Ecological effects of the invasive ant Pheidole megacephala in Laikipia, Kenya, on ground ant biodiversity and host plant health

Abstract

Pheidole megacephala is one of the worst invasive species in the world due to its serious impact on biodiversity and human activities. It has a wide presence across the world and continues to expand out of anthropogenic centers, causing economic damage and drastically reshaping ecosystems. The invasion spreads very quickly (175- 240 m/year) through the red sandy soil of the savanna of East Africa, and results in a significant reduction of ground ant biodiversity. Among acacia ants in a mutualism with Acacia drepanolobium trees, only Tetraponera penzigi can coexist with P. megacephala; T. penzigi does not expand in the presence of P. megacephala, but does successfully retain its existing territory from attacks by P. megacephala. Although P. megacephala displaces both ground and arboreal ants, they do not actively defend host plants from herbivorous insects. The only, highly-localized instance of herbivory protection is in the presence of the aphid gardens that the P. megacephala are tending.