Sustained-release formulations ofBacillus thuringiensis serotype H-14 and plastic formulations of Abate for long-term control of mosquito larvae

The larvicidal activity of sustained-release formulations ofBacillus thuringiensis H-14 (Bactimos briquets) and controlledrelease plastic formulations of Abate against mosquito larvae ofAedes aegypti (L.) has been evaluated. The test formulations provided continuous effective control with 90–100% larval mortality for several weeks. The presence of suspended soil constituents was associated with a lowering of larval mortality and tended to reduce the durations of effective control of Bactimos and Abate plastic pellets against mosquito larvae by about 1.8 and 2.2 times, respectively. Treatments with such formulations did not appear to prevent hatch of eggs which oviposited after application, but all newly hatched larvae failed to develop beyond the second instar.