Choice feeding bioassay

The efficacy of acetamiprid and fipronil baits was tested by a method of evaluating the effectiveness of toxic baits for fly control [26], in a choice feeding bioassay. The first bait consisted 1.5% of acetamiprid, the second bait consisted 0.15% of fipronil, and the third bait was binary and included 0.15% of acetamiprid and 0.015% of fipronil. The baits were diluted with water in a ratio of 1:3 (e.g., 10g of powder and 30g of cold water) under constant stirring. The resulting thick mass was applied in the volume of 2.5 mL on glass pieces of 100 cm² by a paintbrush. The commercial “Agita 10% WG” was diluted with water according to the manufacturer’s recommendations as follows: 100 g of the product in 80 mL of water to treatment 2400 cm² of a surface, and this corresponds 0.417 g of AI/100 cm². Thus, a water solution of “Agita 10% WG” with concentrations of AI at 16.7% was prepared and applied to the glass piece (100 cm²) in the volume of 2.5 mL. The bait matrix containing starch, Z-9-tricosene, and sucrose at the same proportion was used as additional control and was applied at the same rate as bait formulations. After drying at room temperature, the treated glasses were placed in a cage of 25 cm×25 cm×25 cm; as an alternative, the conventional food was placed in the cage (glucose mixed with dry milk). Then, from 100 to 250 flies were released into the cage and were kept at temperature 25±2°C, at 50-60% relative humidity, and a 12:12 light: dark period. The insect mortality was recorded after 24 and 48 h. All laboratory tests were carried out in 3-6 replicates.