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The persistence of cyantraniliprole, a new systemic insecticide of the class anthracitic diamide, was studied under the laboratory conditions in sandy loam soil and the soil amended with farmyard manure (0.5%), after spiking at 1, 2 and 4 ?g kg-1 levels in three different soil moisture regimes viz. air dry, field capacity level and also in saturated conditions. Degradation was comparatively faster in saturated than at field capacity and air dry condition. There was an increase in the persistence with increase in the spiking concentration. The persistence of cyantraniliprole was dependent on soil moisture condition, organic matter content and concentration of cyantraniliprole used.

A field experiment was conducted to study the rate of dissipation of thiamethoxam 25% WG in vegetable cowpea. Thiamethoxam 25%WG @ 0.24 ml l-1 was sprayed at pod formation stage, and samples of pods were harvested at 0 (2 hr after spray), 1, 3, 5, 7, 10, 15 days after spray. Residues were estimated using liquid chromatography tandem mass spectrometer (LC-MS/ MS) at the All-India Network Project on Pesticides Residues, College of Agriculture, Vellayani, Kerala. The mean initial residue was found to be 0.53 μg g-1, and residues were observed persisting up to three days and reached below quantification level on fifth day.

The study on dissipation and harvest time residues of pyrazosulfuron-ethyl 0.75% and pretilachlor 30% WG after foliar application at seedling stage in rice at two doses 2000 g/ha (15 + 600 g/ha) and 4000 g/ha (30.0 + 1200 g/ha) was conducted at Integrated Farming System Research Station, Kerala Agricultural University, Thiruvananthapuram, Kerala. The pyrazosulfuron-ethyl and pretilachlor residues were estimated using LCMS/MS. The mean initial deposit of pyrazosulfuron-ethyl at recommended and double the recommended doses were 0.18 and 0.48 mg/kg, respectively. The residue dissipated with time and reached below limit of quantification (LOQ) of 0.01 mg/kg after 5 days in the recommended dose and 7 days in double the recommended dose. The mean initial deposit of pretilachlor at recommended and double the recommended dose were 8.84 and 15.50 mg/kg, respectively. The residue dissipated with time and reached below LOQ of 0.05 mg/kg within 15 days both in the recommended and double the recommended dose. The half-life values (days) were 1.29 and 1.80 for pyrazosulfuron-ethyl and 1.88, 1.37 for pretilachlor at recommended and double the recommended doses, respectively. In addition, the harvest time residues of pyrazosulfuron-ethyl 0.75% + pretilachlor 30% WG were estimated in samples of rice grain, husk, straw and cropped soil and were found below LOQ.

Pot culture experiment was carried out under glass house condition to evaluate the resistance/tolerance of seven varieties of vegetable cowpea against Meloidogyne incognita. The variety Kadakkal local found as resistant with gall index 1 and all other varieties were highly susceptible to M. incognita. A field experiment was carried out to study the comparative effect of bio agents (Purpureocillium lilacinum and Stenotrophomonas maltophilia) and organic amendment (neem cake) in comparison with chemicals fluopyram and carbosulfan for the management of M. incognita in cowpea. All the treatments increased yield and reduced nematode population compared to untreated. Among the treatments, P. lilacinum cfu 2x106 @ 10 g/m2 in combination with neem cake @ 50 g/m2 and fluopyram 400 SC @ 250 g a.i./ha were statistically on par in increasing yield (53.70-54.63 %) and reducing nematode population in soil (93.03-94.27 %) and root (86.94-88.31 %).

Effect of four essential volatile oils viz., clove (Syzygium aromaticum L.), cinnamon (Cinnamomum zeylanicum Blume), lemon grass (Cymbopogon flexuosus (Nees ex steud)) and pepper (Piper nigrum L.) on mortality of rice weevil, Sitophilus oryzae L. in stored rice was studied under laboratory conditions. Preliminary toxicity bioassays (without food and with food) were carried for fixing the concentrations of these oils. Percentage mortality of weevils by volatile essential oils increased with increase in concentration and period of exposure. Pepper oil @ 200 μl/500 cm-3 volume caused cent per cent mortality without any progeny emergence whereas cinnamon oil @ 30 μl 500 cm-3 caused 95.55 per cent mortality of weevils with 98.81 inhibitions on progeny emergence. The highest concentration (30 μl 500 cm-3) of clove oil caused 76.67 percentage mortality of weevils while lemon grass oil (200 μl 500 cm-3) caused 68.89 percentage mortality.

