Multimarker genetic analyses of Gonimbrasia belina, the most harvested
wild edible insect of mopane woodlands in southern Africa supports
concerns over the sustainability of the species
Abstract
The caterpillars of Gonimbrasia belina, commonly known as mopane worms,
are intensively harvested for human consumption in southern Africa.
Concerns over the sustainability of the species have been raised for the
last two decades due to increasing demand, habitat erosion, and climate
change. Despite its cultural, economic, and nutritional significance,
genetic data for G. belina was largely unavailable. We used a
multi-marker approach including mitochondrial sequences and nuclear
ddRADseq data to assess the genetic diversity, phylogeographical
structure and demographic history of G. belina in Namibia and the
Limpopo River Basin (South Africa and Botswana). Mitochondrial sequences
revealed strong phylogeographical structure at the broad scale
separating Namibia and Limpopo River Basin populations. Within the
Limpopo River Basin, populations are separated by the Limpopo River,
with haplotype sharing only at the border between South Africa and
Botswana. Mitochondrial genetic diversity varies between sampling areas
but overall is highest in South Africa and lowest in Botswana, while
historical demography points to population expansion in Namibia but not
in South Africa and Botswana. Nuclear data in the Limpopo River Basin
revealed some connectivity among populations albeit with significant
genetic differentiation and unique gene pools in some sampling areas.
All sampling areas show low genetic diversity, alarmingly small
effective population size, and signs of recent bottlenecks. We generated
the first baseline data for the genetic monitoring of G. belina
populations and conclude that concerns over the sustainability of the
species are presently justified in Botswana and South Africa.