The mealybugs that have been feasting on our Araliya trees might just have met their nemesis. A neem spray being developed by Sebrin Lanka Ltd combines neem (S. Kohomba) extracts with citronella oil to create a natural pesticide. The spray is believed to repel more than 200 pests of which the mealybug is one, says Dr. Lakshmi Arambewela, the chemist at the head of the Sebrin Lanka team.
If the spray performs as promised it could also aid farmers who are battling the insects on their fruit and vegetable plots – the mealybug is known to enjoy more than its fair share of papaya and guava.
|An affected plant
“The unique feature of neem products is that they do not directly kill the pests, but alter the life processing behaviour in such a manner that the insect can no longer feed, breed, or undergo metamorphosis,” explains Dr. Arambewela, adding that the spray targets only the insects that actually ingest it by eating the leaves. Butterflies and ladybugs, for instance, remain unaffected.
The spray has not yet received the official seal of approval, though. The Ministry of Agriculture says it will not sanction its use until the product is certified by the Pesticide Registrar in Peradeniya. The company says it is yet to apply for this certification as it requires more extensive field testing.
In the meantime, the insects are expected to proliferate in the coming dry season ahead, says the Agriculture Department’s Paddy and Plant Protection instructor Udeni Mangalika. She says a dearth of natural predators in the country has left many of the plants defenceless.
After The Sunday Times published the story about the pest attacking Araliya trees last month, the Ministry has been flooded by calls from Colombo residents who have spotted the strange waxy white layer that causes harm to their plants. First the leaves succumb before eventually falling off, leaving the branches barren.
The pest, which also causes secondary infections like mould and rust, must be caught early if it is to be contained. Outside Colombo, areas like Gampaha have reported some success in curtailing the spread, mostly thanks to early detection followed by measures like spraying water at high pressure from a hose, spraying soap water, sprinkling ash, or kohomba leaf juice regularly.
The Agriculture Department has responded by arranging to have the trees sprayed with chemical pesticides, free of charge. However, where houses are close together this is not advisable. “We are working at a divisional level to try and tackle this problem,” says Ms. Mangalika, adding that because of its non-toxic nature the neem spray might be suitable for use in densely populated urban areas.
The company itself says it will be waiting to run more field tests before it applies for the status of a bio-pesticide and that the spray is currently available in limited quantities as a herbal product. It is currently available in a concentrated form, wherein 5 millilitres have to be diluted in one litre of water before use. The product must be sprayed in the evening as it is sensitive to light, but the company claims field tests have shown results in as little as two days.
Affected trees may be reported to the Department of Agriculture on 011-2607135 or 011-2320303 (Western Province), 034-2222440 (Kalutara) and 033-2222164 (Gampaha). Those wishing to contact Sebrin Lanka may could do so on 0771817094.