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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.

Background: Pigeonpea is a drought resistant legume crop, cultivated in semiarid tropical and subtropical regions of the world mainly for its protein enriched seeds. Insect pests are major biotic constraints implicating yield losses of staggering dimensions. Profenofos is being used for management of pigeonpea pod borer and studying the pattern of dissipation, residual occurrence and hazard index for consumption of pigeonpea grain contaminated with profenofos is very important. Methods: A simple, sensitive and reproducible method for analysis of profenofos in pigeonpea green pods and dry grain was standardized and validated using liquid chromatography tandem mass spectrometry (LC-MS/MS) with electro spray ionization (ESI+). Modified QuEChERS methods with 1 % ethyl acetate in acetonitrile involved in the extraction of profenofos residues from green pods and mature dry grains. Results: The limit of detection and limit of quantification (LOD and LOQ) were 0.002 and 0.006 µgg-1, respectively. The recovery ranges from 88.75 to 101.36 % for the green pods and 88.34 to 98.77 % for mature dry grains with relative standard deviation (RSD) was in the range of 0.99 to 4.05 %. The field study was conducted to investigate the dissipation kinetics of profenofos in pigeonpea. Two applications of profenofos 50 % EC at 500 and 1000 g a.i.ha-1 at 15 days intervals in pigeonpea at the time of pod formation recorded initial deposits of 20.28 and 41.64 ìgg-1 in the green pod, respectively. At15 days after application, residues gradually dissipated to the level of 0.78 and 1.98 µg g-1 accounting to the loss of 96.15 and 95.58 % at 500 and 1000 g a.i. ha-1, respectively. The half-life values were 5.18 and 5.93 days. Hazard index (HI) was found less than 1 at 25th and 35th day after application at 500 and 1000 g a. i. ha-1, respectively.

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