Field trials of VectoLex CG, a Bacillus sphaericus larvicide, in Illinois waste tires and catch basins.

The susceptibilities of Aedes triseriatus (Say), Anopheles punctipennis (Say), Culex restuans (Theobald), and Culex pipiens (L.) larvae to VectoLex CG were determined. VectoLex, formulated on corncob granules (10-14 mesh) was applied to 2 tire dumps and numerous catch basins located in east-central Illinois. VectoLex, formulated as effervescent tablets, was also applied to catch basins. In a sunlit dump, there was a 99.6% reduction in Ae. triseriatus, Cx. restuans, and Cx. pipiens larvae as long as 32 days after treatment, and no pupae were recovered during this interval. There was still a 71.6% larval reduction 74 days after treatment. There was an overall reduction of 22% for An. punctipennis larvae. In a shaded dump, no larval Ae. triseriatus, Cx. restuans, or Cx. pipiens were recovered for 25 days after treatment, and no pupae were recovered 25-67 days after treatment. There was still a 68.7% larval reduction 74 days after treatment. An. punctipennis was unaffected. In one catch basin study, VectoLex was comparable to Altosid (average of 46 days vs. 50 days until larvae were recovered from catch basins). As the summer progressed, the duration of VectoLex control was reduced to 30 days. VectoLex effervescent tablets (evaluated mid-August through September) gave 18-day control. VectoLex was effective against Ae. triseriatus, Cx. restuans, and Cx. pipiens, but was not effective against An. punctipennis in waste tires. VectoLex was effective against Cx. restuans and Cx. pipiens in catch basins.