Simplified approaches to determine the attractant preference of Solenopsis invicta (Hymenoptera: Formicidae)

Abstract

The red imported fire ant, Solenopsis invicta, is an invasive species that has been introduced into the United States and more recently into several countries in the Asian-Pacific region. The foraging dynamics of this pest ant is important in understanding its interactions with native ant species and in devising the most effective toxic bait control methods. In this study the effect of worker density, size of the foraging area, the number of food lures, duration of experiments, and the effect of the queen on foraging activity were investigated under laboratory conditions. The results showed that of the four ant densities investigated (very small, small, medium and high) the medium ant density most consistently had more workers at the food lures than the other ant density situations. The percentage of worker ants at the food lures was negatively correlated with an increase in foraging territory size for all four worker ant densities. Significantly fewer foragers were observed in the foraging areas when a queen was present, then when the queen was absent. In addition, when number of food lures was increased from 1 to 12, the mean number of workers found at the lures was significantly higher when four food lures were present. Furthermore, the number of worker ants observed on the food lures increased for the first 2.5 h and then decreased with time. The study suggests that observations of foraging activity could be restricted to 2.5 h. These data lay the ground work for further studies in optimizing the effectiveness of fire ant bait toxicants.

A new baited trap for monitoring Solenopsis invicta (Formicidae: Hymenoptera) in Taiwan

“…The colonies were provided with water, live tenebrionid beetle larvae, and 30% sugar water for both hydration and as food. Ants were starved for 2 days prior to the experiments to ensure that their midgut was empty and they were hungry enough to search for food (Furman and Gold 2006;Kafle et al 2008Kafle et al , 2009aKafle et al , 2009b.…”

“…The foraging area, nest preparation, and bait placement were adapted from Kafle et al (2008). A circular artificial foraging area 40 cm diameter 9 17 cm high was used in this study.…”

“…A circular artificial foraging area 40 cm diameter 9 17 cm high was used in this study. The detailed arrangement of the artificial nest and bait placement was as described in Kafle et al (2008). Food lures prepared for evaluation (approximately 1 g) were kept on the plastic weighing plate and were placed at equidistant locations along the inner wall of the circular foraging area.…”

“…Twelve active RIFA mounds were selected randomly. The mound constructed by RIFA is a complex, dense network of narrow tunnels and nodules constructed of soil pellets mined from deeper soil levels (5-15 cm depth), linking deeper true subterranean chambers to the aboveground portion of the nest (Kafle et al 2009b). Food lures consisting of hotdogs, shrimp crackers, and potato chips (approximately 1 g each) were kept on plastic weighing plates and placed approximately.…”

“…Generally, RIFA foragers use an extensive system of foraging tunnels 20-70 mm below the soil surface. The exit holes of these tunnels are distributed throughout their foraging territory, such that the foragers need to travel only a short distance, approximately 0.5 m, above ground to reach any point in their territory while foraging (Porter and Tschinkel 1987;Kafle et al 2009b). Therefore, ants walking in the tunnels escape the traditional monitoring tools used by researchers (Hung et al 2006;Oi et al 2008;Tsai et al 2009), such as pitfall traps or potato chips and hotdogs placed on the ground to monitor RIFA in the field.…”