Realized heritability, inheritance and cross-resistance patterns in imidacloprid-resistant strain of Dysdercus koenigii (Fabricius) (Hemiptera: Pyrrhocoridae)

Laccase immobilized on magnetic nanoparticles for the degradation of imidacloprid: Based on multi-spectroscopy and molecular docking

As a typical class of environmental endocrine disruptors, imidacloprid (IMI) poses a potential threat to the sustainable survival and reproduction of living beings and human beings. Consequently, it is crucial to establish an efficient degradation method to remove imidacloprid from the environment. The present study aimed to investigate the immobilized laccase for the detoxification of imidacloprid via multi-spectroscopy and molecular docking. Herein, laccase was immobilized on magnetic nanoparticles (NiFe2O4 NPs) using a novel immobilization technique based on glutaraldehyde cross-linking polymerization. A single factor experiment approach was used to optimize the immobilization conditions, which included temperature, pH, enzyme concentration, and reaction time. Notably, the optimal condition was determined as 50℃, pH 4, laccase concentration of 1.0 mg/mL and 1.5 h. Based on the immobilization conditions, the degradation efficiency of immobilized laccase was 41.92 % after 24 h. Following eight degradations, the immobilized laccase's relative activity stayed at 34.09 % of its initial activity, demonstrating exceptional operational stability and reusability. Moreover, the binding free energy between imidacloprid and laccase was calculated on the basis of molecular docking, as -7.2 kcal/mol. This study provides experimental techniques and theoretical references for the biological digestion of hazardous pesticide residues in the environment. In addition, this study improved the shortcomings of free laccase, provided an environmentally friendly and efficient method for the degradation of imidacloprid.

Realized Heritability, Risk Assessment, and Inheritance Pattern in Earias vittella (Lepidoptera: Noctuidae) Resistant to Dipel (Bacillus thuringiensis Kurstaki)

Earias vittella Fabricius is a potential cotton and okra pest in South Asia. The realized heritability, risk assessment, and inheritance mode of Bacillus thuringiensis Kurstaki (Btk) resistance were determined in the Dipel-selected (DIPEL-SEL) E. vittella. The DIPEL-SEL strain had a 127.56-fold rise in Dipel resistance after nine generations compared to the laboratory reference strain (LAB-PK). The overlapping of 95% fiducial limits in the median lethal concentrations (LC₅₀s) of the F₁ (DIPEL-SEL♂ × LAB-PK♀) and F₁^ǂ (DIPEL-SEL♀ × LAB-PK♂) suggested a lack of sex linkage and an autosomal Dipel resistance. The dominance (D_LC) values for the F₁ (0.86) and F₁^ǂ (0.94) indicated incompletely dominant resistance to Dipel. Backcrossing of the F₁♀ × Lab-PK♂ revealed a polygenic response of resistance to Dipel. The realized heritability estimation (h²) of resistance to Dipel was 0.19. With 20% to 90% selection mortality, the generations required for a tenfold increase in LC₅₀ of Dipel were 4.7–22.8, 3.1–14.9, and 2.3–11.1 at h² of 0.19, 0.29, and 0.39, respectively, and a constant slope of 1.56. At slope values of 2.56 and 3.56 with a constant h² = 0.19, 7.7–37.4 and 10.6–52.0 generations were needed to increase the tenfold LC₅₀ of Dipel in the DIPEL-SEL E. vittella. It is concluded that the DIPEL-SEL E. vittella has an autosomal, incompletely dominant, and polygenic nature of resistance. The h² of 0.19 suggested that a high proportion of phenotypic variation for the Dipel resistance in E. vittella was heritable genetic variation. The present results will support the creation of an effective and suitable resistance management plan for better control of E. vittella.

