The 2019–2020 upsurge of the desert locust and its impact in Pakistan

The recent upsurge of the desert locust Schistocerca gregaria (Forskål, 1775) has had an impact on East Africa and the Middle East as far as India. It has affected and slowed down many aspects of the Pakistani economy. Swarms of locusts have infested many areas and caused immense damage to all types of crops. Both farmers and economists are concerned and are trying to get the most up-to-date information on the best strategy to manage this pest. This paper is an attempt to (i) provide insight into the dynamics of this upsurge internationally as well as in the various regions of Pakistan, (ii) briefly assess its local impact and locust control measures, and (iii) clarify the role of the various stakeholders in the management, both nationally and internationally, suggesting various improvements for the future.

Ecological and Human Diet Value of Locusts in a Changing World

Since ancient times, locusts have been serious pests wreaking havoc on settled agriculture throughout much of the world. Numerous locust practices have been developed to control infestations. This has led to most commentaries portraying locust infestations only in a negative light while focusing on finding best management practices for suppressing locust populations and lessening crop damage caused by swarms. Yet, locusts are also of great ecological significance in being not only an extraordinary natural phenomenon but also major components of ecosystem nutrient cycling, arising long before settled agriculture. Furthermore, for humans, locusts are a nutritious food source, historically and currently being consumed directly. Locust control today should more regularly include their harvesting. This is now more feasible, as environmentally friendly biopesticides can be used to replace harmful organic pesticides. We focus here on the ecological significance of locusts by using calculations based on a 1 km2 area of swarming and breeding Desert locusts, Schistocerca gregaria, and show that the huge biomass of locust individuals contributes greatly to ecosystem processes while also having great potential use in human nutrition, especially where there is an urgent need for improved dietary intake and nutrition.

Distribution of Desert Locust Schistocerca gregaria in Rajasthan, India and Establishing an Early Warning System for Locust Control in India

Desert Locust is considered to be the most serious pests that cause a devastated damage to the crops and the other agricultural products during their invasions. The Desert Locust is a major threat for food security, livelihoods, environment and economic development in a region. The recent Locust Outbreak caused major damage to standing crops and vegetables in the Central and Western states of India, including Rajasthan, Punjab, Haryana, and Madhya Pradesh, with Rajasthan being the most affected. India had experienced such massive locust invasion after two decades. Establishing an Early Warning System for Locust Control in India is essential to reduce the impact by providing timely and relevant information in a systematic way contributing to increasing in resilience of the country. The distribution of Desert Locusts in Rajasthan, India has been presented from June 2019 to August 2020, along with the key Environmental Factors of Temperature, Rainfall, Soil Moisture and Prevalence of Vegetation significantly affecting Locust Activity. All the datasets used were obtained from Secondary sources. These datasets were obtained from Open Government Data (OGD) Platform. The Maps created in the study show the Distribution of Desert Locusts in Rajasthan, India; along with this the Choropleth map show Average- Temperature, Rainfall, Soil Moisture and Normalized Difference Vegetation Index (NDVI), all at District level. The Early Warning System for Desert Locust Control in India is a key integration of four key elements of: Risk Knowledge, Monitoring and Warning Service, Dissemination and Communication and Response Capability, and four-four sub elements of each key element. Establishing an Early Warning System for Locust Control in India is of paramount importance and a major achievement for the nation itself.

New Technology for Desert Locust Control

Locust outbreaks usually begin in remote unpopulated areas following higher than average rainfall. The need to survey such areas has suggested that unmanned aerial vehicles (UAVs), often referred to as drones, might be a suitable means of surveying areas with suitable detection devices to survey areas and detect important locust concentrations. This would facilitate determining where sprays need to be applied at this early stage and would minimise the risk of swarms developing and migrating to feed on large areas of crops. Ideally, a drone could also spray groups of hoppers and adults at this stage. To date, tests have shown limitations in their use to apply sprays, although it has been suggested that using a fleet of drones might be possible. The use of biopesticide in these areas has the advantage of being more environmentally acceptable as the spray has no adverse impact on birds.

Could Entomophagy Be an Effective Mitigation Measure in Desert Locust Management?

The desert locust has been a notorious pest since ancient times. A population upsurge hit Pakistan in 2019 and caused tremendous damage to agriculture and livelihoods. To take advantage of this ongoing upsurge, we conducted a field study to verify whether locust collection could be an interesting control method to protect crops in the event of an invasion, as well as an accepted food resource for poor rural communities. A village in the Thar desertic region was selected as a type-locality. An awareness campaign was launched to promote the collection and consumption of locusts as well as to alert people of their nutritional value. Two large swarms arrived near the village and several other swarms affected places nearby. Around 3033 kg of locusts were collected through handpicking at night. Most of the locusts were eaten and, as a result, hoppers of the next generation did not emerge in the type-locality; however, hopper bands appeared in areas where entomophagy was not practiced. The study area had less locust activity because swarms could not lay eggs due to entomophagy by the villagers. The consumption of desert locusts could be an effective practice to prevent malnutrition and protein deficiency and, to a certain extent, an efficient mitigation measure to help local populations to better protect themselves and their crops against locust outbreaks. Collection and consumption of locusts should be encouraged while remaining realistic about its real impact on locust control. This should also be done in concert with local authorities to take into account the risks to human health and to avoid the consumption of insects treated with pesticides.

High-power microwaves against locusts and other harmful animals.

here are a lot of phytophagous and harmful animals of agriculture and forestry in the entire world. The ultimate goal in locust control is the use of preventive and proactive methods that disrupt the environment to the least possible extent. This would make agricultural production easier and more secure in the many regions where growing crops is of vital importance. The possibility of using microwave systems to combat harmful animals, pests of agriculture and forestry is discussed.

Increased and sex-selective avian predation of desert locusts Schistocerca gregaria treated with Metarhizium acridum

The entomopathogenic fungus Metarhizium acridum in oil-based formulations (Green Muscle® (GM)) is a biopesticide for locust control lacking side-effects on biodiversity, unlike chemical insecticides. Under controlled conditions, GM-treated locusts and grasshoppers attract predators, a complementary advantage in locust control. We assessed avian predation on a population of desert locusts in northern Niger aerially sprayed operationally with GM with 107 g viable conidia ha-1. Populations of adult locusts and birds and vegetation greenness were assessed simultaneously along two transects from 12 days before until 23 days after treatment. Common kestrels Falco tinnunculus and lanners F. biarmicus were the predominant avian predators. Regurgitated pellets and prey remains were collected daily beneath “plucking posts” of kestrels. Locusts started dying five days post-spray and GM had its maximum effect one-two weeks after the spray, with 80% efficacy at day 21. After spraying, bird numbers increased significantly (P<0.05) concurrent with decreasing desert locust densities. Locust numbers decreased significantly (P<0.001) with both time since spraying and decreasing greenness. Before spraying, kestrel food remains under plucking posts accounted for 34.3 ±13.4 prey items day-1, of which 31.0 ±11.9 were adult desert locusts (90.3%), reducing post-spray to 21.1 ±7.3 prey items day-1, of which19.5 ±6.7 were adult desert locusts (92.5%), attributable to decreased use of the plucking-posts by the kestrels rather than an effect of the spray. After spraying, kestrels took significantly (P<0.05) more larger female (75–80%) than smaller male (20–25%) locusts. Avian predation probably enhanced the impact of the GM on the desert locust population, especially by removing large adult females. No direct or indirect adverse side-effects were observed on non-target organisms including locust predators such as ants and birds. These substantial ecological advantages should also be considered when choosing between conventional chemical and biopesticide-based locust control.