Browsing by Subject "Fire ants -- Control"
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Item Humidity preference and temperature tolerances of four species of fire ants (Hymenoptera: Formicidae: Solenopsis)(Texas Tech University, 1982-08) Potts, Lindsey RandalDistributional data of fire ants in Texas indicated differences in temperature and moisture requirements, A study was begun to more fully understand the effects of these two factors and to determine if laboratory responses would correlate with distributional differences. Four fire ant species found in Texas, Solenopsis aurea, S, geminata, S.invicta, and S. xyloni were used in tests of humidity preference, supercooling temperatures, and temperature tolerances. Attempts to acclimatize the ants failed. Humidity preferences were determined with a linear gradient chamber. The four species showed a marked preference for saturated atmosphere {near 100* RH). Supercooling points were determined with a hypodermic needle microprobe and tel-etherraometer- The mean supercooling points for the ants were -6.7° C for S. aurea, -8.6• C for S. geminata, -8.3• C for S. invicta, and -7.0° C for S. xyloni: Solenopsis aurea and S- xyloni ware not significantly different from each other, and S, invicta and S, geminata were not significantly different from each other; the two groups were significantly different. Three caste sizes were tested in the supercooling experiments. There were no differences between the castes of S. aurea and S. xyloni.- Solenopsis invicta major workers supercooled at a significantly lower temperature than did the medium and minor workers, Solenopsis geminate minor workers supercooled at a significantly lower temperature than did the other castes. Temperature tolerances were determined from one hour exposures. Temperature became a significant cause of mortality at approximately 40» C, and at 450 C all ants perished- Regression analysis showed high variability within replications and significance of the independent effects of temperature, species, humidity, and interactions of these effects. The significance of the independent effects was partly due to the confounding of these effects by the variability within replications. All LD50 values were between 41° C and 44°C.Item Predation as a factor in colony establishment of the red imported fire ant (Solenopsis invicta)(Texas Tech University, 1989-05) Nichols, Rebecca JoIn 1987, surface and subterranean pitfall traps containing Solenopsis invicta Buren founder queens were placed at two sites each in central Texas, within and outside of the current S. invicta range, to determine if arthropods are specifically attracted to the queen. The diversity of arthropods collected outside the S. invicta range was much greater than inside, but a directed response toward founder queens in both the infested and uninfested areas was not detected. Vials containing S. invicta founder queens, which had mesh screen over the opening to allow entrance of predators, were placed at four central Texas locations during 1988 to compare queen mortality due to predation and also to document ant predators of the queen. Seventeen ant species were observed killing queens, 12 of which previously had not been documented as S. invicta founder queen predators. Diversity of the local ant faunas decreased from outside of the S. invicta range to inside the range as dominance increased.Item The effect of acute exposure to relative humidity and temperature on the worker caste of four species of fire ants(Texas Tech University, 1982-05) Braulick, Lori SNot available