Risk assessment of resistance to diflubenzuron in Musca domestica: Realized heritability and cross-resistance to fourteen insecticides from different classes

The Musca domestica L. is a well-known vector for a number of livestock and human diseases. One major challenge for maintaining effective control of this pest is its propensity to develop resistance to insecticides. This study utilized laboratory selection and realized heritability methods to examine the risk of resistance development to diflubenzuron in Musca domestica L. Cross-resistance (CR) to fourteen other insecticides was measured in diflubenzuron-selected (Diflu-SEL) strain which was selected for 20 generations. The resistance ratio (RR) of Diflu-SEL larvae to diflubenzuron increased from 30.33 in generation five (G₅) to 182.33 in G₂₄ compared with the susceptible strain, while realized heritability (h²) was 0.08. The number of needed generations (G) for a tenfold increase in the median lethal concentration (LC₅₀) for diflubenzuron ranged from 4 to 45 at h² values of 0.08, 0.18, and 0.28, at a slope of 1.51. At h² = 0.08 and slopes of 1.51, 2.51, and 3.51, the number of needed G for a tenfold increase in the LC₅₀ ranged from 9 to 104. The level of CR shown by the Diflu-SEL strain to all other fourteen tested insecticides (insect growth regulators, organophosphates, and pyrethroids) was either absent or very low compared to the field population. The value of h² and the absent or low CR indicate potential successful management of resistance to diflubenzuron and recommend the use of the tested insecticides in rotation with diflubenzuron to control M. domestica.

First Evaluation of Field Evolved Resistance to Commonly Used Insecticides in House Fly Populations from Saudi Arabian Dairy Farms

The house fly, Musca domestica L. (Diptera: Muscidae), is one of the major vectors of several pathogens that affect humans and animals. We evaluated the toxicity of eight insecticides commonly used for house fly control using five field populations collected from dairies in Riyadh, Saudi Arabia. Among the five tested pyrethroids, non to moderate resistance was found in adults of both sexes compared to a susceptible strain. Resistance ratios ranged from 0.5- to 7-fold for alpha-cypermethrin, 2- to 21-fold for deltamethrin, 4- to 19-fold for bifenthrin, 1- to 9-fold for cyfluthrin, and 1- to 8-fold for cypermethrin. Among the three tested organophosphates, low to moderate resistance was found among adult flies compared to the susceptible strain, and the resistance ratios ranged from 4- to 27-fold for fenitrothion, 2- to 14-fold for chlorpyrifos, and 3- to 12-fold for malathion. The median lethal times for the tested insecticides were 3-33 h for alpha-cypermethrin, 3-24 h for deltamethrin, 5-59 h for bifenthrin, 1-7 h for cypermethrin, 0.3-7 h for cyfluthrin, 6-36 h for fenitrothion, 2-21 h for chlorpyrifos, and 3-34 h for malathion. This study presents baseline data pertaining to registered public health insecticides, and the results will assist future studies monitoring insecticide resistance, and the planning of effective integrated vector management programs.

Sulfoxaflor resistance in Oxycarenus hyalinipennis (Costa) induces negligible cross-resistance to other tested insecticides: stability, risk assessment, and fitness cost

BACKGROUND

Oxycarenus hyalinipennis (Costa) (Hemiptera: Lygaeidae) is a polyphagous insect pest. In Pakistan, O. hyalinipennis is managed by using different insecticides, a major concern for cotton producers, and has developed resistance to many of these. Sulfoxaflor belongs to a newly released sulfoximine family that has high efficacy for controlling sap-feeding insect pests.

RESULTS

A sulfoxaflor selected-population (Sulfo-Sel-Pop) of O. hyalinipennis showed a 3064.92-fold level of resistance after continuous selection for 18 generations with sulfoxaflor compared to unselected population (UNSel-Pop). The Sulfo-Sel-Pop showed a reduction in resistance (from 3064.92 to 635-fold) without exposure for five generations, indicating unstable resistance to sulfoxaflor. Cross-resistance studies of the Sulfo-Sel-Pop revealed no or very low cross-resistance to triazophos (0.42 to 0.30-fold), deltamethrin (0.85 to 0.18-fold) and acetamiprid (1.16 to 4.86-fold) from G₄ to G₁₉ compared to the field population (Field-Pop). The mean value of realized heritability was 0.15 in the Sulfo-Sel-Pop (G₁₉ ). Significantly reduced relative fitness was determined in the Sulfo-Sel-Pop (Rf = 0.21) followed by Cross₁ [(Sulfo-Sel-Pop ♂ × UNSel-Pop ♀) (Rf = 0.58)]_, and Cross₂ [(Sulfo-Sel-Pop ♀ × UNSel-Pop ♂) (Rf = 0.70)] compared with the UNSel-Pop. The values of intrinsic rate of natural increase (r_m ), biotic potential (Bp) fecundity, egg hatching, and net reproductive rate (R0) were also significantly less in the Sulfo-Sel-Pop compared to UNSel-Pop.

