George Salt

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Not to be confused with .

[1]

George Salt FRS (12 December 1903, Loughborough, Leicestershire – 17 February 2003, Cambridge, UK) was an English entomologist and ecologist.[2] He was elected a Fellow of the Royal Society in 1956.[3]

Biography[]

Born as the oldest brother of three siblings,[4] George Salt in April 1911 moved with his family to Calgary in Alberta, Canada. When he was nine years old he began delivering newspapers after school, continued this employment through his high school years, and consistently contributed his earnings to the family income. He enjoyed outdoor activities with his two younger brothers and, when he was nine years old, began collecting the Lepidoptera of Alberta. He did his secondary school study at Calgary's Crescent Heights Collegiate Institute. George and his three siblings graduated from the University of Alberta. He paid his own university expenses by vacation work.[2]

In autumn 1924 he matriculated as a graduate student at Harvard University, where he studied under the famous entomologist William Morton Wheeler. For his doctoral dissertation George Salt investigated the parasitism by wasps belonging to the genus Stylops, specifically the effects of such parasitism on the secondary sexual characteristics, viscera, and behaviour of bees in the genus Andrena.[2][5] He had two interludes during his graduate study at Harvard. After completing his first term, he worked in Cuba at the Harvard Biological Station, where he did research on sugarcane borers and ant mimicry.[2] Two years later he was employed as an entomologist by the United Fruit Company to investigate ways of controlling the banana pests Colaspis hypochlora (a leaf beetle) and Castniomera atymnius humboldti (a moth) in Colombia. A survey of the damage caused by C. hypochlora showed that poorly drained areas were centres of the beetle infestation; study of its larval stages showed that carabao grass (Paspalum conjugatum) is an important food source for C. hypochlora. Improved drainage and carefully planned weeding resulted in partial eradication of the grass and considerable reduction in the damage caused by the beetle.[2][6]

He returned to England in 1928 when William R. Thompson, the director of the Imperial Institute of Entomology, offered him the senior post under the directorship to do research at the institute's laboratory at Farnham Royal, Buckinghamshire. The goal of the research was biocontrol of agricultural pests by using parasites of the pests. In order to control western Canadian infestations by wheat stem sawflies belonging to the species Cephus cinctus, George Salt identified and studied nine primary parasites of Cephus pygmaeus.[2]

... in 1931 he moved to Cambridge to become a research student again, this time under the supervision of James (later Sir James) Gray FRS in the Zoology Department. He now began the work that, with interruptions and diversions, he pursued for over 40 years. In essence his objectives were to examine, experimentally and quantitatively, the biological basis of the control of insect pests by means of parasites.
The first problem he investigated was that of superparasitism—the attacking of a host that was already parasitized. Some had assumed that parasitoids distributed their progeny at random, without regard to previous parasitization. His own work at Farnham Royal had led George to doubt that assumption ... He now proved that the tiny wasp Trichogramma evanescent, which lays its eggs in the eggs of other insects, could distinguish between healthy hosts and those already parasitized, and that the female tended to avoid laying her eggs in a parasitized host ... The ability to avoid superparasitism has since been observed in many other species, but this first and convincing demonstration abruptly altered the course of thinking about the interactions of parasitoids and their hosts.[2]

At King's College, Cambridge, George Salt was elected in 1933 to a Fellowship. In the zoology department of the University of Cambridge, he was University Lecturer from 1937 to 1965 and the Reader in Animal Ecology from 1965 to 1971, when he retired as Emeritus.[3] In 1939 he married Joyce Laing. They had two sons, Michael (born 1943) and Peter (born 1947).[7] During WW II George Salt did research on biocontrol of wire worms which threatened Britain's cereal crops.[2] This research led to the development of the Salt-Hollick soil washing machine.[7][8] He spent the academic year 1948–1949 on sabbatical in East Africa, where he used the Salt-Hollick machine to study soil ecology.[7] As a skilled amateur Alpine mountaineer, he made an extensive collection of insects at high altitude and "did ecological work in six mountainous regions: Kilimanjaro, Mt Kenya, the Ruwenzori, the Aberdares, both North and South Usambaras, and Mt Lemagrut near the Ngorongoro crater." On Mount Kilimanjaro he discovered eight new genera and over 60 new species.[2]

In 1953 he began work that developed into the investigations of the defence reactions of insects to parasitism, using the conveniently large ichneumon wasp Nemeritis canescens as the parasitoid. He described the reaction to Nemeritis of insects representing eight Orders. These exploratory studies showed that living Nemeritis were encapsulated by blood cells and that encapsulation could cause the death of the parasitoid ... The blood cells of the host adhered to the parasitoid after contact. ...
This research programme culminated in a long paper in which George brought together all the information he could find in the literature of entomology, helminthology and histology bearing on the reactions of insects to metazoan parasites ... He set out the primary observations for inspection and critically examined the various reactions that had been described. From this survey he concluded that the only primary defence reaction made by insects against metazoan parasites is that made by their blood cells. This paper attracted the attention of many parasitologists.[2]

For the academic year 1958–1959 he was on sabbatical. During six months of his sabbatical, he did research in West Pakistan on biocontrol of cotton pests.[2] There he focused especially on Rogas testaceus, a wasp species parasitizing the spotted bollworm.[9]

In 1970 George Salt published a monograph Cellular Defence Reactions of Insects,[10] which described experimental analyses of the mechanisms by which some insects disable their parasites.[3] The monograph, written as part of a series intended for biologists who were not overly specialized, introduced George Salt's research to a wider audience.[7]

