Planococcus kenyae (LePelley) -- Pseudococcidae
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The coffee mealybug attacking coffee in Kenya, was originally identified as the citrus mealybug, Pseudococcus citri (Risso) and later Pseudococcus lilacinus Ckll. Biological control efforts against it were, thus, misdirected against these hosts (DeBach 1974). This mealybug was first noticed in Kenya when a severe infestation on coffee occurred in the Thika district in 1923. First it was thought to be a native insect but its rapid spread to other nearby districts and ultimately further coupled with its lack of any important parasitoids made it evident that it was introduced. It soon became one of the notable mealybug problems of the world. Coffee was the principal cash crop attacked but severe damage was done to food plants in native gardens and to ornamentals as well. In fact, the cultivation of yams was halted due to the mealybug and other cropping practices had to be modified (DeBach 1974). The property of thousands of small native landowners was severely affected, and it was estimated that the financial loss on coffee alone, including cost of control, from 1923-1939, was between 1-1.5 million pounds sterling or about 4-7 million U.S. dollars. During the early period in 1925 when the pest was thought to be the citrus mealybug, a parasitoid of that mealybug, Leptomastidea abnormis (Girault), was sent from Sicily to Kenya. Although no parasitoids survived the trip it is doubtful if they would have attacked the target host in Kenya (DeBach 1974).
Another parasitoid, Leptomastix dactylopii, of the citrus mealybug was received later in large numbers from the University of California at Riverside, but it would not successfully reproduce on the coffee mealybug. Later when the mealybug was considered to be Pseudococcus lilacinus, other natural enemies were sought, not only from other mealybug species but especially from P. lilacinus. A major effort was made by Dr. R. H. LePelley to obtain parasitoids of P. lilacinus in the Orient, its presumed native home, and to import and colonize these in Kenya. During 1936-7 he explored many countries and, particularly from the Philippine Islands and Java, successfully shipped large numbers of parasitoids and predators to A. R. Melville in Kenya. But none of the parasitoids obtained attacked the coffee mealybug in Kenya. Some of the predators were cultured and liberated but none are known to have become established.
It became evident during LePelley's trip that the coffee mealybug was sa species distinct from P. lilacinus and since must of the world had been searched most probably was native to Africa somewhere outside of Kenya. Mr. Harold Compere was then exploring for black scale parasitoids in Africa for the University of California in 1937, when he visited Melville in Nairobi while LePelley was still abroad. Compere recalled that he had seen the coffee mealybug in Uganda and told Melville that it was rare there (DeBach 1974). Following LePelley's return from the Orient, staff became available for searching in Uganda and this time A. R. Melville did the exploring with LePelley in charge of receiving, quarantine, culture and colonization aspect. Melville went to Uganda early in 1938 and quickly found the mealybug and sent parasitoids to Nairobi. LePelley successfully cultured 9 species of primary parasitoids, destroying several hyperparasitoids in the shipments. Due to a lack of insectary space, the five most promising parasitoids were emphasized and the other four dropped, with the idea that they could be reacquired if necessary. However, such never proved to be the case. A species of Anagyrus nr. kivuensis was colonized in June 1938 and during September-December, 1938, 15,000 more parasitoids were liberated. From 1939-1941 about an additional 200,000 were liberated each year and the whole of the mealybug infested area was colonized.
Of the five colonized species, three were established, but one, Anagyrus sp. nr. kivuensis Compere is credited with the outstanding results that occurred. According to LePelley it possessed all the chief attributes of an outstanding parasitoid: vigorous, hardy, adaptable, mates readily, excellent searcher. It appeared capable of maintaining itself on very low and scattered mealybug infestations. The establishment of the parasitoids rapidly reduced the population of mealybugs. By 1941 losses in coffee plantations were reduced by 92% and became less and less over the years (also see Kirkpatrick 1927, Anderson 1930, 1931, 1932; James 1929, 1930, 1933; Wilkinson 1929, 1935, 1936; LePelley & Melville 1939a,b; LePelley 1937, 1943a,b, 1959; Melville 1938, 1946; Heinrich 1965).
REFERENCES: [Additional references may be found at: MELVYL Library ]
Anderson, T. J. 1930. Annual report of the senior entomologist. Kenya Dept. Agric. Ann. Rept. 1929: 433-63.
Anderson, T. J. 1931. Annual report of the senior entomologist. Kenya Dept. Agric. Ann. Rept. 1930: 190-205.
Anderson, T. J. 1932. Entomological section annual report. Kenya Dept. Agric. Ann. Rept. 1931: 99-117.
DeBach, P. 1974. Biological Control by Natural Enemies. Cambridge University Press, London & New York. 323 p.
Heinrich, W. O. 1965. Some aspects of biological control of coffee diseases. Diologico 31: 57-62.
James, H. C. 1929. Biological control in Kenya colony with special reference to the problem of the common coffee mealybug, Pseudococcus lilacinus Ckll. Kenya Dept. Agric. Bull. 7E. 5 p.
James, H. C. 1930. Methods for the biological control of the common coffee mealybug. Kenya Dept. Agric. 16 p.
James, H. C. 1933. Taxonomic notes on the coffee mealybugs of Kenya Colony. Bull. Ent. Res. 24: 429.
Kirkpatrick, T. W. 1927. Biological control of insect pests, with particular reference to the control of the common coffee mealy bug in Kenya Colony. South and East Africa Agric. Conf. Proc. 1926: 184-96.
LePelley, R. H. 1937. Entomological work on coffee mealybug investigations. Dr. Le Pelley's report on work in the Orient. Kenya Dept. Agric. Ann. Rept. 1937: 46-101.
LePelley, R. H. 1943a. The biological control of a mealybug on coffee and other crops in Kenya. Emp. J. Expt. Agric. 11(42): 78-88.
LePelley, R. H. 1943b. The establishment of a new species of Anagyrus in Kenya. Bull. Ent. Res. 34: 131-33.
LePelley, R. H. 1959. Agricultural Insects of East Africa. East Africa High Comm., Kenya. 307 p.
LePelley, R. H. & A. R. Melville. 1939a. Entomological work on coffee. Kenya Dept. Agr. Rept. (1937)2: 46-54.
LePelley, R. H. & A. R. Melville. 1939b. Entomological work on coffee. Kenya Dept. Agr. Rept. (1938) 2: 34-41.
Melville, A. R. 1938. Kenya coffee mealybug research. East African Agric. J. 3: 411-22.
Melville, A. R. 1946. Report of the Entomologist. Kenya Dept. Agr. Ann. Rept. 1945: 51-54.
Wilkinson, H. 1929. Annual report of the entomologist, 1928. Kenya Dept. Agric. Ann. REpt. 1928: 172-86.
Wilkinson, H. 1935. Progress report on coffee mealybug. Coffee Board Kenya Monthly Bull. 1: 13, 16.
Wilkinson, H. 1936. Report of the entomological section. Kenya Dept. Agric. Rept. 1935: 60-70.