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Garden Acraea (Acraea horta)

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Johan van Rensburg
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Garden Acraea (Acraea horta)

Unread post by Johan van Rensburg » Mon Oct 17, 2016 3:28 pm

Funny how stuff works out… For now this particular story is about the partnership between Wild Peach trees (Kiggelaria africana) and the Garden Acraea (Acraea horta). I say "for now" because in time a cuckoo may become part of the story line...

The tale goes back two years when I changed to indigenous gardening and part of the effort included the planting of a pair of evergreen Wild Peach trees. I say “a pair” because Wild Peach trees have male and female flowers blooming on separate trees. Also, these trees produce Cyanoglucosides that make the leaves of the Wild Peach toxic and unpalatable to many large herbivores and is generally avoided by them as a result. However, the appeal Kiggelaria africana had for me as a gardener is that it attracts Garden Acraea which uses it as a host plant for its larva, the start of a complicated event chain.

These caterpillars in turn selectively take the plant toxins onboard and store it in their body tissue to serve as a defence. All stages in the life cycle of the Garden Acraea release hydrogen cyanide (HCN) from their crushed tissues. Birds learn very quickly not to target these creepy crawlies. Cuckoos, on the other hand, are capable of dealing with both hairy caterpillars and toxic butterfly larvae. With hairy critters, the pointed hairs are caught up in the soft lining that cover the wall of the cuckoo's gizzard. Patches of mucous membrane plus hairs peel off periodically and are regurgitated. I am not sure how they deal with the toxic Acraea titbits. Some literature suggest that the cuckoo bites off one end of the insect and slices it open with the bill, and then, it shakes it to extract the toxic matter before swallowing it. With the Acraea larva this suggestion wouldn’t make any sense as the larva secretes the toxic fluid on the outside of its body via the multitude of spines that cover it. So, the fascination of the Wild Peach explained, I can’t wait for the cuckoos to arrive…

Image

About middle September I noticed that the pair of Wild Peach was teeming with hordes of dark caterpillars, devouring most of the leaves. The caterpillar poop deposited around the tree serves as fertiliser and soon the trees started to push new growth. Although I had been on the lookout for the pupa stage, it took me all of one month to find the first pupa of the Garden Acraea. In the last week I started noticing an increase in the numbers of the bright orange butterfly floating around in my garden. It had to be as a result of some of the thousands of larva that have been stripping my Wild Peach trees of its leaves, completing its life cycle by first morphing into a pupa (chrysalis) and then emerging as the bright orange creatures floating around in my garden.

Image

To my mind, the pupa stage is the most remarkable of a butterfly’s life. As soon as a caterpillar reaches full size, it transforms itself into a pupa, attaching its rear end to some part of the surroundings with a silky anchor. From the outside the pupa looks as if it is just resting, but the inside is where all of the action is. Within the chrysalis the old body parts of the caterpillar are undergoing a remarkable metamorphosis to become the beautiful parts that make up the butterfly. Tissue, limbs and organs of a caterpillar have all been changed by the time the pupa stage is finished.

I'll be keenly watching this particular pupa in the hope of witnessing the emergence of the butterfly signalling the final stage of a remarkable creature’s life cycle.

As I said earlier, it was the increase in the numbers of Acraea horta that alerted me to start looking for the pupa. It obviously follows that other opportunities would arise, like finding a female depositing her eggs…

Image

Image

…and the reproduction drive…

When in the fourth and final stage of their lives, adult butterflies are constantly on the lookout to reproduce and when a suitable female is located competition to claim mating rights is fierce. Often the cluster of males wrestling for her affections becomes too heavy and she looses her grip resulting in the whole bunch of butterflies falling to the ground where the party continues.

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All this floating about trying to outmanoeuvre the competition makes a man hungry…

Image

(…caught with proboscis in the nectar jar!)

Check out that eye!

Butterflies have a pair of spherical compound eyes, each comprising of up to 17000 individual light receptors each one with its own microscopic lense. These work in unison to produce a mosaic view of the scene around them.

The butterfly is extremely efficient at detecting movement and at gauging the distance of an approaching predator, enabling it to take immediate evasive action. The sensitivity to changes in their visual field, combined with a high flicker-vision frequency of about 150 images per second help butterflies to piece together the thousands of elements of the mosaic image produced by the compound eye. The compound eyes of butterflies also provide them with almost 360 degree vision. They can see everything at the same time, so they can accurately probe into flowers in front of them, and at the same time devote equal concentration to detecting threats from behind. Butterflies can see polarized light, enabling them to determine the position of the sun, even when it is partly hidden by cloud. This lets them relate their position to the sun and use it as a compass when moving around their habitats.

