Efficacy of Bait Formulations of Avermectin Bl and Amdro Upon Male German Cockroaches, 1982

Bait formulations of avermectin Bl and Amdro was evaluated in modified Ebeling choice boxes. The modification consisted of the deletion of screened holes in the sides of the box. The choice box was 30 cm × 30 cm × 15 cm and made of clear white pine. A center partition divided the box into 2 chambers whereas a 1-cm hole near the top center of the partition permitted the movement of cockroaches between chambers. Box bottom was of 0.6 cm replaceable plywood panels. Top was 0.4-cm-thick panels of replaceable plexiglass. In 3 replications both chambers of the choice box were provisioned with water and kept dark. One chamber of each choice box received a 0.5 g sample of Al po dry dog food bait previously treated with a selected concentration of either Bl or Amdro. Preliminary trials indicated that 1,000 or 10,000 ppm Amdro was required for sufficient mortality for analysis. The other choice box chamber received a 0.5-g sample of untreated Al po dog food. Samples were placed into choice boxes in plastic petri dish bottoms. The hole in the center partition was stoppered and 25 male German cockroaches, Orlando Normal biotype, were introduced into each chamber (50 cockroaches per box). One hour later, after the effects of carbon dioxide anesthesia had subsided, the stopper was removed. Once each day at 1 p.m. for 7 days the number of dead or moribund cockroaches in each chamber were recorded and removed. Probit analysis was performed on the data to estimate LT50 values.