**Abstract**

Invasive alien species (IAS) is an exotic species that becomes established in natural or seminatural ecosystems or habitats. It is an agent of change and threatens native biological diversity. Invasive insects in India have been a major threat to household commodities, human health, agricultural produce and environment. India is highly diversified in its weather and climate, which supports the establishment of various introduced insects from other parts of the world. Furthermore, globalisation has facilitated numerous introductions of invasive insect pests. There have been 23 invasive alien insects reported from India to date. This chapter exclusively deals with the characteristics of insects that make them invasive, the common pathways of entry of the invasive insects, the steps through which the introduced insect has established itself in the foreign land and finally the ways to manage them.

**Keywords:** India, invasive, insects, biological control

### **1. Introduction**

India is the seventh largest country in the world with a total area expanse of 3.2 million square kilometres (appox.) [1]. It measures 3214 km from north to south and 2933 km from east to west. India is the largest peninsula, whose three parts are covered with water, *viz.* the Arabian Sea in the west, the Bay of Bengal in the east and the Indian Ocean at the south. India, being such a huge landscape, bears various climatic conditions, soils and vegetations all around the country. This makes India one of the richest diversities in the world. The country has 15 agro-climatic zones comprising of mountains, plateaus, deserts, river, lakes, oceans and grasslands [2]. Apart from that 21.54% of the total area is covered by dense forests [3]. Hence, the complex topography, diversified climate and vegetation make India one of the favourite venues for alien species invasion. Furthermore, India being one of the fastest-growing economies has contributed an export of \$330.07 billion in 2014 to as many as 190 countries in the world. On the other hand, the import statistics reveal an importation of \$462.9 billion from around 140 countries around the world. This excessive trade among nations has made India an opportunistic target for the entry of the alien species [4].

Biological invasion can be well regarded as a biological pollution which causes maximum losses to the biodiversity [5]. Invasive species are threats to agricultural biodiversity as well as human and animal health. These species are non-native

or exotic species which have great power of dispersal and adaptation. They are introduced unintentionally into a new area where they get a favourable climate increase in number and establish. Furthermore, the new area will be devoid of its natural enemy which unleashes the invasive species' growth without any limitation. According to the International Union for Conservation of Nature (IUCN), an invasive alien species (IAS) is an exotic species which becomes established in natural or seminatural ecosystems or habitats, is an agent of change and threatens native biological diversity. India has harboured a total of 173 invasive species including 47 invasive species of agricultural ecosystem, out of which 23 are insects [6].
