Md. Korzukhin et Sd. Porter, SPATIAL MODEL FOR TERRITORIAL COMPETITION AND POPULATION-DYNAMICS IN THE FIRE ANT SOLENOPSIS-INVICTA (HYMENOPTERA, FORMICIDAE), Environmental entomology, 23(4), 1994, pp. 912-922
We developed a simulation model of monogyne red imported fire ant, Sol
enopsis invicta, populations that operates by competitive interactions
of individual colony territories. This model describes six major aspe
cts of colony life history: nest founding, brood raiding, territory ex
pansion, queen death, possible requeening, and colony death. Individua
l colony territories are represented by rectangles, whose sides change
independently depending upon the presence and size of neighboring col
onies. Growing colonies try to occupy free space, while retaining squa
re territorial dimensions whenever possible. The growth of fire ant po
pulations in the model compared well with available field data. The mo
del predicted that competitive exclusion caused by territorial interac
tions should occur when areas reach 70-90% territory coverage. Several
computer experiments were conducted with the model to examine the imp
ortance of colony growth rate, brood raiding activity, and other param
eters on the relative success of sequentially founding colony cohorts.
A 1-wk advantage in founding generally increased the long-term surviv
al of young colonies by 40-80%. We also examined the factors affecting
average coverage of an area by colony territories. Maximum coverage w
as achieved under a continuous influx of 50 queens/(ha.wk) or a single
settlement of 1000 queens/ha; both values were much less than actual
magnitudes of queen influx observed in the field.