Saturday, 5 February 2011

Bristol Mantids 5: The prettiest of them all

Perhaps the most beautiful of all mantids are the various species of flower mantids belonging to the Hymenopodidae. These are among the most specialised (and tricky to keep) of all mantids, and get their name from the camouflage they use to conceal themselves in their favourite perches, the petals and flower stems of various flowers. Mostly small to very small mantids, they are specialist predators of butterflies, bees, and other pollinating insects, and require a fairly specific diet in captivity – crickets will mostly be ignored for example.

The flower mantis we have on show at Bristol, the Banded Flower Mantis Theopropus elegans, belongs to a genus of three species closely related to the true Orchid Mantis, Hymenopus, and is widely distributed in South East Asia. It is a forest species, and is seldom seen in the wild, probably because of its excellent camouflage – even the ones on show at Bristol are hard to spot unless you know what you are looking for). It also seems to prefer the canopy, where it doubtless uses the flowers of epiphytic plants as its hunting sites. One odd feature of the species is that it is quite variable, usually with varying amounts of pink added to the basic green-and white pattern. This may be environmentally determined, at least partially – keeping nymphs against various coloured backgrounds would be an interesting experiment.

Some of the mantids I have talked about earlier in this series can be kept in group. T.elegans is definitely not one of them – they are highly aggressive to other mantids which are rivals for their food supply. Their main predators, apart from each other, are probably spiders, especially the crab spiders that have a similar hunting strategy to the mantids and live near or within flowers.

In the Butterfly House at Bristol you can see how many species of butterfly spend a considerable time inspecting a flower before settling on it to feed – they are checking for spiders and mantids before they risk landing. Since most tropical flowers are open for only a day or two, this means that the mantids have to be constantly on the move, looking for newly opened flowers that are likely to attract the most pollinators. The presence of predators at pollination sites is an aspect of plant biology that I do not believe has been much studied – it would be interesting to examine flowers for possible mechanical or other means they use to deter predatory insects. I wonder whether the tendency for some orchids to remain open for several weeks is an adaptation to ensure that a pollinator eventually ‘makes it through’ the ring of predators to successfully complete the process.

The various Hymenopodid mantids are quite tricky to keep in captivity. Being small species, never more than 5cm or so long (half that for males), providing the correct food can be difficult. Newly hatched nymphs will take fruit flies, larger ones may take houseflies or wax worm moths, or wild caught insects (avoid any that may have been exposed to pesticides). Allowing the feeder insects to feed on fruit juices or sugar solution before being fed to the mantids may help, as their wild prey would contain both pollen and nectar in the digestive system, and these may supply essential nutrients for these specialised predators.

This brings to an end this series on the mantids we have at Bristol – next week a report from our first Research Colloquium of the year on the current situation of conservation in Madagascar – it is not good news I fear.

For an account of wild T.elegans in Singapore, see here:

(image from photobucket)

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