Spinosad-induced intergenerational sublethal effects on Tuta absoluta: biological traits and related genes expressions

The South American tomato pinworm, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), is considered one of the most economically important invasive pests that causes severe damage to tomato crops. The biopesticide spinosad is widely used for controlling T. absoluta. This study aimed to investigate the spinosad-induced intergenerational sublethal effects on T. absoluta. Results showed that spinosad exhibited high toxicity against 3rd instar T. absoluta with the LC50 of 0.04 mg L-1 after 72 h exposure. The LC10 and LC30 of spinosad significantly decreased the durations of various developmental stages and some reproductive parameters of parental (F0) T. absoluta compared to control. The developmental durations, survival rate, reproduction and life table parameters (intrinsic rate of increase, r; finite rate of increase, λ; net reproductive rate, R 0; and oviposition days, Od ) were significantly decreased in the progeny generations (F1 and F2) following F0 exposure to the LC10 and LC30 of spinosad as compared to the control group. Additionally, the mRNA expression levels of development and reproduction related genes such as Vg, VgR, and JHBP were down-regulated in parental and progeny generations at both spinosad treatments as compared to control treatment. The resistance related cytochrome P450 genes CYP321C40 and CYP6AW1, followed by CYP4M116, CYP9A307v2, CYP15C1, CYP339A1, and CYP6AB327 were up-regulated at spinosad-treated groups in the parental and progeny generations of T. absoluta as compared to control. Overall, these results showed that although spinosad exhibited high toxicity and induces intergenerational sublethal effects on the parental and progeny generations, the indiscriminate and long-term application might causes resistance development in of T. absoluta.