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Simple Summary: Aphis gossypii Glover is an economically important sap-sucking insect pest that causes severe damage worldwide. The flonicamid has been widely used for controlling sap-sucking insect pests, but its intergenerational sublethal effects on key demographic parameters of A. gossypii have not been fully studied. The age-stage, two-sex life table analysis was conducted to investigate the sublethal effects of flonicamid on the biological parameters of adult A. gossypii (F0) and its subsequent intergenerational effects on the offspring (F1 generation). The results showed that the sublethal concentrations of flonicamid significantly decreased the longevity, fecundity, and reproductive days of F0 A. gossypii. Moreover, flonicamid induced intergenerational sublethal effects on the subsequent progeny generation (F1) by impacting the key biological and demographic parameters of A. gossypii. Taken together, these results demonstrated that sublethal concentrations of flonicamid negatively affect the demographic parameters of A. gossypii, resulting in the suppression of population growth. Flonicamid is a novel systemic insecticide widely used against aphids. However, the intergenerational sublethal effects of flonicamid on cotton aphid, Aphis gossypii, have not been fully studied. This study aimed to evaluate the sublethal effects of flonicamid on the biological parameters of adult A. gossypii (F0) and its subsequent intergenerational effects on the offspring (F1 generation) through age-stage, two-sex life table analysis. The results of the bioassays indicate that flonicamid exhibits significant toxicity toward adult A. gossypii, as evidenced by an LC50 value of 0.372 mg L−1 after a 48-h exposure period. The longevity, fecundity, and reproductive days of adult cotton aphids (F0) were significantly decreased when treated with the sublethal concentrations of flonicamid. The pre-adult stage exhibited an increase, whereas the adult longevity, total longevity, and fecundity experienced a notable decrease in F1 aphids after the exposure of F0 aphids to sublethal concentrations of flonicamid. Furthermore, the key demographic parameters, including r, λ, R0, and RPd, showed a significant decrease, while the total pre-reproductive period (TPRP) experienced a significant increase in the F1 generation. Collectively, our findings indicate that sublethal concentrations of flonicamid impact the demographic parameters of A. gossypii, resulting in suppression of population growth. This study presents comprehensive information on the overall impact of flonicamid on A. gossypii, which could potentially aid in managing this major pest. [ABSTRACT FROM AUTHOR]

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, r; net reproductive rate, R0; 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. [ABSTRACT FROM AUTHOR]

The bird cherry-oat aphid, Rhopalosiphum padi (L.) (Hemiptera: Aphididae) is one of the most economically important pests of wheat crops worldwide. Thiamethoxam, bifenthrin, and flonicamid are extensively used insecticides for controlling this key pest. However, the indiscriminate use of chemical insecticides has led to the development of resistance in insects. In this study, we assessed the development of selection-induced resistance to bifenthrin, flonicamid, and thiamethoxam under controlled laboratory conditions. Additionally, we employed the age-stage, two-sex life table method to examine the fitness of R. padi. After ten generations of selection, bifenthrin-, flonicamid-, and thiamethoxam-resistant strains of R. padi were developed with resistance levels of 34.46, 31.97, and 26.46-fold, respectively. The life table analysis revealed a significant decrease in adult longevity and fecundity in these resistant strains compared to susceptible strain. Furthermore, the key demographic parameters such as net reproductive rate (R0) and reproductive days exhibited a significant reduction in all resistant strains, while the intrinsic rate of increase (r) and finite rate of increase (λ) were decreased only in resistant strains to bifenthrin and thiamethoxam. Taken together, these findings provide a comprehensive understanding of laboratory-induced insecticide resistance evolution and the associated fitness costs in R. padi. This knowledge could help to design resistance management strategies against this particular pest of wheat. [ABSTRACT FROM AUTHOR]

Flonicamid is a novel systemic insecticide that efficiently controls sap-sucking insect pests. However, the impact of sublethal concentrations of flonicamid on key demographic parameters and the feeding behavior of greenbug, Schizaphis graminum has not yet been studied. In this study, we used the age stage, two-sex life table approach, and electrical penetration graphs (EPGs) to investigate the sublethal effects of flonicamid on the biological traits and feeding behavior of S. graminum. Bioassays showed that flonicamid possesses high toxicity to adult S. graminum with LC50 of 5.111 mg L−1 following 48 h exposure. Sublethal concentrations of flonicamid (LC5 and LC10) significantly decreased the longevity and fecundity of directly exposed parental aphids (F0), while the reproductive days were reduced only at LC10. The pre-adult stage and total pre-reproductive period (TPRP) increased in F1 individuals after exposure of F0 aphids to the sublethal concentrations of flonicamid. Furthermore, the adult longevity, fecundity and key demographic parameters (R0, r, and λ) were significantly reduced in progeny generation (F1). EPG recordings showed that the total duration of phloem sap ingestion and concurrent salivation (E2) decreased substantially in F0 and F1 aphids after exposure to LC5 and LC10 of flonicamid. Taken together, our results showed that the sublethal concentrations of flonicamid affect the demographic parameters and feeding behavior that ultimately suppress the population growth of S. graminum. This study provides in-depth information about the overall effects of flonicamid on S. graminum that might help to manage this key pest. [ABSTRACT FROM AUTHOR]

