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| LOCUSTS: TACKLING THE SURGE | | | Dr. Parveen Kumar, Dr. D. Namgyal
Along with the COVID-19, a global pandemic the world prepares itself for another battle. This battle is for food security that is under threat due to an insect/pest. Unlike the micron-sized virus, however, the new threat is millimeters in size but millions in number; the desert locust. This desert locust is a migratory insect from eastern Africa and Southeast Asia. The multifaceted impact of the desert locust is creating mass panic in an already tenuous situation, especially given its implications for future food security in India.
SPECIES:
There are nine well-recognized species in the world. However in the country four species are found. These include the Bombay locust (Patanga succinct), the migratory locust (Locusta migratorin), Tree locust (Anaeridium sp.) and the desert locust (Schistocerca gregaria) which is very common and most destructive of the three. Desert locusts are a short-horned grasshopper species.
EXTENT AND NATURE OF DAMAGE:
According to a recent report by the Food and Agriculture Organization (FAO), the locust swarm currently affecting parts of India, was responsible for crop infestation in 2,80,000 hectares across 13 countries prior to arrival in India. It entered India through the western state of Rajasthan on May 13, 2020. This year’s attack is the worst seen in 27 years and scientists predict that the crisis will increase as we enter monsoon season. The FAO deems them the most dangerous migratory pests in the world due to their ability to change behaviour and form swarms that consume everything in their path. These swarms prefer arid or semi-arid areas for egg-laying and nymph development. During periods of low density, the locust inhabits a broad belt of arid and semi-arid land which stretches from the Atlantic Ocean to northwest India, spanning 16 million square km in 30 countries. However, as locust density rises, crowding releases serotonin, promoting rapid movement and a varied diet, spawning mass migration. The migration area of desert locust covers about 30 million square km in nearly 64 countries, including parts of the Indian subcontinent. Locusts are voracious feeders, eating up to their body weight daily. They damage crops by devouring all parts of the plants and also by breaking trees by their sheer weight when they settle down in masses. These insects can fly up to 150 km daily. One square km of a locust swarm contains up to 80,000 adults that, each day, consume the equivalent of food for 35,000 people. A solitary female lay about 95-158 eggs. Up to 1000 eggs have been found in a single square meter. A male weighs an average of 2.2 gm and the female 3.2 gm. So, feasting parties of 10 million locusts can devour 200,000 tonnes of green food in just 24 hours.
ECONOMIC AND SOCIAL IMPACT:
Although no locust plague cycles have been observed after 1962, large scale upsurges were reported during 1978 and 1993 in India. Estimated damage was Rs. 2 lakh in 1978 and Rs. 7.18 lakh in 1993. In December 2019, the locusts destroyed over 25,000 hectares of crops in Gujarat. In 2020, the locusts have already been reported to have destroyed crops in 18 districts of Rajasthan and 12 districts of Madhya Pradesh while crops in Uttar Pradesh, Punjab, Haryana, and Maharashtra are under threat of an attack. Given that locusts swarm just prior to the monsoon, this adds economic strain to a tenuous system that relies on the annual monsoon for crop success. Locust plagues also pose a threat to livestock grazers by turning grasslands into barren wastelands. Locust plagues not only rob rural families of their livelihood and income but also take a toll on the lives of women and children. Children often leave school to help their families recover from losses due to locust swarms. Malnutrition was also observed in children post-locust plagues, as locusts consumed the same fodder as domestic cattle, reducing the milk quality produced by the cattle and leading to food insecurity and malnutrition
ENVIRONMENTAL IMPLICATIONS:
In terms of the environmental implications, locusts impact native grazing species that rely upon grasslands and croplands for survival. Swarms consume everything in their path, leaving behind ruined cropland and barren pastures. While they are not known to impact forests or natural tree cover, their voracious consumption of most species of crop creates food scarcity for native fauna and other insects. In Kenya, for example, locust plagues threaten the habitat of the Grevy’s zebra, a threatened endemic species.
CONTROL AND MANAGEMENT:
Cultural control: Locust attack can occur as solitary, localized or migratory swarms. Farmers are advised to be alert, monitor and inspect their fields, crops, trees and bushes around their vicinity. Locust swarms move and damage the crops during daytime and rest on trees and vegetation at night. When on rest, the swarms can be destroyed using insecticidal spray in the morning between 6 to 10 am or in the dusk. The locust swarm can also be pushed away by making high pitch sounds by beating drums, bursting crackers, clanging utensils, playing music, smoking all around the crop or by running tractor without silencer.
Physical and mechanical methods:
Among the physical control methods, locating the egg laid areas is always important, then trench them round, so as to entrap the young hoppers as they move out after hatching. Even actual destruction of eggs on an organized scale may be carried out by ploughing, harrowing and hand digging. For Hopper Control the mechanical methods included entrapping making hopper bands in 2’ x 2’ trenches and burying. If they are resting on bushes or hedges, they can be easily burnt with help of flame throwers. When flying locusts are about to descend in large swarms in cultivated areas, the best way to tackle them is to prevent them by all possible methods, such as waving a white cloth, or creating a cloud of smoke, by burning refuse, etc., spraying with neem kernel suspension as a deterrent to the crop has also been tried with success. Recently with the introduction of aerial application of insecticide makes the control of locust swarms easier.
Chemical methods:
The chemical method includes use of poison baits and dusting of insecticides. Chloropyriphos 20%EC @2.5 ml per litre of water or 1200 ml in 500 litres of water for one hectare; Chloropyriphos 50%EC @ 01 ml per litre of water or 480 ml in 500 litres of water; Fipronil 5% EC @0.25 ml per liter of water or 125 ml in 500 litres of water for one hectare; Malathion 50% EC @3.7 ml per litre of water or 1850 ml in 500 liters of water for one hectare; Malathion 25% WP @7.5 grams per liter of water or 3.70 kg in 500 litres of water for one hectare are recommended for control of the locust.
Integrated management: In a research study in 2010, Michel Lecoq recommended Integrated Pest Management (IPM) i. e use of efficient bio pesticides instead of traditionally used synthetic pesticides. Currently, pheromones and myco pesticides are considered effective as an IPM. Pest management also utilizes semio chemical based control methods including: (a) Mating disruption, a direct method used to distract the insects to go after mating (b) mass trapping of pests and (c) ‘lure and kill.’ The latter two methods use specific olfactory cues, mimicking either food or sex pheromones to attract pests into traps.
The wind speed acts as a catalyst in locust dispersal. With the help of meteorological studies, the speed and direction of wind flow can be monitored in India to predict the trajectory of locust swarms. It requires coordination of all the concerned departments with a more role for the meteorological institutions to collectively share the information regarding the locust to control and manage it in a better way. At the same time, it is also necessary that the government provide incentives to promote such alternative options and offset costs. |
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