Xingliang Wang

Crops genetically engineered to produce insecticidal proteins from the bacterium Bacillus thuringiensis (Bt) have been used extensively to control some major crop pests, but their benefits decrease when pests evolve resistance. Better understanding of the genetic basis of resistance is needed to effectively monitor, manage, and counter pest resistance to Bt crops. Resistance to Bt proteins in at least 11 species of Lepidoptera, including many important crop pests, is associated with naturally occurring mutations that disrupt one or more of three larval midgut proteins: cadherin and ATP-binding cassette proteins ABCC2 and ABCC3. Here, we determined how CRISPR/Cas9-mediated mutations disrupting cadherin, ABCC2, and ABCC3 singly and in pairs affect resistance to Bt proteins Cry1Ab and Cry1Fa in the Asian corn borer ( Ostrinia furnacalis ), which is the most damaging pest of corn in Asia and is closely related to the European corn borer ( Ostrinia nubilalis ), a major pest in Europe and North America. The results from bioassays of six knockout strains and their parent susceptible strain support a model in which Cry1Ab can kill larvae via one path requiring ABCC2 or another path requiring cadherin and ABCC3, whereas Cry1Fa uses only the first path. The model’s predictions are generally supported by results from genetic linkage analyses and responses to Cry1Ab and Cry1Fa of Sf9 cells and Xenopus oocytes modified to produce cadherin, ABCC2, and ABCC3 singly or in pairs. The functional redundancy identified here for Cry1Ab could sustain its efficacy against O. furnacalis and may exemplify a widespread natural strategy for delaying resistance.

BACKGROUND: The overexpression of metabolic enzymes constitutes a crucial mechanism for insects to detoxify xenobiotics and metabolic pesticides. A flavin‐containing monooxygenase gene (PxFMO2) from Plutella xylostella and a P450 gene (SeCYP9A186, F116V mutant allele) from Spodoptera exigua have been reported to be involved in insecticide resistance. In this study, we aim to utilize transgenic technology to validate their in vivo detoxification functions in Plutella xylostella.RESULTS: We established two transgenic strains of Plutella xylostella with expressing an endogenous PxFMO2 gene from Plutella xylostella and an exogenous SeCYP9A186 gene from S. exigua, respectively. Bioassays demonstrated that the transgenic Plutella xylostella strain (IPP‐FMO2) expressing PxFMO2 exhibited a 12‐fold resistance to emamectin benzoate and a 6.4‐fold resistance to chlorantraniliprole compared to the background strain (IPP‐S). In contrast, the transgenic Plutella xylostella strain (IPP‐9A186) expressing SeCYP9A186 displayed a 235‐fold resistance to emamectin benzoate and a 115‐fold resistance to abamectin. Moreover, resistance to emamectin benzoate in the IPP‐9A186 strain of Plutella xylostella was inherited as an incompletely dominant trait and was genetically linked to the transgene locus.CONCLUSIONS: Our results not only elucidated the in vivo contribution of the PxFMO2 and SeCYP9A186 to the insecticide resistance phenotype in Plutella xylostella, but also provided a genetic engineering toolkit to manipulate resistance pathways. These insights and methodologies could further aid in developing sustainable pest management strategies in Plutella xylostella. © 2024 Society of Chemical Industry.

Spodoptera exigua is one of the most serious lepidopteran pests of global importance. With the intensive use of insecticides, S. exigua has evolved resistance to many insecticides, including the sodium channel blocker insecticides (SCBIs) indoxacarb and metaflumizone. In this study, we investigated the role of the V1848I mutation in the voltage-gated sodium channel (VGSC) in SCBI resistance and its inheritance patterns in S. exigua through the development and characterization of a near-isogenic resistant strain. The AQ-23 strain of S. exigua, collected in 2023 from Anqing, Anhui province of China, shows 165-fold resistance to indoxacarb compared with the susceptible WH-S strain. A frequency of 44.6% for the V1848I mutation was detected in the SeVGSC of the AQ-23 strain, while no F1845Y mutation was found. Through repeated backcrossing and marker-assisted selection, the V1848I mutation in the AQ-23 strain was introgressed into the susceptible WH-S strain, creating a near-isogenic strain named WH-1848I. This WH-1848I strain exhibits high levels of resistance to indoxacarb (146-fold) and metaflumizone (431-fold) but remains susceptible to broflanilide and spinosad compared with the WH-S strain. Inheritance analysis revealed that SCBI resistance in the WH-1848I strain is autosomal, nonrecessive, and genetically linked to the V1848I mutation. These findings establish a clear link between the V1848I mutation and SCBI resistance in S. exigua, offering valuable insights for developing molecular detection tools and resistance management strategies.

