November 8, 2018
One of the differentiating characteristics between grasshoppers generally and locusts specifically is the potential for locusts to undergo what scientists call “phase change.” As part of the shift in behaviors associated with phase change, locusts can become gregarious — they group together and form massive swarms as they move across the landscape. It is no surprise then that locust scientists themselves are gregarious, in that effective management of locusts requires coordinated efforts from many different individuals, teams and organizations.
These coordinated efforts, which are essential to effective preventative locust management, are in part the theme of a recent webinar (in Spanish) presented by Cyril Piou of France’s Agricultural Research Center for International Development (CIRAD). Piou holds a PhD from Bremen University in Germany, and since 2010 he has worked as part of the Acridology Team at CIRAD, researching various themes in population dynamics, ecology, and modeling systems. Due to his experience in these areas, Piou frequently collaborates with other locust researchers, including partners through Argentina’s National Institute of Agricultural Technology (INTA), who hosted the webinar.
Argentina is currently experiencing an upsurge in the South American locust (Schistocerca cancellata Serville), and is thus in a position to learn from other locust monitoring and management strategies globally. In the webinar, Piou presented many of the results and lessons learned from CIRAD’s more than 50 years of research to improve preventative management strategies of locusts, with a focus on the desert locust (Schistocerca gregaria Forskål) in northern Africa and the Middle East. Basically, preventative management of locusts focuses on the reduction of gregarious populations as they appear to prevent the development of large-scale swarming populations.
Piou references guidelines developed by the U.N.’s Food and Agriculture Organization for effective preventative management; resources including time, money and equipment must align in space for teams to be mobile and able to respond in the event management of gregarious populations (Fig. 1). However, many questions still need to be answered for organizations to effectively realize and improve preventative management. For example, Piou discussed numerous ongoing lines of research at CIRAD, including the role of soil humidity in locust population growth, genetic variation in solitarious locusts, and the effect of vegetation on gregarization. These results can then help in the development of models to identify where and when to send teams for monitoring or management.
Even if a country or region can effectively conduct preventative management, an occasional locust outbreak may still occur. Researchers have attempted to hypothesize why, with one of the prevailing suggestions relating to the socio-economics of the “vicious locust cycle:” adequate management leads to remission in the populations, which results in reduction in locust management budgets, then a resurgence in locust populations, a call for international support, and finally, adequate treatment and locust remission once again. This cycle continues as funding agencies are often separate from the locust problem and are not likely to dedicate continued funds in non-outbreak years.
As part of their ongoing research, Piou and his team are attempting to identify additional models, e.g. the Anti-Locust Management Multi-Agent System (ALMMAS), which can help identify sensitivities within the locust management structure in order to address any associated problems. For example, ALMMAS suggests that maintaining institutional knowledge, even in non-outbreak years, can eliminate the chance of a locust invasion, while increasing ongoing budgets by even 10 percent can reduce the likelihood of invasions by 33 percent. The results of the initial model primarily suggest that ongoing funding for locust management is one of the most significant factors affecting successful preventative management.
Piou discussed a variety of other lines of investigation and results from CIRAD’s ongoing work, and we highly suggest watching the webinar or contacting Piou directly to learn more. And of course, if you have any news for the Global Locust Initiative, please contact us so we can share your information with the locust and grasshopper community.