No Rhino beetle says Agriculture

Saturday September 14, 2019 Written by Published in Outer Islands
The Ministry of Agriculture says the alleged beetle is most likely the Red-brown Weevil. MICHAEL WHITE 19091343 The Ministry of Agriculture says the alleged beetle is most likely the Red-brown Weevil. MICHAEL WHITE 19091343

The Ministry of Agriculture says photos of insects found by the Penrhyn community are more likely red-brown weevils than the coconut-shredding rhinoceros beetles they fear.


Secretary of Agriculture Temarama Anguna-Kamana said there are three things that could prove the presence of rhinoceros beetles:
* An adult rhinoceros beetle, dead or alive;
*  V-shaped cuts on open coconut palm leaves in association with noticeable boring holes on fronds or trunks caused by adult beetles entering the crown; or
* Breeding sites with eggs, grubs and/or pupae in coconut tree debris or other organic matter.

Anguna-Kamana said the insect in the worried islanders’ photos was most likely the red-brown weevil, Diocalandra taitensis. It has been recorded in the Cook Islands Biodiversity Database since 2004. 

The weevil was first found in Aitutaki in 1975 boring in coconut palms (dead and injured) by J.S. Dugdale. It is also recorded to be present in Rarotonga.

She said the red-brown Weevil is described in a PestNet summary from 2013 as follows: “This species feeds on coconuts, the larvae boring in the husk and petiole of the fruit. It doesn’t appear to cause too many problems, but it may not have been studied much.”

She said that none of the images provided showed any damage that might be caused by coconut rhinoceros beetles, Oryctes rhinoceros.

Anguna-Kamana said an apology was owed to entomologist Dr Maja Poeshko from the people on Penrhyn who had called her professionalism into question. “Maja advised that she did not find any Coconut Rhinoceros beetles on Penrhyn, but her findings were questioned.”

Marine zoologist Dr Michael White, in a report to Penrhyn environmental group spokesman Wilkie Rasmussen, reported extensive tree damage at the whole width of the motu to ocean side. 

He said it could have been some rhino beetle damage, but most was in the form of a longnose beetle or weevil. When he opened a nikau or palm leaves mid-rib, he found a live beetle inside.

“They tunnel through inside of the nikau stem then part of it falls off,” he reported.

“By the time we see outside damage, maybe attack was going for six months or so. The creature is same shape as red palm weevil Rhychophorous ferrugineus – but it wasn't red and black: perhaps it has other colours.”

He mentioned that he had seen a similar one in Lampedusa, Italy- “when overnight all the nikau hung downwards and tree died. Here we're not seeing that pattern.”

Anguna-Kamana also discounted the likelihood of a Red Palm Weevil, another serious pest. “The adult beetles of this species are much larger (up to 50 mm) compared to the weevil on the image next to the hand,” she said.

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