Unsystematic and belated spraying of pesticides is the main reason for the explosion in the population of whiteflies in Tehran in the past several years, since it has led to a decline in the numbers of natural predators, according to the head of the Tehran City Council’s Environment Committee.
Speaking to ISNA, Mohammad Haqqani added that Tehran Municipality’s measures in the past few years to control the population of insects besieging the Iranian capital have failed to put an end to their onslaught.
In the absence of natural predators, the whiteflies spread freely across the city, which grows hot in the summer and is home to plants favored by the pests.
Experts have repeatedly said that the best solution to control the population of the insects is to grow and release the pests’ biological predators that are collectively known as parasitoid wasps.
However, “excessive use of non-organic pesticides is the reason behind the annihilation of the predators of whiteflies and disturbance of the cycle in nature”.
Whiteflies have been a nuisance for Tehranis every summer in the last three years.
The silver leaf whitefly is one of several whitefly species infamous for their devastating impact on farmlands and plants but they are harmless to humans.
Also called the “sweet potato” fly, these sap feeders reduce the overall vigor of plants with their feeding. As infestations become severe, they cause plants to yellow and lose their leaves prematurely.
Whiteflies also produce large amounts of sticky, sugary honeydew, which is colonized by black sooty mold, reducing the marketability of whitefly-infested crops.
Pointing to scientific literature, Haqqani suggested that the best time for pesticide spraying is early spring and winter, when the larvae are developed into whiteflies. He urged TM to observe scientific principles in taking pest control measures.
About two years ago, TM began employing a method known as integrated pest management to control their population without endangering public health.
The University of California, a leader in IPM, defines the method as an eco-friendly strategy that focuses on long-term prevention of pests or their damage through a combination of techniques such as biological control, habitat manipulation and modification of cultural practices.
Washing out the host plants and modifying trimming and pruning methods have been undertaken by Tehran Municipality, but clearly these have not been enough.