Perkinsiella saccharicida Kirkaldy -- Hemiptera, Delphacidae
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Dr. R. C. L. Perkins discovered sugarcane leafhopper in the Hawaiian Islands in 1900. By 1903 there was a significant drop in the total yield of sugar after this pest had spread to all the islands of the area. The Hawaiian Sugar Planters Association created a Division of Entomology to employ entomologists on a full time basis in 1904. Dr. Perkins was appointed superintendent with a staff comprised of O. H. Swezey, G. W. Kirkaldy, F. W. Terry, Alexander Craw and Albert Koebele, all of whom proved preeminent in the field of biological control (DeBach 1974).
It was determined by Kirkaldy that closely allied species of leafhopper occurred in Java, and Perkins found leafhoppers on sugarcane cuttings just arrived from Queensland, Australia. He determined by correspondence and the exchange of specimens that the same P. saccharicida occurred in Cairns, Queensland, but did no noticeable damage there, leading to a simple clue as to where to obtain effective natural enemies. Perkins and Koebele sailed for Queensland on May 11, 1904, and upon arrival in Brisbane and Bundaberg, they immediately found the sugarcane leafhopper and a number of parasitoids attacking it. Koebele discovered the egg parasitoid, Paranagrus optabilis Perkins which played a dominant role in the early reduction of leafhopper in Hawaii. It was generally distributed in Queensland and several shipments were made to Hawaii, but the slow transport by ship caused the specimens to die or become weakened. Nevertheless, Terry on Oahu obtained a few direct colonization of parasitoids in August, October and November 1904. Later Perkins stocked a breeding cage in Australia, which arrived in Hawaii on December 14, 1904. The few parasitoids that survived the journey were either kept for breeding purposes or liberated directly in the field. At the close of 1905 this parasitoid, Panagrus optabilis was recovered in the field, and it became widespread and abundant in 1906-1907, followed by a significant reduction in leafhopper densities. At the same time, a closely related species, Anagrus frequens Perkins, was found to be established, presumably from the late 1904 releases made by Terry, but it was judged to be of small importance. Another species, Ootetrastichus beatus Perkins was discovered in Fiji by Koebele during his return voyage from Australia. This parasitoid became rapidly established and spread throughout Hawaii, but never assumed a prominent role there.
A Dr. Frederick Muir was then hired to do additional foreign collections, due to the failing health of Albert Koebele. In March 1906, Muir collected the parasitoid Haplogonatopus vitiensis Perkins in Fiji, which became established in Hawaii but did not add appreciably to the control level. In China at Mei Chow he found Pseudogonatopus hospes Perkins, which after much difficulty he was able to ship living specimens to Hawaii in December 1906 and early 1907. This parasitoid became established and did add to the biological control level in Hawaii. In 1907-1916 Muir explored throughout the Malay archipelago, The Philippines, New Guinea, Formosa and Japan for several Hawaiian projects, but continued to focus his attention on sugarcane leafhopper. In Formosa during February 1916 he discovered another egg parasitoid, Ootetrastichus formosanus Timberlake, which he transported to Hawaii. A culture was established and later field colonization added still more to the level of biological control. Although the activities of five parasitoid species in Hawaii produced excellent biological control on most sugar plantations, there were sporadic outbreaks of leafhopper in some areas, especially where heavy rainfall occurred throughout the year.
It was obvious by 1919 that in the wetter areas such as Hilo, the leafhopper remained a constant problem. It was concluded that additional natural enemies should be sought which could perform under very wet conditions. Therefore, in May 1919 Muir went to Queensland, Australia for more detailed field studies. He discovered Cyrtorhinus mundulus (Bredd), which is a highly effective predator of leafhopper eggs. This predator had been regarded as a phytophagous species prior to Muir's research. Previously, Koebele and Perkins, as well as Muir and others, had previously overlooked this predator principally because it belongs to the family Miridae in which most of the species are phytophagous (DeBach 1974).
