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Rice is best known as a staple food for half of the world's population. Brown planthopper, Nilaparvata lugens (Stål) (Hemiptera: Delphacidae) is a serious insect pest of rice crops throughout Asia. In case of a severe attack, the whole crop turns brown called 'hopperburn' and farmers face great yield losses. The experiments were performed to evaluate the planting geometry and nutritional effects on N. lugens abundance and yield attributes of the crop using susceptible rice (var. Basmati 515). Results indicated that planting geometries with more space (60 and 90 cm) after 12 lines with a uniform number of plants in each plot had less incidence of N. lugens as compared to narrow spaced (0 and 30 cm) geometries. More number of N. lugens nymphs (80.0-95.0 number/plant) were recorded with less spaced planting geometry as compared to higher spaced planting geometry (27.0-29.5 numbers/plant) during both years. With different planting geometry, no significant difference was recorded in the agronomic parameters except yield and 1000 grain weight. The highest yield was recorded in a plot with 90 cm path followed by 60, 30 and 0cm path, respectively. Towards different doses of nitrogen and phosphorus on N. lugens, the higher dose of nitrogen had a significant effect on N. lugens nymph survival, adult emergence and survival, while the phosphorus induced a non-significant effect. Therefore, in the absence of N. lugens resistant variety, ecological manipulation and nutrients availability could be a better strategy for shortterm N. lugens management in organic rice production. [ABSTRACT FROM AUTHOR]

Contemporary non-target effects of conventional synthetic insecticides necessitate evaluating biorational insecticides owing differential chemistry and modes of action than the conventional ones. This laboratory study comparatively evaluated some selected differential chemistry insecticides against some destructive and economically important insect pests i.e. mango mealybug (Drosicha mangiferae Green), mango leafhopper (Idioscopus clypealis Lethierry), Asian citrus psyllid (Diaphorina citri Kuwayama) and subterranean termites (Odontotermes obesus Rambur). Standard twig- and filter paper-dip bioassay methods were used against sap-feeding pests and termites, respectively. Factorial analyses of variance revealed a significant impact of tested insecticidal formulations and exposure time on the mortality all insect pest individuals. The most effective differential chemistry insecticides against mango leafhopper, citrus psyllids, mango mealybugs and subterranean termites were nitenpyram, clothianidin, thiamethoxam and imidacloprid (causing 74-79% cumulative corrected mortality), thiamethoxam, imidacloprid, clothianidin and spirotetramat (causing 78-85% cumulative mortality), spirotetramat, acetamiprid and thiamethoxam (causing 68-90% cumulative mortality), and chlorantraniliprole, pyriproxyfen and chlorfenapyr (causing 80-85% cumulative mortality), respectively. Overall study findings suggest these above mentioned non-conventional insecticides to be incorporated in the biorational management of these insect pests. [ABSTRACT FROM AUTHOR]