**2. Pathways of invasion**

Pathways are the predicted routes helping the invasive species in transit to new environments. There is a long history regarding the classification of these pathways. The most common pathways include the sea, land or air. There have been several examples of entry of various species through these pathways into India. For example, cashew which is considered as one of the most important cash crops of India was introduced in the sixteenth century by the early Portuguese purposefully realising its importance, through their sea voyages [7]. Today, due to globalisation, the frequency of invasion and its consequences has increased exponentially. Some of the species were knowingly transported to a new ecosystem, while some are a matter of ignorance.

i.**Introduced as contaminants.** The trade of logs is considered to be one of the most profitable businesses. It provides a huge foreign exchange, but it comes with the consequence of introduction of alien species also. Being stored in godowns for a long period without any treatment makes these logs store house of many insects and pathogens. The importation of these logs also transmits their residing alien species [8].

There has been an importation of various food products and seeds to India from foreign countries. In the past when there was a lenient legal restriction for importation of food products, an admixture of contaminants in the food lot have been proven to be detrimental to the importing country. For example, the importation of food grains from the USA under the US PL 480 scheme (a food assistance programme of the US government to India) also brought *Parthenium hysterophorus* along with it [9].


**51**

*Invasive Insects in India*

• Food trade [15, 16]

with passengers.

• Very resilient

• Short life cycle

• Broad host range

• High fecundity

**4. Steps in invasion**

• Voracious feeders

• Benefits from mutualist interaction

• High dispersal ability

*DOI: http://dx.doi.org/10.5772/intechopen.91986*

• Accidental introduction of insects or other organisms [12]

• Cargo shipments by air, land and water [13, 14]

• Infested fruits or vegetables carried by tourists [17]

• Ability to withstand many environmental conditions

introduction, establishment, spread and naturalisation [18].

**3. Characteristics of an invasive species**

• Unintentional transit of alien species from one place to another

There has been enhanced domestic conveyance with enriched networks of railways, highways, airways and harbours which further facilitate the easy spread of the introduced insects all over the country mostly by unintentional transit along

The process of invasion of an alien species follows certain sequential steps, *viz.*

i.**Introduction.** In order to become a habitant of a new locality, beyond the natural ranges, the insect must have to first move or get itself moved from its current habitat. This movement of the insect is called as passive transport which is brought about by vectors. The most common vectors nowadays are humans or human consignments. Passive transports of these invasive species are very common and are difficult to control. Even after strong quarantine inspections, it is difficult to detect the cryptic early stages of the insect which might be transported through the tourists. The transportation of a single gravid female insect also has the ability to create havoc in the introduced environment since it is a prolific breeder and lacks its natural enemy. One of the most common examples


*Invasive Species - Introduction Pathways, Economic Impact, and Possible Management Options*

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

Pathways are the predicted routes helping the invasive species in transit to new environments. There is a long history regarding the classification of these pathways. The most common pathways include the sea, land or air. There have been several examples of entry of various species through these pathways into India. For example, cashew which is considered as one of the most important cash crops of India was introduced in the sixteenth century by the early Portuguese purposefully realising its importance, through their sea voyages [7]. Today, due to globalisation, the frequency of invasion and its consequences has increased exponentially. Some of the species were knowingly transported to a new ecosystem, while some are a

i.**Introduced as contaminants.** The trade of logs is considered to be one of the most profitable businesses. It provides a huge foreign exchange, but it comes with the consequence of introduction of alien species also. Being stored in godowns for a long period without any treatment makes these logs store house of many insects and pathogens. The importation of these logs also

There has been an importation of various food products and seeds to India from foreign countries. In the past when there was a lenient legal restriction for importation of food products, an admixture of contaminants in the food lot have been proven to be detrimental to the importing country. For example, the importation of food grains from the USA under the US PL 480 scheme (a food assistance programme of the US government to India) also brought *Parthenium hysterophorus*

ii.**Living industry pathway.** Living industry implies the trade of living organisms including landscaping or horticultural crops, agriculture, aquaculture/aquarium, pet trade and live seafood trade. There is every possibility that these living entities escort their respective pests while being exported. For example, Apple woolly aphids have been predicted to enter India through the importation of apple rootstock from England [10].

iii.**Transportation related.** India being rich in its cultural heritage attracts numerous tourists every year. The foreign tourist arrival rate has increased from 2.54 million per annum in 2001 to 10.56 million per annum in 2018 [11]. The increase in number of tourists has increased the chances of inva-

transmits their residing alien species [8].

sion by the following ways:

**50**

insects [6].

**2. Pathways of invasion**

matter of ignorance.

along with it [9].

• Infested fruits or vegetables carried by tourists [17]

There has been enhanced domestic conveyance with enriched networks of railways, highways, airways and harbours which further facilitate the easy spread of the introduced insects all over the country mostly by unintentional transit along with passengers.
