Laboratory tests and practical evaluation of novel granule formulations containing BTI or methoprene developed for controlling mosquito and fly larvae

The residual activity of Bacillus thuringiensis subsp. israelensis (BTI) and methoprene, a juvenile hormone analogue (juvenoid) was assessed when their novel granule formulations, were tested on mosquito and fly larvae. BTI B 5 GR mos­ quito larvicide at 5 and 10 ppm (a.i.) gave 100% control against L4 larvae of Aedes aegypti for 4 and 12 weeks, respectively. Similar prolonged 16 weeks efficiency could be demonstrated with the methoprene containing BIOPREN BM 5 GR for­ mulation. When applied at 1 to 20 ppm (a.i.) to L3 and L4 larvae ofAe. aegypti. Under simulated natural conditions, young (L1-L2) and old (L3-L4) larvae of Ae. cantans proved especially susceptible, since methoprene incorporated into these granules at a concentration of 0.1% prevented adult emergence for 5 weeks. Tests carried out with LiAe. aegypti larvae in closed containers revealed that relatively high tempera­ ture and bacterial contamination could decrease the persistence of juvenoid. The spe­ cific morphogenetic activity of methoprene was also observed in tests performed with larvae of Musca domestica. In a laboratory experiment, BIOPREN BM 5 GR inhib­ ited adult emergence for at least 12 weeks even at low dose of 10 mg/kg of pig manure. In another trial conducted in pig-rearing houses with an intensive, cage management system, treatments with the same granules resulted in a significant suppression of pre­ viously massive house fly populations.