Coconut rhinoceros beetle - update India Minimize

September 2017. 

Following on from the post, the discussion turned to virus versus Metarhizium, and the experience of controlling the beetle in India. 

In India both Metarhizium anisopliae and local strain of Baculovirus oryctes has been tried on CRB, as well as the use of the pheromone traps of Sime Darby and PCI. The results have been as follows:

1) Sime Darby pheromones are ineffective in this tropical region - the sachet does not last long not even for 2 months as stated by the supplier. May be because of high temperature. The bucket (Plastic) does not catch the beetles. This increases the pest incidence in the nearby areas where the trap is tied. There is a paper on this aspect in THE PLANTER, KUALA LUMPUR.

Pest Control India (PCI) has come out with some changes in the trap design which is more effective compared to the Sime Darby design. However, this also does not last long. These traps may not be a viable solution for pest management.

2) Green muscardine fungus, Metarhizium, proved effective in our trials. We used the strain of CPCRI, Kasargod, Kerala, India. It controlled all the stages of the beetle, i.e. grub, pupa and adults. However, there was no effect on eggs. It was even found effective when used with Trichoderma viride as the latter is found to have good compatibility.

Oryctes virus did not give good results as we could not get infection even after following all the methods of inoculation, including forced swimming, direct application, etc. Application of Metarhizium anisopliae @10000 spores into the FYM pits, on dead logs of host material and even in the crown, recorded positive results. At the same time, it did not cause any harm/mortality to the earthworms in vermicompost pits.

3) Application of lambda cyhalothrin in the crown proved effective in reducing pest incidence. 

4) In fact, we got good reduction of the pest when coconut was used as a border row to oil palm. This could be due to palatability. In coconut, the beetle commonly attacks the tip of the leaves where as in case of oil palm it is the leaf petiole. Oryctes migrates from oil palm to coconut. Since the petiole region ion oil palm has greater amounts of lignin perhaps that's the reason infestation is less on oil palm compared to coconut. Similar observations were made for the coconut black headed caterpillar.

Another member said that in the Pacific the virus works best on the Pacific strain of beetle, but not the Guam strain. For that the only control seems to be destruction of the breeding sites, which is hard work.