Browsing by Subject "Solenopsis invicta -- Behavior"
Now showing 1 - 3 of 3
Results Per Page
Sort Options
Item Characterization of the brood cuticular hydrocarbons of the fire ant Solenopsis Invicta and their possible role in brood recognition by workers(Texas Tech University, 2004-12) Al Diri, IssamChromatography and mass spectrometry analysis were used to identify and quantify 14 cuticular hydrocarbons in the developmental stages of S. invicta. The following quantitative and qualitative differences in hydrocarbons were observed among brood components. Cuticular hydrocarbons consisted of saturated n-alkanes and methylalkanes, ranging from C23 to C29. The total amount of cuticular hydrocarbons was greatest in prepupae and least in pupal stages. While the total amount of cuticular hydrocarbons was several magnitudes greater in components of sexual brood, as expected since sexual forms are larger than worker forms, the ratio of n-alkanes to methylalkanes in worker brood was generally higher than its counterparts in sexual brood. Discriminant function analysis of the brood subcastes using the five most abundant hydrocarbons within and among colonies showed that the brood subcastes clustered together based on their respective developmental stage, with n-heptacosane being the major component responsible for the observed clustering. Finally, several bioassays were conducted to determine whether cuticular hydrocarbons play a role in brood recognition. Worker retrieval response toward pupae immersed in hexane for 5 min was significantly lower than that towards a control. Immersing pupae in boiling water for 3 sec. also induced a similar response to that caused by hexane. Several concentrations of cuticular extracts in hexane of sexual prepupae applied to a paraffin dummy failed to induce any retrieval response by workers. In addition, manipulation of the composition of brood cuticular hydrocarbons did not seem to affect worker response toward the brood. Taken together, the results suggest that a chemical signal other than cuticular lipids is involved in brood recognition.Item Pheromonal control over worker execution of sexual larvae in fire ants (Solenopsis invicta)(Texas Tech University, 2001-05) Klobuchar, Emily AnnI studied the phenomenon of worker execution of sexual larvae in the red imported fire ant, Solenopsis invicta. Both fertilized and unfertilized queens as well as queen corpses were equally effective in inducing executions by 96 h. Colonies receiving acetone (control) or queen extracts in acetone did not differ in execution rates. In sharp contrast, however, colonies receiving an extract of queens in a buffered solution killed significantly more sexual larvae than those colonies receiving only the solution (control). The extract was as effective as live queens, and, as in all tests, were introduced once every 12 h at concentrations of single-queen equivalents. In addition to having full activity, the extract was stable, as the percentage of larvae killed did not differ between jfresh (Id) and old (21 d) extracts maintained in clear vials at room temperature. The poison sac was identified as the likely storage site of the pheromone. This sac also houses the venom alkaloids and queen retinue pheromone, but these chemicals are readily extracted with strong organic solvents, unlike the 'execution' pheromone. There was no correlation between ratios of the two most abundant alkaloids and queen age, but ratios of saturated to unsaturated alkaloids were significantly greater in wingless queens than in winged queens. The queen venoms are less derived than those of workers perhaps because the execution pheromone has constrained their evolution.Item Response of the red imported fire ant (Solenopsis invicta Buren) to static electrical devices(Texas Tech University, 2001-05) Newbrough, Joseph KirkUsing video technology, the response of Solenopsis invicta Buren to static electrical devices (SEDs) was documented. Three separate studies were performed to evaluate the initial attraction, colony movement towards or away from the device, and behavior of individual workers to alarm pheromone environments caused by electrical shock. The first study was performed by taking video images of the number of ants on or 2.54 cm around the SED. The images were then downloaded to a computer and enhanced, in order to count the number of S. invicta. The results indicated that significantly more ants were on or 2.54 cm around the active SED as opposed to the inactive SED (non-parametric Wilcoxon t-test, P<0 05). The second study used time lapse video and a three chamber apparatus to document the movement of a colony towards or away from an active SED The results indicated that there were no preferential movements of 5. invicta colonies towards or away from an active SED as opposed to an inactive SED (chi-square, analysis P>0.05). The final study used an olfactometer to document the preferential movements of individual S. invicta to the inherent odors of an active SED, and to gaster-flagging nestmates on an active SED The results showed no significant difference between the attraction of S. invicta workers to the inherent odors of an active SED as opposed to the odors of an inactive SED (non-parametric Wilcoxon t-test, P>0.05). Further, the results indicated S. invicta are significantly attracted to gaster-flagging nestmates on an active SED as opposed to non-gaster-flagging nestmates (non-parametric Wilcoxon t-test, P<0.05).