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Buprofezin, a chitin synthesis inhibitor, is widely used to control several economically important insect crop pests. However, the overuse of buprofezin has led to the evolution of resistance and exposed off-target organisms present in agri-environments to this compound. As many as six different strains of bacteria isolated from these environments have been shown to degrade buprofezin. However, whether insects can acquire these buprofezin-degrading bacteria from soil and enhance their own resistance to buprofezin remains unknown. Here we show that field strains of the brown planthopper, Nilaparvata lugens, have acquired a symbiotic bacteria, occurring naturally in soil and water, that provides them with resistance to buprofezin. We isolated a symbiotic bacterium, Serratia marcescens (Bup_Serratia), from buprofezin-resistant N. lugens and showed it has the capacity to degrade buprofezin. Buprofezin-susceptible N. lugens inoculated with Bup_Serratia became resistant to buprofezin, while antibiotic-treated N. lugens became susceptible to this insecticide, confirming the important role of Bup_Serratia in resistance. Sequencing of the Bup_Serratia genome identified a suite of candidate genes involved in the degradation of buprofezin, that were upregulated upon exposure to buprofezin. Our findings demonstrate that S. marcescens, an opportunistic pathogen of humans, can metabolize the insecticide buprofezin and form a mutualistic relationship with N. lugens to enhance host resistance to buprofezin. These results provide new insight into the mechanisms underlying insecticide resistance and the interactions between bacteria, insects and insecticides in the environment. From an applied perspective they also have implications for the control of highly damaging crop pests. Author summary: The evolution of insect resistance to insecticides represents a major threat to the sustainable control of many of the world's most damaging crop pests. To effectively combat resistance it is important to understand the mechanisms underpinning resistance and their contribution to phenotype. Numerous studies have shown that resistance can result from mutations in the insect genome that alter the expression of detoxification enzymes or enhance their activity, or modify the affinity of the insecticide for the target receptor. However, emerging evidence suggests that symbiotic bacteria may also mediate insecticide resistance in host insects. In this study we show that a bacterium commonly found in the environment can be acquired by the economically important pest insect, Nilaparvata lugens, and confer resistance to the insecticide buprofezin. Using genomic and transcriptomic analyses we implicate a Rieske nonheme iron oxygenase (RHO) system and VOC family protein encoded in the Bup_Serratia genome in the degradation pathway of buprofezin. Our studies uncover a new mechanism of N. lugens resistance to buprofezin and illustrate the importance of considering microbe—host insect—environment interactions in the development of integrated pest management strategies. [ABSTRACT FROM AUTHOR]

Simple Summary: Pymetrozine is one of the most common insecticides used to control the rice pest Nilaparvata lugens in China. Because of its unique mechanism of action and the fact that there is no obvious lethal effect after pymetrozine treatment, it is unreasonable to determine the sensitivity of pymetrozine by only calculating the mortality rate. In the context of traditional bioassay methods, which do not reflect pymetrozine's control effect on the pest populations in the field, we established fecundity assay bioassay methods to monitor N. lugens' resistance level to pymetrozine, and systematically evaluated pymetrozine's effect on the fecundity of N. lugens. Treatment with pymetrozine significantly reduced the number of offspring in both N. lugens nymphs and adults. On the basis of the inhibition effects of pymetrozine on the reproductive behavior of N. lugens, we established a bioassay method to accurately evaluate the toxicity of pymetrozine in N. lugens and clarified the level of pymetrozine resistance of N. lugens in the field. In this study, pymetrozine's effects on the fecundity of N. lugens were evaluated using the topical application method and rice-seedling-dipping method. Moreover, the resistance of N. lugens to pymetrozine in a pymetrozine-resistant strain (Pym-R) and two field populations (YZ21 and QS21) was determined using the rice-seedling-dipping method and fecundity assay methods. The results showed that treatment of N. lugens third-instar nymphs with LC15, LC50, and LC85 doses of pymetrozine resulted in a significantly reduced fecundity of N. lugens. In addition, N. lugens adults treated with pymetrozine, using the rice-seedling-dipping and topical application method, also exhibited a significantly inhibited fecundity. Using the rice-stem-dipping method, pymetrozine resistance levels were shown to be high in Pym-R (194.6-fold), YZ21 (205.9-fold), and QS21 (212.8-fold), with LC50 values of 522.520 mg/L (Pym-R), 552.962 mg/L (YZ21), and 571.315 (QS21) mg/L. However, when using the rice-seedling-dipping or topical application fecundity assay method, Pym-R (EC50: 14.370 mg/L, RR = 12.4-fold; ED50: 0.560 ng/adult, RR = 10.8-fold), YZ21 (EC50: 12.890 mg/L, RR = 11.2-fold; ED50: 0.280 ng/adult; RR = 5.4-fold), and QS21 (EC50: 13.700 mg/L, RR = 11.9-fold) exhibited moderate or low levels of resistance to pymetrozine. Our studies show that pymetrozine can significantly inhibit the fecundity of N. lugens. The fecundity assay results showed that N. lugens only developed low to moderate levels of resistance to pymetrozine, indicating that pymetrozine can still achieve effective control on the next generation of N. lugens populations. [ABSTRACT FROM AUTHOR]

