The interactions between red imported fire ant, Solenopsis invicta Buren (Hymenoptera: Formicidae) and potentially competitive ant species, investigated under laboratory and greenhouse conditions.

摘要

The objective of this project was to determine the time span in the life cycle of Red Imported Fire Ant, or Imported Fire Ant (IFA), which is vulnerable to native ants. Four native ant species, Monomorium minimum, Pheidole dentata, Solenopis molesta and Forelius sp., and two exotic species, Tetramorium bicarinatum and Monomorium pharonis were selected to study the interactions with incipient IFA colonies with five different colony sizes, 30, 60, 120, 240, and 480 workers. The findings indicated that M. minimum and P. dentata were able to invade and kill incipient IFA colonies of sizes up to 480, and S. molesta up to the colony size of 240. One exception to the native competitor species examined is Forelius sp. that did not invade the IFA nest. The exotic species, M. pharonis and T. bicarinatum also invaded and killed the IFA colony size of 480 and 240 respectively. The time to invasion and destruction by different species varied with the increase in the IFA colony size and behavioral differences. Species such as IFA, and P. dentata were “aggressive” compared to S. molesta, Forelius sp., and T. bicarinatum. The latter three were “defensive” in comparison with the rest of the species.; Further studies indicated that distance between the colonies had a significant effect on the invading and interacting ability of M. minimum and IFA, whereas the feeding status did not. The data also suggest that M. minimum will most likely invade IFA incipient colony nest with 30 workers if the closest entrance of an IFA colony is 0.2 m away. On the other hand, the interspecific interactions between the two species were observed to occur even at a farthest distance of 6.4 m.; Investigations on the venom of M. minimum suggested that synthetic venom compounds are potential repellents to IFA. Both glass and plexiglas plastic acted as good binding substrates to both the synthetic venom compounds tested. The concentrations of these compounds as low as 0.001 or 0.03 μg/μl were active in terms of reducing the number of IFA walking on the treated substrate.