Indigenous bugs help tackle invasive pest

Entomologists raise hopes of fruit growers troubled by the woolly whitefly

July 15, 2020 10:54 pm | Updated 10:54 pm IST - GUWAHATI

Ladybird beetle grub feeding on woolly whitefly.

Ladybird beetle grub feeding on woolly whitefly.

Two types of ladybird beetles are among the three indigenous bugs found to be the biological weapons against a Caribbean-origin enemy of Indian fruit farmers — the woolly whitefly.

According to the Indian Council of Agricultural Research (ICAR), pests damage 30-35% of crops in the country annually.

Among the newest of 118 exotic pests troubling farmers in India, particularly fruit growers, is the woolly whitefly first described from Jamaica in 1896 and noticed in Florida, U.S. in 1909.

This whitefly ( Aleurothrixus floccosus ) is invasive and polyphagous, meaning a creature that feeds on various kinds of food.

ICAR’s National Bureau of Agricultural Insect Resources in Bengaluru had in 2019 reported the spread of the pest from the Caribbean island through transportation of infested seedlings.

Guava at risk

That year, the pest was recorded from guava plantations in Kozhikode district of Kerala, Ramanagara, Mandya and Bengaluru Rural districts of Karnataka and Coimbatore district of Tamil Nadu.

In what could provide relief to fruit farmers, a team of entomologists from the Centre for Plant Protection Studies at the Coimbatore-based Tamil Nadu Agricultural University zeroed in on three indigenous bugs that can control the pest by devouring them.

The research by K. Elango, S. Jeyarajan Nelson, S. Sridharan and A. Aravind was published in the latest edition of Bionotes , a journal for research on life forms.

“Management of exotic pests is crucial for India’s farm economy, but it is important to employ economically viable and environmentally sound measures. So we focussed on native predators for natural control of the woolly whiteflies,” Mr. Elango told The Hindu .

Also called citrus whitefly, the woolly whitefly of neo-tropical origin is found across the warmer parts of the world.

It has been found to attack some 20 plant families in India, exhibiting a strong preference for guava.

The entomologists found some indigenous bugs feeding on this whitefly in a guava orchard near Coimbatore. The bugs were collected and studied in the laboratory.

“Two of these indigenous predators were ladybird beetles of the Coccinellidae family and one was the green lacewing fly from the Neuroptera order,” Mr. Elango said. These insects having four life stages — egg, grub, pupa and adult — complete their life cycle in 30-40 days. The bugs fed on the woolly whiteflies during the active grub stage for 10-12 days, devouring more of the flies as they grew.

“We found that a tiny predator can eat 200-300 woolly whiteflies throughout its growing stage. We made an attempt to mass multiply these insects for controlling the dominance of the invasive pest,” the entomologist said.

The crop damage and yield loss due to the alien pest is yet to be studied.

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