Bradysia odoriphaga is a major insect pest that infests Chinese chive in northern China. Clothianidin is a second-generation neonicotinoid insecticide that is commonly used against B. odoriphaga. In this study, the effect of sublethal clothianidin concentrations (LC5 and LC10) on key biological characteristics of B. odoriphaga was investigated using an age-stage, two-sex life table method. Bioassays results showed that clothianidin exhibited high toxicity against B. odoriphaga with LC50 of 1.898 mg L−1 following 24 h exposure. The developmental duration of larvae was significantly increased when exposed to the LC5 (0.209 mg L−1) and LC10 (0.340 mg L−1) of clothianidin. No significant effects were observed on the pupal stage, adult pre-oviposition period (APOP), total pre-oviposition period (TPOP), and mean longevities of male and female. The oviposition period and fecundity of B. odoriphaga were reduced in clothianidin-treated groups. Moreover, key demographic parameters, including the intrinsic rate of increase (r), finite rate of increase (λ), and net reproductive rate (R0), were significantly decreased by the LC5 and LC10 of clothianidin, while no effects were noted on mean generation time (T). Overall, this study showed that sublethal concentrations of clothianidin have a detrimental effect on B. odoriphaga developmental period, fecundity, and life table parameters. Therefore, clothianidin has the potential to suppress the population of B. odoriphaga even at sublethal concentrations. [ABSTRACT FROM AUTHOR]

Clothianidin is a second-generation neonicotinoid insecticide, widely used against sap-sucking insect pest including melon aphid, Aphis gossypii Glover (Hemiptera: Aphididae). This pest causes severe economic damage to Cucurbitaceae plants worldwide. In this study, we investigated clothianidin resistance development under continuous selection pressure. Moreover, the age-stage, two-sex life table approach was used to evaluate the impact of clothianidin resistance on the fitness of A. gossypii. A clothianidin resistant strain (CT-R) with a 23.17-fold resistance level was developed from a susceptible strain (CT-S) after continuous selection for 24 generations. Life table results showed a significant reduction in the relative fitness (0.847) of CT-R strain compared to the CT-S strain of A. gossypii. The developmental duration, oviposition days, total pre-oviposition period (TPOP), longevity, and fecundity of CT-R strain were found to be significantly lower when compared to CT-S strain. The demographic parameters, including the intrinsic rate of increase (r), finite rate of increase (λ), net reproductive rate (R0), and mean generation time (T) were also significantly decreased in CT-R strain compared to the CT-S strain. Both the reproductive and survival rates were affected by clothianidin resistance in CT-R strain compared with the CT-S strain of A. gossypii. Overall, our results demonstrate that in-depth knowledge about the trade-off at play between resistance degree and fitness cost might be useful to design resistance management strategies against A. gossypii. [ABSTRACT FROM AUTHOR]

The chive maggot, Bradysia odoriphaga (Yang and Zhang) is an economically important insect pest, affecting many key vegetables, including Chinese chive, especially in northern China. Chlorfenapyr, a halogenated pyrrole insecticide that interferes with mitochondrial oxidative phosphorylation is widely used against B. odoriphaga. In this study, we evaluated selection-induced resistance to chlorfenapyr and fitness costs in B. odoriphaga. The results showed that B. odoriphaga developed 43.32-fold resistance after continuous exposure to chlorfenapyr for over 10 consecutive generations. The life-history traits of chlorfenapyr-resistant and susceptible strains were compared using age-stage, two-sex life table approach. No significant effects were observed on the longevity and pre-adult period. However, reduction in the total pre-oviposition period (TPOP) and fecundity (eggs/female) were observed in the resistant strain. Moreover, the demographic parameters such as intrinsic rate of increase (r), net reproductive rate (R0) and finite rate of increase (λ) were also decreased significantly in the resistant strain compared to the susceptible strain. These results showed the potential of B. odoriphaga to develop resistance against chlorfenapyr under continuous selection pressure. Furthermore, there was a fitness cost linked with chlorfenapyr resistance in B. odoriphaga. We conclude that a better knowlegde on the trade-off at play between resistance degree and fitness cost could be crucial for developing further management of B. odoriphaga in China. [ABSTRACT FROM AUTHOR]

