Community Structure and Functioning of the Soil Macro-invertebrates under Invasion by Wasmannia auropunctata (Roger, 1863) (Hymenoptera: Formicidae) in Mbalmayo Reserve Forest (Centre-Cameroon)

Abstract

Ecological survey in invaded and non-invaded sites allowed the verification of occurrence or persistence of Wasmannia auropunctata (Roger, 1863) (Hymenoptera: Formicidae), and it’s impact on soil macro-invertebrates. Specimens were collected using baits (70% honey and 30% canned sardine, daily checked at 15 min intervals during 2 hours a day and five consecutive days a week), pitfalls (plastic tubes 150 mm length x 15 mm diameter, half filled with 10% formalin, weekly checking starting after seven days), and hand-picking by two peoples. Collections (September to November 2023) were conducted in the Mbalmayo Reserve Forest. A total of 33 sites were visited (29 and four in non-invaded and invaded areas respectively). In a site, three 1x50 m parallel transects were delimited (separation: 10 m), overlapping a plantation and a secondary forest. In a transect, eight quadrats were delimited (1x1 m; separation: 5 m). Baits were used in 1st transect, pitfalls in 2nd, and hand-picking in 3rd. In a site category 24 sessions were conducted (eight for baits, pitfalls, and hand-picking respectively). Captures were stored in labeled pill boxes containing 70% ethanol. A total of 129,916 specimens belonged to three phyla, seven classes, 18 orders, 39 families, and 84 species. Three and one sites were newly and formerly invaded respectively. Assemblage was highly species-rich in non-invaded sites (68 and 34 species in non-invaded and invaded sites respectively). Five orders and 20 families were absent in invaded sites. Oniscidae, Cydnidae, Scarabaeidae and Blaberidae were tolerated by W. auropunctata (highly abundant and dominant). Macro-invertebrates fauna was lowly even in invaded sites and operated by maintenance of a network of information with a weak force of regeneration. W. auropunctata caused disappearance of macro-invertebrates and dictated a functioning order to tolerated species. Sustainable approach may be developed against W. auropunctata.