Population Dynamics and Genetics of <i>Gerbillus nigeriae</i> in Central Sahel: Implications for Rodent Pest Control

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.

From Problem to Progress: Management of Rodents in Urban and Agricultural Settings in Sub-Saharan Africa.

“…In comparison, 22 captures were achieved in five nights with 256 locally-made wire mesh traps, with a capture rate of only 1.7%. This illustrates that the Kornaka traps were 15 times more effective than the wire mesh traps [32].…”

Rodent Proliferation in Urban and Agricultural Settings of Sub-Saharan Africa – Part 2. Towards Integrated Management Strategies, and Beyond

“…In West Africa, such experiences are almost non-existent, although some isolated attempt could already provide elements to more integrated EBRM strategies sensu stricto. For instance, the traditional pitfall traps (the co-called "Kornaka" traps) used by Sahelian farmers appears to be promising to reduce pest gerbils' abundances in extensive pluvial millet fields in Central Niger beyond reliance on chemical rodenticides (e.g., 37 captures in 3 nights with 49 Kornaka traps, equivalent to a capture rate of 25.2%, compared with 22 captures in 5 nights with 256 locally-made wire mesh traps, equivalent to a capture rate of 1.7%: the Kornaka traps were thus 15 times more effective than the wire mesh traps [30]). Due to a shortage of chemical rodenticides, Crop Protection officers in Ogo (Matam, Senegal) have experimented pitfall traps in a 10-15 days' participatory farmer action in four localities in 2021 (B. Diouf, pers.…”