Antonina graminis (Maskell)
Common Name: Rhodesgrass scale
Geographical distribution: Rhodesgrass scale occurs in tropical and subtropical regions, approximately bounded by the 32nd parallel. The pest was first found in the Middle East in the late 1960s. CIE Map #216, 1966.
Host plants: About 100 species of grasses (Gramineae), including many pasture grasses.
Morphology: The female is legless, with short, 2-segmented antennae. The body is dark-red and becomes darker as the scale matures. The spiracles are large, with many surrounding pores. Cerarii absent, anal ring somewhat retracted from posterior end of the body. The female is totally enclosed within a white waxy sac, and produces a long, anal waxy excretory tube or stalk, used to excrete its honeydew away from the body.
Life cycle: Reproduction is by parthenogenesis, each female giving birth to about 150 crawlers. They usually settle at the lower nodes or crowns of grasses, between leaf sheaths, where they feed and produce their excretory stalk. A generation requires about 10 weeks, development being continuous throughout the year except during very cold or very hot periods. Dispersal may be by human transport of infested grasses, by the movement of the crawlers or by being borne on winds. Ants may be associated with these pests. Non-feeding females live for at least five weeks and continue to produce young for much of that period, an attribute that has been used for the mass rearing of its natural enemies.
Economic importance: Damage [especially to rhodesgrass, Chloris gayana Kunth, and to bermudagrass, Cynodon dactylon (L.) is due to the removal of plant sap. Infested plants turn yellow and shrivel. Injury may be compounded by plant stress factors, such as drought, irrigation by low-grade water, close mowing (of lawns and golf courses) and by overgrazing. Infested pastures, unless treated, decline and dry up within 2-4 years.
Sampling: Population size can be estimated by collecting 10 rhodesgrass runners, each with at least 10 nodes, from different parts of a field and counting the number of scales that had settled thereon. Best (most uniform) results are obtained from nodes that have not yet taken root. In addition, data from these nodes provide a better indication of recent changes in the pest’s population, whereas older nodes could have been colonized for longer periods.
Cultural control: Improvements of plant condition by better irrigation, by fertilization and by moderate grazing and mowing. Resistant rhodesgrass varieties are also available.
Chemical control: Systemic organophosphates may provide satisfactory control, but their use (in granulated formulations) is limited to small areas, like golf courses. The cost of applying such pesticides to rangelands is prohibitive.
endoparasitoid Neodusmetia sangwani (Rao) was introduced into Israel in 1971, mass-reared on field-collected A. graminis and released at several rhodesgrass plots. Parasitization rates are very high and at present the pest has almost totally disappeared.
Berlinger, M.J. and Barak, R. 1981. The phenology of Antonina graminis (Mask.) (Hom., Pseudococcidae) and Odonaspis ruthae Kot. (Hom., Diaspididae) on lawn grasses in southern Israel. Zeitschrift für Angewandte Entomologie 91: 62–67.
Chada, H.L. and Wood, E.A., Jr. 1960. Biology and control of the rhodesgrass scale. United States Department of Agriculture, Technical Bulletin #1221, pp. 21.
Gerson, U., Mescheloff E. and Dubitzki, E. 1975. The introduction of Neodusmetia sangwani (Rao) (Hymenoptera: Encyrtidae) into Israel for the control of rhodesgrass scale, Antonina graminis (Maskell) (Homoptera: Pseudococcidae). Journal of Applied Ecology 12: 767-779.
Schuster, M.F. 1967. Response of forage grasses to rhodesgrass scale. Journal of Range Management 20: 307-309.
Schuster, M.F. and Bolling, J.C. 1971. Biological control of rhodesgrass scale in Texas by Neodusmetia sangwani (Rao). Effectiveness and colonization studies. Texas Agricultural Experiment Station, B1104: 1-15.