Development of insecticide resistance in insect populations is a major challenge to sustainable agriculture and food security worldwide. Buprofezin, one of the commonly used chitin synthesis inhibitors, has severely declined its control efficacy against the brown planthopper (BPH, Nilaparvata lugens), a devastating rice insect species. To date, however, mechanism of buprofezin resistance in target pests remains elusive. We conducted a long-term (25 years from 1996 to 2020) and large geographical scale (11 provinces and cities in China) resistance monitoring program for buprofezin in BPH, a notorious pest of rice crop in East and Southeast Asia. BPH rapidly developed resistance with > 1,000-fold resistance being detected in nearly all the field populations after 2015. Using the bulk segregant mapping method, we uncovered a novel mutation (G932C) in chs1 gene encoding chitin synthase 1 from a near isogeneic buprofezin-resistant (> 10,000-fold) strain harboring recessive, monogenic resistance. Using CRISPR/Cas9-based genome-modified Drosophila melanogaster possessing the same mutation as a model, we found that the G932C mutation was not only responsible for buprofezin resistance but also conferred a cross-resistance to cyromazine, an insect molting disruptor, on which the mode of action is largely unknown. Taken together, our study for the first time revealed the molecular mechanism conferring buprofezin resistance in BPH and implicated that cyromazine also targets chitin biosynthesis to confer its toxicity. [ABSTRACT FROM AUTHOR]

Background: Buprofezin, an insect growth regulator, has been widely used to control brown planthopper (BPH), Nilaparvata lugens, one of the most destructive pests of rice crops in Asia. The intensive use of this compound has resulted in very high levels of resistance to buprofezin in the field, however, the underpinning mechanisms of resistance have not been fully resolved. Results: Insecticide bioassays using the P450 inhibitor piperonyl butoxide significantly synergized the toxicity of buprofezin in two resistant strains of BPH (BPR and YC2017) compared to a susceptible strain (Sus), suggesting P450s play a role in resistance to this compound. Whole transcriptome profiling identified 1110 genes that were upregulated in the BPR strain compared to the Sus strain, including 13 cytochrome P450 genes, eight esterases and one glutathione S‐transferase. Subsequently, qPCR validation revealed that four of the P450 genes, CYP6ER1vA, CYP6CW1, CYP4C77, and CYP439A1 were significantly overexpressed in both the BRP and YC2017 strains compared with the Sus strain. Further functional analyses showed that only suppression of CYP6ER1vA, CYP6CW1, and CYP439A1 gene expression by RNA interference significantly increased the toxicity of buprofezin against BPH. However, only transgenic Drosophila melanogaster expressing CYP6ER1vA and CYP439A1 exhibited significant resistance to buprofezin. Finally, the BPR strain was found to exhibit modest but significant levels of resistance to acetamiprid, dinotefuran and pymetrozine. Conclusions: Our findings provide strong evidence that the overexpression of CYP6ER1vA and CYP439A1 contribute to buprofezin resistance in BPH, and that resistance to this compound is associated with low‐level resistance to acetamiprid, dinotefuran and pymetrozine. These results advance understanding of the molecular basis of BPH resistance to buprofezin and will inform the development of management strategies for the control of this highly damaging pest. © 2022 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