The present study was undertaken to assess the insecticide resistance developed in various field collected population of S. litura and to induce susceptibility by using the synergists. Third-instar larvae collected from three different locations of Kerala viz., Thiruvananthapuram (TVM), Pathanamthitta (PTA) and Alappuzha (ALP) were exposed to conventional insecticides like chlorpyriphos, quinalphos, lambda-cyhalothrin and cypermethrin by leaf dip bioassay and resistance ratios were calculated by using the baseline data generated for respective insecticides using susceptible strain. Resistance ratios recorded were 1965, 840 and 320 against chlorpyriphos, 605, 255 and 59 against quinalphos, 926, 250 and 108 against lambda-cyahlothrin and 2566, 534 and 396 against cypermethrin respectively for TVM, PTA and ALP populations. The effect of selected synergists viz., piperonyl butoxide (PBO), diethyl maleate (DEM) and triphenyl phosphate (TPP) was studied in combination with respective test insecticides against the highly resistant population of S.litura collected from TVM of Kerala. The population was tested with insecticide in combination of the above synergists at different ratios. When PBO, TPP and DEM at ratio of 1:4 were used the synergistic ratio was 8.47, 7.26 and 3.98 for chlorpyriphos, 6.09, 5.26 and 3.05 for quinalphos, 13.37, 4.53 and 7.39 for lambda cyhalothrin and 4.77, 3.36 and 3.40 for cypermethrin respectively. PBO showed highest synergistic activity against both the organophosphates tested followed by DEM and TPP. Highest synergistic activity against synthetic pyrethroids also was shown by PBO, followed by TPP and DEM. The results obtained from the present study revealed that PBO at 1:4 ratio showed higher synergism with the test insecticides against the resistant populations of S.litura and proved to be an effective molecule alternate for breaking the resistance against conventional organophosphates and synthetic pyrethroids.

Adults of spiralling whitefly, Aleurodicus disperses (Hemiptera: Aleyrodidae) were collected from three different locations viz, field with no pesticide application (location I), field where insecticides were applied and control failure were also observed (location II) and field where insecticides were applied but with no known reports of control failure (location III). Three insecticides quinalphos 25% EC @ 250 g a.i ha−1, fenvalerate 20% EC @ 25 g a.i ha−1 and imidacloprid 17.8% SL @ 20 g a.i ha−1at seven different concentrations were selected to test the resistance/ susceptibility of the populations. Population collected from location-II showed resistance with resistance ratio of 2.60, 2.90 and 1.85 and population from location-III showed resistant ratio of 1.14, 1.62 and 1.28 against quinalphos, fenvalerate and imidacloprid respectively. The resistant population was effectively managed by new generation insecticides, thiamethoxam 12.6% + lambda cyhalothrin 9.5% ZC @ 33+ 15.75 g a.i ha−1, clothianidin 50% WDG @ 20 g a.i ha−1 and flonicamid 50% WG @ 75 g a.i ha−1at laboratory experiments. Higher mortality of whitefly was observed with thiamethoxam 12.6% +lambda cyhalothrin 9.5% ZC @ 33+15.75 g a.i ha−1 under field conditions.

The results of a study conducted to assess the degradation pattern and risk assessment of dinotefuran in chilli pepper and soil using LC-ESI-MS/MS are reported. A modified “QuEChERS” method for the extraction and clean up giving acceptable recovery value for all the three matrices was used. Residues in fresh chilli peppers reached below the limit of quantitation, (LOQ 0.01 mg kg-1) on 15th and 21st d of application of dinotefuran at 27.5 and 55 g a.i. ha−1 respectively whereas in dried chilli peppers, these reached below 0.01 mg kg−1 on the 21st and 25th d. The residues got magnified by 2.69 to 3.00 times during sun drying of fresh chilli peppers, necessitating detailed study on its dynamics during different processing steps. Half-live of dinotefuran at the standard and double doses were 2.1 and 2.4 d for fresh chilli peppers, and 2.3 and 2.6 d respectively in the dried chilli peppers. The corresponding calculated waiting periods were 1.34 and 3.45 d for fresh chilli peppers. The residue in soil reached below the LOQ on the 10th d, registering a half-life of 1.86 and 1.43 d at the standard and the double doses respectively. The risk assessment showed that the the theoretical maximum residue contribution (TMRC) in fresh chilli peppers on 0 d were 3.024 and 5.739 μg person−1 d−1 at the standard and the double doses respectively. The residues present in the food were considered safe since the TMRC value was lower than the maximum permissible intake (MPI). Therefore, the dinotefuran applied at the standard and the double doses in chilli pepper did not pose any risk to humans, even on the day of its application. It can be incorporated as one of the insecticides in integrated management of pest complex in chilli under the humid climatic conditions.

