Population Dynamics and Genetics of &amp;lt;i&amp;gt;Gerbillus nigeriae&amp;lt;/i&amp;gt; in Central Sahel: Implications for Rodent Pest Control

Hima Karmadine,Brouat Carine,Granjon Laurent,Ndiaye Arame,Dobigny Gauthier,Gauthier Philippe

doi:10.11648/j.eeb.20190404.11

Abstract

Gerbillus nigeriae is a sand-dwelling and semi-arid adapted rodent species restricted to the West African Sahel where it causes extensive damages to cereal crops such as millet and sorghum. It also displays one of the most extensive floating chromosomal polymorphisms currently known in mammals, showing a non-random spatial distribution of diploid numbers (2N). We combined population dynamics and genetics to determine dispersal and mobility parameters of G. nigeriae in the species distribution range characterized by low 2N. To do so, we performed a three-year long population survey at Gangara, in the central east Niger. We used both time-dependent monitoring trough capture-mark-recapture (CMR) methods and genetic analyses performed on the 134 monitored individuals. CMR results showed low to very low population densities (maximum 27.5 individuals/ha) throughout the study. Abundance cycle was single-phased and strongly dependent on rainfall patterns. Mobility parameters showed very low individual mobility, with means of distance between successive (re) captures (DRS) and maximal distance between (re) captures (DMR) of 7.8 and 14.4 meters, respectively. Genetic analyses revealed significant isolation by distance as well as spatial structuration, thus confirming poor dispersal capacity. Our results are discussed in terms of rodent pest control in arid areas of Niger where cereal crops production is crucial for human food security.

Highlights

Gerbillus nigeriae (Muridae, Gerbillinae) is a sanddwelling rodent species that lives within a narrow Sahelian strip from Chad to the Mauritanian coast [1, 2]
We believe that the grid here considered is well representative of G. nigeriae habitat conditions in this area, where millet crops and open savanna on sandy soils dominate in the landscape
Our results indicate that the G. nigeriae population of Gangara presents a single-phase cycle characterized by important inter- and intra-annual variations

Summary

Introduction

Gerbillus nigeriae (Muridae, Gerbillinae) is a sanddwelling rodent species that lives within a narrow Sahelian strip from Chad to the Mauritanian coast [1, 2]. Its diet consists mainly in seeds and, it causes major damage to seedlings and young plants in the field, as well as household and village food stocks of millet, sorghum, cowpea and peanut [3,4,5]. The destruction of up to 60% of millet seedlings was recorded in the Tanout department in the central-east part of Niger, and local but complete destruction is routinely reported in villages throughout Niger [6]

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