BACKGROUND: The brown planthopper, Nilaparvata lugens, is considered the most destructive pest of rice in many Asian countries including China. Use of pymetrozine in insect resistance management (IRM) has been one strategy to control this pest. In this study, we reported the status of pymetrozine resistance in Nilaparvata lugens (Stål) collected from China over the period 2017–2021 and selected a strain of N. lugens resistant to pymetrozine and evaluated the cross‐resistance, inheritance and fitness costs of the resistance. RESULTS: Monitoring data (2017–2021) showed that field populations of N. lugens in China developed moderate‐ to high‐level pymetrozine resistance during these 5 years. By continuous selection with pymetrozine in the lab, the pymetrozine selected N. lugens strain (Pym‐R98) developed a 225.2‐fold resistance compared to a susceptible strain. The Pym‐R98 strain showed high cross‐resistance to dinotefuran (66.6‐fold) and low cross‐resistance to nitenpyram (5.2‐fold) and sulfoxaflor (5.8‐fold). Inheritance pattern analysis of Pym‐R93 revealed that resistance to pymetrozine was polygenic, autosomal and incompletely dominant. Fitness costs of pymetrozine resistance were present in Pym‐R90 and WA2020 strains with a relative fitness of 0.72 and 0.60, respectively. The developmental duration of Pym‐R90 and WA2020 was significantly longer and hatchability was significantly lower compared to pymetrozine‐susceptible strain (Pym‐S). CONCLUSIONS: N. lugens has developed high level of resistance to pymetrozine. Pymetrozine‐resistance brown planthopper had cross‐resistance with some of neonicotinoids such as dinotefuran, nitenpyram and sulfoxaflor. The autosomal, incompletely dominant and polygenic resistance to pymetrozine in N. lugens and the fitness costs associated with this resistance can be exploited in IRM strategies to preserve the lifetime of pymetrozine for control of N. lugens in China. © 2022 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

BACKGROUND Pymetrozine is commonly used for the control of Nilaparvata lugens, and resistance to pymetrozine has been frequently reported in the field populations in recent years. However, the mechanism of brown planthopper resistance to pymetrozine is still unknown. RESULTS: In this study, a pymetrozine‐resistant strain (PMR) was established, and the potential biochemical resistance mechanism of N. lugens to pymetrozine was investigated. Pymetrozine was synergized by the inhibitor piperonyl butoxide (PBO) in the PMR with 2.83‐fold relative synergistic ratios compared with the susceptible strain (Sus). Compared with the Sus, the cytochrome P450 monooxygenase activity of PMR was increased by 1.7 times, and two P450 genes (NlCYP6CS1 and NlCYP301B1) were found to be significantly overexpressed more than 6.0‐fold in the PMR. Pymetrozine exposure induced upregulation of NlCYP6CS1 expression in the Sus, but the expression of NlCYP301B1 did not change significantly. In addition, RNA interference (RNAi)‐mediated suppression of NlCYP6CS1 gene expression dramatically increased the toxicity of pymetrozine against N. lugens. Moreover, transgenic lines of Drosophila melanogaster expressing NlCYP6CS1 were less susceptible to pymetrozine, and had a stronger ability to metabolize pymetrozine. CONCLUSIONS: Taken together, our findings indicate that the overexpression of NlCYP6CS1 is one of the key factors contributing to pymetrozine resistance in N. lugens. And this result is helpful in proposing a management strategy for pymetrozine resistance. [ABSTRACT FROM AUTHOR]