CONCLUSION

A very high fitness cost, unstable resistance and no or very low cross-resistance in the Sulfo-Sel-Pop have great implications in designing effective strategies for managing insecticide resistance to O. hyalinipennis. © 2021 Society of Chemical Industry.

Risk Assessment of Flonicamid Resistance in Musca domestica (Diptera: Muscidae): Resistance Monitoring, Inheritance, and Cross-Resistance Potential

Flonicamid is a chordotonal modulator and novel systemic insecticide that has been used frequently for controlling a broad range of insect pests. The risk of flonicamid resistance was assessed through laboratory selection and determining inheritance pattern and cross-resistance potential to five insecticides in house fly, Musca domestica L. Very low to high flonicamid resistance in M. domestica populations was found compared with the susceptible strain (SS). A flonicamid-selected (Flonica-RS) M. domestica strain developed 57.73-fold resistance to flonicamid screened for 20 generations compared with the SS. Overlapping 95% fiducial limits of LC50 of the F1 and F1ǂ, and dominance values (0.87 for F1 and 0.92 for F1ǂ) revealed an autosomal and incomplete dominant flonicamid resistance. The monogenic model of resistance inheritance suggested a polygenic flonicamid resistance. The Flonica-RS strain displayed negative cross-resistance between flonicamid and sulfoxaflor (0.10-fold) or clothianidin (0.50-fold), and very low cross-resistance between flonicamid and flubendiamide (4.71-fold), spinetoram (4.68-fold), or thiamethoxam (2.02-fold) in comparison with the field population. The estimated realized heritability (h2) value of flonicamid resistance was 0.02. With selection mortality 40-90%, the generations required for a 10-fold increase in LC50 of flonicamid were 94-258 at h2 (0.02) and slope (3.29). Flonicamid resistance was inherited as autosomal, incomplete dominant, and polygenic in the Flonica-RS. Negative or very low cross-resistance between flonicamid and sulfoxaflor, clothianidin, flubendiamide, spinetoram, and thiamethoxam means that these insecticides can be used as alternatives for controlling M. domestica. These data can be useful in devising the management for M. domestica.

Monitoring of field-evolved resistance to flonicamid, neonicotinoid, and conventional insecticides in the Oxycarenus hyalinipennis costa

Oxycarenus hyalinipennis Costa is a polyphagous insect pest and can develop insecticide resistance. The resistance of O. hyalinipennis to neonicotinoids (clothianidin and dinotefuran), flonicamid, and conventional insecticides; carbamates (methomyl and carbosulfon), organophosphates (chlorpyrifos and malathion), and pyrethroids (cypermethrin and zeta-cypermethrin) was evaluated. The O. hyalinipennis populations were sampled from four locations in Pakistan and performed bioassays against the insecticides by leaf dip protocol. The O. hyalinipennis' populations showed low resistance to carbosulfan (resistance ratio (RR) = 2.06-6.34) and methomyl (RR = 2.78-7.27), moderate to high resistance to chlorpyrifos (RR = 30-45), malathion (RR = 20.29-88.19), and flonicamid (RR = 14.24-46.97), in comparison with the susceptible strain. Susceptibility to low resistance against cypermethrin (RR = 1.27-2.82), zeta-cypermethrin (RR = 2.62-3.38), and clothianidin (RR = 1.74-3.40), and low to moderate resistance to dinotefuran (RR = 3.84-13.43) in the field populations, was observed compared to the susceptible strain. A rotational usage of carbamates and pyrethroids with an integrated pest management tool should be considered to deal with O. hyalinipennis' insecticide resistance.

Inheritance mode and metabolic mechanism of the sulfoximine insecticide sulfoxaflor resistance in Oxycarenus hyalinipennis (Costa)

BACKGROUND

Dusky cotton bug (DCB), Oxycarenus hyalinipennis (Costa) (Hemiptera: Lygaeidae), is a key insect pest of cotton. It causes huge losses to cotton and many other economically important crops. Sulfoxaflor is a newly introduced systemic insecticide that is effective against many sap-feeding insect pests such as aphids, whiteflies and true bugs. The present study was designed to characterize the inheritance of sulfoxaflor resistance in DCB. Moreover, the role of synergists in reducing sulfoxaflor resistance in DCB was also assessed.

