May 2011. An email from Samoa saying that although the baculovirus and Metarhizium fungus have been introduced into the country, farmers are still having problems with Oryctes. Are there other control measures that should be considered, such as cover crops, sanitation and use of pheromone?

It was pointed out by a member that the management of Orytes was one of the early successes of biocontrol using pheromone traps and microbial biological controls. So what is the problem today? Are these not working as they were previously?

There were a large number of emails in response.

Chemical control

A member who had worked in Samoa from 1957-1960 recalled that an entomolgist, Paul Surany, came to the Pacific in 1959 and collected some diseased Oryctes larvae which he sent to Germany for identification. There were two diseases, one of which became known as Heidenreich’s disease and another, the name of which was not recalled. The pathogens were later released in Samoa in larval habitats, and were highly successful. Oryctes beetle damage to palms almost disappeared. Before that Oryctes was controlled around the port of Apia by placing sawdust impregnated with DDT into the crowns of trees. This was a tedious job which involved climbing the palms to apply DDT each time a new frond opened, so it was only done around the port to prevent beetles flying onto ships at night. It was not known how successful it was.

More recently, and following the outbreak of Oryctes in Guam, there are reports that insecticides were used, but their application did not produce good results and they were discontinued.

A member from India also mentioned the difficulty of chemical control in oil palm. In that case, phorate granules in perforated sachets are used. Application is a difficult and laborious task, especially as the leaves have spines and the sachets have to be moved frequently as the palms produce two leaves a month. Other methods were used, without great effect:

• Applications of carbaryl dust and Metarhizium to the farm yard manure pits – it demands frequent aplication to be effective
• Applications of coarse sand to the base of the stem in one-year-old palms [Editor: is that to the base of the fronds?]

Cover crops

As for cover crops, they are not planted in Samoa, but wild vines such as Meremia and Mikania cover the breeding sites of dumped rubbish, rotten logs, palms, etc. There was doubt that invasive plants such as these were useful in the control of Oryctes. However, in the early days of the Oryctes control programme in Samoa led by the Samoa/German Crop Protection Project in the late 60s, early 70s, Pueraria lobata was the cover crop of choice in the IPM strategy developed at that time. In response a PestNet member who was working with FAO in Samoa in the late 60s, said that cover crops were not advocated believing that attention to breeding sites was more important, particularly the removal or destruction of decaying coconut logs. The beetles’ abundance was always related to the density of breeding sites, even in the presence of the virus.

IPM

Both Malaysia and the Philippines mentioned a comprehensive set of treatments to manage Oryctes. A member from Malaysia said that FELDA (Felda Agricultural Services Sdn Bhd) successfully uses Metarhizium and pheromone trapping over a 30,000 hectare annual replanting programme. Artificial breeding sites are a part of the strategy. The Philippine Coconut Authority reported successful management in both coconut and oil palm using microbial controls (virus and fungus), pheromones and cultural management for the past 10 years.

Dogs have been reported to have been trained to sniff out breeding sites in Guam. See: ww.physorg.com/news176030615.html. However, the general opinion was that virus, fungus and pheromone together were sufficient to provide good control of this pest. Indonesia reported the experience of one farmer that the nematode, Steinernema carpocapsae, is quite effective as a biological control organism, better than Metarhizium.

A somewhat contrary view on the use of Metarhizium was mentioned by the same member who was working with the FAO (see above). Members of the FAO team never believed that Metarhizium had any major effect in field control. But it worked in sawdust heaps. Others, working with different projects at that time, disagreed saying that it was valuable in control. Also, it is important to point out that the virus works best in large populations as it is transferred beetle to beetle during mating, i.e., it is density dependent.

AgResearch, Christchurch, New Zealand was said to have started some activities with the Oryctes viruses in the Pacific and can be contacted for technical advice.

The virus strain used in India not effective against Oryctes attacking oil palm, and the pheromone was not effective either. It was thought that this was because of the high temperatures and low relative humidities. Additionally, the bucket traps failed; instead of entering the traps, the beetles attacked nearby palms! By contrast, success was achieved in Palawan, Philippines in a 2000 ha plantation using sawdust traps treated with Metarhizium. In addition, two Oryctalure pheromone traps were placed per ha, and every other day beetles were collected. One hundred beetles were collected per trap during the first 4-5 months, with captures starting to decline after 10 months. The Metarhizium/sawdust traps also yielded many infected larvae. As with coconut, pheromone works best in young palms when they are lower than the traps. In mature plantations, there is less success in controlling the beetle.

India, too, recommends Metarhizium for control of the beetle in the breeding sites. See

In Malaysia, artificial breeding sites near pheromone traps are established and treated with Metarhizium (ORY-X powder), with the result that thousands of larvae are colelcted. Thirty to forty per cent of these are infected with Metarhizium. A paper will be presented at the International Conference of Biopesticides
in Chiang Mai (11-16 Dec 2011).

Members also discussed whether chickens, pigs, etc. eat the larvae.

Note, The International Society for Pest Information (ISPI) ([email protected]) is in the process of starting a new wiki site which also has some information on Oryctes and the virus, see, wiki.pestinfo.org/wiki/Oryctes_rhinoceros and wiki.pestinfo.org/wiki/Oryctes_rhinoceros_nudivirus_(entomopathogen).