Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Choice of food helps hungry caterpillar

08.06.2004


For one caterpillar, eating an unusual fruit may be the key to an easy food supply and protection against parasites, according to a team of Penn State researchers.


Heliothis subflexa caterpillar on partially eaten fruit inside Physalis angulata calyx.
Credit: Penn State, Andrew Sourakov and Consuelo M. De Moraes


Predatory wasp, Cardiochiles nigriceps on branch of Physalis angulata. Heliothis subflexa caterpillar on partially eaten fruit inside Physalis angulata calyx hangs below branch.
Credit: Penn State, Andrew Sourakov and Consuelo M. De Moraes



The Heliothis subflexa caterpillar is a specialist herbivore that eats only the fruit of Physalis plants which include ground cherry, tomatillo and Chinese lantern. H. subflexa’s choice of food turns out to have unusual benefits in the three-way struggle between herbivores, their predatory wasps and the plants.

"We know that many plants produce volatile chemicals when chewed on by herbivores and that some of these chemicals attract wasps that parasitize the caterpillars," says Dr. Consuelo M De Moraes, assistant professor of entomology. "However, when we investigated H. subflexa’s spit, it did not contain volicitin, a chemical elicitor that signals the plant to produce the volatile chemicals that attract wasps."


H. subflexa somehow does not turn on the plant’s defenses.

"The co-evolution of plants, herbivores and their parasitoids is complex," says Dr. Mark C. Mescher, assistant professor of biology. "We do not fully understand how the system is influenced by the interactions of the three players and we need to understand this to develop more environmentally friendly ways to deal with agricultural products and pests."


Thinking the absence of elicitor was related to the caterpillar’s food, the researchers fed H. subflexa on a different food source and fed a different caterpillar on Physalis angulata. The Physalis-fed caterpillar did not produce the elicitor either, but H. subflexa, fed on a different food, did produce elicitors.

The researchers report in this week’s online edition of the Proceedings of the National Academy of Sciences that the Physalis angulata fruits used "lack linolenic acid." Linolenic acid is necessary to produce the chemical in caterpillar spit that elicits the production of volatile wasp attracting substances.

Linolenic acid, however, is not just used to make the elicitor, but is a necessary chemical in the growth and maturation of many insects including other caterpillars and wasps.

"Physiologically, we do not know how the caterpillars manage to survive without it in their diet," says Mescher. "It is a process of specialization and we plan to look at this next."

The absence of linolenic acid explains why H. subflexa is the only caterpillar that feeds on Physalis. Other caterpillars forced to feed on the fruit rarely survived and those that did were often deformed. By somehow adapting to the lack of linolenic acid, H. subflexa manages to secure a food supply that only they can eat.

Physalis is characterized by a fruit enclosed in an inflated calyx, forming the Chinese lantern or husk tomato type of fruit. The caterpillar carefully bores a small hole in the calyx because, unlike the fruit, the leaves and flowers of the plant do produce linolenic acid. Caterpillars will often squeeze out of the same hole, even though they have grown.

"A caterpillar will eat three or four fruits during its lifetime," says De Moraes. "Because they are protected by the calyx when feeding, the caterpillars are most likely to be parasitized when moving from one fruit to another."

The absence of linolenic acid in the fruit appears to be passed on to caterpillar. Wasp larvae cannot develop within the caterpillar and so H. subflexa avoids becoming a home for wasp larvae.

The researchers note that the ability of H. subflexa larvae to develop without linolenic acid seems to give them almost exclusive access to Physalis fruit. H. subflexa can also exploit the protection from predators provided by the fruit’s calyx. Combining that protection with the protection afforded by an absence of linolenic acid for parasite development, H. subflexa has a very low level of parasites compared with other caterpillars.

By adapting to a fruit that no other caterpillar wants, H. subflexa has found a niche where life is good. An uncontested food supply, a way to eat the fruit without calling up the plant’s defenses and immunity to parasites make for successful caterpillars.


This work was supported by the National Research Institute of the U.S. Department of Agriculture, the Beckman Foundation, and a David and Lucille Packard Young Investigator Award.

A’ndrea Elyse Messer | EurekAlert!
Further information:
http://www.psu.edu/

More articles from Life Sciences:

nachricht Cancer diagnosis: no more needles?
25.05.2018 | Christian-Albrechts-Universität zu Kiel

nachricht Less is more? Gene switch for healthy aging found
25.05.2018 | Leibniz-Institut für Alternsforschung - Fritz-Lipmann-Institut e.V. (FLI)

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Powerful IT security for the car of the future – research alliance develops new approaches

The more electronics steer, accelerate and brake cars, the more important it is to protect them against cyber-attacks. That is why 15 partners from industry and academia will work together over the next three years on new approaches to IT security in self-driving cars. The joint project goes by the name Security For Connected, Autonomous Cars (SecForCARs) and has funding of €7.2 million from the German Federal Ministry of Education and Research. Infineon is leading the project.

Vehicles already offer diverse communication interfaces and more and more automated functions, such as distance and lane-keeping assist systems. At the same...

Im Focus: Molecular switch will facilitate the development of pioneering electro-optical devices

A research team led by physicists at the Technical University of Munich (TUM) has developed molecular nanoswitches that can be toggled between two structurally different states using an applied voltage. They can serve as the basis for a pioneering class of devices that could replace silicon-based components with organic molecules.

The development of new electronic technologies drives the incessant reduction of functional component sizes. In the context of an international collaborative...

Im Focus: LZH showcases laser material processing of tomorrow at the LASYS 2018

At the LASYS 2018, from June 5th to 7th, the Laser Zentrum Hannover e.V. (LZH) will be showcasing processes for the laser material processing of tomorrow in hall 4 at stand 4E75. With blown bomb shells the LZH will present first results of a research project on civil security.

At this year's LASYS, the LZH will exhibit light-based processes such as cutting, welding, ablation and structuring as well as additive manufacturing for...

Im Focus: Self-illuminating pixels for a new display generation

There are videos on the internet that can make one marvel at technology. For example, a smartphone is casually bent around the arm or a thin-film display is rolled in all directions and with almost every diameter. From the user's point of view, this looks fantastic. From a professional point of view, however, the question arises: Is that already possible?

At Display Week 2018, scientists from the Fraunhofer Institute for Applied Polymer Research IAP will be demonstrating today’s technological possibilities and...

Im Focus: Explanation for puzzling quantum oscillations has been found

So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics

Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

In focus: Climate adapted plants

25.05.2018 | Event News

Save the date: Forum European Neuroscience – 07-11 July 2018 in Berlin, Germany

02.05.2018 | Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

 
Latest News

In focus: Climate adapted plants

25.05.2018 | Event News

Flow probes from the 3D printer

25.05.2018 | Machine Engineering

Less is more? Gene switch for healthy aging found

25.05.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>