Investigation on the insecticidal activities of cyanobacterial extracts as an alternative source for the management of fall armyworm, Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae)

The Spodoptera frugiperda is a notorious pest with a broad host range. It severely damages crops, mainly in areas of the globewhere maize and sorghum are grown. The pest is difficult to control due to its adaptive nature and resistance to several insecticides available in the market. So, an identification of the alternative strategy is the prime important in the present context. Insecticidal activities of cyanobacterial extracts were evaluated in the laboratory as a biocomponent against S. frugiperda. The crude extracts of Nostoc muscorum and Spirulina sp. were prepared by using ethanol, methanol and petroleum ether solvents. Soxhlet apparatus was used for extraction. S. frugiperda larvae in their second instar were given access to fragments of maize leaf that had been treated with various cyanobacterial extracts. The findings displayed that the petroleum ether extract of N. muscorum had the lowest LC50 value of 155.22 ppm, followed by petroleum ether extracts of Spirulina, ethanol extract of N. Muscorum, methanol extract of N. muscorum, ethanol and methanol extract of Spirulina with an LC50 values of 456.02, 710, 780, 1050 and 1070 ppm respectively. Later, the effect of LC50 values on many biological parameters like the larval duration and pupal stages, the percentage of pupation, the weight of the pupal stage, the malformation of the pupal and adult stages, adult emergence percentage, fertility and the longevity of the male and female adult stages of S. frugiperda was examined. The gas chromatography-mass spectrometry (GC-MS) was used to analyse the crude extract to identify the bioactive components that were responsible for the insecticidal properties. The major compounds detected were diethyl phthalate (19.87 %), tetradecane (5.03%), hexadecanoic acid, ethyl ester (4.10 %), dodecane (4.03%), octadecane (3.72%), octadecanoic acid, methyl ester (3.40 %), ethyl oleate (3.11 %), methyl ester. octadecenoic acid (3.04 %), heptadecane (3.04 %) and phytol (3.02 %). The presence of several bioactive chemicals in the cyanobacterial extracts may be the reason for their insecticidal actions, thus it can be used as an alternative and new source to combat fall armyworm and other crop pests.

Determination of 73 multi-class pesticides in okra (Abelmoschus esculentus L.) fruits using LC-MS/MS and GC-MS/MS and estimation of analytical uncertainty of measurement

This study developed a method to simultaneously determine 73 multi-class pesticides in okra fruit using LC-MS/MS and GC-MS/MS. The sample was extracted with acetonitrile and subsequent clean-up through dispersive-SPE method. The quantification level of the technique was 0.01 µg g-1 and compliance to the MRLs fixed by the regulatory bodies like EU and FSSAI. The recovery at 10, 50, and 100 µg kg-1 spiked levels; intra and inter-day precision at 50 µg kg-1 were found within 70-120% with RSD less than 15% with LC-MS/MS and GC-MS/MS. Measurement uncertainty was in the range of 1.81 to 12.91 µg kg-1 estimated at 50 µg kg-1. The matrix effects were slightly higher for LC than GC-compatible pesticides. Risk assessment for pesticides detected in the field and market samples found no hazardous to the consumers except profenofos. The proposed method is highly sensitive, reproducible for the complex matrix like okra, and meets the regulatory standards.

A new species and new record of the genus Pexicopia (Lepidoptera: Gelechiidae) feeding on Abutilon indicum from India

A new species, Pexicopia tungabhadrai sp. nov. (Lepidoptera: Gelechiidae), feeding on Abutilon indicum is described from Karnataka, India. Also, this is the first report of the genus Pexicopia Common, 1958 from India. Images of adult moths, male and female genitalia and immature stages are provided.

Determination of imidacloprid in brinjal and okra fruits, decontamination and its dietary risk assessment

Brinjal and okra are being sprayed withdifferent formulations of imidacloprid which leads to significant deposition of residues on fruits. Here in this study, we validated a method that could detect the traces of imidacloprid residues in a short run time using LC-MS/MS. LOD of 0.001 and LOQ of 0.003 μg/g for brinjal and in compliance with the MRL (0.2 mg/kg). The recovery at different spiking levels recorded 89.67 to 115.55 with an RSDr range of 3.02 and 5.22%. For okra, 0.0025 and 0.008 μg/g were observed as LOD and LOQ, respectively. Recovery was obtained between 88.69 and 93.74%. Precision in terms of repeatability (RSDr) and reproducibility (RSDwR) was found satisfactory in both matrices. Two applications of imidacloprid 17.8% SL in both vegetables showed faster dissipation initially and persisted up to 15-25 days. Decontamination with 2% salt solution followed by boiling for 15min. removed 96.43 and 73.66% of imidacloprid residues from brinjal and okra, respectively. Risk assessment was found to be less than one (HI < 1) for brinjal and okra matrix and can be safely consumed.

