At the time when the country is fighting COVID-19 pandemic, an uninvited problem in the form of “locust plague” is decimating the standing crops. Not once, but repeated attacks on the crops after the first attack reported recently in December 2019. This locust attack is reported as the worst attack in the last 27 years1. The locust plague destroyed over 25,000 hectares of crops in Gujarat in December 2019 alone. It has caused 33% damage2 to the standing crops in several districts of Rajasthan, Panjab, Haryana, and Madhya Pradesh recently. And, the locust swarm is expected to attack the northern part of India yet again.
Locusts are similar to grasshoppers but have different behavior and life cycle. During the solitary lifestyle, the locusts feed on the patchy areas of land and avoid contact with each other3. The lifestyle changes to gregarious (group) phase due to over-crowding in the rainy season. A swarm containing millions of insects travel several thousands of kilometers and devastate the crops on their path to avoid a threat of cannibalism during the over-crowding.
The current methodology to fight this menace is the use of pesticides. Dichlorvos (DDVP)4 is a potent insecticide and is used to kill the locusts. A drone or helicopter, equipped with high-power imported spraying machines, is used to spray the pesticide on locust swarms. One can imagine the ill-effects of such powerful insecticides on the environment and inhabitants. As per the European Chemicals Agency (ECA), the Dichlorvos is fatal upon inhalation and is a highly toxic pesticide5. This pesticide is thus banned as a plant protection product by the European Union6. The Government of India had also banned the new registration to manufacture it. A complete ban is expected to be in place by December 31, 20207. Many beneficiaries argue that prohibiting the pesticide would negatively impact the country’s food security due to lack of alternative solution. However, the land contamination by this pesticide and direct/indirect consumption would affect the people severely in the long-term. Don’t we have an alternative solution to this problem? The earliest records of locust plague is mentioned in Atharvaveda. It puzzles any curious mind on how our ancestors tackled this menace in the absence of toxic pesticides.
Neem (Nimba, in Sanskrit) is found to be the forgotten ancient solution by the Indian farmers to withstand the crops against the periodic locust infestations. Although the medicinal benefits of the Neem are known from the ancient Sanskrit texts of Ayurveda, the modern scientific understanding made specific observations to the “Locust Swarms”. Indian scientists, RN Chopra and MA Hussain, in the 1920s reported that a 0.001-percent aqueous suspension of ground neem kernels repels the desert locusts8. It is yet again proved the efficiency of this method in the 1960’s by S. Pradhan through field demonstration. The method was demonstrated by spraying the suspension prepared by mixing the ground-up neem kernels with water over different standing crops. Interestingly, the locusts did not disturb the crops for up to 3 weeks after the treatment8. Prof. Heinrich Schmutterer, a German entomologist, was drawn on this work and revealed a similar effect of Neem through his studies on the behavior of treated locust nymphs and beetles9. Extract from Neem leaves also might be adequate to safeguard crops from the locust swarms, but it requires further investigation.
Some more exciting ideas have surfaced at the time of writing this article. A “mud-spray” or “soil-spray”10, an out-of-the-box technique, is proposed by Chintala Venkata Reddy, a famous organic farmer, who received the Padma Shri award this year. He suggests mixing the subsoil from the farms with sufficient water to bring it to soft consistency for spraying over the crops. Mr. Reddy suggested this technique earlier for improving the plant growth, for driving away the pests and insects, and for crop acclimatization11. Mr. Reddy argues that locusts don’t eat the soiled crop as they can’t digest. Spraying water afterward will help in removing the mud.
People in Jaipur were seen bursting firecrackers to drive away the locusts12. Although attacking millions of flying locusts with crackers appears quite amusing, the method seems logical if one has sufficient knowledge on the locust behavior. Past studies showed that disturbance to the collective motion of the locust bands could lead to cannibalism13, which results in the self-destruction of the plague. Further studies based on the collective behavior of locusts are thus required in effectively attacking the locust swarm to favor the cannibalism.
Out of many local ideas presented above, only some of them may require rigorous experimentation and studies to prove their effectiveness. The farming community needs to quickly adopt the existing and tested ideas to save the harvest from the locust plague, and the governments must play a responsible role in this.
- https://timesofindia.indiatimes.com/india/iaf-choppers-to-be-pressed-into-service-for-anti-locust-ops/articleshow/76242202.cms
- http://www.xinhuanet.com/english/2020-02/23/c_138810325.htm
- https://phys.org/news/2012-08-solo-sociablehow-locusts-cannibalism.html
- https://www.thehindubusinessline.com/economy/agri-business/pesticide-to-tackle-locusts-attacks-to-be-banned-from-december-31/article30894172.ece
- https://echa.europa.eu/substance-information/-/substanceinfo/100.000.498
- https://www.pan-europe.info/old/Resources/Links/Banned_in_the_EU.pdf
- https://www.thehindubusinessline.com/economy/agri-business/pesticide-to-tackle-locusts-attacks-to-be-banned-from-december-31/article30894172.ece
- National Research Council. (2002). Neem: a tree for solving global problems. The Minerva Group, Inc.
- Schmutterer, H. (1990). Properties and potential of natural pesticides from the neem tree, Azadirachta indica. Annual review of entomology, 35(1), 271-297.
- https://telanganatoday.com/telanganas-desi-mud-solution-to-check-locusts
- https://telanganatoday.com/a-green-ray-of-hope
- http://collectivebehaviour.com/locust-swarms/
*This article is written by Dr. Tadikonda Venkata Bharat, Associate Professor, IIT Guwahati