The discovery of the predator came only after a very thorough scientific investigation, and is detailed by Muir (1931) as follows: "In 1919 I went to Australia to make further investigations of the habits of a small carabid beetle which I had noted previously preying on Perkinsiella, but owing to the very exceptionally dry season these beetles were so scarce I could make no progress with this work, so turned my attention to other phases of the question. It soon came to my notice that a very large percentage of Perkinsiella eggs were dead and attacked by a fungus, a fact that Perkins noted in 1903-4. I found the fungus in the form of yeast-like spores present in old egg shells from which the young had hatched, which could be recognized by the egg cap being off, and also in unhatched eggs, which in itself was intriguing. In moist cells these spores gave rise to mycelia and then to fruiting bodies and yeast-like spores similar to the original ones. Further investigation showed that these spores were present in all young and adult leafhoppers in the body cavity, where thy multiplied by division; that they passed through the walls of the ovarian tubes and entered the young eggs, congregating in a small round ball at one end of the egg, and eventually becoming mostly incorporated into the embryo. As these were universal, it then became evident that the fungus could not be the cause of the dead eggs, as otherwise all could be destroyed. Upon killing the egg by pricking, the spores developed. This led to observations in the field to discover what led to the death of the egg. The fact was then revealed the Cyrtorhinus mundulus pierced the egg and sucked it. In some cases the egg was sucked nearly dry, in others the egg was only pierced and very little sucked, but it led to the death of the egg and to the development of the fungus. Thus the fungus is symbiotic and passes from adult to embryo and is always present. Whether the leafhopper can be reinfected by spores developed outside is not known. It is highly probable that the spores play some part in the metabolism of the insect, as similar bodies are found in all species of Delphacidae and many other Homoptera."
In June 1920 Muir returned with a cage of living Cyrtorhinus mundulus and following careful studies to eliminate any possible dependency on sugarcane leaves, but required leafhopper eggs for food, liberations were made in July. Dr. J. G. Myers, who was in charge of the test for phytophagous habits, hesitated considerably before recommending liberations of the predator in Hawaii. Once approved, additional predator material was obtained from Fiji, and following establishment in Hawaii the sugarcane leafhopper became an insignificant pest.
For further details on biological control effort and biologies of host and natural enemies, please also see the following (Perkins 1903, 1905-06; Pemberton 1919, 1920; Swezey 1919, 1936, Muir 1920, Timberlake 1927, Verma 1955, Williams 1958, Clausen 1978).
REFERENCES: [Additional references may be found at: MELVYL Library ]
Clausen, C. P. 1978. Delphacidae. In: C. P. Clausen (ed.), Introduced Parasites and Predators of Arthropod Pests and Weeds. U. S. Dept. Agric., Agric. Handbk. No. 480. 545 p.
DeBach, P. 1974. Biological Control by Natural Enemies. Cambridge Univ. Press, London & New York. 323 p.
Muir, F. 1920. Report of entomological work in Australia, 1919-1920. Hawaiian Planters Rec. 23: 125-30.
Muir, F. 1931. Introduction in: The Insects and Other Invertebrates of Hawaiian Sugar Cane Fields. Francis X. Williams. Expt. Sta. Hawaiian Sugar Planters Assoc. 400 p.
Pemberton, C. E. 1919. Leafhopper investigations in Hawaii. Hawaii. Planters' Rec. 21: 194-221.
Pemberton, C. E. 1920. Insecticide sprays: their relation to the control of leafhoppers by parasites. Hawaii. Planters' Rec. 22: 293-95.
Pemberton, C. E. 1948. History of the Entomology Department Experiment Station. HSPA 1904-45. Hawaiian Planters Record 52(1): 53-90.
Perkins, R. C. L. 1903. The leaf-hopper of the sugar cane. Hawaii Bd. Commrs. Agric. & Forestry Div. Ent. Bull. 1. 38 p.
Perkins, R. C. L. 1905-06. Leaf-hoppers and their natural enemies. Hawaii. Sugar Planters' Assoc. Expt. Sta., Div. Ent. Bull. I, Pts. 1-4, 6, 8 & 10.
Swezey, O. H. 1919. Notes on the Chinese dryinid parasite of the sugarcane leafhopper. Hawaii. Planters' Rec. 20: 239-42.
Swezey, O. H. 1936. Biological control of the sugar cane leafhopper in Hawaii. Hawaii. Planters' Rec. 40: 57-101. (Reprinted as Hawaii. Sugar Planters' Assoc. Expt. Sta., Ent. Ser. Bull. 21).
Timberlake, P. H. 1927. Biological control of insect pests in the Hawaiian Islands. Hawaii. Ent. Soc. Proc. 4: 529-56.
Verma, J. S. 1955. Biological studies to explain the failure of Cyrtorhinus mundulus (Breddin) as an egg-predator of Peregrinus maidis (Ashmead) in Hawaii. Hawaii. Ent. Soc. Proc. 15: 623-34.
Williams, J. R. 1958. Cane pests. Mauritius Sugar Indus. Res. Inst. Rept. 1957: 66-71.