Dr Munir Ahmad
LOCUSTS whenever change their migratory behaviour become menace for the humans. They eat almost every kind of vegetation and damage the food chain system of humans and livestock. When in swarms, they are millions with aggressive feeding and breeding behaviour and capable of long distance flight in search of food. Asian and African countries mostly suffer from this menace and it results in life threatening situations. Locusts are the grasshoppers which are mostly green in colour but change into yellowish when food is scarce, over populated in unit area and face threat to their life. When green, they love to live separate, eat less and damage less, too. Once they change into gregarious form (family or swarm like), they develop a totally different attitude to care for each other, live quite closely, eat more and multiply and mass propagate. Their tiny but different brain triggers for long distance movement on swarms of millions of locusts together. Even they have ability to cross the sea through long distance continuous flight of more than two hundred kilometre, covering sea surface to protect the upcoming swarms to land, rest and fly again for the next destination in search of food. Through land, they move from African countries to Arabian countries like Saudi Arabia, Iraq, UAE, Iran and enter Pakistan from Iran. Their peculiar character of hibernation (diapause) in winter and summer months to protect their eggs and coming progenies keep them protected even for two to three years. Once environmental conditions get suitable as rainy and moist weather with sandy soils let young hoppers emerge within two weeks to start the same vicious cycle. Young wingless hoppers have five different life stages and only hop to move as wings are not developed until they transform into adults.
According to the Food and Agriculture Organization’s (FAO) Plant Protection Departments at federal and provincial levels, it swarmed into Pakistan last summer April-May 2019 after more than two decades. Control measures were adopted to minimize their establishment in Pakistan. However, some survivals got successful to get laid eggs for their next progeny and now it has established in some areas of Punjab, Sindh and Balochistan. FAO and Provincial Disaster Management Authority (PDMA) in close cooperation with Plant Protection Agriculture Department and other agriculture departments are jointly working for its continuous monitoring, surveillance and management in their resources and capacity. In the recent past, some damage to canola crop, fruit trees and forest trees has been reported in different parts of the country. However, wheat crop survived of the attack probably due to some least liked palatable leaves. Other crops of Kharif season are now under major threat particularly cotton and broad leaves. At the moment, country is facing two facets of locust threat, one from the established locust population in different areas of Punjab, Sindh and Balochistan especially their deserts and sandy areas. Second major threat is the continuous new invasion of swarms from neighbouring countries like Iran coming from African countries which are under continuous and alarming threat of locusts. Central Punjab and Sindh having deserts offer suitable breeding and hibernation grounds for its growth and development. Regular and timely surveillance with community interaction in area wide monitoring can serve early detection of the problem for its early and quick control.
Our villages are highly populated and hinder aerial application which is the most suitable when going for large locust swarms. Ground applications face many hurdles like availability of trained manpower, uneven and inaccessible landscape, provision of basic resources like water for spray dilution, spray machines for high and dense forest areas etc. Provision of appropriate spray machines, insecticide, vehicles should be made available in most vulnerable areas for immediate need and use. There is need to implement short (immediate control) and long-term methods to avoid present threat and avoid its future invasions and establishment on our grounds. Short-term management mainly requires use of synthetic insecticides with fast, reliable and very fine mist of spray insecticide solution to locust hoppers or adults. Synthetic insecticides like lambda cyhalothrin, deltamethrin, bifenthrin, malathion, chlorpyrifos, fipronil are the most recommended for quick and efficient kill in non-agricultural and agricultural crop areas.
Other options are quite specific and desire a bit more time. They are also specific for insects and less hazardous to other non-chitinous animals and humans. Chitin synthesis inhibitors like lufenuron, diflubenzuron, flufenoxuron and some others like methoxyfenozide and tebufenozide are other specific insecticides. Some insecticides based on fungi, bacterial and other microbes are also available but desire very specific conditions in application and time to apply. Other alternate measures can also include their collection by the community and utilization as alternate food source for poultry and birds. The best time of collection is after sunset to early morning as adult hoppers rest on plants and soil. Use of barbed branches can be of great help to kill them physically at places where spray of insecticide is not possible or inapplicable. Such practices can help us to protect our crops and save the food, feed and other plant resources necessary for our survival. Efforts of agriculture departments in locust management need to be highlighted in media and local public cooperation can be very effective as part of long-term strategy for locust control.
—The writer is Associate Professor, PMAS-Arid Agriculture University, Rawalpindi.
