In its recent work based on the previous three reports, CASEarth working group “Monitoring and assessment of Desert Locust in Asia and Africa” combined multi-source Earth Observation data (including GF series in China, MODIS and Landsat series in US, and Sentinel series in EU), meteorological data, field data, with self-developed models and algorithms to continue the research on dynamic monitoring of Desert Locust in Asian and African countries. This report focuses on the locust plagues in Somalia and Pakistan.

  The results showed that, by the end of March 2020, 11 states in Somalia had been harmed since Desert Locusts invaded northern Somalia in June 2019. The vegetation damaged area is 2239.4 thousand hectares, including 9.3 thousand hectares of cropland, 596.7 thousand hectares of grassland and 1633.4 thousand hectares of shrub, accounting for 9.6%, 15.3% and 3.7% of the total cropland, grassland and shrub in Somalia, respectively. In March 2020, Desert Locust in Pakistan harmed about 449.5 thousand hectares of vegetation area (including 374.1 thousand hectares of cropland and 75.4 thousand hectares of grassland), mainly distributed in Punjab, Khyber-Pakhtunkhwa, Federally Administered Tribal Areas in northern Pakistan and Baluchistan in the southwest. At present, locusts spring breeding are underway in Somalia and Pakistan. Considering that April is the best period for Desert Locust control, it’s very important for Somalia and Pakistan to focus on locust hatching and conduct monitoring, warning, prevention and control of locusts during this month. April-June is an important growing or harvesting season for wheat and corn in both countries. If the locust could not be controlled properly, it will bring major threat to agricultural and pasture production and national livelihoods. It is necessary to carry out the monitoring and early warning of the intercontinental Desert Locust plague continuously and dynamically, and organize joint prevention and control in multiple countries, to ensure the safety of agricultural and pasture production and regional stability.

1.Monitoring and assessment of Desert Locust in Somalia

  In May 2018, the tropical cyclone brought lots of rainfall to northern Somalia. The increasing vegetation provided suitable conditions for locust breeding. In September, Desert Locust began breeding locally in Berbera (northwestern Somalia).

  From June to July 2019, mature locust swarms of Yemen moved southward across the Gulf of Aden to northern Somalia. Mature locust swarms appeared along the coast of Bosaso in the northeast and Berbera in the northwest. In early August, part of swarms on the northwestern coast of Somalia migrated to eastern Ethiopia. At the end of August, swarms appeared on the plateau between Boroma and Burao in the northwest. There were a large number of adults on the east coast of Berbera and swarms continue to breed on the plateau between Hadaaftimo and Iskushuban in the northeast. Till the end of September, locusts had invaded Awdal, Woqooyi Galbeed, Togdheer, Sanaag and Bari in northern Somalia. Grassland and cropland were severely affected, with a damage area of 494.4 thousand hectares (2.7 thousand hectares cropland, 38.5 thousand hectares grassland, and 453.2 thousand hectares shrub). In Mid to late October, swarms in Ethiopia migrated southeast to Bohotley at the border between Somalia and Ethiopia, and Laascaanood in northern Somalia. In November, swarms in eastern Ethiopia continued to multiply and spread to Gaalkacyo in central Somalia. In early December, locusts spreaded to Dhuusa Mareeb and Beled Weyne. At the end of December, locusts in eastern Ethiopia and central Somalia migrated southward through Huddur to Garbaharey. The newly added damage area was about 940.8 thousand hectares (3.2 thousand hectares cropland, 307.7 thousand hectares grassland, and 629.9 thousand hectares shrub).

  In January 2020, swarms in central and southern Somalia continued to migrate south to the middle of Jubbada Dhexe at the junction of southern Somalia and northeastern Kenya, and continued to move to northeastern Kenya and began to lay eggs. At the end of January, locusts appear in the Garowe of northeast Somalia. In February, the locusts in Beledwin and Galkayo of central Somalia continued to multiply, and the immature locust population was found in northeast Garowe. In March, locusts continued to breed in northeastern, central and southern Kenya. Till the end of March, Somalia increased about 804.2 thousand hectares of damaged area (3.4 thousand hectares of cropland, 250.5 thousand hectares of grassland and 550.3 thousand hectares of shrub), shown in Fig 1 and Fig 2.