The chive maggot, Bradysia odoriphaga Yang and Zhang (Diptera: Sciaridae) is an economically important insect pest, affecting many important vegetables, including Chinese chive, especially in northern China. Clothianidin is a second-generation of neonicotinoid insecticide that is currently used for the management of B. odoriphaga. In the present study, we investigated the development of resistance after continuous laboratory selection and associated fitness costs in B. odoriphaga against clothianidin insecticide. The results showed that B. odoriphaga population developed 76-fold resistance, following exposure with clothianidin insecticide for 10 generations. Similarly, life table analysis showed that the fecundity, along with male and female longevity in a resistant strain of B. odoriphaga was decreased significantly compared with the susceptible strain. The developmental duration of larvae and pupae were increased dramatically in the resistant strain, while no effects were observed on egg hatchability. Furthermore, the demographic parameters such as the intrinsic rate of increase (r) (d-1), net reproductive rate (R0) (offspring/individual) and finite rate of increase (?) (d-1) were found to be significantly decreased in the laboratory selected resistant population when compared with the susceptible strain of B. odoriphaga, in addition, only mean generation time (T) (d) increased significantly. These results suggest that B. odoriphaga responded quickly and develop a high level of resistance against clothianidin insecticide under continuous selection pressure. Additionally, the associated fitness costs may have direct implication for the management of B. odoriphaga against clothianidin. [ABSTRACT FROM AUTHOR]

The green bug, Schizaphis graminum Rondani (Hemiptera: Aphididae), is a major pest of wheat plants through direct feeding and indirectly by transmitting several viruses around the world. Insecticides including thiamethoxam, bifenthrin, and flonicamid, are widely used to control this pest. However, indiscriminate chemical applications cause resistance in several insect pests, including aphids. In the current study, we investigated the evolution of thiamethoxam, bifenthrin, and flonicamid resistance in S. graminum after continuous selection pressure. Furthermore, we assessed the fitness of all resistant strains compared to susceptible strains using the age-stage, two-sex life table method. Thiamethoxam, bifenthrin, and flonicamid-resistant strains were evolved with 38.57, 28.67, and 21.31-fold resistance after selection for over ten generations. Life table analysis showed that all resistant strains had significantly reduced adult longevity, fecundity, and reproductive days, and an increased total pre-reproductive period compared to susceptible aphids. In addition, the key demographic parameters such as the intrinsic rate of increase (r) and the net reproductive rate (R0) were substantially reduced in the resistant S. graminum populations. These findings provide in-depth information about the risk of insecticide resistance evolution and the associated fitness costs in S. graminum. [ABSTRACT FROM AUTHOR]

The melon aphid, Aphis gossypii is a globally distributed crop pest with a wide host range. The intensive use of insecticides against this insect over several years has led to develop resistance against many insecticides including acetamiprid. Understanding the relationship between acetamiprid resistance and fitness of A. gossypii is essential to limit the spread of the resistant population in the field. In this study, age-stage, two-sex life table approach was used to investigate these relationships in the lab. Results showed that resistant strain (Ace-R) had a reduced fitness (relative fitness = 0.909) along with significantly decreased adult longevity, fecundity, net reproductive (R 0), mean generation time (T) and gross reproductive rate (GRR). Compared to the susceptible strain (Ace-S), the pre-adult period and total pre-oviposition period (TPOP) were also significantly shorter in Ace-R strain. Moreover, the expression profiles of EcR , JHBP , JHAMT , JHEH, USP and Vg genes supposed to be involved in insect reproduction and development were analyzed using Quantitative Real Time PCR. The EcR , JHBP , JHAMT and USP genes were up-regulated, Vg gene was down-regulated while the mRNA level of JHEH gene was statistically same in the Ace-R strain compared to the Ace-S strain. Collectively, this study provides the occurrence and magnitude of fitness costs of A. gossypii against acetamiprid resistance and could be helpful to manage the resistance evolution in field populations. Unlabelled Image • Age-stage, two-sex life table approach was used to investigate the fitness of acetamiprid-resistant (Ac-R) and susceptible (Ace-S) strains of A. gossypii. • Acetamiprid resistance development reduced the survival rate and reproductive capacity of resistant A. gossypii. • The Ace-R strain suffered reduction in demographic parameters and relative fitness. • Up-regulation of EcR , JHBP , JHAMT, and USP , and down-regulation of Vg in Ace-R may have important role in observed trade-off. [ABSTRACT FROM AUTHOR]