Integrated management of waste tire mosquitoes utilizing Mesocyclops longisetus (Copepoda: Cyclopidae), Bacillus thuringiensis var. israelensis, Bacillus sphaericus, and methoprene.

This study evaluated the compatibility and efficacy of using a predatory copepod, Mesocyclops longisetus in concert with 3 "biorational" compounds for mosquito control in waste tires. The toxicity of Bacillus thuringiensis var. israelensis (B.t.i), Bacillus sphaericus, and methoprene to Mesocyclops longisetus was assessed in the laboratory using concentrations 10 times the maximum labeled or suggested rate and based on a water depth of 7.6 cm. Microbials were tested using mature copepods exposed for durations of 24, 48, and 72 h. Methoprene bioassays consisted of individually exposing newly hatched copepods (i.e., nauplius larvae) and monitoring their development to maturity. The toxicity tests indicated B.t.i., B. sphaericus, and methoprene were not deleterious to copepods at concentrations exceeding those expected in the field. Copepods exposed to methoprene matured normally, and when mated, 50% developed egg sacs. A 5-month field test, integrating the copepod and B.t.i., B. sphaericus, and methoprene provided better mosquito reduction together than either copepods or control agents alone. When copepods were combined with B.t.i. or methoprene, overall reduction of 3rd- and 4th-instar larvae during the 5-month interval was equal to or greater than 90%. Bacillus thuringiensis var. israelensis alone temporarily produced a high degree of larval reduction (up to 100%), however reapplications were necessary to maintain that level of control. Of all the treatments, B. sphaericus alone produced the lowest degree of mosquito suppression due to lack of toxicity to Aedes albopictus, the predominant species during the study. It is recommended that mosquito control managers consider integrating M. longisetus and B.t.i. or methoprene against mosquitoes in waste tires.