RESUMEN
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.
RESUMEN
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.