Effect of sub lethal concentrations of thiocyclam insecticide on biological parameters of Liriomyza sativae (Diptera: Agromyzidae) under laboratory conditions

Liriomyza sativae Blanchard is considered as one of the most important pests of greenhouse and farm vegetables. According to the recommendation of using thiocyclam insecticide against the mentioned pest, in the present study the lethal and sub-lethal effects (LC10= 49.15, LC20= 87.1 and LC30= 131.5 a.i. mg/L) of thiocyclam insecticide (Evisect® SP50%) was evaluated on the biological parameters of this pest under laboratory conditions. The method used in the experiments was Leaf dip technique for leaves containing fly larva. Data analysis was performed using Age-stage two sex life table theory.  The results showed that adult lifespan/longevity was significantly reduced by sublethal concentration. Fecundity was also affected by the studied concentrations and the lowest amount of this parameter (34.23 eggs/female) was recorded in LC30 concentration. Accordingly, sublethal concentrations reduced the net reproductive rate (R0), and there were significant differences among the values of this parameter at all treatments tested when compared with control (control: 78.01, LC10: 63.76, LC20: 33.6 and LC30: 11.58 offspring/individual). Other parameters such as intrinsic rate of increase (r), finite rate of increase (l) were also significantly lower than the control. The highest estimated values for r and λ were recorded at control (0.19 and 1.21 day-1, respectively). Finally, with the reduced rate of development for individuals treated with sublethal concentrations, the mean generation time (T) was significantly higher in individuals exposed to any concentration tested, So that it was the lowest in the control with 22.49 days and the highest in LC30 with 26.25 days. The findings of the present research indicate that thiocyclam insecticide has a good potential in controlling the leaf miner in lethal and sublethal concentrations, and the importance of considering the role of sublethal effects when attempting to evaluate the total impacts of specific pesticide on an insect pest population and its natural enemy.