**1. Introduction**

Climate change is a worldwide threat that is unavoidable and immediate which encompasses a combination of natural and anthropogenic changes in the environment. Worldwide attention has been attracted by recent changes in global climate phenomena and consequent losses. Climate change, according to the Intergovernmental Panel on Climate Change (IPCC), is described as "any change in climate over time, whether due to natural variability or as a result of human activity". Human activities are responsible for much of the warming that has been observed over the last 50 years. From 1990 to 2100, the global mean surface

temperature is expected to rise by 1.4 to 5.8°C. In the next 100 years, if temperatures increase by around 2°C, the detrimental global warming effects will begin to spread in much of the world's region [1]. In addition, CO2 levels rose from 280 ppm to 401 ppm in 2015 (Mauna Loa Observatory: Hawaii).

Insects constitute over half of the estimated 1.5 million organism species of the biodiversity identified so far on the planet and are fundamental to the structure and function of ecosystems. Insects are among the most susceptible groups of organisms to climate change as they are ectothermic, so thermal changes have strong direct effect upon their growth, reproduction and existence [2]. The effects of climate change on insect pests are of greater significance because insects are involved in many biotic interactions, such as plants, natural enemies, pollinators and other organisms, which play a major role in the ecological functioning of insect pests [3]. The impact of climate change on arthropod extinction rates is 100 to 1000 times greater than what has occurred previously, with about 45 to 275 species becoming extinct on a daily basis. An increase in a temperature rise of 6°C would result in the mass extinction of species, including humans. For example, due to hot temperatures (like heat waves) related to climate change, have resulted in a decrease in bumblebee populations by 46 per cent in North America and by 17 per cent across Europe compared to the base period of 1901 to 1974. In India Basavarajappa S, has observed a 2 per cent decline in rock bee, *Apis dorsata* colonies every year in Mysore due to increase in temperature, altering its local climate.

Climate change and extreme weather events affect insects and plants, and the direct effect of anthropogenic climate change has been recorded on every continent, in every ocean and in the majority of major taxonomic groups. In the modern era, plants are habitually vulnerable to new environmental factors *i.e.,* solar radiation, high temperatures, rise in CO2 levels and shifts in pattern of rainfall over the seasons, as a result of natural cycles and anthropogenic activities and their impact on the global environment. Because of the close relationship between insects and host plants, through the changes undergone by their host plants, insect herbivores are likely to experience direct and indirect consequences of climate change. Global climatic changes are also expected to influence interactions between insects and plants in many ways. They may directly affect insects through changes in physiology, behaviour and life history parameters, as well as indirectly through changes in their own life history experienced by host plants.
