Monday, 14 December 2009

Sibling Cannibalism

.....Common Spotted Ladybird (Harmonia conformis )


The macabre practice of cannibalism is rife in Tasmania. It's been occurring since long before the days of convict Alexander Pearce and right up to the present day. It takes place not only in the remote wilderness areas but even in some of the more affluent suburbs of our cities and towns. Read on if you dare.

A few weeks ago I posted a photo of some ladybird eggs on my nectarine tree. Well the tree is now covered in all stages of the ladybird life cycle.


(Click on photos to enlarge)
Newly hatched ladybirds - Harmonia conformis

After hatching, many insects feed on their own egg shells for their first meal. In the photo above you can see newly hatched larvae feeding on the eggs. I knew something was wrong with this photo but it took a few moments for it to dawn on me that the eggs in the photo have not hatched.

Note the empty (white) egg shells on the left

A few centimetres away you can see the empty eggs shells where the larvae have come from. They have then moved along to feed on their unhatched siblings.

Sibling cannibalism among ladybirds is not unusual. In fact it can be quite common, particularly if there is a shortage of food. It's a mechanism which appears to allow at least some of the ladybirds to get a good start in life as opposed to them all going hungry and dying off.

Larval Moult

This one is doing well. It has shed it's skin and entered another stage in it's development. You have to wonder how many siblings and cousins have helped it to get to this stage.


A larger (probably final instar) larva.


A pupa which looks ready to emerge


A newly emerged adult.



Adult Harmonia conformis


References:

* Osawa, N. 1992.
Sibling cannibalism in the ladybird beetle Harmonia axyridis - Fitness consequences for mother and offspring.
Researches on Population Ecology 34, 45-55.


* Nakamura, K.; Miura, K.; Jong, P.W. de; Ueno, H. (2006)
Comparison of the incidence of sibling cannibalism between male-killing Spiroplasma infected and uninfected clutches of a predatory ladybird beetle, Harmonia axyridis (Coleoptera: Coccinellidae)
European Journal of Entomology 103 . - p. 323 - 326.

11 comments:

  1. well Im just glad Im not a ladybird if thats what your siblings do to you.
    Well spotted alan you must really like the nature side of life.

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  2. Pictures are great. Snails do this often. It is possible that some of the eggs may not be fertilized but may just have yolk in them. Some invertebrates produce such eggs for the hatchlings to feed on.

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  3. Fascinating - but I don't think I like ladybirds as much as I did before!

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  4. Interesting. And not quite so fraught as human cannibalism, with its many deniers.

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  5. Thaks Mystery - Sure do - endlessly fascinating and yes - ladybirds are "Well Spotted"

    Thanks AYDIN ÖRSTAN - ...and even some frogs. The eggs in the photo are yellow so they may be infertile or else they may be of a more recent batch.

    Thanks Mick - not as innocent as you thought eh?

    Thanks Tony - There's still a bit of it around but hopefully odds are better being human than a ladybird :-)

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  6. My Goodness.
    Is there some "end of season" virus going around? People are getting morbid in their comments.
    .
    And their Ladybird puns are just dotty.
    .
    Some of the eggs appeared to have black spots on them, which I took to be an indication that they were fertilised. In which case, it is just an issue of the "quick and the dead" (eaten).
    .
    Now if we could complete the festive season with a Cuckoo throwing out a baby bird, we would just about have the set.
    .
    Lovely lifecycle series there, Mosura, especially the adult emerging from the pupal stage.
    .
    Cheers
    Denis

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  7. G'day mosura,
    Great pics of a fascinating process. Well observed. The miniature world of the invertebrates is sure a complicated one when you look closely.
    Thanks,
    Gouldiae.

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  8. Thanks Denis - Some bad puns going around too eh :-)

    Thanks Gouldiae - That, for me, is what keeps it interesting.

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  9. I was doing some traffic survey work outside Eastlands last week and there were very large numbers of these going through their life cycle, including several dozen on the visible branches of one tree. Some eggs were visible but mostly it was juveniles, adults and all stages in between.

    A beetle would emerge, very fragile and pale yellow. Soon after emerging it would extend its wings behind it for a while, and then, over a period of maybe 4-5 hours, the colour spots would develop and the beetle would change from yellow to orange.

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  10. Thanks Kevin - Interesting observations. When they first emerge they are still soft and are described as teneral. They gain their full colour when they harden up. I had noticed spots on the newly emerged one above had not yet fully darkened but did not know how long the process would take.

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  11. Nice photo series.

    Instar determinations are easy in Coleoptera - virtually all species have just three instars. Small, medium, and large :).

    Regards--ted

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