‘Foreign pest’ threat to tapioca crops in south India

Date:09-22-2020

Even as the Covid19 pandemic has battered the health and economy of the country, entomologists are alarmed at the “unauthorised introduction” of foreign invasive pests, which are destroying Indian crops and causing untold misery to our hapless farmers. Cassava mealybug (Phenacoccus manihoti Matile-Ferrero) is the latest of invasive pests, which has cast a shadow for tapioca (cassava) farmers in the three south Indian states of Tamil Nadu, Kerala and Karnataka. 

“Cassava mealybug recently arrived in India from Thailand, reportedly through some plant material or unauthorised introduction,” Dr Shylesh, principal entomologist, National Bureau of Agricultural Insect Resources (NBAIR), Bengaluru said. He added that this was not the first time that foreign pests have “unauthorizedly” been introduced in the country.“In the last two years we saw coconut rugose whitefly (Aleurodicus rugiperculatus) and fall armyworm (Spodoptera frugiperda), which have reportedly gained unauthorised entry from the Mexican region and Sri Lanka. They have destroyed coconut and maize farms across the country,” said Dr Shylendra.

“This is the first time we have found cassava mealybug in India. It was spotted in tapioca plants in Salem, Dharmapuri along the Karnataka-Tamil Nadu border and Thrissur district in Kerala four months ago. Each pesticide has a label claim. There is no label claim for mealybug in the country since it is a new bug,” he added. 

“The available pesticides don’t enter the body of the mealybug host because of its wax coating. If we use the systematic pesticides, then there is a danger that residual toxicity may remain in the tapioca tuber and produce. They cannot be marketed,” said Dr Shylendra. “In the absence of a parasitoid, entomologists are using Metarhizium and Verticillium fungus to manage cassava mealybug,” he said. The Indian Council of Agricultural Research (ICAR) has sent an MoU to its counterpart in Thailand requesting a parasitoid specifically mealybug. “Bangkok has responded with a similar request for parasitoid on coconut. The importation of parasitoids is looked into by the National Biodiversity Authority of India and the ICAR,” said the chief entomologist.

Tapioca is cultivated throughout the year in India, mostly confined to Kerala, Tamil Nadu, Andhra Pradesh and the North-East. It is a major industrial crop in Tamil Nadu. Sago (small pearl shaped globules), chips and wafers, noodles and starch are some of the products made out of tapioca.