In the context of food self-sufficiency, the River Senegal Valley has been undergoing profound environmental changes for several decades. Rice production has increased due to the development of vast irrigated perimeters, which has been accompanied by recurrent proliferations of rodent populations that are crop pests and reservoirs of zoonoses. The aim of our study was to determine the factors underlying these phases of increased rodent abundance over a ten-year (2008 to 2019) sampling period during the hot dry season (February-May). A total of 1,867 rodents of four species were captured, among which Arvicanthis niloticus and Mastomys huberti dominated. Our results showed that, during this season, rodent abundance (i) increases significantly with rainfall from the previous year, (ii) is higher in cultivated than in uncultivated plots, (iii) increases with plant cover, (iv) increases, for M. huberti, with the presence of open water. We showed that in an area that was first sparsely cultivated and then impacted by hydro-agricultural rehabilitation of irrigation and drainage infrastructure, the abundance of A. niloticus changed following this program, reaching the level of a nearby area that has been intensively cultivated for decades. Moreover, we showed that the proportion of adults among the captured individuals was lower in rice plots than in vegetable gardening fields and uncultivated plots. The breeding pattern of adult individuals was also affected by land use. Results suggest that uncultivated areas and vegetable gardening fields constitute refuge and breeding ground hotspots and would thus form a starting point for the invasion of rice fields. Following these results, we advocate for regular monitoring of rodent breeding and abundance patterns, with a special focus on these refuge areas, particularly during the hot dry season. We recommend implementing effective and sustainable science-based control strategies at national and community levels to keep rodent populations within tolerable limits.
This article analyses the recurring topics in the epistemology of the leading 20th-century French sociologist and political theorist Raymond Aron, drawing on his doctoral dissertation Introduction à la philosophie de l'histoire (1938) and on a range of works he published in his later years. The author first discusses six different reasons for Aron's conspicuous absence from many contemporary handbooks on the social sciences: his deliberate avoidance of developing a system in his work, his disinclination towards abstract theoretising, his lack of interest in empirical research, and his refusal to specialise in one field, and also the changes that occurred in the social scientific context in which his work was received and changes in the surrounding political and social circumstances, most notably the collapse of the communist regimes. The author notes that a major feature in Aron's epistemological thought was his neo-Kantian awareness of the limits of strictly scientific knowledge, which he identified with the domain of causal analysis. The second crucial theme, recurring throughout Aron's work, is the indispensability of philosophy for providing the foundations for social scientific analysis, always in need of being positioned with respect to values. His enduring interest in international relations and contemporary history is taken as an indication of the third basic element of his epistemology: a passion for the analysis of singular events. The author concludes that, given his preoccupation with the singular and the particular, the key, albeit somehow implicit, aspect of his epistemology is the capacity for judgment in the Kantian sense.