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 Study shines light on brain cells that coordinate movement
26.06.2017 | University of Washington Health Sciences/UW Medicine

nachricht New insight into a central biological dogma on ion transport
26.06.2017 | Aarhus University

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Study shines light on brain cells that coordinate movement

26.06.2017 | Life Sciences

Smooth propagation of spin waves using gold

26.06.2017 | Physics and Astronomy

Switchable DNA mini-machines store information

26.06.2017 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>