Butterflies are ultra-sensitive to UV as well as visible light. Flowers have ultra-violet patterns that are invisible to humans but which can be recognised by butterflies. These UV patterns guide butterflies to the source of nectar in much the same way that runway lights guide an aircraft in to land.
Last edited by Johan van Rensburg on Wed Nov 16, 2016 5:58 pm, edited 3 times in total.
727 Latest lifers: Hartlaub's babbler, Chirping cisticola, Coppery-tailed coucal, Red-billed spurfowl, White-browed coucal, Scharlow's turaco, Copper sunbird, Long-toed lapwing, Eastern bronze-naped pigeon, Malagasy pond heron, Soft-plumaged petrel.

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Re: Ganden Acraea (Acraea horta)

Unread post by MATTHYS » Mon Oct 17, 2016 3:52 pm

Very interesting info/story, thanks Johan 8) !
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Re: Ganden Acraea (Acraea horta)

Unread post by Ladybirder » Mon Oct 17, 2016 4:57 pm

Thanks for the info Johan and wonderful pics :clap: :clap:

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Re: Ganden Acraea (Acraea horta)

Unread post by Karin Mitton » Mon Oct 17, 2016 5:53 pm

Wonderful story, and spectacular photography!

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Re: Ganden Acraea (Acraea horta)

Unread post by arks » Tue Oct 18, 2016 10:12 am

Fascinating, JvR! :gflower:
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Re: Ganden Acraea (Acraea horta)

Unread post by DinkyBird » Tue Oct 18, 2016 11:00 am

As always, a great story teller, and photographer - that even had me read the entire post, and learn a great deal about a subject I would normally just glance over.

Thanks JvR :gflower:
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Re: Ganden Acraea (Acraea horta)

Unread post by RemiE » Tue Oct 18, 2016 1:58 pm

Fascinating stuff Johan. Thank you for the beautiful :cam: :cam: and the story behind this cycle.
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Re: Garden Acraea (Acraea horta)

Unread post by Elsa » Wed Oct 19, 2016 8:58 am

Fascinating story with some wonderful pics to illustrate.
Thanks Johan! :clap:

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Re: Garden Acraea (Acraea horta)

Unread post by Johan van Rensburg » Wed Oct 19, 2016 11:54 am

RemiE, Elsa, arks, Karin Mitton, Ladybirder, MATTHYS... thanks for leaving your silky trace to show appreciation of the way this pensioner spends his idle moments! :lol:

DinkyBird wrote: As always, a great story teller, and photographer - that even had me read the entire post, and learn a great deal about a subject I would normally just glance over.


The pleasure is all mine, DB. I love getting diligent, hard-working you procrastinating... :twisted:

In keeping tabs on this celeb, I found four more like it on the same tree. Relocating them every time that I go back to monitor morphing progress of the pupa mostly attached under a leaf, together with their natural camouflage in this leafy milieu caused much frustration. Don't talk about watching paint dry… or grass grow… This is much "tougher"!

So, a plan had to be made. Bits of bright orange string to the rescue.

Image

Now it takes but a minute to check up on the progression of morphing process (mostly imperceptible at this stage) of the five critters.

Literature suggests the chrysalis stage “does not take long”, anywhere from 8 days on, depending on climatic conditions. :big_eyes: With the Manic Mission requiring my undivided attention five days hence, it may turn out that the magic moment for these specific pupae will go unrecorded. (Holding thumbs that they start breaking records…)

In researching this critter, I learnt that the caterpillar tends to wander off the food plant to find a suitable spot to pupate, often quite out in the open. OK, so I should check the immediate area around the Wild Peach trees as well!

The successfully mated female of all acraeas develops a "fertilization plug" (the "sphragium"). Once she is “plugged” males loose interest in her after a cursory glance, leaving her to the important job of depositing eggs, roughly 100 - 150 per batch! :shock:

My Wild Peach trees are going to have a tough time keeping up its growth rate of new leaves this summer… Hoping the cuckoos will soon save the day…
727 Latest lifers: Hartlaub's babbler, Chirping cisticola, Coppery-tailed coucal, Red-billed spurfowl, White-browed coucal, Scharlow's turaco, Copper sunbird, Long-toed lapwing, Eastern bronze-naped pigeon, Malagasy pond heron, Soft-plumaged petrel.

