First report of resistance in Spodoptera frugiperda (Lepidoptera: Noctuidae) to lambda-cyhalothrin from Pakistan: baseline susceptibility, selection, occurrence of cross-resistance, realized heritability, and inheritance mode of resistance.

Fall armyworm (FAW) Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), is a global pest causing damage to several crops. However, its management using chemical control is a challenge due to its capacity to evolve resistance to insecticides. After 6 generations of selection with lambda-cyhalothrin, the LC50 for the insecticide-resistant strain (Lambda-Sel) was 486 ppm, higher than that of the field strain (FAW-MUL) (7.5 ppm), susceptible laboratory strain (Lab-PK) (0.46 ppm), and laboratory unselected strain (UNSEL) (5.26 ppm). Laboratory selection with lambda-cyhalothrin increased resistance from 16.3- to 1056.52-fold and 1.43- to 92.4-fold to lambda-cyhalothrin compared to Lab-PK and UNSEL strains, respectively. The selected strain of S. frugiperda (Lambda-Sel) presented low cross-resistance to chlorpyrifos, moderate to deltamethrin and indoxacarb, very low to spinosad, and no cross-resistance to emamectin benzoate. The realized heritability (h2) of lambda-cyhalothrin resistance in the Lambda-Sel strain was very high (0.88). The reciprocal cross progenies of F1 (Lambda-Sel ♀ × Lab-PK ♂), F1' (Lambda-Sel ♂ × Lab-PK ♀), BC1 (F1 ♀ × Lambda-Sel ♂), and BC2 (F1 ♀ × Lab-PK ♂) showed high resistance ratios of 545.64-, 396.52-, 181.18-, and 146.54-fold, respectively compared to Lab-PK. The degree of dominance values for lambda-cyhalothrin in F1 and F1' indicates incompletely dominant resistance. The difference between observed and expected mortality in backcross populations (BC1 and BC2) revealed a polygenic resistance. In conclusion, the resistance to lambda-cyhalothrin was autosomal, incompletely dominant, and polygenic. These findings provide new insights for insect resistance management strategies to mitigate the occurrence of resistance in this global pest.

Foliar application of ascorbic acid enhances growth and yield of lettuce (Lactuca sativa) under saline conditions by improving antioxidant defence mechanism.

Lettuce (Lactuca sativa L.) production is low because of different environmental stresses. Salt stress significantly reduces lettuce growth and yield. Foliar application of ascorbic acid is considered as a possible way to mitigate the adverse salinity effects on plants. This current study investigated the effect of foliar spray of ascorbic acid (control, 100, 200, 300 and 400mg/L) to mitigate negative effects of salinity (0, 50, 100 and 150mMNaCl) in lettuce plants in 2019 and 2020. Salinity level of 200mMNaCl significantly reduced growth and yield traits; i.e. leaf length and diameter, number of leaves, fresh plant weight, number of roots, root length and root dry weight and these traits increased under foliar application of ascorbic acid concentration of 400mg/L. Two salinity levels (150 and 200mMNaCl)×400mg/L ascorbic acid enhanced superoxide dismutase (SOD) content in lettuce plants. Peroxidase (POD) content increased in 200mMNaCl and 400mg/L ascorbic acid. Catalase (CAT) content increased in 100, 150 and 200mMNaCl and 400mg/L ascorbic acid. Ascorbic acid was significantly greater in 200mMNaCl and 400mg/L ascorbic acid. Phenolic content was the maximum in 200mMNaCl and 300mg/L and 400mg/L ascorbic acid. Titratable acidity was higher in 0, 50, 100, 150 and 200mMNaCl and control of ascorbic acid. We conclude that ascorbic acid had potential to mitigate the adverse effects of salinity by reducing oxidative injury in agricultural crops especially lettuce.

Sewage wastewater reclamation with sand column filter and reduction of heavy metal accumulation in tomato and okra.

Heavy metal accumulation has much increased in edible parts of fresh fruits and vegetables due to use of industrial waste/effluent, and wastewater. In the current work, sewage wastewater was reclaimed through a column filled with sand having a mesh size of 0.5 mm and its effect was investigated on concentration of different heavy metals, vegetative growth, and yield of okra and tomato. The use of unfiltered sewage wastewater (UFSW) had considerably higher concentrations of heavy metals but it substantially increased plant height, leaf number, and leaf area in both okra and tomato plants in contrast to filtered sewage wastewater (FSW). The application of UFSW resulted in a significantly higher accumulation of lead (Pb), nickel (Ni), iron (Fe), and copper (Cu) in roots and edible parts of okra and tomato as compared with FSW treatment. However, FSW and UFSW did not significantly influence concentrations of chromium (Cr) and cadmium (Cd) in roots and edible parts of both okra and tomato. In conclusion, sand column filtration technique could be efficiently used for the reclamation of sewage wastewater, and reduction of various heavy metals present in sewage wastewater-irrigated crops.