Feeding is essential for animal survival and reproduction and is regulated by both internal states and external stimuli. However, little is known about how internal states influence the perception of external sensory cues that regulate feeding behavior. Here, we investigated the neuronal and molecular mechanisms behind nutritional state-mediated regulation of gustatory perception in control of feeding behavior in the brown planthopper and Drosophila. We found that feeding increases the expression of the cholecystokinin-like peptide, sulfakinin (SK), and the activity of a set of SK-expressing neurons. Starvation elevates the transcription of the sugar receptor Gr64f and SK negatively regulates the expression of Gr64f in both insects. Interestingly, we found that one of the two known SK receptors, CCKLR-17D3, is expressed by some of Gr64f-expressing neurons in the proboscis and proleg tarsi. Thus, we have identified SK as a neuropeptide signal in a neuronal circuitry that responds to food intake, and regulates feeding behavior by diminishing gustatory receptor gene expression and activity of sweet sensing GRNs. Our findings demonstrate one nutritional state-dependent pathway that modulates sweet perception and thereby feeding behavior, but our experiments cannot exclude further parallel pathways. Importantly, we show that the underlying mechanisms are conserved in the two distantly related insect species. Author summary: Food intake is critical for animal survival and reproduction and is regulated both by internal states that signal appetite or satiety, and by external sensory stimuli. It is well known that the internal nutritional state influences the strength of the chemosensory perception of food signals. Thus, both gustatory and olfactory signals of preferred food are strengthened in hungry animals. However, the molecular mechanisms behind satiety-mediated modulation of taste are still not known. We show here that cholecystokinin-like (SK) peptide in brown planthopper and Drosophila signals satiety and inhibits sugar attraction by lowering the activity of sweet-sensing gustatory neurons and transcription of a sugar receptor gene, Gr64f. We show that SK peptide signaling reflects the nutritional state and inhibits feeding behavior. Re-feeding after starvation increases SK peptide expression and spontaneous activity of SK producing neurons. Interestingly, we found that SK peptide negatively regulates the expression of the sweet gustatory receptor and that activation of SK producing neurons inhibits the activity of sweet-sensing gustatory neurons (GRNs). Furthermore, we found that one of the two known SK peptide receptors is expressed in some sweet-sensing GRNs in the proboscis and proleg tarsi. In summary, our findings provide a mechanism that is conserved in distantly related insects and which explains how feeding state modulates sweet perception to regulate feeding behavior. Thus, we have identified a neuropeptide signal and its neuronal circuitry that respond to satiety, and that regulate feeding behavior by inhibiting gustatory receptor gene expression and activity of sweet sensing GRNs. [ABSTRACT FROM AUTHOR]

• Two maltase genes and one lipase gene were identified in the brown planthopper. • Refed induces digestive enzyme secretion in Nilaparvata lugens. • Sulfakinin injection reduces digestive enzyme activity. • Sulfakinin injection decrease transcriptional levels of digestive enzyme genes. In animals, feeding can regulate release of digestive enzymes. Digestive enzymes are produced and released in response to specific ratios of nutrients, so the quality and quantity of food ingested are important factors in the secretion and activity of digestive enzymes. In general, the enzyme activity and secretion in the fed insects are relatively higher than that in the unfed insects. Neuropeptides and peptide hormones are important regulators of enzyme activity. In several insects, the neuropeptide sulfakinin (SK) is known to be a regulator of feeding and digestion similar to cholecystokinin in mammals. However, the roles of diet and SK in regulation of activity of digestive enzymes in the important pest insect, the brown planthopper (Nilaparvata lugens), are unknown. In this study, we identified six genes encoding different digestive enzymes and cloned three of these. We found that enzymatic activity and transcriptional levels of digestive enzymatic activity genes were upregulated by refeeding animals for 5 h after 24 h starvation. Furthermore, injection of N. lugens SK reduces digestive enzyme activity and leads to a downregulation of digestive enzyme gene transcripts. This study provides new views into the action of diet and SK in regulation of digestive enzymes in (hemimetabolous) insects. Taken together with the roles of SK in inducing satiety, our data strongly suggest that SK signaling is important in regulation of food ingestion and processing. [ABSTRACT FROM AUTHOR]

