Marbled white parasites

[Susie]

I though some people might find the pic of this poor little blighter interested. I don't think the parasites are supposed to hurt the butterfly but I can't see that they do it any good. It certainly makes for a colourful and rather Christmasy picture.

[essexbuzzard]

Does anyone know how these parasites get on the butterfly? Are they picked up from the nectar plants? They seem common on some sites-Aston Rowant for example-but completely absent from many others. Though i have to say,that's the most i've seen, Susie! Surely,all these sucking blood must do some damage?

[Susie]

I think from other threads we have had these are actually the larvae of a form of arachnid (tick). I imagine they start off absolutely tiny, like dust to the human eye, when eggs and are sprinkled liberally about by the adult females. I really don't know anything about the life cycle though but I am sure someone on here does and can help us.

[essexbuzzard]

So you think they come through through caterpillar and chrysalis stage? Sounds plausable. Yes,it would be interesting to hear other opinions a well.
Kind regards,Mark.

[Susie]

I'm not sure about caterpillar and chrysalis - I think I phrased it badly in my previous post - but I think they start as eggs and then become nymphs before the adult form. But again I am only guessing.

[Gibster]

This is shamelessly lifted from the web - "Abstract 1. The incidence of parasitism by larvae of the mite species Trombidium breei was reported in one population of the lycaenid butterfly Polyommatus icarus, four populations of the satyrine butterfly Maniola jurtina, one population of the satyrine butterfly Aphantopus hyperanthus, and two populations of the satyrine butterfly Pyronia tithonus, as well as on one specimen of the dipteran Alophorus hemiptera. A considerable proportion of butterflies (11-50%) was infested in all study populations.

2. The pattern of infestation was examined in detail in M. jurtina. Males had a significantly higher incidence of infestation than females, and middle-aged butterflies had a higher incidence of infestation than old or young butterflies. The incidence of infestation peaked in the middle of the flight season, and this seasonal effect was independent of the effect of butterfly age.

3. Using a model based on capture-recapture data, it was estimated that a hypothetical ideal male M. jurtina that lives exactly the mean expected lifespan of 9-10 days has an approximately 75% chance of becoming infested with mites at least once during its lifetime, a mean time to first infestation of 3-4 days, and an average infestation persistence time of 2-3 days.

4. Capture-recapture data failed to show any effect of mite infestation on the lifespan or within-habitat movement rate of M. jurtina.

5. In experiments in which individual butterflies were taken out of their normal habitat and released, M. jurtina and P. tithonus that were infested with mite larvae did not differ from uninfested individuals in the efficiency with which they returned to suitable habitat. Thus, parasitism by T. breei larvae had no detectable effects on flight performance or orientation ability.

6. The results suggest that trombidiid mite larvae have limited potential in the biological control of insect pests."


Very interesting to read that males are more prone to infestation than females, and middle-aged butterflies especially so. But why?

(I guess middle-aged males are the most attractive and juicy? Ooh, is that a tick on me leg? )

Gibster.

[essexbuzzard]

Yes,i see what you mean. May be they rely on high densities of butterflies,whih could explain their absence from some sites.Thanks Susie

[essexbuzzard]

Just read this, very interesting. Thanks Gibster.
P. S. you're too modest!

[Susie]

Interesting stuff, Gibster. So many questions!

In the meantime, another one.

[Mark Colvin]

Mites and ticks are members of the class Arachnida which includes, amongst others, the spiders and scorpions. A number of British butterfly species can often be found covered in the small red mite Trombidium breei. These are not the juvenile stage of a tick but are a species in their own right. They undergo a form of incomplete metamorphosis i.e. egg, larva, nymph (of which there are a number of stages) and adult. T. breei feeds on the blood of the living butterfly and it is believed that small numbers do no harm.

I hope this helps?

Kind regards. Mark

[Susie]

Oh dear, I am confusing things, I didn't think that these were the type of tick that feed on deer and middle aged humans but I did think these were the immature stage rather than the adult - thanks for clearing it up, Mark.