In 1986 Roderick C. Fisher published a paper on George Salt's influence on the development of experimental insect parasitology.[7][11]

In retirement, George Salt did much excellent work in calligraphy and water coulor painting.[7] He gave his papers to King's College, Cambridge in 1998 and 2001.[12]

Selected publications[]

  • Salt, George; Myers, John Golding (1926). I. Report on Sugar-cane Borers at Soledad, Cuba. Harvard University Press.
  • Salt, George (1931). "Parasites of the Wheat-stem Sawfly, Cephus pygmaeus, Linnaeus, in England". Bulletin of Entomological Research. 22 (4): 479–545. doi:10.1017/S0007485300035355. ISSN 0007-4853.
  • Salt, George (1934). "Experimental studies in insect parasitism. II.―Superparasitism". Proceedings of the Royal Society of London. Series B, Containing Papers of a Biological Character. 114 (790): 455–476. Bibcode:1934RSPSB.114..455S. doi:10.1098/rspb.1934.0019.
  • Salt, George (1935). "Experimental studies in insect parasitism III—host selection". Proceedings of the Royal Society of London. Series B - Biological Sciences. 117 (805): 413–435. Bibcode:1935RSPSB.117..413S. doi:10.1098/rspb.1935.0037.
  • Salt, George (1937). "The sense used by Trichogramma to distinguish between parasitized and unparasitized hosts". Proceedings of the Royal Society of London. Series B - Biological Sciences. 122 (826): 57–75. Bibcode:1937RSPSB.122...57S. doi:10.1098/rspb.1937.0010.
  • Salt, George (1938). "Experimental Studies in Insect Parasitism. VI.—Host Suitability". Bulletin of Entomological Research. 29 (3): 223–246. doi:10.1017/S0007485300035574.
  • Salt, George (1940). "Experimental Studies in Insect Parasitism. VII. The Effects of different Hosts on the Parasite Trichogramma evanescent Westw.(Hym. Chalicidoidea.)". Proceedings of the Royal Entomological Society of London. 15 (10–12): 81–95. doi:10.1111/j.1365-3032.1940.tb00575.x.
  • Salt, George; Hollick, F. S. J. (1944). "Studies of wireworm populations". Annals of Applied Biology. 31: 52–64. doi:10.1111/j.1744-7348.1944.tb06208.x.
  • Salt, George (1963). "The defence reactions of insects to metazoan parasites". Parasitology. 53 (3–4): 527–642. doi:10.1017/S0031182000073960. PMID 14080003. 1963
  • Salt, George (1968). "The Resistance of Insect Parasitoids to the Defence Reactions of Their Hosts". Biological Reviews. 43 (2): 200–232. doi:10.1111/j.1469-185X.1968.tb00959.x. PMID 4869949. S2CID 21251615. 1968

References[]

  1. ^ Jones, Stephanie L. (2005). "In Memoriam: George William Salt, 1919–1999". The Auk. 122: 354. doi:10.1642/0004-8038(2005)122[0354:IMGWS]2.0.CO;2. ISSN 0004-8038.
  2. ^ Jump up to: a b c d e f g h i j k Bateson, Patrick (2003). "George Salt. 12 December 1903 — 17 February 2003". Biographical Memoirs of Fellows of the Royal Society. 49: 447–459. doi:10.1098/rsbm.2003.0026. S2CID 85628029. (On p. 449 the phrase "Elected FRS 1965" contains a typographical error and should be "Elected FRS 1956".)
  3. ^ Jump up to: a b c Bateson, Patrick (4 March 2003). "Obituary. George Salt: Entomologist specialising in parasites". The Independent.
  4. ^ George Salt's sister Mary Cecilia Salt was born in 1907.
    The youngest brother Reginald Wilson Salt (1910–2009) became a professional entomologist, working at the Lethbridge Research and Development Centre, AAFC. "Reginald Wilson Salt". McInnis & Holloway Funeral Homes. 2009.
    The other brother Walter Raymond Salt (1905–1996) became a professor of anatomy at the University of Alberta and published extensively on Alberta birds. "W. Ray Salt (1905–1996)" (PDF). North American Bird Bander. 21 (4): 177. 1996.
  5. ^ Salt, George (1927). "The effects of stylopization on aculeate hymenoptera". Journal of Experimental Zoology. 48: 223–331. doi:10.1002/jez.1400480107.
  6. ^ Salt, George (1928). "A Study of Colaspis hypochlora, Lefèvre". Bulletin of Entomological Research. 19 (3): 295–308. doi:10.1017/S0007485300020630.
  7. ^ Jump up to: a b c d e f Friday, Adrian (17 June 2021). "George Salt: entomologist and ecologist". Department of Zoology, University of Cambridge.
  8. ^ Wilcocks, C.R.; Oliver, E.H.A. (1971). "A rapid mechanical method for extracting soil arthropods". New Zealand Journal of Agricultural Research. 14 (3): 725–734. doi:10.1080/00288233.1971.10421666.
  9. ^ "The fate of a braconid parasite, Rogas testaceus, in four species of hosts". Biologia (Lahore). 5: 84–95. 1959.
  10. ^ Salt, George (2 October 1970). The Cellular Defence Reactions of Insects. Cambridge Monographs in Experimental Biology, Volume 16. Cambridge University Press.
  11. ^ Fisher, R.C. (1986). "George Salt and the development of experimental insect parasitology". Journal of Insect Physiology. 32 (4): 249–253. doi:10.1016/0022-1910(86)90035-1.
  12. ^ "The Papers of George Salt, Reference: GBR/0272/GS". The National Archives (nationalarchives.gov.uk).
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