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ThesisItem Open Access Effect of imidacloprid on reproductive performance of Eudrilus eugeniae and Metaphire posthuma(Punjab Agricultural University, Ludhiana, 2021) Harpreet Kaur; Hundal, S.S.The current study investigated the effect of neonicotinoid insecticide imidacloprid on the reproductive performance of exotic earthworm Eudrilus eugeniae and indigenous earthworm Metaphire posthuma. The experiments were conducted in the Department of Zoology, Punjab Agricultural University, Ludhiana. The earthworm species were exposed to different concentrations of imidacloprid (1.00, 2.50, 4.00, 5.50 and 7.00 mg/kg dry soil) to calculate the LC50 value. Dosages were selected based upon the studies performed by earlier workers. The LC50value calculated was 3.19 mg/kg (2.65 mg/kg ~3.74 mg/kg) and 2.23 mg/kg (1.87 mg/kg ~2.59 mg/kg) for earthworm Eudrilus eugeniae and Metaphire posthuma respectively. In artificial test soil Eudrilus eugeniae and Metaphire posthumawere exposed to different doses (0.3, 0.6 and 1.0 mg/kg) to evaluate reproductive potential along with biochemical and genotoxicity studies as per OECD guidelines. Upon exposure to doses (0.3, 0.6 and 1.0 mg/kg) a significant (p<0.05) decrease in body weight was observed in both the earthworm species. Subsequently cocoon production and hatching success in dose 0.3 mg/kg decreased significantly (p<0.05) tending towards nil in doses 0.6 and 1.0 mg/kg. Mortality due to morphological alterations was 0.33% and 10% for Eudrilus eugeniae and Metaphire posthuma respectively in 1.0 mg/kg dose. The activity of AchE and GST are potential biomarker to assess toxicity levels. The inhibited activity of these enzymes in the applied doses followed an increasing pattern 0.3< 0.6< 1.0 mg/kg. Comet assay revealed a high DNA damage in both the earthworm species. These laboratory studies have revealed that effect of imidacloprid is species specific as well as dose and duration dependent leading to toxicity in earthworm physiology. Metaphire posthuma the indigenous species is more susceptible as compared to Eudrilus eugeniae leading to loss of soil fauna.ThesisItem Restricted Dissipation and persistence of indoxacarb and thiamethoxam in chilli(Punjab Agricultural University, Ludhiana, 2021) Harpreet Kaur; Sharma, SmritiSupervised field trials were conducted for two consecutive years to study the residues of indoxacarb and thiamethoxam in chilli, following two foliar applications of Indoxacarb 14.5 SC @ 55 and 110 g a.i. ha-1 and seed treatment of Thiamethoxam 30 FS @ 2.1 and 4.2 g a.i. ha-1. The chilli fruit samples were collected at different time intervals and were processed by following QuEChERS methodology and determination of indoxacarb and thiamethoxam residues were done by Gas Liquid Chromatography (GLC) and Gas Chromatography-Mass Spectrometry (GC-MS/MS). The average initial deposits of indoxacarbon green chilli fruits were found to be 2.75 and 5.93 mg kg-1 while 2.56 and 5.68 mg kg-1 respectively, in year 2019 and 2020, that reached below its limit of quantification (0.01 mg kg-1) after 25 and 35 days at single and double dose, respectively. The mean residues of thiamethoxam in seedlings, green chilli fruits and red chilli fruits were observed to be below its limit of quantification (0.05 mg kg-1). The half-life value of indoxacarb in green chilli was calculated to be 3.46-4.77 and 3.58-3.76 days while 3.85 and 4.93 days in soil, respectively at single and double the recommended dose. Household processing methods were studied for reduction of residues of indoxacarb in chilli and it was observed that boiling found most effective (71.27-78.75%) followed by acetic acid + washing (70.74-74.73%), followed by sodium chloride + washing (60.06-75.75%) and baking soda + washing (61.22-74.91%). Sun drying of red chilli fruits resulted in increase in the residues of indoxacarb by 1.58-2.10 folds and thiamethoxam residues by 2.62-2.83 folds.
