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EUCALYPTUS SNOUT BEETLE

Gonipterus scutellatus Gyllenhal -- Coleoptera, Curculionidae

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Serious problems developed with the eucalyptus snout beetle in many African countries when Eucalyptus spp. plantings were expanded (Tooke 1955). The weevil arrived in South Africa from Australia on planting stock before 1916, and subsequently spread into Zimbabwe, Malawi and in the 1940's and later it was found in Kenya, Mauritius, Madagascar and St. Helena (Waters et al. 1976).

Biological control began in Australia in 1926 with the discovery of an egg parasitoid, which was shipped to Cape Town and Pretoria, South Africa (Tooke 1955). The parasitoid, Patasson nitens (Girault), was reared at Pretoria and released that year at Johannesburg. A total of 620,000 P. nitens were released in all major infested areas in South Africa by 1931. Damage fell below economic levels in all areas by 1935 except the High Veld, where climatic conditions apparently hampered the reproduction of the parasitoid to consistently effective numbers. At elevations above 4,000 ft, the results are highly variable, not only in different areas but from year to year. One of the important factors bearing on this situation is rainfall, with its influence on the time of production of new, fresh foliage and the resultant effect on the cycle of the beetle. Damage to the trees is greatest during summers of light rainfall. Winter temperatures are such that no eggs are laid for 5-6 months, thus imposing a severe handicap on the maintenance of adequate parasitoid populations. However, severe damage in the higher elevations is now limited almost entirely Eucalyptus viminalis (Tooks 1955, Clausen 1978).

The parasitoid spread naturally to the north in Zimbabwe and Malawi and increased rapidly so that the weevil no longer was injurious. Transfer of the parasitoid to East Africa was begun in 1945 with equal success. It was then introduced into Mauritius and in 1948 into Madagascar where egg parasitism ranged as high as 67% within six months. In 1958 it was introduced into St. Helena where a rapid increase in parasitism resulted in significant protection to the eucalyptus plantations beginning in 1959 (Waters et al. 1976).

Greathead (1971) rates this project as a resounding success. I shows how rapidly an efficient parasitoid can effect control of an introduced pest in an intensive timber culture. Control of the weevil also has been achieved by P. nitens in New Zealand. Introductions from Australia in 1927-29 resulted in the establishment in both North and South Islands. Subsequent records are few, but high levels of parasitism have been observed at times and it is considered an important factor in the regulation of weevil populations throughout the range of the pest there (Waters et al. 1976) (also see Clark 1931, 1936; Moutia & Vinson 1945, Kevan 1946; Moutia 1946, 1947; Frappa 1950).

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

Clark, A. F. 1931. The parasite control of Gonipterus scutellatus Gyll. New Zealand J. Sci. & Tech. 13: 22-8.

Clark, A. F. 1936. Biological control of forest insect pests. New Zealand J. Sci. & Tech. 18: 585-88.

Clausen, C. P. 1978. Curculionidae. In: C. P. Clausen (ed.), Introduced Parasites and Predators of Arthropod Pests and Weeds. U. S. Dept. Agric., Agric. Handbk. No. 480. 545 p.

Frappa, C. 1950. Sur l'introduction et l'acclimatement a Madagascar d'Anaphoidea nitens Gir., insecte auxiliare parasite du charancon de l'eucalyptus. Bul. Agric (Madagascar) 2(17): 14-19.

Greathead, D. J. 1971. Eucalyptus snout beetle--Gonipterus scutellatus Gyll. Commonw. Inst. Biol. Control. Tech. Commun. 5: 49-50.

Kevan, D. K. M. 1946. The eucalyptus weevil in East Africa. East African Agric. J. 12: 40-4.

Moutia, L. A. 1946. Notes sur l'introduction a Maurice de l'insecte: Anaphoidea nitens Gir., le parasite du charancon de l'eucalyptus: Gonipterus scutellatus Gyll. REv. AGric. Maurice 25: 211-12.

Moutia, L. A. 1947. En marge de la lutte contre loherbe conde: Cordia macrostachya (Jacq.) Roem and Schult.: la fourmi rouge: Solenopsis geminata F. et le charancon de l'eucalyptus: Gonipterus scutellatus Gyll. Rev. AGric. Maurice 26: 125-37.

Moutia, L. A. & J. Vinson. 1945. Le charancon d l'eucalyptus, Gonipterus scutellatus Gyll. REv. Agric. Maurice 24: 25-30.

Tooke, F. G. C. 1955. The eucalyptus snout beetle, Gonipterus scutellatus Gyll., a study of its ecology and control by biological means. Ent. Mem. Dep. Agric. S. Africa 3: 282 p.

Waters, W. E., A. T. Drooz & H. Pschorn-Walcher. 1976. Biological control of pests of broad-leaved forests and woodlands. In: C. B. Huffaker & P. S. Messenger (eds.), Theory and Practice of Biological Control. Academic Press, New York. 511 p.