Tackling the locust menace

Desert locusts, a type of grasshopper, are the most destructive of all the pests. They are also very prolific breeders and voracious eaters, devouring any vegetation that comes their way. Moreover, they are good fliers and if aided by winds can cover up to 150 km in a day to migrate to areas across countries and geographical regions.

Unsurprisingly, therefore, the current locust outbreak, spotted first in East Africa in March 2019, surfaced later in areas around the Red Sea and Southwest Asia, including Iran, Afghanistan, Pakistan and India. Thousands of hectares of cropland have already been ravaged by locusts in the Indian states bordering Pakistan — notably Gujarat, Rajasthan and Punjab. Of late, it has spread to the Sirsa region of Haryana as well. Though the timely response by the central and state authorities, coupled with efforts of the vigilant farmers, have managed to prevent the locust situation from getting out of hand, the threat is not yet over and perhaps the worst is still ahead.

According to the United Nations Food and Agriculture Organisation (FAO), the recent heavy rain in the sou­thern coast of Iran, where locust swa­rms have already laid eggs, have created conditions conducive for them to undergo couple of additional breeding cycles. This might lead to exponential proliferation of their population in coming months. Migration of some of them to the India-Pakistan region cannot be ruled out. Besides, some locust flocks already present along the India-Pakistan border have also found fa­vo­urable soil moisture regime for breeding, thanks to overabundant winter rains this year. This is bad news for agriculture. Pakistan has already declared a national emergency over locust outburst in Sindh, South Punjab and Khyber Pakhtunkhwa.

In India, locusts have been noticed since last June. Gujarat and Rajasthan have witnessed tangible crop damage due to them. Punjab and Haryana have begun to feel the pinch now. The Ra­ja­sthan government has formally ap­p­ro­ached the Centre to treat the locust on­slaught as a national calamity. The agriculture ministry, which is assisting the affected states in combating this menace, is planning to widen this fight by inviting 30 locust-infested countries to prepare a joint road map for coordinated international action against locusts.

The FAO, which is monitoring the locust situation in various regions, at present, is focused more on Africa where the infestation has assumed perilous proportions. The locust swarms in some African nations have become so intense that one cannot see the sky. The global body has sought liberal donations to cope with this scourge.

Locusts are, indeed, hard to control because of the huge magnitude of their swarms and their unique propagation technique. The females lay clusters of eggs, encapsulated in pods, below the soil surface by digging holes, which are later covered with soil. This makes it difficult to destroy the eggs to stall the multiplication of locusts at this stage itself. The nymphs and adults tend to get scattered over vast stretches, necessitating simultaneous control measures over large contiguous areas. Only specialised organisations and government agencies can undertake such operations. Moreover pesticides are required to be applied in concentrated doses through vehicle-mounted or aerial sprayers. Special precautions are needed to save humans, livestock and other non-targeted fauna from the pesticides.

Some bio-pesticides, such as neem extract and certain types of fungi and bacteria, have also been found to be ef­fective against locusts, but these take much longer, often a week to 10 days, to show results. By then, the damage is usually done. Some other bio-control agents and natural enemies of locusts, such as wasps, predatory beetle larvae, birds and reptiles, are also of limited utility because of their slow action. Fa­rmers, on their part, can do little except scaring locusts away from their fields by beating drums and kitchen utensils, blaring out loud noise from loudspeakers and burning fires. But this only shi­fts the menace to the neighbouring are­­as. Effective monitoring for timely warning and prompt large-scale control operations, preferably through aerial spraying, seems imperative for good results. 

surinder.sud@gmail.com