**4.3 Impact of climate change on invasive insect species**

Climate change is altering important aspects of the environment such as temperature and precipitation, the occurrence of extreme weather events, as well as air composition and land cover. The main factors driving the survival of organisms are temperature, atmospheric CO2 concentration and available nutrients. It is most likely that changes in these variables might stress the ecosystems and facilitate the chances of invasions. According to the Convention on Biological Diversity (CBD) invasive alien species are considered to be the greatest threat to biodiversity loss worldwide and by altering their geographical structure, function and diversity, inflicts high costs on agriculture, forestry and aquatic ecosystems. Climate change imposes direct effects on insect physiology and their behaviour and indirectly effect through biotic interactions. The introduction, establishment, distribution, impact and changes in the effectiveness of mitigation strategies of invasive insect species are expected to be the significant drivers of anthropogenic and global climate change. Global warming is expected to increase the ecological consequences such as new pests introduction, by changing phenological events such as flowering times mainly in plants of temperate species as many tropical plants can tolerate the phenological changes. The key issue favouring the introduction of insect susceptible cultivars or crops is the invasion of new insect-pests. For example, during 2018 and 2019, fall armyworm, *Spodoptera frugiperda* which is a recent invasive insect from Africa has spread to several countries like India, Thailand, Myanmar, China, Republic of Korea, Japan, Philippines, Indonesia and Australia. The relationship between temperature and the rate of development primarily affects its biology, distribution and abundance. As insect development occurs within a defined temperature range, a change in temperature will consequently affect the developmental rate, life-cycle duration and finally affects the survival. Rise in ambient temperature to near the thermal optimum of insects causes an increase in their metabolism and activity.

From the end of 2019 to early 2020, a desert locust (*Schistocerca gregaria*) outbreak has posed a significant risk to food security and livelihoods across many East African nations. Changes in climate such as increasing temperatures and precipitation over desert areas, and heavy winds combined with tropical cyclones can provide a new environment for reproduction, growth and migration of pest. This means that global warming played a role in establishing the conditions needed for the growth, outbreak and survival of the locust. Oceans absorb around 90 per cent of anthropogenic heat [53] and in the western part of the Indian Ocean in the tropical Ocean system, the most rapid warming occurs with a summer average rise of 1.2°C [54]. In neighbouring areas, this warming has increased the frequency and intensity of extreme climate events and thus favoured the movement of locust plague to various countries like Pakistan, India etc.
