Bio-efficacy of various treatment schedules, viz T 1 (phorate + chlorpyriphos + imidacloprid + cartap hydrochloride), T 2 (imidacloprid + acephate + chlorpyriphos + cypermethrin), T 3 (phorate + chlorpyriphos + azadirachtin + Bacillus thuringiensis var. Kurstaki), T 4 (Bacillus thuringiensis var. Kurstaki + azadirachtin ), T 5 (phorate + imidacloprid + chlorpyriphos + cypermethrin), T 6 (phorate + azadirachtin + Bacillus thuringiensis var. Kurstaki) and T 7 (control) were evaluated against Agrotis ipsilon (Hufner) and mole cricket, Gryllotalpa africana, P.de. Beau. in single potato variety, Kufi Chandramukhi during rabi season of two potato-growing years in 2013-2014 and 2014-2015 from November to February. The percentage of plant (shoot) damage was found low in T 1 (5.82 -5.87%), than by T 3 (6.12 -6.49%), T 2 (6.86 -6.92%), T 5 (7.31 -7.62%), T 6 (8.21 -8.81%), T 4 (8.61 -9.32%) and T 7 (10.70 -11.13%) respectively. Similarly percentage of tuber damage of potato was noted highest in T 7 (34.29 -43.90 %) and it was lowest in T 2 (13.15-15.66 %). Maximum marketable yield (t/ha) of potato tubers was obtained in T 2 (26.28-26.80 t/ha), which was succeeded by T 1 (26.19 -26.92 t/ha) than other treatments and it was recorded minimum in control T 7 (11.17-12.69 t/ha). Maximum cost-benefit ratio (CBR) was recorded in T 5 (1:2.03 -1:2.04) while it was found minimum in T 6 (1:1.11 -1:1.17). Among the different treatment schedules T 5 and T 2 were most effective in increasing marketable yield of potato tubers and reduction of soil pest incidence over control T 7 and also over other treatments.

An experiment was conducted in the pre-kharif season during the months of January–June of the years 2018 and 2019 at farmer’s field at Benuria, Birbhum, in the lateritic zone of West Bengal, India. ‘Tejaswini’, a promising popular variety, was taken for the study. Four-week old plants were transplanted and plot size was 5.0×5.0 m2, in a Randomized Block Design with thirteen treatments, including control with three replications in both the seasons. Three consecutive sprayings were done at 30, 50 and 70 days after planting. The lowest population of thrips was observed in Broflanilid 20% SC @ 25 g a.i. ha-1 and it was statistically superior over Dinotefuran 20% SG @ 30 g a.i. ha-1, Profenofos 50% EC @ 500 g a.i. ha-1 and Azadirachtin 3% @ 15 g a.i. ha-1.While, non-significant differences in insect populations were recorded among Spinosad 45% SC @ 73 g a.i. ha-1, Fipronil 5% SC @ 50 g a.i. ha-1, Spirotetramat 15.31% OD @ 60 g a.i. ha-1, Tolfenpyrad 15% EC @ 150 g a.i. ha-1, Imidacloprid 17.80 % SL @ 25 g a.i. ha-1, Thiamethoxam 25% WG @ 25 g a.i. ha-1, λ-cyhalothrin 5% EC @ 15 g a.i. ha-1 and Difenthiuron 50% WP @ 300 g a.i. ha-1, respectively. The newer molecule, Broflanilid 20% SC @ 25 g a.i. ha-1 was found most efficacious against the chilli thrips among the treatments, and this molecule can be recommended to effectively manage the chilli thrips.

No abstract

Chilli var. Tejaswini was grown in three quadrates (5.0×6.0 m2) during pre-kharif season (January-June) of 2018 and 2019 at farmer’s field, Sriniketan, West Bengal, India to study the fluctuation of thrips population during the crop growing seasons under the influence of varying weather parameters. Population fluctuation of the thrips was recorded at weekly intervals starting from one week after transplanting till the last harvest. The insect first appeared on 6-8 leaves stages of the crop during both seasons and the population gradually reached to peak  at 14 MSW (10.95 thrips leaf-1) and 13 MSW (9.83 thrips leaf-1) during 1st and 2nd seasons, respectively. Correlation of thrips population with both previous and same meteorological standard week data showed different results. Significant negative correlation with relative humidity (r=-0.561*) but positive with sunshine hours (r=0.476*) recorded only during 2018 when correlations were studied with previous week weather data. Studies on multiple regression revealed that combined effect of weather parameters on the population build up of thrips had 26.0% (R2= 0.260) and 55.4% (R2=0.554) during 1st season while it was 40.6% (R2=0.406) and 18.9% (R2=0.189) during the 2nd season. Trend analysis revealed that during 1st season maximum and minimum temperatures around 35.0°C and 20°C found favourable for pest population build-up, while relative humidity (65% or higher), rainfall (6.0 mm), and bright sunshine (8 h) negatively affected the thrips population. A similar trend in insect population build-up was also recorded during the 2nd season.