Influence of German cockroach (Dictyoptera: Blattellidae) fecal extract on food consumption and harborage choice

Abstract

The influence of fecal extract on German cockroach, Blattella germanica (L.), consumption and harborage choice was evaluated in 24-h dual choice arena tests. The mean number of German cockroaches entering and remaining in harborages containing food treated with fecal extract (100 or 1,000-μl dose levels; no effect was observed at the 10-μl dose level) was significantly greater than that expected from a 50% distribution. However, the fecal extract applied directly on the food source did not enhance consumption. At the 1,000-μl dose level, consumption of the control food was significantly greater than that of the extract-treated food. These results indicate that German cockroaches preferentially consumed the food in control harborages but left the food to aggregate in harborages containing fecal extract. Dual-choice arena tests where fecal extract was placed adjacent to the food source (inside the harborage) resulted in significantly more German cockroaches (>50%) aggregating in harborages containing the fecal extract. Food consumption in harborages containing the fecal extract (100 and 1,000 μl) was also significantly greater than in controls with no fecal extract. These results demonstrate that the number of German cockroaches in the harborage increased when fecal extract was present. Larger numbers of cockroaches resulted in increased food consumption when fecal extract was placed adjacent to the food source.