Transmembrane channel-like (TMC) genes encode a family of evolutionarily conserved membrane proteins. Mutations in the TMC1 and TMC2 cause deafness in humans and mice. However, their functions in insects are is still not well known. Here we cloned three tmc genes, Nltmc3 , Nltmc5 , and Nltmc7 from brown planthoppers. The predicted amino acid sequences showed high identity with other species homologs and have the characteristic eight or nine transmembrane domains and TMC domain architecture. We detected these three genes in all developmental stages and examined tissues. Interestingly, we found Nltmc3 was highly expressed in the female reproductive organ especially in the oviduct. RNAi-mediated silencing of Nltmc3 substantially decreased the egg-laying number and impaired ovary development. Our results indicate that Nltmc3 has an essential role in the ovary development of brown planthoppers. [ABSTRACT FROM AUTHOR]

BACKGROUND Octopamine, the invertebrate counterpart of adrenaline and noradrenaline, regulates and modulates many physiological and behavioral processes in insects. It mediates its effects by binding to specific octopamine receptors, which belong to the superfamily of G‐protein coupled receptors (GPCRs). The expression profiles of octopamine receptor genes have been well documented in different developmental stages and multiple tissue types in several different insect orders. However, little work has addressed this issue in Hemiptera. RESULTS: In this study, we cloned four octopamine receptor genes from brown planthopper. The deduced amino acid sequences share high identity with other insect homologues and have the characteristic GPCRs domain architecture: seven transmembrane domains. These genes were expressed in all developmental stages and examined tissues. The expression of NlOA2B3 and NlOA3 was relatively higher in egg and first instar nymph stage than in other stages and other receptor genes. All of these receptor genes were more highly expressed in brain than other tissues. CONCLUSION: The identification of octopamine receptor genes in this study will provide a foundation for investigating the diverse roles played by NlOARs and for exploring specific target sites for chemicals that control agricultural pests. © 2019 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Octopamine, the invertebrate counterpart of adrenaline and noradrenaline, controls and modulates many physiological and behavioral processes in protostomes. It mediates its effects by binding to specific receptors belonging to the superfamily of G-protein coupled receptors. We report the cloning of a cDNA from the brown planthopper ( Nloa2b2 ) sharing high similarity with members of the OA2B2 receptor class. Activation of NlOA2B2 by octopamine increased the production of cAMP in a dose-dependent manner (EC 50 = 114 nM). Tyramine also activated the receptor but with much less potency than octopamine. Using a series of known agonists and antagonists of octopamine receptors and cAMP measurements, we observed a rather unique pharmacological profile of NlOA2B2. The potency ranking of the tested agonists was naphazoline > clonidine. The activated effect of octopamine is abolished by co-incubation with epinastine, mianserin, phentolamine, methiothepin, butaclamol or methysergide. Nloa2b2 was expressed in different developmental stages and in various tissues including female reproductive regions known to be involved in egg-laying behavior. Using in vivo pharmacology and RNAi methodology, we demonstrated that interference of NlOA2B2 signaling pathway had a strong impact on the egg-laying behavior of female brown planthopper. The data presented here mark the first comprehensive study—from gene to behavior—of a OA2B2 receptor in the rice brown planthopper. [ABSTRACT FROM AUTHOR]

