Effect of vegetation on density thresholds of adult desert locust gregarization from survey data in Mauritania

Cissé, Sory; Ghaout, Saïd; Mazih, Ahmed; Ebbe, Mohamed Abdallahi Ould Babah; Benahi, Ahmed Salem; Piou, Cyril

doi:10.1111/eea.12121

Cited by 44 publications

(53 citation statements)

References 29 publications

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“…One might conclude that when the gregarization process is engaged, the rain is not the best indicator of the presence of larvae. This seems consistent with what is known otherwise of the gregarization process, which happens more likely in clumpy and drying habitats (Boua€ ıchi et al, 1996;Despland et al, 2000;Cisse et al, 2013Cisse et al, , 2015. This is also consistent with the less strict ecological requirements of transiens and gregariouscompared to solitariousdesert locusts (Despland, 2005).…”

Section: North and South Differences In Light Of Water Availabilitysupporting

confidence: 89%

“…The resulting large databases – initially made for operational purposes and not for research – are exploited. They have already helped to better assess the distribution of these solitarious locust populations in the Sahara (Popov, ; Guendouz‐Benrima et al., ; Babah Ebbe, ; Piou et al., ) or to evaluate the population density at which gregarization could happen (Cisse et al., ). The objective of this study is to identify the respective roles of environmental and intrinsic factors explaining local and regional dynamics of solitarious and transiens population development in recession periods.…”

Section: Introductionmentioning

confidence: 99%

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Importance of solitarious desert locust population dynamics: lessons from historical survey data in Algeria

Lazar

Piou

Doumandji-Mitiche

et al. 2016

Entomologia Exp Applicata

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The desert locust, Schistocerca gregaria (Forskål) (Orthoptera: Acrididae), is a major pest and well known in its gregarious phase. However, it is not well understood during recession periods, when the solitarious phase populations are discrete. Nonetheless, these populations are at the origin of the invasions when ecological conditions become favourable. This lack of knowledge of the solitarious phase individuals impedes effective preventive management of this pest. Archive data collected in Algeria from 1980 to 2011 were used to analyse solitarious population dynamics across the Algerian Sahara where some outbreak areas are located that play a major role in the invasion process. The results confirm previous empirical observations on solitarious population dynamics. First, a clear difference could be documented between the northern and southern Saharan regions of Algeria concerning the locust dynamics and the impact of environmental conditions. The importance of runoff was clear to create suitable habitats over a long period and to very distant places from rainy areas. Second, a link, on an annual basis, between green vegetation and presence of solitarious locusts was found. Third, statistical relationships between various locations demonstrated a clear regional dynamics. Our study confirmed the importance of migrations of solitarious populations among Algerian regions and more generally within the recession area of this species. The operational implications of these findings are multiple. First, they confirm the need of a flexible and scalable preventive system during the year, from 1 year to another and with a clear distinction between the northern and southern Saharan areas of Algeria. Second, they also confirm the necessity for the inclusion of wadis and soil moisture estimations from remote sensing in geographic information systems for preventive management. And third, they clearly illustrate the importance to target solitarious locusts for more efficient preventive survey operations.

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Section: North and South Differences In Light Of Water Availabilitysupporting

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Importance of solitarious desert locust population dynamics: lessons from historical survey data in Algeria

Lazar

Piou

Doumandji-Mitiche

et al. 2016

Entomologia Exp Applicata

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“…These results completely support the development of tools which help to guide surveys as soon and as spatially precisely as possible . They also support the development of indicators to decide on whether or not a situation needs to be controlled . In addition, our results support the importance of the quality of feedback information from the field to the funders.…”

Section: Discussionsupporting

confidence: 74%

Improving preventive locust management: insights from a multi‐agent model

Lecoq

Piou

2017

Pest Management Science

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BACKGROUND: Preventive management of locust plagues works in some cases but still fails frequently. The role of funding institution awareness was suggested as a potential facilitating factor for cyclic locust plagues. We designed a multi-agent system to represent the events of locust plague development and a management system with three levels: funding institution, national control unit and field teams. A sensitivity analysis identified the limits and improvements of the management system. RESULTS: The model generated cyclic locust plagues through a decrease in funding institution awareness. The funding institution could improve its impact by increasing its support by just a few percent. The control unit should avoid hiring too many field teams when plagues bring in money, in order to ensure that surveys can be maintained in times of recession. The more information the teams can acquire about the natural system, the more efficient they will be. CONCLUSION:We argue that anti-locust management should be considered as a complex adaptive system. This not only would allow managers to prove to funders the random aspect of their needs, but would also enable funders and decision-makers to understand and integrate their own decisions into the locust dynamics that still regularly affect human populations.

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“…In an alternative approach towards defining the locust density threshold for transformations to the gregarious stage, Cisse et al [2013] used field data from the RAMSES database for Mauritania from 2003 to 2011 to explore relations between locust density, phase status and vegetation, by investigating the influence of vegetation on the gregarization thresholds of the desert locust. They showed that the latter varied from 208 to 1525 adults ha-1, dependent upon vegetation cover and condition.…”

Section: Introductionmentioning

confidence: 99%

A Locust Phase Change Model with Multiple Switching States and Random Perturbation

Xiang

Tang

Cheke

et al. 2016

Int. J. Bifurcation Chaos

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Insects such as locusts and some moths can transform from a solitarious phase when they remain in loose populations and a gregarious phase, when they may swarm. Therefore, the key to effective management of outbreaks of species such as the desert locust Schistocercagregaria is early detection of when they are in the threshold state between the two phases, followed by timely control of their hopper stages before they fledge because the control of flying adult swarms is costly and often ineffective. Definitions of gregarization thresholds should assist preventive control measures and avoid treatment of areas that might not lead to gregarization. In order to better understand the effects of the threshold density which represents the gregarization threshold on the outbreak of a locust population, we developed a model of a discrete switching system. The proposed model allows us to address: (1) How frequently switching occurs from solitarious to gregarious phases and vice versa; (2) When do stable switching transients occur, the existence of which indicate that solutions with larger amplitudes can switch to a stable attractor with a value less than the switching threshold density?; and (3) How does random perturbation influence the switching pattern? Our results show that both subsystems have refuge equilibrium points, outbreak equilibrium points and bistable equilibria. Further, the outbreak equilibrium points and bistable equilibria can coexist for a wide range of parameters and can switch from one to another. This type of switching is sensitive to the intrinsic growth rate and the initial values of the locust population, and may result in locust population outbreaks and phase switching once a small perturbation occurs. Moreover, the simulation results indicate that the switching transient patterns become identical after some generations, suggesting that the * Author for correspondence evolving process of the perturbation system is not related to the initial value after some fixed number of generations for the same stochastic processes. However, the switching frequency and outbreak patterns can be significantly affected by the intensity of noise and the intrinsic growth rate of the locust population.

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Effect of vegetation on density thresholds of adult desert locust gregarization from survey data in Mauritania

Cited by 44 publications

References 29 publications

Importance of solitarious desert locust population dynamics: lessons from historical survey data in Algeria

Importance of solitarious desert locust population dynamics: lessons from historical survey data in Algeria

Improving preventive locust management: insights from a multi‐agent model

A Locust Phase Change Model with Multiple Switching States and Random Perturbation

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