S. Bradleigh Vinson, C. J. Coates, T. Haisheng, A. Rao, and Togahara Azizi. Entomology, Texas A&M University, College Station, TX 77843
Reproduction by queen Imported Fire Ants, Solenopsis invicta Buren, involves a complex of interactions that regulate reproduction. For example, winged females in the mother colony only dealate following a mating flight within a few hours, along with the initiation of flight muscle degeneration (FMD) and eggs are laid within a day. However, if the mother queen dies some alates will dealate within the colony within 2 days and may begin to lay eggs within 3-4 days. If alates are isolated (no workers) dealation and egg laying maybe delayed by a several more days. Factors such as JH, CO2 and factors associated with the mating flight have been reported to initiate dealation, FMD, and egg production, however these studies were not clear as to alate age. We have repeated these studies looking at the effects of tethered flight, JH, CO2, ecdysone, artificial mating and natural mating on dealation, FMD, and egg production using alates of known age. We have also isolated and characterized the vitellogenins (there are 3) from the RIFA and found one in workers as well as queens while another is present in the hemolymph prior to egg maturation. Results suggest the receptor (VgR) is involved in egg production and we find that VgR is present in ovaries and is up regulated by a JH analog. Using suppression subtractive hybridization we have isolated 7 highly differentially expressed genes in dealate queens including 2 of 3 Vg genes that differ in several subdomains. Only 2 Vg’s are found in eggs. Once the colony is initiated resources are brought in, processed by bacteria and enzymes in larvae and cycled to the queen sustaining egg production. However, as larvae pupate the queen’s reproduction is increased. We have refined much of this information that will be presented.
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