Featured Research

from universities, journals, and other organizations

Tiger mosquito, vector of chikungunya virus and dengue fever, is more flighty than first thought

Date:
November 5, 2012
Source:
Institut de Recherche pour le Développement (IRD)
Summary:
Female tiger mosquitoes, vectors of the chikungunya virus and of dengue fever, had been thought to mate only once during their short few weeks of life. They are apparently much less faithful than imagined, however. Scientists have discovered that they may in fact mate with several males during their short lives. What is more, the same clutch of eggs can be engendered by different fathers. For their part, the males can mate with over 10 different females.

Tiger mosquitoes mate with several males during their short lives. What is more, the same clutch of eggs can be engendered by different fathers. For their part, the males can mate with over 10 different females.
Credit: © EID Méditerranée / J-B Ferré

Female tiger mosquitoes, vectors of the chikungunya virus and of dengue fever, had been thought to mate only once during their short few weeks of life. They are apparently much less faithful than imagined, however. A team representing the IRD and its partners(1) has discovered that they may in fact mate with several males during their short lives. What is more, the same clutch of eggs can be engendered by different fathers! For their part, the males can mate with over 10 different females.

These recent studies, conducted on the island of Reunion and published notably in the journal PLOS ONE, will make it possible to perfect the "sterile insect technique." This innovative approach to fighting against vectors of disease consists of fooling females into mating with infertile males so as to reduce the population of mosquitoes in the wild. Researchers will, in particular, be able to establish what quantity of sterilised males to release in order to compensate for the infidelities of the females.

Dengue fever and the chikungunya virus continue to take their toll all over the world. In the absence of either a vaccine or effective treatment, attacking the vector remains the sole course of action. If this new method proves promising, it will offer an ecologically acceptable alternative to the use of insecticides.

Female tiger mosquitoes, the vectors of the chikungunya virus, are much less faithful than entomologists had previously thought. A team of researchers from IRD and its partners(1) recently discovered that the ladies of the Aedes albopictus species, to give them their scientific name, mate several times during their short lives. Until now specialists had thought that they copulated with a single male during their few short weeks of existence. According to this generally accepted hypothesis, once they had been impregnated they developed an aversion to any further insemination. The discovery of an unexpected sexual appetite on their part has major implications for the newly-developed "sterile insect technique."

Objective: to fool the females

IRD researchers on the island of Reunion have been working on this antivector strategy for several years. Based on the sterilisation of male mosquitoes, it is intended to reduce the population of vectors found in natural conditions. The method consists of releasing sterilised, and therefore infertile males in order to 'deceive' the females, who had been thought to mate only once, into doing so with these infertile individuals. As shown in previous studies, male mosquitoes sterilised by radiation(2) in the laboratory nevertheless succeeded in mating normally with the females. The latter continue to produce a large number of eggs, but they are non-fertilised and will thus produce no offspring.

One mother, several fathers

To optimise this new antivector technique, a good understanding of biology, ecology and the behaviour and competitiveness of mosquitoes is essential. The researchers thus attempted to determine whether the eggs of the female tiger mosquitoes captured in Reunion actually came from a single male or had involved several male progenitors. Thanks to genetic markers, they were able to demonstrate that the same clutch of eggs could be the result of mating with several different males. The new study, published in PLOS ONE, thus reveals that the females are in reality likely to have recourse to multiple inseminations. This result suggests that the repulsion felt by females of the species for any new union after mating a first time is not systematic.

Highly active males

During a previous study, the research team had also shown that male tiger mosquitoes are very efficient. They remain sexually active for over 14 days. Moreover, scientists have underlined the high number of females impregnated by a single male: the tiger mosquito is capable of mating with over ten females on average during this period. Where does this great reproductive success come from? This fundamental question remains unanswered. Sterilised male mosquitoes do, however, seem a little less competitive.

These results will enable researchers to maximise the effectiveness of the sterile male technique, and in particular to specify how many infertile males should be released in order to increase the probability that a female will mate with one of them and so as to compensate for their slightly lower attractiveness.

Dangerous females

The much-feared tiger mosquito is responsible for the transmission of several diseases throughout the world. It is the main vector of the chikungunya virus and the second of dengue fever -- after another mosquito of the genus Aedes. As in the case of the famous members of the anopheles genus that carry malaria, it is the females that transmit the viruses to men and to animals. They in fact bite the latter in order to feed on their blood and thus ensure the development of their eggs.