Determination of chlorantraniliprole 18.5% SC in the paddy ecosystem and its risk assessment

Chlorantraniliprole belongsto theanthranilic diamide group is widely used against broad range of lepidopteron pests in a variety of vegetable and rice pests includingyellow rice stem borer and leaf folder. Supervised field trials were conducted duringRabi (2018-2019) and Kharif (2019) to evaluate the dissipation pattern and risk assessment of chlorantraniliprole 18.5% SC in paddy ecosystem following foliar application at 30 and 60 g a.i. ha^-1 in two different cropping seasons.Modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) technique was used for the extraction of CAP residues with acetonitrile and determined by LC-MS/MS (ESI +).The limit of quantification (LOQ) was 0.01 µg g^-1 for paddy leaf, straw, husk, and brown rice, respectively and 0.005 µg g^-1 for soil. The average recoveries obtained were 84.30-88.92% from paddy leaf, 94.25-97.81% from straw, 90.21-93.38% from husk, 93.57-96.40% from brown rice and 89.93-91.14% from soil. The residues in paddy leaf dissipated within 35-40 days with a half-life of 4.33-5.07 days in Rabi and 3.92-4.86 days in Kharif at 30 and 60 g a.i. ha^-1, respectively. The residues in soil dissipated within 15-21 days with a half-life of 14.44-15.75 days in Rabi and 13.33-14.44 days in Kharif at respective doses. At harvest chlorantraniliprole residues were not detected in straw, husk, and brown rice. The dietary risk of paddy leaf (green fodder) for cattle was found safe for consumption as the hazard index is less than one. Soil ecological risk assessment was found to be less than one (RQ < 0.1) for earthworms (Eisenia foetida) and arthropods (Aphidiusrhopalosiphi). The presentmethod could be useful inthe analysis ofchlorantraniliproleresidues in different cereals and vegetable crop ecosystems and application at recommended dose is safe for the final produce at harvest.

Characterization of phyto-components with antimicrobial traits in supercritical carbon dioxide and soxhlet Prosopis juliflora leaves extract using GC-MS

This study aimed to screen the bioactive compounds from Prosopis juliflora leaf supercritical fluid extract and to assess its antimicrobial properties. Supercritical carbon dioxide and Soxhlet methods were used for extraction. The extract was subjected to Gas Chromatography-Mass Spectrometer (GC-MS) and Fourier Transform Infrared for the characterization of the phyto-components. When compared to soxhlet extraction, more components (35) were eluted by supercritical fluid extraction (SFE), according to GC-MS screening. Rhizoctonia bataticola, Alternaria alternata, and Colletotrichum gloeosporioides were all successfully inhibited by P. juliflora leaf SFE extract, which demonstrated strong antifungal properties with mycelium percent inhibition of 94.07%, 93.15%, and 92.43%, respectively, compared to extract from Soxhlet, which registered 55.31%, 75.63% and 45.13% mycelium inhibition respectively. Also, SFE P. juliflora extracts registered higher zone of inhibition 13.90 mm, 14.47 mm and 14.53 mm against all three test food-borne bacterial pathogens viz Escherichia coli, Salmonella enterica and Staphylococcus aureus respectively. Results obtained from GC-MS screening revealed that SFE is more efficient than soxhlet extraction in recovering the phyto-components. P. juliflora may provide antimicrobial agents, a novel natural inhibitory metabolite.

Simultaneous determination of dimethoate and its metabolite omethoate in curry leaf using LC-MS/MS and risk assessment

This study presents the method development, validation, and simultaneous determination of dimethoate and its metabolite omethoate in curry leaf. Samples were extracted following modified quick, easy, cheap, effective, rugged, and safe extraction protocol and analyzed using liquid chromatography-tandem mass spectrometry. The limit of quantification in the matrix was 0.005 μg g^-1 for dimethoate and omethoate. Extraction using acetonitrile recorded the average recoveries in the range of 82.25 to 112.97% for dimethoate and 85.57 to 107.22% for omethoate at 0.005, 0.025 and 0.050 μgg^-1 fortification levels and relative standard deviation less than 5%. Similarly, the relative standard deviation values for intraday (Repeatability) and interday (Reproducibility) tests were less than 15%. Dissipation kinetics of dimethoate 30% emulsifiable concentrate at 200 and 400 g a.i h^-1 recorded initial deposits of 5.20 and 10.05 μg g^-1 and 0.33 and 0.48 μg g^-1 for dimethoate and omethoate, respectively, and half-life of 3.07 and 3.34 days. The estimated hazard index value found more than one at a day after dimethoate application. It is not safe for consumer health to use curry leaves in the initial days after application. This article is protected by copyright. All rights reserved.

