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rhinoceros beetle larvae


Hugh
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At the risk of being chased off this forum I will admit that as a tropical tree crop agronomist specialising in breeding disease resistant coconut palms, the rhinoceros beetle (Oryctes spp) is a pest.

The particular disease I am concerned with is lethal yellowing and an infected palm will die in 4-6 months, leaving a rotting stem as an ideal Oryctes breeding site.

Unless the palm stem is cut down, cut up and destroyed by burning the adult beetles that emerge go directly to the disease resistant seedlings that I have supplied and that the farmer has planted and many seedlings die as a result.

It has been suggesed that instead of removing the dead palm stems the farmers could be encouraged to regularly collect larvae before metamorphosis and cook them to produce chicken feed or even human food.

At a stroke the farmer is saved the expense of cutting and burning the old palm stems, has saved the new seedlings from being killed and has produced food for the farm animals, the farmers family or for sale, thereby recovering some of the income that was lost when the coconut palms got lethal yellowing.

Please can anyone say if anything like this has already been tried?

Hugh Harries

Honorary Research Associate

Royal Botanic Gardens

Kew

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I don't know if it has been tried but how does one get to the larvae easily if they're up in the tree?

How is Oryctes nasicornis listed as a pest if larvae only feed on the palms after a disease has killed the plant? Wouldn't a pest need to attack living trees, not already dead ones?

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I don't know if it has been tried but how does one get to the larvae easily if they're up in the tree?

How is Oryctes nasicornis listed as a pest if larvae only feed on the palms after a disease has killed the plant? Wouldn't a pest need to attack living trees, not already dead ones?

The situation under investigation is a combination of two pests and I don't think it has been described yet (see reference below).

The rhinoceros beetle can defoliate palms of any age or height, rarely killing adult palms but extremely dangerous to seedlings and young palms.

What is killing adult palms of any height is coconut lethal yellowing disease and it can wipe out an entire plantation in 4 years, leaving only the topless stems.

These have to be removed otherwise the beetle larvae have an almost unlimited food supply and when the adults emerge they attack seedling coconuts, planted to replace those destroyed by lethal yellowing.

I want to know if the larvae are edible because that would encourage farmers to "harvest" them - thereby eliminating danger from the adult beetle and perhaps generating an income until the seedling coconuts come into bearing.

Hugh

The following is from Mariau, D. (1999) The Insect Pests of Coconut In: J.G. Ohler (ed) Modern Coconut Management, Part 1, Chapter 7, pp 103-116

<http://ecoport.org/ep?SearchType=earticleView&earticleId=127&page=1307>.

"From the axil of a young leaf, the adult bores a tunnel through the spear. When opened, the affected leaves show a V-formed cut. In severe and repeated attacks (the tunnels may reach a length of 1 metre), defoliation may be serious, even in adult palms. The palms are rarely killed, except under conditions that are particularly favourable to the insect. In young palms, however, this is not the case, as the tunnels often reach the tissues near the meristem of the growing point, causing serious deformations of the stem and, if the meristem has been affected, resulting in the death of the palm.

The larvae live in decomposed wood and in compost, where they complete their development through three stages. Their cycle covers about 3 months. The larvae are curved and are white-greyish, with a head equipped with powerful, hardened jaws. The pupal stage, which takes about 20 days, is passed in a hole cut in the wood, or within a fibrous cover."

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There are many cultures around the world that eat coleopteran larvae (out of banana roots, gum trees, rotten logs...). Usually they are loaded with nutritious oils and fats, of course proteins too. The only thing I can think of is if the larvae live on seeds or fruit that is harmful for humans to eat. I don't think coconut palm wood would be bad for humans to eat since I don't think palms have chemical defense in them like many conifers and such. I don't think that they, themselves, secrete any defense like some adult beetles. I would eat one if I had a chance...go ahead give one a try!

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Thanks but I'm not living near any affected coconut palms. I'm in England, but I am advising an overseas plantation and I would like to find if a company exists anywhere that is already processing beetle grubs for local consumption or for export.

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