Ants community structure in the urban and the city suburbs areas of Douala (Littoral-Cameroon)

The Douala harbour represents the main gateway through which human activities introduce invasive ants, so that Solenopsis geminata (Fabricius, 1804) originating from Neotropics has been reported in several areas of the Littoral region of Cameroon. But nothing is known about the ant community structure and composition of the coastal zone. We hypothesized that environmental perturbations around Douala have repercussions on the native litter-dwelling ants. Collections conducted in 33 houses, six gardens of 225 m² each, 41 plantations of one hectare each and 34 two-year old fallows of one hectare each suggested lowly even communities, low species richness, low diversity and low dominance by a few species. Among 28 species recorded four species were mostly represented: two foreign origin species [S. geminata (Fabricius, 1804) and Trichomyrmex destructor (Jerdon, 1851), from tropical America and India respectively], one native species [Pheidole megacephala (Fabricius, 1793)] and two ambiguous native range species [Paratrechina longicornis (Latreille, 1802) and Tapinoma melanocephalum (Fabricius, 1793)] since they have long been recorded as having a widespread distribution. Alien species were highly represented than native ones (52.9% and 47.1% respectively, p<0.001). Inside houses, gardens and plantations the ant species were distributed according to the geometrical progression (Motomura’s model) while in the old fallows abundance distribution suggested an evolved ecosystem (Mandelbrot’s model). Between the three dominant species [Pa. longicornis (Latreille, 1802), Ph. megacephala (Fabricius) and S. geminata (Fabricius)], the first species was positively correlated with the third one while other associations were not significant. These dominant species appeared influencing the abundance of the rare species. Dominance and high abundance of a few species indicated that areas were influenced mostly by interspecies competition and/or disturbance by human activities.