RESULTS

A field population of DCB has developed 1132.0-fold resistance to sulfoxaflor after 11 selected generations in the laboratory. Nonsignificant difference of reciprocal crosses was observed depending on the LC₅₀ (median lethal concentration) values (95% confidence intervals overlapped), suggesting an autosomal mode of sulfoxaflor resistance inheritance. The degree of dominance of 0.7 for F₁ (Sulfo-Sel Pop ♀ × Lab-Pop♂) and 0.6 for F₁ '(Sulfo-Sel Pop ♂ × Lab-Pop♀), respectively, suggested that sulfoxaflor resistance was incompletely dominant. According to the monogenic model, the number of genes involved to induce sulfoxaflor resistance revealed that sulfoxaflor resistance was polygenic in nature. The realized heritability (h² ) value for sulfoxaflor resistance was 0.2. The synergists experiment indicated that esterases were involved in the sulfoxaflor resistance mechanism in DCB.

CONCLUSIONS

The current results indicate that there is autosomal, incompletely dominant and polygenic inheritance of sulfoxaflor resistance in DCB. Our results would be helpful in delaying sulfoxaflor resistance against DCB in the field. © 2021 Society of Chemical Industry.

Genetic basis and realized heritability of laboratory selected spirotetramat resistance for insecticide resistance management in Oxycarenus hyalinipennis Costa (Hemiptera: Lygaeidae)

Dusky cotton bug, Oxycarenus hyalinipennis Costa (Hemiptera: Lygaeidae) is become a major pest of cotton. It causes damage to cotton by sucking the cell sap or by staining the cotton seed. Insect pests in Pakistan are mainly managed by use of insecticides, applying this practice leads to resistance development. In this study, O. hyalinipennis was selected with spirotetramat under laboratory conditions to investigate genetic mode of resistance to spirotetramat. Selection with spirotetramat for eleven generations resulted in a 727-fold resistance compared to the susceptible strain. The LC₅₀ values of spirotetramat in both reciprocal crosses were significantly different from each other and degree of dominanace values were 0.25 for cross-1 and 0.01 for cross-2. Monogenic model proved the contribution of more than one gene in controlling the spirotetramat resistance. Moreover, the value for realized heritability of spirotetramat resistance was 0.13. It can be concluded that spirotetramat resistance was sex linked, polygenic and incompletely dominant. These findings could be helpful in management of spirotetramat resistance in O. hyalinipennis as incompletely dominant and polygenic resistance tend to develop slowly and is manageable.

Fitness cost of imidacloprid resistance in the cotton-staining bug, Dysdercus koenigii

Dysdercus koenigii, a serious cotton-staining insect pest in many countries, has shown high resistance to imidacloprid, a systemic neonicotinoid insecticide used to control sap-sucking pests. With the aim of creating an effective management strategy, the biological traits of susceptible (SS) and imidacloprid-resistant (Imida-RS) D. koenigii, as well as their reciprocal crosses (CR1 and CR2), were investigated here using a life table established on age, stage, and two-sex patterns. Compared with SS D. koenigii, Imida-RS and CR1 strains had lower relative fitness (0.80 and 0.47, respectively) and fecundity (eggs per female); prolonged egg duration and a prolonged adult preoviposition period; shorter nymphal duration, male/female total longevity, and oviposition days, and a shorter total preoviposition period. However, there were no differences among strains in nymphal survival rates and female ratio. The CR2 D. koenigii had similar relative fitness value (1.09), suggested no fitness cost in most of the parameters. Demographic parameters, including net reproductive rate, were lower in the Imida-RS strain than in SS and CR2 D. koenigii. Similarly, the Imida-RS and CR1 strains had shorter generation time and doubling time, lower reproductive value and life expectancy relative to the SS and CR2 D. koenigii. In addition, age-specific fecundity was negatively affected in the CR1 strain compared with the other strains. These findings could help facilitate the development of rational D. koenigii control strategies.