Transient receptor potential (TRP) is a superfamily of important cation channels located on the cell membrane. It can regulate almost all sensory modality and control a series of behaviors, including hearing, locomotion, gentle touch, temperature sensation, dry air and food texture detection. The expression profiles of TRP channels have been well documented in the model insect Drosophila melanogaster. However, little is known about the TRP channels of agricultural pests. In this study, we cloned 9 TRP ion channel genes from brown planthopper. Their amino acid sequences are highly conserved with homologues of other insects and have typical TRP channel characteristics: six transmembrane domains (TM1 - TM6) and a pore region between TM5 and TM6. These TRP channels of N. lugens were expressed in all developmental stages and various body parts. The expression levels of almost all TRP channels were relatively higher in adults than nymph stages, and lowest in the eggs. Antenna and abdomen were the main body parts with high expression of these genes. Furthermore, the mRNA levels of these TRP genes were significantly decreased in the third-instar nymphs injected with double-stranded RNA (dsRNA). The survival rate of different TRP dsRNA injected nymphs all exceeded 81%, which was no significant difference compared with the control group. These results suggested that these 9 TRP channels are expressed throughout the body and all ages of the brown planthopper, and are involved in regulating multiple physiological and behavioral processes. The identification of TRP channel genes in this study not only provides a foundation for further exploring the potential roles of TRP channels, but also serves as targets to develop new insecticides for the control of agricultural pests. [Display omitted] • Nine TRP ion channel genes were isolated from Nilaparvata lugens. • All hallmarks of these TRP channels are highly conserved with homologues of other insects. • The expression levels of almost all TRP channels were relatively higher in adult, antenna and abdomen. • These nine TRP genes do not interfere with the survival of N. lugens. [ABSTRACT FROM AUTHOR]

Abstract NompC channel is a member of the transient receptor potential (TRP) ion channel superfamily. It can regulate gentle-touch, locomotion, hearing and food texture detection in Drosophila. We cloned the NompC gene of Nilaparvata lugens (NlNompC). The full length NlNompC possessed similar structure as DmNompC, which belongs to TRPN subfamily. The expression pattern analysis of different developmental stages and body parts showed that the transcription of NlNompC was more abundant in adult stage and in the abdomen. Injection of double-stranded RNA (dsRNA) of NlNompC in the third-instar nymphs successfully knocked down the target gene with 75% suppression. At nine days after injection, the survival rate of dsRNA injected nymphs was as low as 9.84%. Behavioral observation revealed that the locomotion of the dsRNA injected nymphs was defective with much less movement compared to the negative control. Feeding and honeydew excretion of the dsRNA injected insects also decreased significantly. These results suggested that NlNompC is a classical mechanotransduction channel that plays important roles in proprioception and locomotion, and is essential for the survival of N. lugens. The results also contribute to the understanding of how TRP channels regulate proprioception. Graphical abstract Image 1 Highlights • NlNompC was expressed in all developmental stages and the examined tissues (especially in the leg and antennae). • NlNompC is essential for BPH survival. • Silencing of NlNompC impaired the gentle-touch sensation and food intake of N. lugens. • NlNompC is a classical mechanotransduction channel playing important roles in proprioception and locomotion. [ABSTRACT FROM AUTHOR]

