Desert Locusts and its Impact on Food Grains

Introduction

Locusts are invertebrates belonging to the Acrididae family which are herbivores and have a life span of a few months. It is weighing around 0.00019 kg and its length is ranging from 0.0127 to 0.076 m which is almost equal to the size of a paper clip. Its appearance is similar to a grasshopper and the unique feature between these two is gigantic rear legs which favour them flight or jump.

Characteristics

These are capable of developing flocks (group) moving crossways to different areas, consuming harvests and parting severe farming destruction in their wake up. It can travel a very long distance specifically few species cover 130 km/day and even further. In 1954, a swarm flew from northwest Africa to Great Britain while in 1988 another completed the long journey from West Africa to the Caribbean a journey of five thousand km (approximately) within the span of ten days. They can stopover in the air for extended phases habitually fascinating uninterrupted journeys across the Red Sea.

A distinctive swarm contains 150 million locusts / km2 flying along with the principal current of air. It is estimated that a locust swarm of one km2 spread is sufficient enough which can eat the food required for 35,000 members/ day. The varying weather conditions crucially impact the evolution of these species which can adjust themselves with the changing climate pattern. Initially, they were found to be smaller wings, extremely prolific with no intention to migrate turned into travelling over long distances with lengthy wings. Over a period of time, they are capable of forming locust plagues assaulting fresh parts (inter / intra country or continent) and are living unobserved in fewer magnitudes.

Types of Locusts in India

Only four types of locust swarm are reported in India.

1. Schistocerca gregaria : Desert locust
2. Locusta migratoria: Migratory locust
3. Nomadacris succinct: Bombay Locust
4. Anacridium sp.: Tree locust

Among the four, the desert locust is the most dangerous.

Life Cycle

The introverted locusts are united compulsory together with remaining vegetation during dry weather conditions. This sudden upsurge in the density of locusts generates serotonin secretion in the nerve system which enhances varying patterns of hunger with swift movements. A seamless gale like situation arises due to copious greeneries with soggy soil. The rapid production phase starts and the population of locusts increases exponentially. In this stage, the solitary lifestyle is converted into swarms that are capable of changing body shape and colour with an increase in the size of the brain.

After successful copulation between adult males and females, within a period of several hours, the female locust laid a good number of eggs with a single insemination. It is then searching for suitable topsoil comprising of appropriate temperature, high degree of wetness also in the vicinity of remaining egg-laying partners. Utilizing the abdomen, the female locust senses all the above phenomena and if found suitable then it digs a pit of length 0.03 to 0.04 m with a depth of 0.1 m which is known as an egg pod. Based on the surrounding weather conditions and the moisture content in the soil the incubation period varies from fourteen days or even more.

The egg, nymph and winged adult are the three phases of desert locust as represented in the following figure. Metamorphosis (lagging of papa part) is totally absent in locusts whereas butterflies and houseflies have this phase.
The cuticle is a superior type of skin that has 3 diverse coatings and covers the entire skeleton of the locust. The coating in the close proximity of the body is elastic and lenient in nature. The middle coating is hard and the outer coating is thinly composed of wax. This wax layer provides water-resistant capability. The saw-like jaw enables the locusts to cut the vegetation which can move from side to side, secondary jaws promote holding of vegetation with the lower lip.

Locusts have saw-like jaws which move from side to side to cut through plant food. They are also equipped with a pair of secondary jaws that help in holding the food and a lower lip. When locusts are teeming more, the near bodily contact triggers large hind legs to knock on one another which simulates a chain of comportment and metabolic deviations. Among them are colour changes (green to yellow and black, brown to pink or yellow), body size reduction and secretion of pheromone (attracted towards each other), swelling the hopper band and leading to ensuing creation of swarm. The characteristics of nymph pheromone are totally different from the adult pheromone; this means that when nymph pheromone is exposed to adult, they become perplexed and tangled. Also, they cannot smell the others even though they have excellent tactile and visual functions. After some time the hopper bands are fragmented or diluted.

Medicinal Benefits of Locusts

Phytosterol is a kind of phytosterol found in plants that have a similar structure to cholesterol in human beings which prevents or control cholesterol from being absorbed. The same phytosterol is abundantly available in the locusts and utilised for cholesterol control applications thereby preventing heart-related ailments. In addition to that Locusts have a high degree of protein and are used as a protein supplement. Further, regular intake of locusts in food leads to boosting the immune system against cancer. Consuming locusts’ food is accepted as halal in Islam also.

Latest Attack and its Origin

Flocks of desert locusts confronted Gurugram fields on 27th January 2021 in spite of the early warning was given by the administration a day before. The inhabitants were taken aback as the flocks run down the entire area of Gurugram. After observing a swarm in the district of Mahendragarh, the administrators had sounded an alarming signal to shut down the doors and windows of their houses on the 26th of January 2020[source: The Economic Times].

A new wave of locust throngs on the way from Africa is expected to invade India within a month time when rapid harvest implanting take off. If Pakistan is able to contain these swarms, then there is no other way is available for these flocks to enter the Indian soil since on setting of monsoon makes them enter Pakistan and then India[source: The Economic Times, dated 11th June 2020].