Do the invasive Fall Armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae), and the maize lepidopteran stemborers compete when sharing the same food?

Abstract

In insect communities, the outcome of intra- and inter-specific competitions for food utilisation depend primarily upon density and duration even inter-specific competitions can occur when they are not sharing the same feeding niche such as between foliar feeders and stemborers. Experimental manipulations of larval densities and the durations of common diet feeding of fall armyworm (FAW), S. frugiperda, and the African lepidopteran stemborers, Busseola fusca, Sesamia calamistis and Chilo partellus, were conducted to determine how the density and the duration of resource utilization affected larval survival and the relative growth rate (RGR) in intra- and inter-specific interactions. The results showed both intra- and interspecific competitions were observed among all the four species and interspecific competition was significantly stronger between the stemborers than between the FAW and the stemborers. The results showed that multiple infestations of cereal plants with low larval densities of each species at optimum conditions will very likely prolong the coexistence between FAW and stemborers. In addition, the time partitioning of the resource use significantly influenced this coexistence.