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Migration OF INSECTS

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A Collection of slides how insects migration effects agriculture and environment

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Migration OF INSECTS

  1. 1. Migratio n in insects Praveen Kumar CCSHAU, HISAR
  2. 2.  Involves displacement of entire populations  Displacement from breeding, feeding and overwintering sites  Individuals displaced hundreds of kilometers  Regular feature of seasonal cycle for some insects  The word "migration" is referred to movements of animals in a direction and for a distance over which they have control, and which result in a temporary or permanent change of habitat. (Williams, 1957) Migration
  3. 3. Flight boundary layer A layer of air at an altitude where wind speed remain below the flight speed of insects A. Migration within the boundary layer Insects are capable of self direction Insects engage in continuous wing flapping and active forward motion Eg: Butterflies, Dragonflies (Srygley and Dudley, USA, 2008)
  4. 4. B. Migration above the boundary layer Daytime migration Smaller insects are carried upward beyond the limits of their boundary layers by thermals rising from ground Insect may not be in control of flight Transported by wind Eg: Aphids
  5. 5. Migration at night No radiation thus no thermals Insects depend on their own activity to carry them upward. Take off in large numbers soon after sunset Eg. Grasshopper ( Aiolopus), locust (Schistocerca)
  6. 6. Control of migratory behaviour  In Oncopeltus flight behaviour is stimulated by intermediate level of JH  JH increases more quickly in insects exposed to long day lengths than short day.  At low JH concentration flight behaviour increases  At high JH concentration oogenesis occurs and flight behavior come to end (Rankin,2004)(Rankin, 1978)
  7. 7. The fall migration flyways of monarch butterflies in eastern North America revealed by citizen scientists From Canada and the United States to Mexico (Elizabeth Howard & Andrew K. Davis, USA, 2008)
  8. 8.  In summer, found in Southern Canada and United States  Southward movement- Gulf of Mexico– July to October (peak in September)  On the way roosting in trees, clustering on cold night and remaining until temperature rise above 13°C  In warmer part- free flying and breeding occur  But in colder (Florida and California)- roosting in dense colonies in trees  In Feb. and March – Temp. rises and return movement to North
  9. 9. Distribution of Danaus plexippus in North America
  10. 10. The monarch, Danaus plexippus, a spectacular insect migrant. Monarchs at their winter roost in central Mexico. Roosts
  11. 11. Numbers of monarch roost observations from Journey North Participants from 2005 to 2007, grouped by week
  12. 12. From India to Mozambique, the insect world’s greatest migrant  Dragonfly, Pantala flavescens  Dragonfly moves Southwards by way of the Maldives every year for breeding.  Swarms starts with beginning of NEM in Maldives.  The numbers peaked in November and December.  Dragonflies returned to India through Maldives in the April due to SWM (Charles Anderson, Britain, 1983)
  13. 13. Dragonfly migration from India to Africa (Anderson,1983)
  14. 14. Locust  Locusta migratoria - Europe, Africa, India, Pakistan, Australia  Schistocerca gregaria - Northern Africa and India  Locustana paradalina and Nomadacris septemfasciata - Southern Africa  Patanga succineta - India , Sri lanka, Malaysia
  15. 15. Schistocerca gregaria North central Africa to Middle East, Arabia and India 20 km2 swarm = 1billion locusts 30 million sq. km area in 64 countries 2,05,785 sq. km area in India
  16. 16.  The desert locust inhabit the dry areas of Northern Africa.  Downwind movement of swarm  Spring breeding is synchronized with the arrival of the cyclonic rains in Meditarrnean area and local seasonal rains in Red Sea and East African regions  Summer breeding associated with rains at the Inter-Tropical Convergence Zone (ITCZ).  Migration occur for breeding and food.
  17. 17. Types of swarm Stratiform swarm : Flat Flying within few meters of the ground level Locusts are highly concentrated with densities 1-10/m3 Formed in absence of temperature gradient Cool, overcast weather favours Cumuliform swarm: Towering Towering 1000m above the ground Locusts are widely dispersed with densities 0.001-0.1/m3 Formed in presence of temperature gradient Convective updrafts on hot afternoons promote
  18. 18. Years Loss in rupees 1926-31 10 crore 1940-46 2 crore 1949-55 2 crore 1959-62 50 lakh 1978 2 lakh 1993 7.18 lakh Losses due to locusts in India Dte. of plant protection, quarantine and storage, Faridabad
  19. 19. Migration of insects in India
  20. 20. Phenology of Migration and Decline in Colony Numbers and Crop Hosts of Giant Honeybee (Apis dorsata ) in Semiarid Environment of Northwest India  Migration of honeybee- survey at three year interval from 1984 to 2012.  Presence of honeybee nests at main campus buildings and trees.  Immigration in postrainy season - October - Peak flowering on Pigeonpea  Foraging- Nov. - Dec. Toria Dec. - Feb. Chickpea Feb. - March Barseem March- May Sunflower Ram Chander Sihag, Hisar, 2014
