Indigenous Bt species to curb pests and mosquito larvae

Nadeesha Warnasuriya and Disna Mudalige

Sri Lankan indigenous species of Bacillus thuringiensis (Bt) have been cultured and isolated by Dr K.R.R. Samarasekara and co-researchers of the Industrial Technology Institute (ITI) and the disclosing of their research outcome took place at the Hilton Colombo commemorating the 10 years service of the National Research Council to the Nation and its scientific community.

Bt is an environmentally friendly bacterium capable of killing pests and insects and two of Bt isolates was identified against lepidopteron pests of cabbage and cauliflower. It has been proven at laboratory and field levels that it is effective against diamondback moth, semilooper, cabbage head caterpillar and cutworm. Meanwhile, mosquito larvicidal activity of these indigenous Bt has also been proven for all larval stages of Aedes aegyptie (Dengue), Culex quinquefasciatus (Filaria and Japanese encephalitis) and Anopheles tessellatu (Malaria).

“Bacillus thuringiensis incorporated products, invert oil emulsion and liquid suspension for cabbage and cauliflower and mosquito larvicidal products such as liquids, powders, granules, pellets and slow releasing products were developed for field application,” Dr. Samarasekara added. She emphasized that the fish toxicity of insecticidal Bt isolates was also evaluated using food fish and indigenous species and found that tested Bt isolates have no fish toxicity.

Subsequently the research outcome will lead to reducing the load of chemicals in the environment foe insecticidal usage and thus improving agricultural productivity through organic farming. At the same time the mosquito larvicidal product has the potentiality to control mosquito population resulting in a reduction of Dengue, Malaria, Filaria and Japanese Encephalitis.