❗The Silent Pest Invasions Driven by Climate Change

 

One of the effects of global warming has been an increase in pest populations and the appearance of new pests and diseases in agriculture. This is because rising temperature can prompt insects to mature faster, reproduce earlier and cause population explosions. This makes a minor pest a major one. 

 

Pest populations also migrate to new areas where the earlier cooler conditions were not hospitable. The altered weather conditions become favourable to the pests and pathogens that were not adjusted to the earlier habitats. For example, pests that were historically found in the warmer tropical and subtropical regions are now moving north to cooler temperate areas because these have become more inviting thanks to a warming world.

 

The biting cold of our North Indian winters has acted to some extent as a natural regulator, killing off pests and limiting the size of the population and hence the scale of infestations. But now, as temperatures rise and winters become milder, more pests can survive the winter, extend their breeding seasons and expand into regions where colder temperatures previously restricted them. Warming climates are inviting new, often invasive pest species to migrate into agricultural zones where they were previously unknown. 

 

What is urgently needed is an early warning system that can sound the alert as soon as  anew pest is detected in a region. This will enable agencies to introduce measures to tackle the nascent population before it becomes a full blown infestation. The work of breeding new pest resistant varieties should start much earlier though, in anticipation of possible attacks from new pests.  FAO for instance, tracks the movement of the two significant fungal diseases Wheat Rust and Wheat Bunt and warns countries if they are found approaching their areas so that prophylactic measures can be put in place,

 

The scale of the threat from new pests is already alarming. According to the FAO, up to 40% of global crop production is lost to plant pests and diseases every year, costing the global economy more than US$220 billion annually. And the danger could grow significantly as the planet warms. The International Plant Protection Convention estimates that losses in major crops such as wheat, rice and maize due to insect pests could increase by 10–25% for every additional degree of global warming. Even a single unusually warm winter, an FAO-IPPC scientific review warns, can help an invasive pest establish itself in a new region.

 

An ICAR review states that 20–30% of India’s potential crop production is destroyed by insect pests, diseases, weeds and rodents. Another ICAR publication estimates that pests and pathogens alone account for 15–20% yield losses in major field and horticultural crops, while noting that the profile of key pests and pathogens is changing rapidly due to factors including climate change.

 

India has already seen how quickly a new pest can invade its agricultural landscape. Fall Armyworm, a pest native to the Americas, was first officially reported in India in 2018. By June 2019, it had spread to 20 states and affected more than 376,000 hectares.