  21. 21. Emigration - May to Mid July “Why” emigration? a) High temp. in summer (43-48°C) b) Non availability of bee forage Advantage of migration:  Act as pollinator of more than 30 crop plants
  22. 22. Annual migratory and colony decline patterns
  23. 23. Bidirectional movement of butterflies at South Eastern plains of India  A ten meter wide imaginary strip for quantification of butterfly at the way of swarm  Number of butterflies passing through strip over a 15 minutes duration counted  Migratory species: Catopsilia pyranthe Catopsilia pomona Papilio demoleus (Ramesh et al., Kalpakkam, 2012) Towards North Towards South
  24. 24. Bidirectional movement:  Towards North -during October due to NEM -the swarm flew across the wind Towards South -during July due to SWM -the swarm not only flew across the wind but also flew against it. -wind opposing movement reduce migration (density) of butterflies.
  25. 25. “Why” migration?  Avoidance of excessive rain due to NEM and SWM  To avoid competition at site of emergence  To utilize availability of larval host plant resources at destination site
  26. 26. Long distance migration of aphids and other small insects in Northeast India  Aerial netting at height of 150 m. during November  Yellow pan traps placed at ground level  Movement of aphids from plains to hills in spring on southwesterly winds  From hills to plains in Autumn (Oct.-Nov.) on northeasterly winds (Riley,1995) Riley at el., UK, 1995
  27. 27. Flight paths for aphids migrating over aerial netting site at Haringhata
  28. 28. Mean aerial densities( no. per 104 m3 ) of aphids caught in aerial net between 14 to 23 November 1992
  29. 29. Yellow pan trap catch
  30. 30. Losses due to aphids:  Direct losses due to L.erysimi 20-50%  Spreading viruses (chilli mosaic virus by Aphis gossypii) and mycoplasma (sesame phyllody by Orosius albicinctus ) “Why” migration?  To avoid high temp. of plains  To avoid winter temp. of upland area
  31. 31. Migration of butterfly in the reserve forest of Nilgiri Biosphere Reserve  Counts were made by surveyor for one minute at 20 minutes interval standing 5m away from path of butterfly migration.  The orientation of flight was from North-East to South- West along banks of the river Karimpuzha  Maximum density at 1200-1300 hr.  Highest abundance during hottest period (Mathew and Binoy, Kerala, 2002)
  32. 32. Periodicity of migrant butterfly 160
  33. 33. Species: 1) Appias albina darada 2) A. wardii 3) A. indra shiva 4) Cepora nadiana remba 5) Graphium sarpedon teredon “Why” migration? Depletion of host plant due to population outbreak Availability of larval and adult food resources (Drypetes and Polyalthia longifolia) at migratory site
  34. 34. Remote sensing technology
  35. 35. Advantages of RADAR  To detect insects simultaneously at a range of altitudes that can reach more than 1 km AGL  The large sampling volume  Insects are unaffected by flying through the radar beam  Gives information such as the size, shape, displacement direction and body alignment of each insect target  Continuous and autonomous monitoring of pest migrations(Beerwinkle et al, 1995)  Monitoring high-altitude insect migration (Chapman et al., 2002)
  36. 36. Vertical Looking RADAR The Rothamsted Radar Entomology Unit (RREU) United Kingdom
  37. 37. Significance of migration  Seasonal climate change makes habitat unsuitable  In North temperate regions the winter is unfavourable period, while in tropics dry season unfavourable for insects  Migration enables a species to face changes in the location of its habitats  Exchange of genetic pool takes place  Increases the range of species
  38. 38. Conclusion  Migration is of primary remarkable feature of insects to overcome adverse climatic conditions  Migration also occur due to unavailability of food sources  Migration is regulated by hormones  Migratory patterns of insects helps us to know the weak links in the life cycle and helps in control  Detailed observations are required to clearly understand the cause of migration in insects.
  39. 39. References  Howard, E. and Davis, A. K. (2008). The fall migration flyways of monarch butterflies in eastern North America revealed by citizen scientists, J Insect Conserv. 147:170–174  Riley, J.R., Reynolds, D.R., Mukhopadhyay, S., Ghosh, M.R. and Sarkar, T.K. (1995). Long distance migration of aphids and other small insects in northeast India. Eur.J. Entomol. 92:639-653  Sihag, R.C. ( 2014). Phenology of Migration and Decline in Colony Numbers and Crop Hosts of Giant Honeybee (Apis dorsata ) in Semiarid Environment of Northwest India. Journal of Insects. 20:368- 377.  Chapman, R.F. (1988). The insects: structure and function. Edward Arnold (Publishers) Ltd, London.  Johnson, C.G. (1969). Migration and dispersal of Insects by Flight. Methuen and Co. Ltd, England.