Locusts

Abstract

The term ‘locust’ is given to those species of grasshoppers, which are capable of forming large swarms under certain conditions. They belong to family Acrididae, suborder Caelifera, order Orthoptera and class Insecta. The locust swarms move over wide and distant areas and cause severe damage to cultivated and natural vegetation, where the swarms settle. There are many species of locusts, amongst which desert locust, Schistocerca gregaria, is the most damaging pest. The locust problem is not new. Since the beginning of civilisation, they have been a serious threat to agriculture. A substantial increase in locust population, which may cause serious devastation of crops, is known as outbreak. Each locust can exist in two main forms, i.e. solitary phase (phasis solitaria) and gregarious phase (phasis gregaria), which are quite distinct morphologically as well as behaviourally. An intermediate phase (phasis transiens) also occurs in between two extreme phases. Each locust is a grasshopper, but every grasshopper is not a locust.

Locust breeding and seasonal migration patterns follow no international boundaries; hence, international intervention and cooperation is essential for their control. A locust plague begins, when sufficient rains are there in potential outbreak areas, simultaneously leading to tremendous breeding and increase in locust populations, resulting into upsurge of locust population. Like other pest management, locust control also aims at protecting agricultural productions.

Current information on locust breeding, density and phase is the starting point of all control operations. Chemical control has superseded various other traditional methods for killing, viz. digging trenches, burning, beating and smoking the hopper bands and swarms.

The first international locust conference took place in Rome in 1920. The International Locust Information Network and Anti-locust Research Centre were established in London in 1930. After 1993, the latest swarms of desert locust invaded India on 21 May 2019, which is still continued in major parts of northwest India. The Locust Warning Organization (LWO) and Field Station for Investigation on Locusts (FSIL), established by the Government of India, are active to control the locust swarms and outbreaks. Using certain improved technology for spraying operations, Global Positioning Systems (GPS) leading to new navigational technology, other modern gadgets and mathematical models under integrated pest management (IPM) programme, we will be able to combat the locust problem with international cooperation.