osquito titer)

Proportion of dead larvae

0.08

8.5

8

r = 0.5787, P<0.0001 7.5

0.6 0.4 0.2 0.0

7 2

2.2

2.4

2.6

2.8

3

3.2

Wing Length

3.4

3.6

3.8

4

Low 20°C

Low 27°C

High * 20°C

*

High 27°C

Low 34°C

High 34°C

#

Food Level * Temperature *Temperature (χ2=8.7265, df = 2, P<0.0127),#Food level (χ2=5.0123, df = 1, P<0.0252), Interaction (χ2= 6.9914, df = 1, P<0.0303)

Larval temperature and nutrition alter the susceptibility ...

(58). Temperature and food treatment medians and means for female development time to adulthood and wing length. Within a measured variable different letters denote significance. *H= 2322.46; df = 5; P <0.0001 , # F = 261.56; df = 5; P<0.0001. Correlation analysis of natural log of CHIKV whole mosquito titers and wing ...

169KB Sizes 0 Downloads 51 Views

Recommend Documents

Larval Nutrition
The conditions under which larval mosquitoes are maintained can profoundly affect the physiology of the resulting adults. Using Aedes aegypti as a model, I determined how adult mosquito physiology is affected by larval nutrition and environmental tem

the role of larval cases in reducing aggression and cannibalism ...
Abstract: Larvae of wetland caddisflies supplement their detrital diets with animal material. In some species this supplement is obtained by preying on other caddisflies. In this study, we conducted a series of laboratory experiments to a) compare in

Marine subsidies alter the diet and abundance of ...
We analyzed eight years of survey data on all ... For example, while the Gulf of California ..... University (Department of Biology, Graduate College, Boritski.

Dia 1 - ALTER-Net
7 - 17 September 2016, Peyresq, France. Biodiversity ... Peyresq, Alpes de Haute-Provence, France. ALTER-Net ... www.alter-net.info/summer-school with a.

DHT11 - Humidity and Temperature Sensor Features ... - RoboCraft.ru
Jun 20, 2012 - Product's Page: www.sunrom.com/p-1141.html. DHT11 - Humidity and ... you can only get new data from it once every 2 seconds. Features.

Perioperative Thermoregulation and Temperature ...
ture is achieved by means of behavioral and autonomic mechanisms that ... ous than a comparable degree of cooling. .... Science 2005;307(57):1469; with.

Sea Brightness Temperature and the Effects of Spray
can be derived from brightness temperature with a known emissivity of the sea .... 2 , with s2 being the mean-square surface-slope; Cox and Munk suggested. C.

Colour temperature and line spectra summary
White light is made up of many different colours. ... whether or not the element is present in a star. ... Here are some emission line spectra for other elements.

Direct mapping of the temperature and velocity gradients in discs ...
(2017) recently intro- duced a method to map the thermal and density gas structure of ...... We use the Monte Carlo radiative transfer code MCFOST. (Pinte et al.

Temperature Graph.pdf
Temperature. Page 1 of 1. Temperature Graph.pdf. Temperature Graph.pdf. Open. Extract. Open with. Sign In. Main menu. Displaying Temperature Graph.pdf.

Susceptibility of Mepraia spinolai and Triatoma ...
asite Trypanosoma cruzi, the causative agent of the disease. Triatoma infestans (Reduviidae: Triatominae) is the domestic vector, so far controlled (Lorca et al.,.

Oceanic dispersal barriers, adaptation and larval retention: an ...
Dec 24, 2008 - Adult mudprawns are restricted to ... pling sites indicated in boldface, and those for the larval rearing experiments from the northernmost (Mngazana) and southern- ..... comparatively more limited in terms of social interactions.