Tragacanth gum coating modulates oxidative stress and maintains quality of harvested apricot fruits.

Tragacanth gum is a polysaccharide-based complex with a good coating property. However, its use in postharvest storage of fresh fruits and vegetables is very limited. In the current work, the effect of tragacanth gum (1%) was investigated on postharvest quality of apricot fruits during storage at 20 ± 1 °C for 8 days. Apricot fruits coated with tragacanth gum coating showed significantly reduced weight loss, decay and electrolyte leakage, hydrogen peroxide and malondialdehyde production. Tragacanth gum coating suppressed increase in total soluble solids and showed higher titratable acidity compared with control. The coated fruits had higher total phenolics and ascorbic acid along with greater 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity in contrast with control. Postharvest application of tragacanth gum coating maintained markedly higher activities of ascorbate peroxidase (APX), catalase (CAT), superoxide dismutase (SOD) and peroxidase (POD) enzymes activities as compared with control. In addition, tragacanth gum application suppressed polygalacturonase (PG), pectin methylesterase (PME), and cellulase (CX) enzymes activities, thereby suppressed softening of apricot fruits. Sensory quality attributes such as taste, juiciness, aroma, appearance, and overall acceptability were also significantly higher in tragacanth gum coated fruits compared with control. In conclusion, tragacanth gum coating could be considered suitable for postharvest quality conservation of apricot fruits.

Phytochemical, antimicrobial and time-kill kinetics potentials of Euphorbia nivulia Buch.-Ham.: A Cholistan desert medicinal plant.

Euphorbia nivulia a locally occurring plant species possesses antiseptic, analgesic and anti-inflammatory properties and is ethnopharmacologically used in various ailments like skin, ear disorders, boils, and worm infestation. Preliminary phytochemical screening showed presence of flavonoids, polyphenolics, glycosides, alkaloids, tannins and triterpenoids in (70% aqueous-ethanolic) Euphorbia nivulia crude extract (En cr) and its four fractions, i.e., hexane fraction (En hex), butanol fraction (En bt), chloroform fraction (En ch), and aqueous fraction (En aq). In current study, Agar well diffusion and time-kill kinetic assays were performed for antimicrobial activity. 300 mg/ml concentration showed maximum inhibitory zone. Highest zone of inhibition (15.5mm) was demonstrated by En ch fraction against Proteus mirabilis. Staphyllococcus aureus was the most sensitive bacteria against whom all fractions except En aq fraction were active. Maximum MIC (15.3 mg/ml) was shown by En ch fraction against Proteus mirabilis. Similarly, En ch fraction showed (15.1 mg/ml) remarkable MIC against Candida albicans. Significant higher antibacterial and antifungal activity was revealed in high concentration. Time-kill kinetics studies revealed bacteriostatic action. Noteworthy antimicrobial activity may be due to bioactive compounds of extract which may be a potential antibacterial and antifungal agent.

Assessing the combined toxicity of conventional and newer insecticides on the cotton mealybug Phenacoccus solenopsis.

Reduced susceptibility to insecticides often results in failure of insect pest control and repetitive use of broad-spectrum insecticides, which could have detrimental effects on beneficial arthropods and surrounding agro-ecosystems. The cotton mealybug, Phenacoccus solenopsis Tinsley is a pest of worldwide importance that can be effectively controlled using a number of insecticides. This insect has developed resistance due to injudicious use and repeated exposure to insecticides throughout the year. The aim of the present study was to investigate the toxicity of the insecticides chlorpyrifos, deltamethrin, spinosad, emamectin benzoate and indoxacarb tested either singly or in combination on laboratory susceptible (Lab-PK) and field population (Field Pop) of P. solenopsis. In the Field Pop, combination of chlorpyrifos with either spinosad or emamectin benzoate or indoxacarb showed a synergistic effect at 1:1, 1:10 and 1:20. The combination of deltamethrin with either emamectin benzoate or indoxacarb at all ratios showed synergistic effect, while the combination of deltamethrin with spinosad at 1:1 and 1:20 ratios showed antagonistic effects and that at 1:10 ratio showed synergistic effect against Field Pop. The results of synergism experiments using piperonyl butoxide (PBO) and S,S,S-tributylphosphorotrithioate (DEF) enzyme inhibitors, when combined with insecticides against the Field Pop, toxicities of all tested insecticides were significantly increased. The present study suggests that insecticide combinations and synergism could help achieve effective control of less susceptible populations of P. solenopsis. This would contribute to suitably managing resistance of this pest to insecticides with reduced negative impacts on the surrounding environment.