ESMAT A. KARES
Biological Control Dept. Plant Protection Research Institute, ARC , Dokki . Giza , Egypt

ABSTRACT

The efficacy of two commercial products of Bacillus rhuringiensis , Bactospeine and Thuricide ; two different chemical insecticides, Cyanophos and Fenvalerate and their combinations on the 4th instar larvae of the pink boliworm Pecrinophore' gonssypiella was studied . The LC50 values were 3.65 x i0 I.U. for Bactospeine and 4.6 x i04 I.U. for Thuricide. Results indicate that Bactospeine was more efficient than Thuricide . The toxicity of Fenvalerate was higher than that of Cyanophos, where the LC50 values were 20.5 p.p.m for Fenvalerate and 35 p.p.m for Cyanophos Bactospeine and Thuricide when combined with LC10 of Cyanophos or Fenvalerate at low concentrations of 1.5 x 1O4 and Thuricide was combined with the synthetic pyrethroid Fenvalerate , the potentiation effect was more active ( + 49.54 and + 28.30 ) than when each of them was combined with the organophosphorus compund Cyanophos ( +46.66 and +24.52) . In general, Bactospeine was more active than Thuricide when it is combined with cyanophos or Fenvalerate . At high concentrations of Baccospeine and Thuricide (4.5 x 1O4, 6 x io and 7.4 x iO I.U. ) , combination with LC10 of Cyanophos or Fenvalerate generally produced additive effects.

Key Words: Bacillus rhuringiensis. Insecticides . Pectinophora gossypiella.