Simultaneous determination, dissipation and decontamination of fungicides applied on cabbage using LC-MS/MS

A method for simultaneous determination of carbendazim and tebuconazole residues in cabbage was developed and validated in LC-MS/MS. Samples were extracted and purified following the modified QuEChERS procedure, which enabled the elution of carbendazim and tebuconazole at 0.96 and 5.31 min, respectively. LOD and LOQ were 0.0005 and 0.0015 mg kg^-1, respectively. Mean recovery was in the range of 78.94 to 104.89% for carbendazim and 76.07 to 98.62% for tebuconazole. The field samples recorded residues of 0.274 and 0.481 mg kg^-1; and 0.194 and 0.392 mg kg^-1 at single and double dose for carbendazim and tebuconazole, respectively. Half-life values were 2.17 and 2.99 for carbendazim and 2.74 and 2.81 for tebuconazole at single and double dose, respectively. Decontamination with saltwater wash followed by cooking and lemon water wash found superior in the removal of residues more than 90%.

Evidence for facultative migratory flight behavior in Helicoverpa armigera (Noctuidae: Lepidoptera) in India

Despite its deleterious impact on farming and agriculture, the physiology and energetics of insect migration is poorly understood due to our inability to track their individual movements in the field. Many insects, e.g. monarch butterflies, Danaus plexippus (L.), are facultative migrants. Hence, it is important to establish whether specific insect populations in particular areas migrate. The polyphagous insect, Helicoverpa armigera (Hübner), is especially interesting in this regard due to its impact on a variety of crops. Here, we used a laboratory-based flight mill assay to show that Helicoverpa armigera populations clearly demonstrate facultative migration in South India. Based on various flight parameters, we categorized male and female moths as long, medium or short distance fliers. A significant proportion of moths exhibited long-distance flight behavior covering more than 10 km in a single night, averaging about 8 flight hours constituting 61% flight time in the test period. The maximum and average flight speeds of these long fliers were greater than in the other categories. Flight activity across sexes also varied; male moths exhibited better performance than female moths. Wing morphometric parameters including forewing length, wing loading, and wing aspect ratio were key in influencing long-distance flight. Whereas forewing length positively correlated with flight distance and duration, wing loading was negatively correlated.

Simultaneous determination of 79 pesticides in pigeonpea grains using GC-MS/MS and LC-MS/MS

Pigeonpea grains are important sources of vegetarian proteins. It is the paramount importance to check the pesticide residues due to their frequent use during production. The LC-MS/MS and GC-MS/MS analytical method was developed and validated for the simultaneous determination of 79 pesticide residues in pigeonpea. The LOD and LOQ of the analytical method were in the range of 0.53 to 3.97 and 1.60 to 10.05 µg kg^-1, respectively, with a correlation coefficient of more than 0.997. Average recoveries were in the range of 80 to 118.8%, with the RSD of less than 15%. Measurement uncertainty (U_x) for pesticides was in the range of 3.42 to 12.76 µg kg^-1 evaluated at 50 µg kg^-1. The method was applied to analyze the sample collected from the farmer's field. This method could be useful for routine analysis of selected pesticide residue for monitoring purposes.

Genome Mining and Expression Analysis of Carboxylesterase and Glutathione S-Transferase Genes Involved in Insecticide Resistance in Eggplant Shoot and Fruit Borer, Leucinodes orbonalis (Lepidoptera: Crambidae)

The shoot and fruit borer, Leucinodes orbonalis (Lepidoptera: Crambidae) is the major cause of low productivity in eggplant and insecticides being the mainstay of management of L. orbonalis. However, field control failures are widespread due to the evolution of insecticide resistance. Taking advantage of the whole genome sequence information, the present study investigated the level of insecticide resistance and the expression pattern of individual carboxylesterase (CE) and glutathione S-transferases (GSTs) genes in various field collected populations of L. orbonalis. Dose-mortality bioassays revealed a very high level of resistance development against fenvalerate (48.2–160-fold), phosalone (94-534.6-fold), emamectin benzoate (7.2–55-fold), thiodicarb (9.64–22.7-fold), flubendiamide (187.4–303.0-fold), and chlorantraniliprole (1.6–8.6-fold) in field populations as compared to laboratory-reared susceptible iso-female colony (Lo-S). Over-production of detoxification enzymes viz., CE and GST were evident upon enzyme assays. Mining of the draft genome of L. orbonalis yielded large number of genes potentially belonging to the CE and GST gene families with known history of insecticide resistance in other insects. Subsequent RT-qPCR studies on relative contribution of individual genes revealed over-expression of numerous GSTs and few CEs in field populations, indicating their possible involvement of metabolic enzymes in insecticide resistance. The genomic information will facilitate the development of novel resistance management strategies against this pest.