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Re: Garden Acraea (Acraea horta)

Unread post by Johan van Rensburg » Wed Oct 19, 2016 5:05 pm

All we need to do is take a side road off the beaten path of our busy goal-focused life to become aware of new stuff in this wonderful world we live in. And it looks like I'm still going to learn stacks about this common little acraea that is currently leading me on a merry chase...

So, I expanded my search for more pupa of Acraea horta and ended up finding another dispersed horde, some as far as 15m from the original food source and 4m up the side of my house! Now I am spoiled for choice! (Just imagine the wanderlust that drives this epic journey!)

One particular find was quite exciting: an adult larva with its bum-end attached to the wall, but not yet into the change process to pupate. Now I have another specific critter to monitor and perhaps I’ll be lucky enough to record the magic of caterpillar turning into pupa…

Image

As I said earlier in this thread, the pupa stage is where some real magic takes place: one day the caterpillar stops eating and wanders away from the tree where it had spent the last four weeks since emerging from a tiny egg as a minute larva, focused on eating itself to adulthood. At some stage it prepares a silken anchor-hold which it grabs hold of with its hind end. The future of this critter now totally depends on its connection with the silk button. After establishing a firm foothold the chrysalis begins to form underneath the skin. Sporadic twitching and stretching is take place. The caterpillar has started to release enzymes that literally turn most of its own body into goop from which the butterfly will begin to form. The next stage will involve the spines wilting and the skin of the pupa splitting near the head to allow the chrysalis to emerge…
727 Latest lifers: Hartlaub's babbler, Chirping cisticola, Coppery-tailed coucal, Red-billed spurfowl, White-browed coucal, Scharlow's turaco, Copper sunbird, Long-toed lapwing, Eastern bronze-naped pigeon, Malagasy pond heron, Soft-plumaged petrel.

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Re: Garden Acraea (Acraea horta)

Unread post by Elsa » Thu Oct 20, 2016 3:49 pm

I look forward to the next stage of this fascinating process Johan! 8)

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Re: Garden Acraea (Acraea horta)

Unread post by Johan van Rensburg » Sun Oct 23, 2016 8:58 am

Elsa wrote:I look forward to the next stage of this fascinating process Johan! 8)


IT'S HAPPENING! :dance: :dance: :dance:
727 Latest lifers: Hartlaub's babbler, Chirping cisticola, Coppery-tailed coucal, Red-billed spurfowl, White-browed coucal, Scharlow's turaco, Copper sunbird, Long-toed lapwing, Eastern bronze-naped pigeon, Malagasy pond heron, Soft-plumaged petrel.

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Re: Garden Acraea (Acraea horta)

Unread post by Philip1 » Sun Oct 23, 2016 9:51 am

Wow Johan :mrgreen:

Thank you for sharing what we all see with closed eyes. :D
There is nothing like NATURE!

Looking forward to "IT'S HAPPENING!" :dance: :dance: :dance:
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Re: Garden Acraea (Acraea horta)

Unread post by Johan van Rensburg » Sun Oct 23, 2016 12:24 pm

Image

I’m sure my beard grows quicker than this acraea is emerging from its pupa… Not the most comfortable spot to be in for such a long monitoring stint! (5 hours now, and the butterfly looks like it still has a lot of work to do!)
727 Latest lifers: Hartlaub's babbler, Chirping cisticola, Coppery-tailed coucal, Red-billed spurfowl, White-browed coucal, Scharlow's turaco, Copper sunbird, Long-toed lapwing, Eastern bronze-naped pigeon, Malagasy pond heron, Soft-plumaged petrel.

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Re: Garden Acraea (Acraea horta)

Unread post by Johan van Rensburg » Sun Oct 23, 2016 3:08 pm

The butterfly fell out of the chrysalis after seven hours... It has continued wriggling around on the floor... This is an unusually long transformation period, mainly due to complications in the morphing process: some part of the chrysalis has remained stuck on the head and thorax of the acraea... :cry:
727 Latest lifers: Hartlaub's babbler, Chirping cisticola, Coppery-tailed coucal, Red-billed spurfowl, White-browed coucal, Scharlow's turaco, Copper sunbird, Long-toed lapwing, Eastern bronze-naped pigeon, Malagasy pond heron, Soft-plumaged petrel.


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