Tiwari, RuchiraRawat, Divya2019-01-092019-01-092018-05http://krishikosh.egranth.ac.in/handle/1/5810089529The field studies were conducted on the biodiversity of insect pests of wheat crop, screening of wheat genotypes and efficacy of some newer insecticides against wheat aphids and their natural enemies during rabi crop seasons 2015-16 and 2016-17 at NEBCRC, G B Pant University of Agriculture and Technology, Pantnagar, Uttarakhand. The present field studies clearly indicated that there was incidence of several important insect pests such as wheat aphids, armyworm, pink borer, termites, gram pod borer on wheat at Pantnagar area during 2016-17. The natural enemies perpetuated on the insect pests of wheat cropping system were some predators viz., Coccinella, Chrysoperla, Syrphid flies and Parasitoids. On the other hand, out of 50 genotypes screened against wheat aphids, 12 genotypes appeared to be promising and may be used in breeding programme and the development of host-plant resistance in wheat crop against wheat aphids. It was evident from the present study that the plots treated with foliar spray of neonicotinoids (Imidacloprid and Thiamethoxam) were proved the most effective against wheat aphids as their population (pooled data 2015-16 and 2016-17) was recorded significantly lowest in plots treated with Imidacloprid 17.8 SL (2.17 aphids/shoot/plant) followed by Thiamethoxam 25 WG (2.69 aphids/shoot/plant) as compared to synthetic insecticides i.e., Dimethoate 30 EC (3.11 aphids/shoot/plant) and Oxy-demeton Methyl 25 EC (3.79 aphids/shoot/plant) which was significantly less than untreated control (13.39 aphids/shoot/plant). The population of coccinellids (15 days after spray) both grubs (0.57/m2), adults (0.45/m2) and Chrysoperla larvae (0.33/m2) were recorded highest in Imidacloprid 17.8SL followed by Thiamethoxam 25 WG with coccinellids both grubs (0.26/m2), adults (0.20/m2)and Chysoperla larvae (0.30/m2) while population of natural enemies was significantly reduced in Dimethoate 30 EC with coccinellids both grubs (0.13/m2)and adults (0.10/m2) and Chrysoperla larvae (0.10/m2) and Oxydemeton Methyl 25 EC with coccinellids both grubs (0.05/m2) and adults (0.02/m2) and Chrysoperla larvae (0.05/m2) as compared to untreated control with coccinellids both grubs (1.16/m2) and adults (0.94/m2) and Chrysoperla larvae (0.55/m2). Similarly, the pooled data worked out for average grain yield of wheat for rabi crop seasons, 2015-16 and 2016-17 revealed that the highest grain yield (34.61 q/ha) was obtained from plots treated with Imidacloprid 17.8 SL followed by Thiamethoxam 25 WG (32.14 q/ha) which was significantly higher in comparison to Dimethoate 30 EC (29.74 q/ha) and Oxy-demeton Methyl 25 EC (28.03 q/ha) whereas, the average yield obtained from untreated control was 20.24 q/ha. It has been clearly seen that there was a significant decrease in the population of wheat aphids and natural enemies in insecticide treated plots as compared to untreated control, however, it was revealed that mean number of coccinellids and chrysopids were significantly more in plots treated with neonicotinoids (Imidacloprid and Thiamethoxam) as compared to plots treated with other insecticides. Thus, newer insecticides i.e. Imidacloprid 17.8SL @125ml/ha and Thiamethoxam 25WG @ 50ml/ha, appeared to be the most effective insecticides against the wheat aphids and caused least harm to natural enemies and gave more grain yields. This clearly demonstrated the use of host-plant resistance and comparatively safer insecticides for the management of aphids in wheat and can ultimately be a good alternative over conventional insecticides and can easily be incorporated in IPM program for wheat aphids by reducing the total load on synthetic pesticides.ennullThesis