Abstract The commercial insecticide pymetrozine has been extensively used for brown planthopper control in East Asia. The transient receptor potential vanilloid (TRPV) channel, which consists of two proteins, Nanchung (Nan) and Inactive (Iav), has recently been shown to be the molecular target of pymetrozine in the fruit fly (Drosophila melanogaster) and pea aphid (Acyrthosiphon pisum). In this study, we characterized the Nan and Iav TRPV channel subunits of N. lugens and measured the action of pymetrozine on them. NlNan and NlIav are structurally similar to homologs from other insects. The expression pattern analysis of various body parts showed that NlNan and NlIav were both more abundantly expressed in antennae. When NlNan and NlIav were co-expressed in Xenopus laevis oocytes, they formed channels with high sensitivity to pymetrozine (EC 50 = 5.5 × 10−8 M). Behavioral observation revealed that the gravitaxis defect in the fruit fly nan 36a mutant was rescued by ectopically expressed NlNan and the rescued behavior could be abolished by pymetrozine. Our results confirm that NlNan and NlIav co-expressed complexes can be activated by pymetrozine both in vitro and in vivo and provide useful information for future resistance mechanism studies. Graphical abstract Unlabelled Image Highlights • We cloned and characterized the first TRPV channels, NlNan and NlIav, in the brown planthopper. • NlNan and NlIav were both abundantly expressed in antenna, an important sensory organ of insects. • Pymetrozine acts modulating brown planthopper TRPV channels NlNan and NlIav. • NlNan protein was functionally conserved in regulating anti-gravitaxis behavior in Drosophila. [ABSTRACT FROM AUTHOR]

Three rice planthoppers, brown planthopper, Nilaparvata lugens , white-backed planthopper, Sogatella furcifera and small brown planthopper, Laodelphax striatellus , are important pests of cultivated rice in tropical and temperate Asia. They have caused severe economic loss and developed resistance to insecticides from most chemical classes. Dinotefuran is the third neonicotinoid which possesses a broad spectrum and systemic insecticidal activity. We determined the susceptibility of dinotefuran to field populations from major rice production areas in China from 2013 to 2015. All the populations of S. furcifera and L. striatellus were kept susceptible to dinotefuran (0.7 to 1.4-fold of S. furcifera and 1.1-to 3.4-fold of L. striatellus ) However, most strains of N. lugens (except FQ15) collected in 2015 had developed moderate resistance to dinotefuran, with resistance ratios (RR) ranging from 23.1 to 100.0 folds. Cross-resistance studies showed that chlorpyrifos-resistant and buprofezin-resistant Sogatella furcifera , chlorpyrifos-resistant and fipronil-resistant L. striatellus , imidacloprid-resistant and buprofezin-resistant Nilaparvata lugens exhibited negligible or no cross-resistance to dinotefuran. Synergism tests showed that piperonyl butoxide (PBO) produced a high synergism of dinotefuran effects in the DY15 and JS15 populations (2.14 and 2.52-fold, respectively). The obvious increase in resistance to dinotefuran in N. lugens indicates that insecticide resistance management strategies are urgently needed to prevent or delay further increase of insecticide resistance in N. lugens . [ABSTRACT FROM AUTHOR]

Pymetrozine is a promising chemical used to control brown planthopper, which developed resistance to imidacloprid and buprofezin in the past decade. Field efficacy indicates that pymetrozine can reduce the number of offsprings of brown planthopper, but the specific physiological mechanism is unknown. In this study, we systematically described the mating process of brown planthopper including 8 steps (abdominal vibration, following, positioning, wing extension, attempted copulation, copulation, terminated copulation and leaving) and explored the optimal mating time after adult eclosion (3–5 days) and observation time (30 mins). Also, behavioral data showed that pymetrozine can affect the mating behavior and female fecundity of brown planthopper and fruit fly. As one of the target genes for pymetrozine, Nanchung (Nan), the nan 36a mutant male courtship index, female receptivity and the number of offsprings were significantly decreased. Behavioral defects in nan 36a mutant flies can be rescued by expressed NlNan. Our results indicated that Nan plays essential roles in the mating behavior and female fecundity. These findings provide useful information for demonstrating that pymetrozine effectively reduce the reproduction of brown planthopper and contribute to our understanding of reproductive strategies controlled by pymetrozine in insects. Unlabelled Image • We systematically described the mating process of brown planthopper including 8 steps and explored the optimal mating time. • Pymetrozine can both affect the mating behavior and female fecundity of brown planthopper and fruit fly. • Nan is essential for reproductive behavior in Drosophila. • NlNan protein was functionally conserved in regulating mating behavior and female fertility in Drosophila. [ABSTRACT FROM AUTHOR]