Red weevils pose serious threat to Egypt's palm trees
Red palm weevils, tiny insects that burrow into palm trunks and devour the trees from within, are becoming a nuisance to date palm farmers. Infestations can often go unnoticed until weevils have hollowed out the palm trunk, interfering with the flow of nutrients through the trunks and killing the tree.
"The big thing is that the insects are not seen and the infestation is not recognized, and then suddenly a tree collapses," says Mohamed Samir Abbas, a researcher at the Plant Protection Research Institute in Giza.
The blight, said to be native to Africa and India, first appeared in Ismailia in the early 1990s. Since then, infestations have spread throughout Egypt's agricultural regions.
Though no official statistics exist, experts estimate that up to 25 percent of Egypt's 12 million trees have been infested.
However, farming practices such as over-irrigation exacerbate the problem and make the palm trunks ideal homes for weevils.
Ridding a date grove of a sick or dead tree can prove tricky. If the tree is killed by an infestation, the entire palm should be torched, otherwise the tenacious weevils can infect nearby trees or farms.
Adult weevils can fly up to 900 meters at a time, and travel up to 7km in three to five days. They are difficult to kill with traditional pesticide sprays.
Pheromone traps have been somewhat successful. The traps are filled with a mixture of chemical scents and date oil and half buried in sand on the farms to lure pests away from the trees. When the insects land in the buckets they drown in water at the bottom.
Yet these traps, which need to be replaced monthly, are far more expensive and labor-intensive than other methods. Instead, many farmers rely on pesticides, which fail to penetrate the center of the tree where the insects live. Abbas advocates injecting palm trees with insecticides, particularly during the breeding season in April and May.
But even that has its drawbacks. Heavy use of pesticides erodes soil quality, and can contaminate fruits and vegetables. Pests eventually build up a resistance to the toxins, forcing farmers to rely on more chemicals.
Ahmed Zeitoun, an agricultural expert in Alexandria, says pesticides should be avoided for non-decorative trees. Zeitoun advocates the use of a green method developed by Dr. Nabawy Metwaly, in which a machine makes pressurized injections of bacteria and oil that travel through the trunk and kill the insect.
Existing methods have only had partial success in combating weevils, but new innovations may help track the spread of infestations. The Defense Ministry has developed a machine that scans the tree, searching for the insect's molecular DNA signature. Not only does the machine detect whether or not a tree has weevils, but also where the infestation is spreading within the tree.
Amin Amin, the engineer who developed the machine, won second prize in March in the best new technique section of the third annual Khalifa International Date Palm Awards in the United Arab Emirates.
The Agriculture Ministry has run campaigns to raise farmer awareness and quarantine infestations, according to Dr. Ahmed Anis Saeed, the head of the Plant Protection Research Institute.
“Recently in New Valley we were able to remove 280 unhealthy trees, out of the region's 1.3 million [healthy trees],” he adds.
Experts note that weevil infestations are a worldwide issue. Weevils have been found in over 50 countries, and are widely considered to be the most damaging pest for palms, according to the University of California-Riverside's Center for Invasive Species Research.
According to the center, international trade of live palms is most likely accountable for the spread of the blight. The pest ― moved as eggs, larvae or pupae ― establishes itself easily in new areas because it moves with its food source.
For Zeitoun, the solution lies in better cooperation between palm exporters on an international level.
“We need one program internationally to protect the fruits of date palms without chemicals,” he says. “It's the same whether shipping from city to city or exporting to other countries.”
According to the UN Food and Agriculture Organization's 2001 figures, Egypt is one of the top five date-producing countries in the world, accounting for almost 21 percent of global production. But experts say the impact of red palm weevils has yet to be felt heavily in the industry.
“Of course it affects the date industry in Egypt; but it's not dangerous yet, because it takes an infestation three or four generations before it hollows out a tree and it collapses. We need to treat it when the first generation appears,” Abbas says.