Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Parasitoid turns host into bodyguard

04.06.2008
Parasites can induce dramatic changes of behaviour in their host species. This behaviour is thought to be detrimental to the host, but beneficial to the parasite.

In a joint publication in PLoS One, researchers from the University of Amsterdam and University of Viçosa (Brazil) show evidence of spectacular behavioural changes induced by a parasitic wasp in the caterpillar of a moth species.

After the wasp has oviposited eggs in the body of the caterpillar, these develop into larvae that live on the body fluids of the caterpillar. After the wasp larvae crawl out of the caterpillar to pupate, the caterpillar acts as a bodyguard to defend them from predator attacks.

A research team from the Institute for Biodiversity and Ecosystem Dynamics (IBED) of the University of Amsterdam worked together with the Entomology section of the Federal University of Viçosa (Brazil) to study such behavioural changes induced by parasites. In a recent publication in the new electronic journal PLoS One, the researchers offer evidence that behavioural changes of the host are beneficial to the parasite in the field. In Brazil, the team studied the caterpillars of a moth that feed on leaves of the native guava tree and an exotic eucalyptus.

These small caterpillars are attacked by insect parasitoid wasps, which then quickly insert up to 80 eggs into them. Inside the caterpillar host, a cruel drama takes place: the eggs of the parasitoid hatch and the larvae feed on the body fluids of the host. The caterpillar continues feeding, moving and growing like its unparasitised brothers and sisters. When the parasitoid larvae are full-grown, they emerge together through the host’s skin, and start pupating nearby. Unlike many other combinations of host and parasitoid, the host remains alive and displays spectacular changes in its behaviour: it stops feeding and remains close to the parasitoid pupae.

Moreover, it defends the parasitoid pupae against approaching predators with violent head-swings (see films via link below). The caterpillar dies soon after the adult parasitoids emerge from their pupae, so there can be no benefit whatsoever for it. In contrast, unparasitised caterpillars do not show any of these behavioural changes.

The research team found that parasitoid pupae that were guarded by caterpillars in the field suffered half as much predation as those without a bodyguard. Hence, the behavioural changes of the host result in increased survival of the parasitoids due to the host acting as a bodyguard of the parasitoid pupae. Whereas it is still unclear how the parasitoid changes the behaviour of its host, it is tempting to speculate. The research team found that one or two parasitoid larvae remained behind in the host. Perhaps these larvae affect the behaviour of the caterpillar, and sacrifice themselves for the good of their brothers and sisters.

Cause or effect?

There are many examples of parasites that induce spectacular changes in the behaviour of their host. Flukes, for example, are thought to induce ants, their intermediate host, to move up onto blades of grass during the night and early morning. There they firmly attach themselves to the substrate with their mandibles, and are thus consumed by grazing sheep, the fluke’s final host. In contrast, uninfected ants return to their nests during the night and the cooler parts of the day. Another example of behavioural change is that of terrestrial insects, parasitised by hairworms, which commit suicide by jumping into water allowing the adult hairworms to reproduce. Behavioural changes like these are thought to be induced by the parasite so as to increase its transmission to the final host, but there are alternative explanations. It is possible, for example, that the hosts already behaved differently before becoming infected. Hence, infection is a consequence of different behaviour, not its cause. Increased transmission can also be called into question: the behavioural changes of the host may result in increased attacks by other non-host animals, and this would seriously decrease the probability of transmission. Increased transmission should therefore always be tested under natural conditions. The research of the Dutch and Brazilian researchers is the most complete and convincing case for induction of behavioural changes, clearly showing that it is the parasite that profits from it.

This research was supported by the Tropical Research division of the Netherlands Organisation for Scientific Research (NWO-WOTRO).

Publication information:
‘Parasitoid increases survival of its pupae by inducing hosts to fight predators’. Amir H. Grosman, Arne Janssen, Elaine F. de Brito, Eduardo G. Cordeiro, Felipe Colares, Juliana Oliveira Fonseca, Eraldo R. Lima, Angelo Pallini and Maurice W. Sabelis. PloS One, June 4, 2008.

The online article can be viewed via: http://www.plosone.org/doi/pone.0002276. This website also includes accompanying images.

Laura Erdtsieck | alfa
Further information:
http://www.plosone.org/doi/pone.0002276
http://www.uva.nl

Further reports about: Bodyguard Host Transmission induce larvae parasite parasitoid pupae

More articles from Life Sciences:

nachricht New eDNA technology used to quickly assess coral reefs
18.04.2019 | University of Hawaii at Manoa

nachricht New automated biological-sample analysis systems to accelerate disease detection
18.04.2019 | Polytechnique Montréal

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Explosion on Jupiter-sized star 10 times more powerful than ever seen on our sun

A stellar flare 10 times more powerful than anything seen on our sun has burst from an ultracool star almost the same size as Jupiter

  • Coolest and smallest star to produce a superflare found
  • Star is a tenth of the radius of our Sun
  • Researchers led by University of Warwick could only see...

Im Focus: Quantum simulation more stable than expected

A localization phenomenon boosts the accuracy of solving quantum many-body problems with quantum computers which are otherwise challenging for conventional computers. This brings such digital quantum simulation within reach on quantum devices available today.

Quantum computers promise to solve certain computational problems exponentially faster than any classical machine. “A particularly promising application is the...

Im Focus: Largest, fastest array of microscopic 'traffic cops' for optical communications

The technology could revolutionize how information travels through data centers and artificial intelligence networks

Engineers at the University of California, Berkeley have built a new photonic switch that can control the direction of light passing through optical fibers...

Im Focus: A long-distance relationship in femtoseconds

Physicists observe how electron-hole pairs drift apart at ultrafast speed, but still remain strongly bound.

Modern electronics relies on ultrafast charge motion on ever shorter length scales. Physicists from Regensburg and Gothenburg have now succeeded in resolving a...

Im Focus: Researchers 3D print metamaterials with novel optical properties

Engineers create novel optical devices, including a moth eye-inspired omnidirectional microwave antenna

A team of engineers at Tufts University has developed a series of 3D printed metamaterials with unique microwave or optical properties that go beyond what is...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Revered mathematicians and computer scientists converge with 200 young researchers in Heidelberg!

17.04.2019 | Event News

First dust conference in the Central Asian part of the earth’s dust belt

15.04.2019 | Event News

Fraunhofer FHR at the IEEE Radar Conference 2019 in Boston, USA

09.04.2019 | Event News

 
Latest News

New automated biological-sample analysis systems to accelerate disease detection

18.04.2019 | Life Sciences

Explosion on Jupiter-sized star 10 times more powerful than ever seen on our sun

18.04.2019 | Physics and Astronomy

New eDNA technology used to quickly assess coral reefs

18.04.2019 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>