Day 52 - The Painted Grasshopper and the milkweed - toxic yet sustainable relationship

 Monsoon is the peak time for these grasshoppers, and I found them in abundance on my morning walk today.

This one seemed to be looking at me as I wondered why it was not on a Calotropis.
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In fact it was on Indian acalypha - kuppameini in tamil - the plant which sends cats on a high!  I learnt this interesting factoid from Gayathree's explanations last Saturday on the adyar river trail walk. When cats sniff or chew on these they  become like dogs - playful and fun.  😅

Anyways back to the grasshoppers and the Calotropis.  As I walked down the sparrow alley, I did see one sparrow, but I saw tons of of these grasshoppers, all over a particular milkweed bush.  These grasshoppers just hop around - they are weak fliers..

I counted 46 on this one bush!

They have unusual mating behaviour.  That is the larger female, with the smaller male on top. No matter they are upside down!  The can remain coupled like this for hours or even  whole day!

Another pair, and many others in the background.  Males usually approach the larger females cautiously, and use their hind legs and antennae to tap or touch the female tentatively.  The female could deliver a good kick or push if she's not interested.  

P. pictus is a specialist feeder on milkweed (Calotropis species). These plants contain toxins that these  grasshoppers not only tolerate but sequester in their own body, making themselves poisonous to predators. Its vivid yellow, blue, and green coloration is a danger warning.  

And then on top of everything else when disturbed, the grasshopper exudes a frothy, bitter-tasting fluid from its behind, so I am a bit wary of them, maintaining a respectful distance.  

Like the domino cockroach which I wrote about yesterday, here also, the breeding cycle is related to the monsoon.  They will breed now, and lay eggs soon, and by December the adults will die.  The species survives the dry winter as eggs in the soil. These eggs remain dormant  until the next monsoon cycle, imagine that.

I wondered how the Calotropis benefits from this relationship - after all these grashoppers are feeding on the leaves and flowers. At the same time, if it destroys the host it destroys itself.  So in a way, there is obviously a sustainable relationship between the two, and the Calotropis is "guarded" from other predators by P pictus.

The Carpenter bees are the main pollinators for this milkweed with its magnificent flowers.

So, this grasshopper is a host-faithful specialist and never becomes a pest, and the plant continues to thrive.  If this milkweed disappears so will these grasshoppers, as they are closely tied together.  

I am also fascinated with how the host plant is culturally significant and associated with Ganesha.  Vinayaka chaturthi will soon be upon us and arukku leaves and flowers will be bundled and sold for worship, along with some grasses.  When you pluck leaves or the flower, there is a milky latex which is quite unpleasant, yet it is used - I like to believe that our ancestors knew the value of what we today call weeds.   

Two species - milkweed and grasshopper, sort of unsung and unpretty.  Milkweeds are not just “weeds.” They are keystone plants in dry and disturbed habitats.