Rarely fatal, the chikungunya virus is nevertheless considered a major public health problem in Asia, South America and Africa. In 2006 on the island of Reunion, the infection affected almost a third of the population, equivalent to hundreds of thousands of people in total throughout the Indian Ocean. The most frequent symptoms are fevers, joint pains and headaches. No vaccine or treatment has been developed to date. The only available means of action thus continues to be the antivector strategy.

In light of this, the sterilisation of male mosquitoes could offer an alternative that is more respectful of the environment and of ecosystems than the use of insecticide sprays. If at the end of the laboratory research phase this approach is indeed judged promising, researchers may proceed in the next few years with experimental releases in the field. A significant effort is needed beforehand in order to increase awareness, however, to ensure that the new method is well accepted and supported by the local population.

(1) These studies were conducted in partnership with the Centre for the Study and Monitoring of Emerging Diseases in the Indian Ocean (CRVOI) in Reunion, the Indian Ocean Regional Health Agency and the International Atomic Energy Agency in Austria.

(2) Sterilisation by radiation consists of exposing a body very briefly to a source of radioactive emissions. This procedure is currently used on food and sanitary products, etc.


Story Source:

The above story is based on materials provided by Institut de Recherche pour le Développement (IRD). The original article was written by Gaëlle Courcoux, DIC. Note: Materials may be edited for content and length.


Journal References:

  1. Sebastien Boyer, Celine Toty, Maxime Jacquet, Guy Lempérière, Didier Fontenille. Evidence of Multiple Inseminations in the Field in Aedes albopictus. PLoS ONE, 2012; 7 (8): e42040 DOI: 10.1371/journal.pone.0042040
  2. S. Boyer, J. Gilles, D. Merancienne, G. Lemperiere, D. Fontenille. Sexual performance of male mosquito Aedes albopictus. Medical and Veterinary Entomology, 2011; 25 (4): 454 DOI: 10.1111/j.1365-2915.2011.00962.x

Cite This Page:

Institut de Recherche pour le Développement (IRD). "Tiger mosquito, vector of chikungunya virus and dengue fever, is more flighty than first thought." ScienceDaily. ScienceDaily, 5 November 2012. <www.sciencedaily.com/releases/2012/11/121105081501.htm>.
Institut de Recherche pour le Développement (IRD). (2012, November 5). Tiger mosquito, vector of chikungunya virus and dengue fever, is more flighty than first thought. ScienceDaily. Retrieved August 27, 2014 from www.sciencedaily.com/releases/2012/11/121105081501.htm
Institut de Recherche pour le Développement (IRD). "Tiger mosquito, vector of chikungunya virus and dengue fever, is more flighty than first thought." ScienceDaily. www.sciencedaily.com/releases/2012/11/121105081501.htm (accessed August 27, 2014).

Share This




More Plants & Animals News

Wednesday, August 27, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Super Healthful Fruits and Vegetables: Which Are Best?

Super Healthful Fruits and Vegetables: Which Are Best?

Ivanhoe (Aug. 27, 2014) — We all know that it is important to eat our fruits and vegetables but do you know which ones are the best for you? Video provided by Ivanhoe
Powered by NewsLook.com
Bad Memories Turn Good In Weird Mouse Brain Study

Bad Memories Turn Good In Weird Mouse Brain Study

Newsy (Aug. 27, 2014) — MIT researchers were able to change whether bad memories in mice made them anxious by flicking an emotional switch in the brain. Video provided by Newsy
Powered by NewsLook.com
Do Couples Who Smoke Weed Together Stay Together?

Do Couples Who Smoke Weed Together Stay Together?

Newsy (Aug. 27, 2014) — A study out of University at Buffalo claims couples who smoke marijuana are less likely to experience intimate partner violence. Video provided by Newsy
Powered by NewsLook.com
Panda Might Have Faked Pregnancy To Get Special Treatment

Panda Might Have Faked Pregnancy To Get Special Treatment

Newsy (Aug. 27, 2014) — A panda in China showed pregnancy symptoms that disappeared after two months of observation. One theory: Her pseudopregnancy was a ploy for perks. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins