Do battles lead to coexistence? Role of interference competition in structuring the insect community on fermented tree sap

1. In insect communities on fermented tree sap, agonistic interactions occur frequently among the component species. This study examined the effects of such interference competition on community structure and species co-occurrence on a spatio-temporally small scale. 2. Experimental removal of giant hornets (Vespa mandarinia), one of the most dominant species, showed no effect on either species richness or total abundance of the remaining insects. Significant increases in abundance were detected for five out of 19 taxa: V. ducalis, V. crabro, Lasius japonicus, Cryptarcha lewisi, and a group of micro sap beetles (Epuraea spp., Haptoncus spp., and Haptoncurina spp.). 3. Behavioural observations indicated that interference did not alter the staying time at a patch (an exuding spot on a tree) for V. mandarinia, Rhomborrhina japonica, and Neope goschkevitschii. Interference-mediated departure from a patch was less frequent than departure without interference for all nine species observed, except for R. japonica. These behavioural contexts varied yearly for several species. 4. These results suggest that interference competition is a minor determinant of overall community structure, despite its conspicuousness. This weak effect of interference may be attributed to the short stay of dominant species and to individual behavioural responses, such as competitor avoidance. The variable influence of interference might be related to differences in species attributes, such as dominance hierarchies.