Tillage can alter the soil habitats wherein many insect pests and their natural enemies reside during at least part of their life cycle. To enhance crop productivity and reduce climate change effects, conservation agriculture (CA) with reduced-tillage or no-tillage practices have been advocated to farmers. However, information relating to the effect of CA on insect pests and their natural enemies is very scarce, at least in the Indo-Gangetic region. In this study, the effect of tillage on the abundance of, and damage by, major insect pests (foliar aphids, root aphids, termites, and pink stem borer) and their natural enemies in wheat managed under three tillage practices, i.e., zero-till (ZT), reduced tillage (RT), and conventional tillage (CT) with (protected) and without (unprotected) insecticide protection scenarios, was investigated. Foliar aphid and termite numbers were lowest in the ZT-protected system, and highest in the CT-unprotected system. Pink stem borer damage was significantly higher in the ZT-unprotected system, whereas the root aphid number was maximum in the RT-unprotected system. The natural enemies of these four major insect pests of wheat showed variable trends under the studied tillage systems. The abundance and damage of these major insect pests showed a positive correlation with the normalized difference vegetative index (NDVI) and canopy temperature. The dynamics of the insect pests and their predators were driven by soil habitat-related changes (direct) as well as crop growth-related effects (indirect). A fine-tuning of insect-pest management tactics based on these relations would enhance the success of CA systems.

Wheat (Triticum aestivum L.) is a major crop with largest area under cultivation in India and plays a significant role in economic stability of the country. Many insect pests attack wheat in India, severe damage is caused by aphids as serious pest of wheat crop which cause yield losses either directly (35-40%) by sucking the sap of the plants or indirectly (20-80%) by transmitting viral and fungal diseases. They can multiply very rapidly under favourable conditions on leaves, stems and inflorescence. The infestation causes severe distortion of leaves and inflorescence and can significantly decrease the yield through direct feeding. The production of chlorophyll (green colour) is prevented by the attack of aphid resulting in curling of leaves and delayed head emergence causing improper maturity of grains. The aphid incidence level differed in different cultivars of wheat. The resistance of crop is an index of the balance that exists between the preference of the pest for crop and its antibiosis against it. The mechanical barriers possessed by the plants which prevented insects from feeding or ovipositing on them. The infestation significantly affected the root dry weight, number and height of tillers and number of spikes per head. Leaf epicutticular wax, ultra structure and leaf trichome were different on susceptible wheat cultivar and resistant cultivar. Leaf trichome density and position may act as a physical obstracle to the Russian wheat aphid feeding. An increased amount of glutamic acid, glutamine, alpha amino butyric acid, phenylalanine and proline and less methionine, produce resistance in wheat plants against aphids. Hydroxamic acids (Hx) have been shown to be a major biochemical mechanism of resistance of wheat to aphids, acting through antibiosis and feeding deterrency.

In India, more than 85% of the total potato production is realised from the subtropical Indo-Gangetic plains where potato is cultivated during winter. The cotton whitefly, B. tabaci is a major pest of potato as it transmits the Tomato leaf curl New Delhi virus (potato) causing the Apical leaf curl disease which leads to huge yield losses. The population dynamics of cotton whitefly was studied at 12 locations across the northern plains of India from 2015–17. It was observed that the cotton whitefly appears on potato immediately after crop emergence. The whitefly adults exhibited four different patterns of population dynamics at different locations. Whiteflies remained on the potato crop as long as minimum daily temperature was above 10–12ºC after which the whiteflies either disappeared from the crops or their flight activity was considerably reduced as indicted by the yellow sticky trap catch data. The whitefly incidence was higher at locations where potato is preceded by crops preferred by whitefly such as cotton, broad beans, groundnut etc. Perusal of the data on number of eggs laid and ensuing nymphs per plant indicated that the contribution of immigrating adults to the whitefly population is much higher than that of the colonising population for major part of the crop period. Thus, in addition to temperature, cropping sequence acts as a major factor in shaping the pattern of whitefly infestation. The results will help in deciding cropping pattern and better timing of insecticidal applications for healthy seed potato production.

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Field experiments were conducted during Rabi 2012-13 to 2014-15 at Agricultural Research Station, Niphad, Maharashtra, India to determine the efficacy of promising insecticides used for seed treatment for the management of wheat pests. The insecticides