Dissipation behaviour of the chloronicotinyl insecticide, imidacloprid (Tatamida 17.8 % SL), in fresh and cured cardamom capsules was studied following application at doses 20 and 40 g a.i. ha(-1) in a cardamom plantation of Indian Cardamom Hills (ICH), Idukki, Kerala, India. A single-laboratory ultra performance liquid chromatography mass spectrometry (UPLC-MS/MS) method was developed and validated for the estimation of imidacloprid and its six metabolites (5-hydroxy, olefin, guanidine, urea, 6-chloronicotinic acid and nitrosimine) in fresh and cured cardamom. At the lower dose, the initial deposits of total imidacloprid residues were 1.91 and 7.23 μg g(-1), respectively, in fresh and cured cardamom. At the higher dose, the initial residues were 3.94 and 14.72 μg g(-1), respectively, in fresh and cured capsules. The residues dissipated below the quantitation level of 0.01 μg g(-1) after 21 and 28 days at lower dose and after 28 days for both at higher dose. The half-lives of imidacloprid in fresh and cured cardamom were 4.02 and 3.63 days, respectively, at lower dose and 3.61 days for both at higher dose. The waiting periods of imidacloprid on fresh and cured cardamom at lower and higher doses were 21.40, 27.10, 23.85 and 30.70 days, respectively. The mean processing factor of imidacloprid was 3.96 at 20 g a.i. ha(-1). Amongst metabolites of imidacloprid, urea had maximum residues in fresh and cured cardamom followed by 5-hydroxy and guanidine. Other metabolites such as 6-chloronicotinic acid, olefin and nitrosimine were not detected either in fresh or cured cardamom.

The persistence of organophosphorus insecticides chlorpyriphos and profenophos @ 300 and 500 g a.i. ha−1 in cabbage following two foliar applications at 15 d interval during the head formation stage, is reported. Samples collected at 0 (2h), 1, 3, 5, 7, 10 and 15 d after the last (second) spray were extracted by QuEChERS method and residues estimated by gas liquid chromatography equipped with flame photometric detector (FPD). The mean initial deposits of chlorpyriphos and profenophos were 1.52 and 1.02 μg g−1 respectively which dissipated with time and reached below the quantitation level of 0.05 μg g−1 within 15 d with half-life values of 1.91 and 2.01 d, respectively. The Limit of detection (LOD) and limit of quantitation (LOQ) of the two insecticides in cabbage were 0.01 and 0.05 μg g−1, respectively.

A single laboratory UPLC-MS/MS method was developed and validated for the estimation of fipronil and its metabolites in fresh and dry chilli pepper fruits. Dissipation of fipronil on chilli fruits was studied following the application of fipronil (Jump 80 WG) at 40 and 80 g active ingredient (a.i.) ha(-1) in the fruiting stage of the crop. The initial deposits of total fipronil on fresh chilli fruits at single and double dose application were 0.69 and 1.43 μg g(-1), respectively, and were dissipated to below quantitation level at 27 days after application. The half-life of fipronil at single and double dose in fresh chilli pepper was 4.22 and 4.32 days and the waiting period was 25.9 and 30.6 days, respectively. Processing factor due to sun drying was calculated by measuring fipronil residues in dry chilli fruits, and it ranged from 2.96 to 3.50 during 0 to 21st day after application. Among the metabolites of fipronil, fipronil desulfenyl and fipronil sulfone had maximum residues in fresh and dried chilli, respectively, followed by fipronil sulfide. Dipping in solutions of tamarind, turmeric, vinegar and slaked lime and wet scrubbing could remove more than 90% of fipronil residues in fruits.

Studies on the management of resistant populations of Maruca vitrata (F.) revealed that 100% mortality was recorded in the population treated with spinosad 75 g a.i. ha−1, emamectin benzoate 10 g a.i. ha−1 and indoxacarb + acetamiprid 100 g a.i. ha−1 after 12 h of treatment under laboratory trial. No significant difference was observed in the mortality when treated with chemicals like chlorantraniliprole 30 g a.i. ha−1, indoxacarb 60 g a.i. ha−1, flubendiamide 100 g a.i. ha−1 and acephate + imidacloprid 518 g a.i. ha−1 which showed a per cent mortality of 93.33 per cent each and less mortality was recorded in population sprayed with chlorpyriphos 600 g a.i.ha−1 (20%) and novaluron 100 g a.i. ha−1 (33.33%) after 24 h of treatment under laboratory trial.