  Our results showed that by the end of March, the locusts had affected 2239.4 thousand hectares of vegetation area in Somalia, including 9.3 thousand hectares of cropland, 596.7 thousand hectares of grassland and 1633.4 thousand hectares of shrub, accounting for 9.6%, 15.3% and 3.7% of the total cropland, grassland and shrub, respectively. Gedo, in southern Somalia at the border with northeastern Kenya, suffered the largest area as 440.1 thousand hectares. Togdheer and Woqooyi Galbeed have the damaged area of about 304.2 thousand hectares and 299.2 thousand hectares. Mudug and Bakool have the damaged area of about 211.6 thousand hectares and 177.2 thousand hectares. Sanaag and Sool have the damaged area of about 133.7 thousand hectares and 132.9 thousand hectares. Bay and Galguduud have the damaged area of about 120.7 thousand hectares and 112.5 thousand hectares. Awdal and Bari have the damaged area of about 90.3 thousand hectares and 88.1 thousand hectares. Hiiraan, Shabeellaha Dhexe, Jubbada Dhexe and Nugaal have the damaged area of about 87.7 thousand hectares, 25.7 thousand hectares, 11.9 thousand hectares and 3.6 thousand hectares. The locust plague has devastated pastureland and cropland in Somalia, causing huge losses to local farming and animal husbandry. It was the worst locust disaster in Somalia for the past 25 years, exacerbating the food and nutrition crisis of the local vulnerable groups.

  Comprehensive analysis showed that, from April to June 2020, the Desert Locusts in northern, central and southern Somalia will continue its spring breeding. It is expected that the swarms will migrate to summer breeding areas in northeastern Ethiopia, Djibouti and the southern coast of Yemen from April to June. At the same time, the locusts in the spring breeding area of the central Somalia are expected to migrate towards the Indo-Pakistan border with the southwest monsoon of the Indian Ocean in June. At present, a large number of locusts in Somalia have laid eggs on the ground and next generation of spring breeding is already begin. If the Desert Locusts could not be controlled effectively, the plague will continue, which may bring a heavy blow to the agricultural and pasture production in Somalia.

Fig.1. Migration path of Desert Locust in Somalia (2019-2020)

Fig.2. Monitoring of Desert Locust damage in Somalia (June 2019-March 2020)

2.Monitoring and assessment of Desert Locust in Pakistan

  From late February to the end of March 2020, the Desert Locusts in Pakistan were mainly distributed in central Punjab, southern Khyber Pakhtunkhwa, central Federally Administered Tribal Areas, and southwestern and Central Balochistan. From February 25th to March 5th 2020, the China Locust Control Working Group went to Pakistan to conduct a field survey of the Desert Locust plague, and provided technical support for locust prevention. China provided 14 sets of locust control equipment and 250 barrels of insecticide to Pakistan on March 9th. The locust plague was under initial control. Our research results showed that in March 2020, the Desert Locusts in Pakistan endangered the area of vegetation in the country by a total of 449.5 thousand hectares, of which 374.1 thousand hectares of cropland and 75.4 thousand hectares of grassland. Damaged areas are mainly located in the north central part of Punjab (damaged area about 354.6 thousand hectares), the southern part of Khyber Pakhtunkhwa (damaged area about 53.2 thousand hectares), the central part of Federally Administered Tribal Areas (damaged area about 19.7 thousand hectares) and the central and southwestern of Balochistan (damaged area is about 18.4 thousand hectares). In addition, Sind also had a small area of damage area of 3.6 thousand hectares adjacent to Balochistan (Fig 3).

  We used Planet images with higher spatial resolution as 3 m to monitor the Desert Locusts damage in the severely damaged cropland of northern Pakistan (Fig 4). The study areas located in Punjab. Area 1 is located in Chawinda of northeast Punjab, about 80 km south to Lahore and 40 km southwest to Gujranwala. The Degh Nala River flows through this area. The main vegetation type in Area 1 is cropland with a total area of 52.2 thousand hectares. The monitoring results showed that the cropland was obviously damaged by Desert Locusts in February 2020, with an area of 4.3 thousand hectares, accounting for 8.2% of the total area. Area 2 is located in the north-central part of Punjab, about 10 km northeast to Chiniot and 20 km southeast to Faisalabad. The Genab River flows through the northern edge of Area 2. The main vegetation type is cropland, with a total area of 52.4 thousand hectares. The monitoring results showed that the cropland in Area 2 was obviously damaged by the Desert Locusts in February 2020, with an area of 4.5 thousand hectares, accounting for 8.6% of the total area. The results of our research showed that Desert Locusts caused great damage to cropland and seriously threaten food security.

  At present, the locust eggs in Pakistan are gradually hatching, and the best period for locust prevention and control is early-mid April. Pakistan could carry out targeted Desert Locust egg removal and monitor adults migration. In Pakistan, 52% land is grassland, and desert grasslands with water sources are the key areas for Desert Locusts eggs laying. Therefore, it is necessary to focus on monitoring the hatching of Desert Locusts in desert grassland areas. April-May is the harvest season of wheat and corn in Pakistan. If the Desert Locusts are not effectively controlled, the locust plague will continue to erupt, which may cause a heavy blow to agricultural production in Pakistan.

Fig.3. Monitoring of Desert Locust damage in Pakistan (March 2020)

Fig.4. Monitoring of Desert Locust damage in cropland of northern Pakistan based on Planet images

  The research is supported by Strategic Priority Research Program of the Chinese Academy of Sciences (XDA19080000), National Key R&D Program of China (2016YFB0501501), National Key R&D Program of China (2017YFE0122400) etc.