Contents
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Locust Outbreaks
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Locust Upsurge
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Locust plague
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Reason
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- If there is good rain and green vegetation develops, Desert Locusts can rapidly increase in number and within a month or two.
- It can lead to the formation of small groups or bands of wingless hoppers and small groups or swarms winged adults.
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- An ‘upsurge’ is formed when an outbreak or contemporaneous outbreaks are not controlled.
- If widespread or unusually heavy rains fall in adjacent areas, several successive seasons of breeding can occur that causes further hopper band and adult swarm formation.
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- The most serious category, a ‘plague’ can develop when an upsurge is not controlled and ecological conditions remain favorable for breeding.
- Locust populations continue to increase in number and size, and the majority of the infestations occur as bands and swarms.
- This does not happen overnight; instead, it takes at least one year or more for a plague to develop through a sequence that commences with one or more outbreaks and followed by an upsurge.
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Expanse
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- Such a situation is called an ‘outbreak’, and usually occurs with an area of about 5,000 sq. km (100 km by 50 km) in one part of a country.
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This is a more serious Desert Locust situation and generally affects an entire region.
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- A major plague exists when two or more regions are affected simultaneously.
- The area in which plagues occur covers about 29 million sq. km and can extend across 58 countries.
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FAO Warning
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- Before the outbreak stage, the FAO first issues ‘Desert Locust threats’ that are determined from an analysis of national survey and control data combined with remote sensing imagery and historical records.
- Such threats have been issued in 2012, 2013, and 2015.
- Not all threats develop into an outbreak.
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- In its latest update FAO said spring-bred locust swarms, which migrated to the Indo-Pakistan border and travelled east to northern states, are expected to return back to Rajasthan
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- There have been six major plagues in the 1900s, one of which lasted almost 13 years, the FAO website notes.
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