EFFECTS OF SOME INSECTICIDES ON THE DIVISION OF A SPODOPTERA-LITTORALIS CELL-LINE AND ON THE REPLICATION OF SL BACULOVIRUS (NPV)

The impact of several insecticides has been studied on a Spodoptera li ttoralis cell line and their effects on the replication of S. littoral is nucleopolyhedrovirus (Sl NPV). Four chemical insecticides, Chloropy rifos, Fenitrothion, Cypermethrin and Carbaryl which belong to three d ifferent groups of pesticide, organophosphorus, pyrethroid, and carbam ate, respectively, were used. The results demonstrate an increase of m ore than 25% in the multiplication of SI cells when treated with Chlor opyrifos dilutions compared with untreated cells. The most destructive pesticide was Cypermethrin, which caused 84% inhibition of cell devel opment (0.4 x 10(6) cell/ml) at a concentration of 10(-3) mu g/ml in p reliminary tests. In the presence of both SI NPV and sublethal doses o f these insecticides, the TCID50 values revealed that the Cypermethrin (10(-8) mu g/ml) was the most toxic (ID50 was 6.48 x 10(5)/ml) wherea s Chloropyrifos was the least toxic (ID50 9.29 x 10(12)/ml) at a conce ntration of 0.731 mu g/ml. The PFU values confirm the results that the same concentration of Chloropyrifos (0.731 mu g/ml) was the least tox ic (PFU 6.41 x 10(13)/ml) and Cypermethrin was the most toxic (4.47 x 10(6)/ml PFU) for the other concentrations as well as the different in secticides the PFU values ranged between 2.8 x 10(8) for Chloropyrifos at a concentration of 10-3 mu g/ml and 9.76 x 10(12) for Carbaryl at 10(-5) mu g/ml. A comparison with the results obtained using SI NPV wi thout chemicals (the PFU 3.5 x 10(9)/ml) indicates an increase in the production of virus and titer, and a synergistic effect of the chemica ls. These results confirm the effect of these insecticides in vivo. As the Cypermethrin may have a potent effect on the exchange of ions thr ough the cell membrane in vitro and in vivo, it could be partially exp lain the impact of the insecticides and their mode of action.