Abstract
A method, introduced here as the Multiple Stick Array (MSA), was devised to calculate surface densities of Solenopsis iniicta scouts over time and space. Four sub arrays of six sticks each were deposited on the substrate and all ants that cross the sticks are noted. Four habitat types that are common throughout the landscape matrix of Texas and other regions of the southern U.S. were examined for surface scouting activity: cattle pasture, fallow field, forested edge (post oak forest), and pond edge. Observations at the sub array level (surface area ca. 0.5m2) over a period of time (5 minutes) in each of these habitats were executed from the fall of 1995 through the fall of 1996. When S. invicia scouts were active (> 3 ants noted per observation period per MSA), the average number of ants intercepting the observation area in cattle pasture was 0.509, in fallow field 0.273, in forest 0.482, and at pond edge 11.293. Surface activity of ants followed a bi-modal pattern in open pastures, the majority of activity occurred during either morning or late afternoon/evening. Ants ceased activity in the morning when the mean (shaded) surface temperature approached 31.4'C and resumed activity in the afternoon as temperatures fell towards 33.9'C, showing a statistically significant difference between the temperature means (t =-2.89-df = 20; P = 0.009). Surface activity in shaded forest areas usually continued at low levels throughout the day. Surface activity at pond edges continued at high levels throughout the day. Based on these observations, I speculate that the three most important abiotic components influencing scouting behavior (presence or absence on the surface) of S. invicia are surface temperature, surface humidity, and amount of solar radiation impacting the surface, and the interactions between these factors.
Martin, James Benjamin (1996). Surface activity of the red imported fire ant Solenopsis invicta Buren (Hymenoptera:Formicidae), in polygyne infested areas of Brazos Co., Texas. Master's thesis, Texas A&M University. Available electronically from
https : / /hdl .handle .net /1969 .1 /ETD -TAMU -1996 -THESIS -M374.