Insecticides have been instrumental in the prevention and management of key agricultural insect pests, thereby contributing to increased food production. However, the effectiveness of insecticides diminishes when targeted pests develop resistance, a phenomenon linked to species evolution and survival instincts. The Arthropod Pesticide Resistance Database, maintained by Michigan State University, has documented 18,934 cases of resistance to insecticidal active ingredients worldwide from 1914 to the present. This special collection comprises eight original research articles that delve into the monitoring, mechanism and management of insecticide resistance. Two papers present multi‐year resistance monitoring results in Chilo suppressalis and Spodoptera litura. Two studies employ transcriptome data to examine the candidate genes implicated in solanine‐induced response in Phthorimaea operculella and chlorantraniliprole‐induced response in Galeruca daurica, respectively. Additionally, two papers describe the genetic and physiological impacts of insecticides, while others explore the potential mechanisms underlying chlorfenapyr resistance in Glyphodes pyloalis and pyrethroids resistance in Laodelphax striatellus. The new results, conclusions and suggestions presented in this collection are anticipated to contribute to the advancement of knowledge on insecticide resistance and facilitate the development of a sustainable approach to managing insect pests.

Chlorfenapyr is a broad‐spectrum halogenated pyrrole insecticide with a unique mode of action. Due to the misuse and overuse of this chemical, resistance has been reported in several arthropods, including Plutella xylostella, which is one of the most destructive insect pests afflicting crucifers worldwide. A better understanding of the cross‐resistance and genetics of field‐evolved chlorfenapyr resistance could effectively guide resistance management practices. Here, the chlorfenapyr resistance of a field‐derived population of P. xylostella was introgressed into the susceptible IPP‐S strain using a selection‐assisted multigenerational backcrossing approach. The constructed near‐isogenic strain, TH‐BC₅F₂, shared 98.4% genetic background with the recurrent parent IPP‐S strain. The TH‐BC₅F₂ strain showed 275‐fold resistance to chlorfenapyr, but no significant cross‐resistance to spinosad, abamectin, chlorpyrifos, β‐cypermethrin, indoxacarb, chlorantraniliprole, or broflanilide (no more than 4.2‐fold). Genetic analysis revealed that resistance was autosomal, incompletely dominant, and conferred by 1 major gene or a few tightly linked loci. The synergism of metabolic inhibitors (PBO, DEM, and DEF) to chlorfenapyr was very weak (5F₂ strain were not significantly elevated compared with the IPP‐S strain. The results enhances our understanding of the genetic traits of chlorfenapyr resistance, and provides essential information for improving resistance management strategies.

Background: Pesticide application before transplanting crops has been widely used in rice as an economical and effective method for reducing the use of chemical pesticides. This study focused on the feasibility of the application of pesticides before transplanting in a fresh corn nursery to control Spodoptera frugiperda. Methods: Three pesticides, including 35% Chlorantraniliprole WDG, 6% Spinetoram SC, and 3% Emamectin Benzoate WDG, combined with Polyorganosilicon (HTY-A8) or special flight additives (MF) as synergists were used and their toxicity was determined in the larvae of S. frugiperda feeding on sweet corn in the third leaf stage treated with 5 and 25 times the conventional field application concentration. The best combinations were tested in the field. The results showed that S. frugiperda exhibited high sensitivity to the three pesticides. The period of pest control validity of 35% Chlorantraniliprole WDG and 6% Spinetoram SC in the larvae was about 20 days, while that of 3% Emamectin Benzoate WDG was much shorter. The active component content of Chlorantraniliprole in the corn leaves was significantly higher than that of Emamectin Benzoate and Spinetoram. The pest control effects of Chlorantraniliprole were significantly promoted by HTY-A8 and MF. The field experiment showed that the control effect on S. frugiperda could last for 17 days by spraying Chlorantraniliprole or Spinetoram at 25 times the conventional concentration before transplanting, Furthermore, this method could reduce the amount of active ingredient to 4/5 or 3/4 of that found in a single field spray or seed coating treatment, respectively. Conclusions: This study puts forward a new method to effectively control S. frugiperda in the seedling stage of fresh corn.

In this study, the complete mitochondrial genome of Ia io from Guizhou Province, China. The genome was a circular mitochondrial genome of 16689 bp in length, containing 13 protein-coding genes (PCGs), 22 transfer RNA genes (tRNA), 2 ribosomal RNA genes (rRNA), and a control region. The average base composition is 32.76% A, 24.59% C, 14.49% G, and 28.16% T. The first complete mitochondrial genome of I. io provides fundamental data for future systematic taxonomic studies of the genus Ia.