More on A really complex interaction between plant host, fungus, moth, and parasitoid

[Michael Gochfeld]

"Stanley A. Gorodenski" wrote in response to my post: :

> You said: "How does the moth know this?"  Maybe it doesn't. If there is
> no fungus, the imatures are more successful in not being seen by the
> parasitoid (this follows from what you have said). As a result, the
> parasitoids will spend less time on plants that don't have the fungus
> because they cannot find the larvae. The adult moth may be queing off
> the abundance of parasitoids flying around a plant while it itself is
> looking for a suitable plant upon which to lay eggs.
>
> I am just basing this upon my understanding of what you wrote. Maybe
> more information is needed to come up with a better hypothesis.
>
> Stan
>

Yes, but this seems like a catch-22 for the moth. If the parasite avoids plants with the fungus
because there aren't enough larvae because the female moths are looking for unparasitized plants and the
parasitoid then frequents unparasitized plants, why would the female moths want to queue to them.

Maybe there is more to the story.

Nature is puzzling.  MIKE GOCHFELD



>
> Michael Gochfeld wrote:
> >
> > As I understand the following article:
> >
> > The plant Silene is a favored food item for a moth  Hadena.
> > The moth caterpillars are parasitized by a specialist parasitoid  Microplitis.
> > The moth caterpillars hide from the wasp in the seed capsules where they eat the seeds.
> > The fungus reduces the number of seed capsules so there is less food and the wasps are more successful in hitting the moths.
> > Therefore the adult female moth prefers to lay on Silene plants that don't have the fungus.  Not a surprise really, but...
> > How do the moths know this?
> > Does the fungus care whether the moth is successful or not?
> >
> > A really neat system.  MIKE GOCHFELD
> >
> > Neal Smith wrote:
> >
> > >  Once you read it twice, you will get comfortable with the concept of "Enemy-Free Space"!!!!!!!!!!!!!!
> > >  It has some nice color photos to guide you through this non-simple interaction!!!!!!!!!!!!!!!!!
> > >
> > >  A plant pathogen reduces the enemy-free space of an insect herbivore on a shared host plant
> > >  Arjen Biere ; Jelmer A. Elzinga ; Sonja C. Honders ; Jeffrey A. Harvey
> > >  Proceedings The Royal Society Biological Sciences      Volume: 269 Number: 1506 Page: 2197 -- 2204
> > >
> > >
> > > Abstract: An important mechanism in stabilizing tightly linked host-parasitoid and prey-predator interactions is the presence of refuges that protect organisms from their natural enemies. However, the presence and quality of refuges can be strongly affected by the environment. We show that infection of the host plant Silene latifolia by its specialist fungal plant pathogen Microbotryum violaceum dramatically alters the enemy-free space of a herbivore, the specialist noctuid seed predator Hadena bicruris, on their shared host plant. The pathogen arrests the development of seed capsules that serve as refuges for the herbivore's offspring against the specialist parasitoid Microplitis tristis, a major source of mortality of H. bicruris in the field. Pathogen infection resulted both in lower host-plant food quality, causing reduced adult emergence, and in twofold higher rates of parasitism of the herbivore. We interpret the strong oviposition preference of H. bicruris for uni!
> nf!
> > ected
> > > plants in the field as an adaptive response, positioning offspring on refuge-rich, high-quality hosts. To our knowledge, this is the first demonstration that plant-inhabiting micro-organisms can affect higher trophic interactions through alteration of host refuge quality. We speculate that such interference can potentially destabilize tightly linked multitrophic interactions.
> > >
> > >
> > >
> > >   ------------------------------------------------------------------------
> > >                           Name: enemy-freespace.pdf
> > >    enemy-freespace.pdf    Type: Portable Document Format (application/pdf)
> > >                       Encoding: base64
> >
> >
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