Relationship between mistletoe, birds and butterflies

Tropical mistletoes are semi-parasitic green plants that grow on the branches of trees (above) LINK. Brought in by birds that deposit the sticky seeds on the branch LINK, these seeds germinate and send out a specialised organ, the haustorium, into the host’s tissues (below). The haustorium taps the host’s supply of water and nutrients but the green leaves of the mistletoe manufacture its own food. These plants are thus termed semi-parasites.

Birds love the fruits of these mistletoes as well as the nectar that the flowers provide (below). In taking nectar, the birds assist in the pollination of the flowers LINK. Flowerpeckers LINK, sunbirds LINK, parakeets LINK, hanging-parrots LINK and even bulbuls are attracted to these plants.

The fruits are regularly fed to developing chicks LINK and LINK.

Unfortunately, maintenance crews tend to remove mistletoes growing on the branches of trees by the roadside as well as in gardens. Yes, mistletoes can be destructive to the host trees but there is no need to remove all of them from a tree. Remove them when their growth is excessive but leave some to regenerate back. In this way biodiversity of urban areas can be maintained.

The Malayan mistletoe (Dendrophthoe pentandra) is the food plant of the Painted Jezebel (Delias hyparete metarete), an attractive common garden butterfly (below left: butterfly emerging from pupa), The caterpillars of this butterfly can completely defoliate the mistletoe plant such that the plant can never recover LINK. But this happens only when the mistletoe is not prolific and the caterpillars are plentiful. As such, the Painted Jezebel can be exploited as a natural control of this semi-parasite.

The caterpillars (above right) are attacked by certain wasp species but I have yet to be aware of any documentation of birds taking the caterpillars or the butterflies. Can it be that the colourful caterpillars and butterflies are poisonous to birds?

Allowing mistletoes to proliferate among our roadside trees help increase the biodiversity of our urban areas. These semi-parasitic plants attract birds that take nectar from the flowers and eat the fruits. The plants attract butterflies, whose caterpillars can, to a certain extent, control the former’s excessive growth. The caterpillars as well as the butterflies are food for certain animals but whether birds benefit from them has yet to be demonstrated.

YC Wee
Singapore
July 2013

References:
1.
Lim, F. L. K., 2011. The Singapore mistletoe story: An expose of a botanical marvel. Singapore, Carnegale Press. 116pp.
2. Wee, Y. C. & A. Ng, 2008. Life history of the painted jezebel, Delias hyparete Linnaeus, 1758 (Order Lepidoptera). Nature in Singapore 1: 103-108.

8 Responses

  1. S. Devasahayam

    In Kerala (India), mistletoes were very common earlier on most of the trees along major roads and in homesteads and are visited by flowerpeckers, sunbirds and spider-hunter. There is always great commotion on these plants within a tree and also much display of aggressiveness between the visitors as they chased and darted in between the mistletoe clumps. The plants when in bloom are also visited by iora, tailor bird and leaf warbler, in search of insects, which added to the commotion. However, in recent years, most of the trees in major roads have been cut for widening of raods and the shrinking size of residential compounds do not permit the growing of large trees where mistletoes can survive.

  2. Sun Chong Hong

    I have seen mistletoes growing on small trees such as Coral Jasmine (Nyctanthes arbor-tristis) and grafted White Champaca (Magnolia x alba).

  3. For the past few months, I have been observing 3 nos. of Dendrophthoe pentandra (Malayan Mistletoe) growing on an Albizia saman (Rain Tree) located on a lawn & has a 35m-wide crown. Although these mistletoes have been flowering & fruiting from time to time, I have yet to see any associated birds or butterflies visiting the said mistletoes.

    The only noteworthy phenomenon: Even though this Rain Tree is neither small nor young (it existed since the early 1980s), the impact of the 3 clumps of mistletoes the tree’s health is quite apparent. If there is no heavy rain at least once a week, the branches hosting the mistletoes & several nearby branches will progressively lose their foliage, until the tree becomes half-bare. So far, rain has returned in time such that the tree managed to revive itself. Otherwise, it might need manual watering.

    I have also seen Dendrophthoe pentandra growing on Terminalia mantaly (Madagascar Almond) in a HDB neighbourhood & on Kopsia arborea (Penang Sloe) along a minor road.

    However, the mistletoes are so luxuriant that EVERY tree of the aforementioned species at the 2 locations are severely infested with multiple nos. of the said mistletoes — to the point that the trees have totally lost their original foliage & instead resemble Dendrophthoe pentandra “trees”. Some of the above infested trees may already be dead (or on the way there). Interestingly, I haven’t seen any associated butterflies or birds on/near the mistletoes at these 2 locations either.

    At HortPark’s Golden Garden, there is a variegated Ficus rumphii tree, on which I have previously spotted at least 1 no. Dendrophthoe pentandra. (It seems that excess ones are removed periodically.) The mistletoe(s) becomes more obvious when the tree loses its foliage.

  4. […] Malayan Mistletoe (Dendrophthoe pentandra) grows on the branches of many of the plants in my garden LINK. This semi-parasitic mistletoe is host to the Painted Jezebel (Delias hyparete metarete) and the […]

  5. I have a parasitic mistletoe on my balcony and for the second time in a year there are Lady Jezebel caterpillars feeding on it. The last time this happened they ran out of food and died. This will happen again unless I can find more mistletoe. Any ideas.

    • If you happen to have another similar mistletoe nearby, you can transfer the caterpillars or some of them over. Otherwise you can “cull” the caterpillars to a manageable number (they are voracious eaters) as they will eat up all the leaves before they are ready to pupate. I suppose this is nature’s way of controlling the presence of mistletoe on the host plant.

      Please see… http://www.besgroup.org/2007/09/28/painted-jezebel-distasteful-to-birds/

  6. Thanks for your article. That is great! I have tried to find this answer these few days since I found some caterpillars suddenly appears on my pomergranate trees (HDB Balcony). I have put those caterpillars in a glass jar and given them pomergrande leaves to eat, but they did not eat that leaves and only eat the “special leaves”- the one that I have known is mistletoes after reading your article. That is so amazing! :)

    To link up everything together: I have known that the little bird (now I know this is the sun-bird) have been visited my HDB garden recently and they left mistletoe seed on my pomergranade tree. And the butterflies laid eggs only on that mistletoe and the caterpillar only eat that leave. Now I need to find more food for them (12 of them) and waiting for the day they can get into their pupa. 😀 So excited. My little daughter should be very happy seeing that.

    Once again, thanks a lot for the articles! :)

    Cheers,
    Linh.

  7. […] Obviously the flowerpecker had been eating mistletoe fruits whose seeds are sticky. Being semi parasitic and growing from branches of other plants, the seeds need to be stuck to branches to germinate and develop LINK. […]

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