Early intervention against desert locusts: Current proactive approach and the prospect of sustainable outbreak prevention

Authors: Showler, Allan; EBBE, MOHAMED - Inter-State Standing Committee On Drought Control In The Sahel; LECOQ, MICHEL - Cirad, France; MAENO, KOUTARO - Japanese International Research Center For Agricultural Sciences (JIRCAS) - Japan

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/7/2021
Publication Date: 2/10/2021
Citation: Showler, A., Ebbe, M.O., Lecoq, M., Maeno, K.O. 2021. Early intervention against desert locusts: Current proactive approach and the prospect of sustainable outbreak prevention. Agronomy Journal. 11:312. https://doi.org/10.3390/agronomy11020312.
DOI: https://doi.org/10.3390/agronomy11020312

Interpretive Summary: The desert locust, a major Old World pest, causes serious agricultural losses and undesirable societal effects. There are three broad approaches to its control: reaction, proaction, and outbreak prevention. Reaction protects crops from swarms but it is costly and disruptive. Proaction involves early intervention during outbreaks to avert further development to plague status; it is in current use because it is effective, relatively inexpensive, and it is the best available option for now. Outbreak prevention, unavailable since the 1970s, will require highly sensitive surveillance to detect the onset of gregarization behavior. Sufficiently early intervention can, hypothetically, extend desert locust recession indefinitely. While research on desert locust biology and behavior is, almost, no longer an urgent requirement to improve the efficacy of control,, new priorities have arisen for developing outbreak prevention capability (and for enhancing proaction). Salient needs presently include long residual tactics for prophylactic (preventive) control in breeding areas, intervention thresholds, and improved, sustainable coordination among stakeholders at national, regional, and international levels. The most recent desert locust episode of 2020 provides an illustrative example of how prevention might have averted the entire upsurge, and how proaction in some countries contained the spread of swarms. The initial outbreak in Saudi Arabia escaped control due to unpreparedness, and impacts of armed conflict in Somalia and Yemen that weakened surveillance and control, further contributed to the invasion of '22 countries, and spraying '2.8 million ha, by mid June 2020.

Technical Abstract: The desert locust, Schistocerca gregaria (Forskål) (Orthoptera: Acrididae), a major Old World pest, is associated with agricultural losses and undesirable societal effects. There are three broad approaches to its control: reaction, proaction, and outbreak prevention. Reaction protects crops from swarms but it is costly and disruptive. Proaction involves early intervention during outbreaks to avert further development to plague status; it is in current use because it is effective, relatively inexpensive, and it is the best available option for now. Outbreak prevention, unavailable since the 1970s, will require highly sensitive surveillance to detect the onset of gregarization. Sufficiently early intervention can, hypothetically, extend desert locust recession indefinitely. While research on desert locust biology and behavior is, almost, no longer an urgent requirement to improve the efficacy of control,, new priorities have arisen for developing outbreak prevention capability (and for enhancing proaction). Salient needs presently include long residual tactics for prophylactic (preventive) control in breeding areas, intervention thresholds, and improved, sustainable coordination among stakeholders at national, regional, and international levels. The most recent desert locust episode of 2020 provides an illustrative example of how prevention might have averted the entire upsurge, and how proaction in some countries contained the spread of swarms. The initial outbreak in Saudi Arabia escaped control due to unpreparedness, and impacts of armed conflict in Somalia and Yemen that weakened surveillance and control, further contributed to the invasion of '22 countries, and spraying '2.8 million ha, by mid June 2020.