| At the biochemical level two novel proteins (A & B) were identified in the hemolymph of newly collected mated queens that were not present in the hemolymph of either virgin queens or in queens two days post-mating. In a reverse genetics approach we were able to isolate a 252 bp DNA fragment corresponding to protein B that is homologous to the cysteine protease inhibitor (CPI) in plants. Similarly, a 671 bp PCR product was generated corresponding to protein A that showed homology to Lactate Dehydrogenase (LDH). Based on these findings, we suggest that putative fire ant queen CPI may be involved in flight muscle histolysis. The expression of putative CPI was monitored at transcriptional levels to establish its role in flight muscle histolysis. A significant increase in the expression of putative CPI in mated queens was observed as compared to alate virgin queens. The enhancements in the expression of putative CPI started from day 0 post-mating continued to increase for another three days. On day 7, the expression almost vanished. In our second experimental approach, the roles of mating, flight, CO2 level, juvenile hormone (JH), 20-hydroxyecdysone and male lipoproteins in the flight muscle histolysis of adult virgin fire ant queens were investigated. We found that topical application of methoprene (JH analog) at a concentration of 0.44 ng per ant stimulated 90% of alates to shed their wings. Artificial insemination also resulted in apoptotic nuclei in flight muscles. In contrast, the other factors tested did not induce flight muscle histolysis in fire ant queens, nor did they cause any significant dealation. |
