Effects of pesticides on division of two lepidopteran cell lines and onAutographa Californica MNPV development in TN368 cells

Abstract

The concentration of each of 10 pesticides (azinphosmethyl, captan, carbaryl, chlordimedorm, dichlorvos, dimenthoate, fenvalerate, methomyl, methyl parathion, trichlorfon) causing a 50% inhibition (ID50) in cell number relative to an untreated culture for a time period equal to four cell doublings was determined for the TN368 and IPLB-HZ1075 cell lines. The range of ID50 values with either of the cell lines was similar, with captan being most toxic within an ID50 range of 5 to 6 μM/2×105 cells/ml, and methomyl least toxic within a range of 2900 to 3200 μM/2×105 cells/ml. Yet there were significant differences between cell lines in pesticide susceptibility. Fenvalerate, dichlorvos, and chlordimeform were 16, 3, and 1.5 times more toxic, respectively, for TN368 cells than HZ1075 cells, whereas dimethoate and carbaryl were each 2 times more toxic for HZ1075 cells. In general, increasing toxicity paralleled decreasing water solubility, although the order of the pesticides varied somewhat according to the particular cell line and medium. Moreover, there was little aberrant cell morphology in either of the cell cultures during incubation with most of the pesticides at their ID50 levels. Preincubation of TN368 cells with any one of seven different pesticideis before inoculation withAutographa californica MNPV, and subsequent incubation of infected cells in medium plus pesticide, did not significantly suppress polyhedra development except for trichlorfon-incubated cells. In addition, there was a small but consistent variation from control cells in extracellular virus titers assayed from two of five of the pesticide incubations. The titer was consistently depressed with trichlorfon and elevated with fenvalerate, however, further work is required to determine the biological significance of these differences.