In a warmer, wetter world, pests are multiplying faster and damaging crops severely

Subject : Environment

Section: Climate Change

Context:

In April, tea planters from southern India sought urgent government intervention, saying that the tea mosquito bug is causing havoc in the most unlikely places.

Details:

The United Planters Association of Southern India (UPASI) has issued a press release that states the tea mosquito bug (species of Helopeltis) is affecting tea production in both low and high elevation plantations in northern and southern states.
In a 2013 study the scientists write that in India, such warming is likely to result in pest attacks on staple crops such as cotton, wheat, barley, oats, rice, pulse crops, maize, sorghum, oilseed and vegetables, on which a majority of the population relies for daily nutrition.
They have identified pests such as mealy bug, whitefly, tobacco caterpillar, cereal aphids and plant hoppers as the major threats to crops, along with leaf folders, Lepidopterous pod borers, spider mites and other kinds of aphids.
The UN Food and Agriculture Organization (FAO) estimates that 15 plant pests have spread and may expand further owing to climate change. The increase in agricultural pests due to climate change directly attacks FAO’s target of achieving 50 per cent food production by 2050 to feed an estimated population of 9.1 billion.

Tea mosquito bug:

The bug, recognised as a serious pest of fruits and tea plantations across the world, is usually confined to low elevation areas.
Now, it is spreading to plantations in high elevation areas.

Increasing presence of pests across India:

Helopeltis theivora, the most predominant tea mosquito bug species in India, is spreading in an alarming form in tea plantations of Tamil Nadu’s Anaimalai and Valparai hills.
- In Tamilnadu’s Valparai hills, the tea production has declined by 50%.
Sikkim has recorded the first infestation of H theivora in red cherry pepper.
H bradyi, which has so far been restricted to Peninsular India, was reported for the first time in the high altitude Tura region of Meghalaya.
H antonii, which causes damage to cashew crops, is now being reported in Gujarat, Chhattisgarh and Odisha.
Tidda (leafhoppers) and silverleaf whitefly (Bemisia tabaci) are damaging the wheat, millets, mustard, vegetables and pulse crops in Rajasthan region.

New challenges:

As these insects and pests are new to the farmers, so they have to face several new challenges like:
- Usage of chemical pesticide instead of organic pest.
- Since farmers are unable to identify the pests, they are unable to take remedial actions.
- Shifting rainfall is causing the stay of pests longer than usual.
- Changes in soil conditions.

Warming, a multiplier:

Unlike humans who have a single generation of about 60 years, insects with shorter life cycles tend to adapt and mutate their DNA at a faster rate.
- It is estimated that the insect’s generation may increase by one to five for every 2°C rise in temperature.
- The insects will attain accelerated metabolic rates, leading to faster consumption of nutrients, and shorten the time of diapause—when insects display reduced food intake due to overwintering.
The impact of warming will profoundly affect aphids—soft-bodied insects that suck into plant saps to deform leaves and flowers.
- About 250 aphid species are recognised as crops pests for agriculture, as they can affect multiple crops of different plant families.
- They are also known to transmit plant viruses.
- Aphids are found across the world and have the ability to migrate up to 1,300 km, typically during spring and autumn seasons.
- Since they are sensitive to changes in ambient temperatures, this will translate to changes in their lifecycle.

CO2 concentration:

The increase in carbon dioxide concentrations in the atmosphere will aggravate the abundance and behavior of herbivorous insects.
Carbon dioxide emissions enable increase in photosynthesis, leading to higher accumulation of sugar and starches on leaves. This may favour insect attacks and their propagation.

Indian scenario:

In India, which is home to 6.83 per cent of the world’s insect species, 1°C rise in temperature would enable them to expand in presence about 200 km northwards and 40 meters upward in terms of altitude.
The areas that are not favorable at present due to low temperature may become conducive with rise in temperature.