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Pseudococcus citriculus Green -- Pseudococcidae





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This mealybug was first noticed in August 1938 in Israel when a severe outbreak occurred in some citrus groves on the coastal plain.  In 1938 the infestation was spreading rapidly and by 1939 became catastrophic (DeBach 1976).  At a meeting called by the citrus industry in May 1939 the opinion was expressed that the intensity of damage caused and apparent rapidity of spread threatened to annihilate the citrus industry.  At this meeting it was agreed that spraying experiments should be carried out but that major stress should be on biological control by importation of parasitoids from other countries (DeBach 1976).


Insecticides and oil sprays failed to control the mealybug.  Although Israel Cohen <PHOTO>, Director of biological control insectaries in Israel, was not trained as an entomologist, he had studied agriculture at the University of California during the period when another very serious mealybug pest, Pseudococcus fragilis has been completely controlled there by introduced parasitoids, and he was convinced that their hope in Israel lay in a similar direction (DeBach 1976).  He sent samples of their new mealybug to various experts who identified it erroneously as P. comstocki.  He then wrote to various entomologists to ascertain where parasitoids of this Comstock mealybug might be obtained.  Japan was suggested as the native home but certain parasitoids were also known to be present in the eastern United States where P. comstocki had become established.  About this time Dr. I. Carmon, the citriculturist of the Experiment Station at Rehovot, Israel was about to journey to the United States.  Cohen suggested that he route his return trip via Japan and search for parasitoids there.  Cohen raised funds to cover the extra cost and contracted USDA and University of California entomologists to help and advise Dr. Carmon. 


Carmon then collected and sent parasitoids of P. comstocki to Israel in two airmail shipments in December 1939.  DeBach (1976) stated that this apparently represents the first lengthy intercontinental transport of natural enemies by air.  Additionally, Carmon personally returned by boat in 1940 with many pupae of the various Japanese parasitoids of P comstocki.  Meanwhile, Cohen had a special temporary laboratory/insectary constructed and invited Dr. E. Rivnay to direct it.


Dr. Rivnay sorted out the various primary parasitoids and hyperparasitoids received from Japan and determined that Clausenia purpurea Ishii was the most effective.  The hyperparasitoids were eliminated.  Clausenia purpurea was cultured and 100 specimens colonized under a tent on one tree in April 1940.  It became established immediately and spread rapidly.  Mass production was started later in 1940 so as to distribute the parasitoid.  Trees which received 25 parasitoids in 1940 showed marked decreases in the mealybug infestation by August 1941, and in a short time control was complete and has remained so ever since (DeBach 1976).


One of the most interesting parts of this story, as related by DeBach (1976) was that the pest was later found to be P. citriculus rather than P. comstocki.  This was learned because a Japanese parasitoid, Alloptropa burrelli Muesebeck, which had been established on P. comstocki in the United States would not develop in the presumed P. comstocki in Israel, thereby indicating the Israeli mealybug to be a different species.  Therefore, the pest was controlled with a mixture of skill and luck by a parasitoid of another mealybug species.  DeBach (1976) states that this illustrates very strikingly the point that effective natural enemies may sometimes be obtained where least expected, and it also shows that personal initiative as well as support by government and industry of a biological control effort is of prime importance.  Neither Cohen nor Carmon were entomologists, yet between them they collaborated to import a parasitoid responsible for one of the world's great biological control successes (Rivnay 1968).  Also please refer to the following references for notations  on citriculus mealybug (Goncalves 1940, Klein & Perzelan 1940, Rivnay 1942, 1946; Rivnay & Perzelan 1943, Mason 1943, Haeussler & Clancy 1944, Bodenheimer 1951, Murakami et al. 1967, Rosen 1967).



REFERENCES:          [Additional references may be found at:   MELVYL Library ]


Bodenheimer, F. S.  1951.  Citrus Entomology in the Middle East.  Junk Publ, The Hague.  663 p.


DeBach, P.  1976.  Biological Control by Natural Enemies.  Cambridge University Press, London & New York.  323 p.


Goncalves, C. R.  1940.  Observacoes sobre Pseudococcus comstocki (Kuw. 1902) atacando citrus no baixada fluminense.  Rodriguesia 4:  179-98.  [in Portuguese].


Haeussler, G. J. & D. W. Clancy.  1944.  Natural enemies of Comstock mealybug in the Eastern States.  J. Econ. Ent. 37:  503-09.


Klein, H. Z. & J. Perzelan.  1940.  A contribution to the study of Pseudococcus comstocki in Palestine.  Hadar 13:  107-110.


Murakami, Y., R. Morimoto & H. Kajita.  1967.  Possibilities of biological control of Pseudococcus comstocki in Japan.  Mushi 39:  85-96.


Rivnay, E.  1942.  Clausenia purpurea Ishii, a parasite of Pseudococcus comstocki Kiuw.  Introduced into Palestine.  Bull. Soc. Fouad Ier Ent. 26:  1-19.


Rivnay, E.  1943.  A study of the efficiency of Sympherobus amicus Navas in controlling Pseudococcus citri Risso on citrus in Palestine.  Bull. Soc. Fouad Ier Ent. 27:  57-77.


Rivnay, E.  1946.  The status of Clausenia purpurea Ishii and its competition with other parasites of Pseudococcus comstocki Kuw. in Palestine.  Bull. Soc. Fouad Ier Ent. 30:  11-19.


Rivnay, E.  1968.  Biological control of pests in Israel.  Israel J. Ent. 3(1):  1-156.


Rivnay, E. & J. Perzelan.  1943.  Insects associated with Pseudococcus spp. (Homoptera) in Palestine, with notes on their biology and economic status.  J. Ecn. Soc. South Africa 6:  9-28.


Rosen, D.  1967.  Biological and integrated control of citrus pests in Israel.  J. Econ. Ent. 60:  1422-27.