The red palm weevil, a beetle known for its devastating effect on palm trees, can be stopped in its tracks by clove and thyme oil â offering hope of new control options for growers hit hard by the insectâs damage to their crops.
Researchers at the University of Malaysia, Terengganu tested the effect of eight chemicals derived from the two essential oils on feeding by larvae of the red palm weevil (Rhynchophorus ferrugineus). It is one of the worldâs most invasive species and severely affects the date, coconut and palm oil industries.
In a study of 225 larvae over a two-week period, the beetlesâ daily consumption of blocks of sago palm (Cycas revoluta) soaked with either clove or thyme oil derivatives was at least 35 per cent lower than their consumption of untreated blocks. Of the chemical compounds found in these oils, ethers reduced weevil feeding more than esters, and two stood out as particularly effective. These have the potential to be used as targeted bioinsecticides, says the research team.
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âBotanical biopesticides are seen as increasingly important crop-protection tools. This stems, in part, from the reduced availability of synthetic pesticides,â says at Harper Adams University in Edgmond, UK, who wasnât involved in the work.
He says such insecticides derived from natural materials like plants reduce the risk of resistance developing in pest populations that comes with conventional pesticides, and they linger in the environment for less time.
âDespite this, all biopesticides should be integrated within dynamic pest-management programmes and not seen as âsilver bulletsâ,â says Pope.
While a number of products work against red palm weevils under lab conditions, the problem is how to deliver such deterrents, says at the French National Institute for Agriculture, Food and Environment, who wasnât involved in the research.
This study focused on palms that were already infested, he says, meaning some beetles couldnât be reached by spraying the plants with the biopesticide. âThe only solution to reach them is by injection. The injection issue is very complex and requires studies on the possibilities of injectable formulations.â
Another project by researchers at Prince of Songkla University in Thailand characterised the genes behind the red palm weevilâs sense of taste. The findings should further assist work exploring ways to prevent the species feasting on palms, an economically important food source. This team identified 50 taste genes that detect sugar, carbon dioxide and bitter flavours.
Insects
Insects
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