6.83 Prostephanus truncatus (Horn) : larger grain borer
Species: Prostephanus truncatus (Horn, 1878) [Coleoptera : Bostrichidae]
Synonyms or changes in combination or taxonomy: Dinoderus truncatus Horn, 1878.
Common names(s): larger grain borer, greater grain borer.
Hosts: maize and dried cassava, also in young woody shoots of a wide range of tree species. In the laboratory it can be made to breed slowly on other grains, eg. wheat, however it is not been found to be a pest of grains other than maize.
Part of plant affected: seeds, roots and woody twigs.
Distribution: Natural range - northern South America, Central America, Mexico and far south of USA. In Mexico it is widely distributed in a wide range of climatic conditions from montane to seasonally arid tropics. In the USA it is an occasional pest of maize in southern states, especially those bordering Mexico. No information appears to be publicly available as to its presence in natural habitats in the USA. It may be occasionally intercepted further north in the USA or in Canada as a result of grain movements but is unlikely to persist in such areas. From the late 1970’s onwards it was introduced by accident into Africa, initially into Togo and Tanzania. It has since become widely spread in surrounding countries and is still spreading rapidly in sub-Saharan Africa.
Life history:- This species is primarily a wood-borer feeding on young shoots of a wide range of tree species in natural bush habitats. Such populations act as a major reservoir for invasion of the storage environment. Its appearance in storage structures in affected areas is unpredictable. When populations do become established in stored maize or cassava they can cause very severe damage. Typically it is a pest of farm stored grain stored on the cob, especially under conditions of subsistence agriculture. While it is not regarded as an important pest of bulk stored grain, it can survive in such grain and in it capable of being moved great distances. Adults are 3-4 mm in length, cylindrical and dark brown to black in colour The adult is a strong flier and infestation can occur in the field or after the crop is harvested. The beetle can breed rapidly in maize and dried cassava. Huge quantities of dust and frass are produced as adults tunnel from grain to grain. Females lay between 30-600 eggs on the grain or in damaged parts of the plant. Larval development takes place inside grains and shoots. Development is completed between 18-37°C and and 30-70% R.H., with optimum conditions being at 32°C and 70% R.H at which eggs can compete development to adults in 25 days. It is very tolerant of dry grain and can breed in maize of moisture contents of less than 10%.
Entry potential:- Negligible on grain sourced / moved from and through areas where insect is not established. Risk increases if grain is sourced from areas where insect is found.
Establishment potential:- High, in areas which grow maize. This insect is very likely capable of becoming an environmental pest in Australia. Native genera of woody shrubs and trees eg Acacia spp. appear at risk of being attacked. Official attempts at eradication and control of spread have not been very successful.
Spread potential:- Very high. They are long lived and are good fliers. They can also conceal themselves by boring into wooden structures. Native vegetation potentially offers a reservoir for this species. They are also strong fliers. Attempts to control this insect in Africa have at best only slowed its spread.
Economic importance: Damage to maize stored on cob can be severe with weight losses as high as 34% observed after only 3-6 months storage. Losses in dried cassava after six months storage average between 19% to 30%. Should this insect become established here, trade in commodities at risk could become difficult or badly disrupted as this pest is subject to official quarantine control in most countries.
Quarantine Status: Quarantine (High).
Anon (1979) Stored Grain Insects. Agriculture Handbook No. 500, USDA, Washington DC : USA, 57pp.
GASGA (1993) Larger Grain Borer. Technical Leaflet No. 1, 2nd Ed. CTA : Netherlands.
Hodges, R.J. (1986) The biology and control of Prostephanus truncatus (Horn) (Coleroptera:Bostrichidae) – a distructive pest with an increasing range. Journal of Stored Product Research 22: 1-14.
Nang’ayo, F.L.O., Hill, M.G., Chandi, E.A., Chiro, C.T., Nzeve, D.N., & Obiero, L.W. (1993) The natural environment as a reservoir for the Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae) in Kenya. African Crop Science Journal 1: 39-47.
6.84 Pseudeurostus hilleri (Reitter)
Species: Pseudeurostus hilleri (Reitter, 1877) [Coleoptera : Ptinidae]
Synonyms or changes in combination or taxonomy: Niptus hilleri Reitter 1877; Eurostus hilleri (Reitter, 1877); Pseudeurostus hilleri (Reitter, 1877); Eurostus aligenus Brown, 1840
Distribution: Canada, USA, Australia
Entry potential: n/a, may not be present in Australia
Economic Importance: likely scavenger and inhabitant of residues, potential minor pest of feed mills and warehouses
Quarantine Status: Non-Quarantine
Bousquet, Y. (1990) Beetles Associated with Stored Grain Products in Canada : An Identification Guide. Agriculture Canada : Ottawa, 220 pp.
Pest Infestation Control Laboratory Library Index, Slough: UK, now known as Central Science Laboratory, York, Ministry of Agriculture, Fisheries & Food: UK. Copy held in Stored Grain Research Laboratories, CSIRO Entomology, Canberra, Australia
6.85 Psocatropos microps (Enderlein) : booklouse
Species: Psocatropos microps (Enderlein, 1903) [Psocoptera : Psyllipsocidae]
Synonyms or changes in combination or taxonomy: Axinopsocus microps Enderlein, 1903; Psocatropos lesnei Badonnel, 1931; Psocinella slossonae Banks, 1900; Vulturops floriadanus Corbett & Hargeaves, 1915
Common name(s): booklouse
Distribution: USA, Australia
Entry potential: n/a, present in Australia
Economic Importance: structural pest of grain storage in tropical coastal areas
Quarantine Status: Non-Quarantine
Smithers, C.N. (1996). Psocoptera. Pp. 1-79, 333-361 (App. I-IV), 363-372 (Index) In Wells, A. (Ed.) Zoological Catalogue of Australia. Vol. 26. Psocoptera, Phthiraptera, Thysanoptera. Melbourne : CSIRO Publishing, Australia 418pp.
Mockford, E.L (1993). North American Psocoptera (Insecta), Sandhill Crane Press, Inc., Florida