(Hall, 1923)

Diagnosis
Adult female scale cover in life mussel-shaped, convex, 2.0-3.0 mm long, light to dark brown, with pale straw-coloured terminal exuviae occupying about 1/3 of total length of scale cover. A thin, white ventral scale is produced. Scale cover of male similar to that of female but smaller, narrower, light to dark brown. Exposed body of live adult female white (Hall, 1923; Balachowsky, 1954).

Body of slide-mounted adult female elongate, more than 1.8 times as long as wide, membranous; median lobes not zygotic, with pair of gland spines between their bases; without any club-shaped internal sclerosis arising from each median lobe; perivulvar pores present in five groups; with four or five enlarged marginal macroducts present on each side of pygidium. ACASACP.jpg

Host range
Acanthomytilus sacchari has been recorded only on hosts from the plant family Gramineae (Borchsenius, 1966), such as species of Anadelphia, Arundo, Imperata, Phragmites, Saccharum.

Affected plant stages: vegetative growing, flowering and fruiting stages

Affected plant parts: on stems under the leaf sheath

Biology and ecology
The biology of A. sacchari has not been studied. Crawlers are the primary dispersal stage and move to new areas of the plant or are dispersed by wind or animal contact. Mortality due to abiotic factors is high in this stage. Dispersal of sessile adults and eggs occurs through human transport of infested plant material.

Economic impact
No mention of economic damage by A. sacchari has been found in the literature.

Detection and inspection methods
Pull back the leaf sheaths of sugarcane and other giant grasses and look for brown mussel scale covers on the exposed stems.

Phytosanitary risk
Balachowsky, 1954, expressed concern about the likely impact if A. sacchari were accidentally introduced to other tropical continents. It could have damaging effects on sugarcane production and natural ecosystems.

Natural enemies
The natural enemies of Acanthomytilus sacchari have not been studied.

Distribution
See Acanthomytilus sacchari distribution.

Microscopic examination of slide-mounted adult females is required for authoritative identification to species.

Acanthomytilus intermittens (Hall, 1924) could be misidentified as A. sacchari, but it has only one submarginal macroduct on each side of abdominal segment VII, whereas A. sacchari has two or more macroducts in this position ACASACP.jpg. A. intermittens is known from Italy, Algeria, Morocco, Crete, Egypt, Israel, Iraq, Iran, Tadjikistan and Mauritius on grasses including species of Bambusa, Imperata, Panicum, Pennisetum, Vetiveria and Saccharum (Balachowsky, 1954; Borchsenius, 1966; Williams and Williams, 1988; Longo et al., 1995). Adult female scale cover in life mussel-shaped, convex, 2.0-2.2 mm long, medium to light brown with terminal exuviae. Scale cover of male similar to that of female but smaller, 1.6 mm long, light brown. Exposed body of live adult female white with a brownish pygidium (Balachowsky, 1954).

Acanthomytilus vermiformis (Takahashi) could be misidentified as A. sacchari, but it has a body more than 8 times as long as wide ACVERS.jpg , whereas in A. sacchari the body is about 3-4 times as long as wide. Acanthomytilus vermiformis is known from Taiwan and China (Hong Kong) on Bambusa vulgaris (Takagi, 1970; The Natural History Museum collection, London, UK). ACVERP.jpg

Comments
Acanthomytilus sacchari probably originated in tropical Africa on giant grasses (Balachowsky, 1954). It has not been recorded from the Western Hemisphere, Australia, or from the Pacific islands.

Europe
Cyprus: The Natural History Museum collection, London, UK
Hungary: present, no further details (Danzig and Pellizzari, 1998)
Italy: present, no further details (Longo et al., 1995; Danzig and Pellizzari, 1998)
Sicily: present, no further details (Longo et al., 1995)

Asia
India: present, no further details (Williams and Greathead, 1990)
Tamil Nadu: The Natural History Museum collection, London, UK
Pakistan: The Natural History Museum collection, London, UK
Taiwan: present, no further details (Tao, 1999)

Africa
Central Africa: present, no further details (Danzig and Pellizzari, 1998)
Egypt: present (Hall, 1923; Williams and Greathead, 1990)
Kenya: present, no further details (Williams and Greathead, 1990)
Guinea: present (Balachowsky, 1954)
Sierra Leone: present (Hall, 1923; Balachowsky, 1954)
Tanzania: present, no further details (Williams and Greathead, 1990)