Rhopalosiphum rufiabdominalis (Sasaki)
Taxonomic placing: Insecta, Hemimetabola, Hemiptera, Sternorrhyncha, Aphidoidea, Aphididae.
Common name: Rice root aphid.
Geographical distribution: Cosmopolitan; CIE Map #289, 1971.
Host plants: Rice (Oryza sativa Linnaeus), Banana, several Cyperaceae, Poaceae (Graminae), Solanaceae and various ornamentals.
Morphology: The body of the apterous females is about 1.8 mm long, green-bluish; the head, siphunculi and cauda are brown-black. The head, thorax, siphunculi, cauda and legs of alate females are black, the abdomen is blue-green. Body length is 1.4-2.4 mm.
Life cycle: In the Middle East this aphid reproduces only by viviparous parthenogenesis on Poaceae. In winter the pest descends to the roots of grasses, where it is often attended and protected by ants. In spring the alates may infest banana seedlings. When reared on rice, the threshold of development was calculated to be at about 6.0ºC and at 25ºC it completed a generation in 7-8 days. Each female produced an average of 63 progeny at 20ºC and about 30 at 30ºC. Different gramineous hosts strongly affect its biology: when feeding on rye it had almost 80 progeny and lived for 40 days, whereas on maize (corn) it had only 3 progeny, living for 20 days. The primary hosts of this aphid in eastern Asia are species of Prunus, on which it is holocyclic.
Economic importance: This aphid is a serious pest of rice and transmits virus diseases of barley and of maize. It infests the roots, causing wilt, distortions and even plant death when occurring in large numbers. The aphid infests the subterranean parts of banana seedlings in the spring. Affected tissues turn yellowish due to feeding and the injection of toxins, as well as becoming contaminated by the abundant honeydew and the ensuing sootmold. Under drought-like conditions the pest occurs at very high infestation levels, significantly reducing yields of forage and winter wheat. More recently R. rufiabdominalis has become a pest of plants grown in hydroponic systems in greenhouses, infesting plants outside its usual host range.
Management
Chemical control: As this aphid is only a minor pest in the Middle East, chemical control is seldom needed.
Biological control: The entomopathogenic fungus Verticillium lecanii (Zimmerman) Viegas) (now in the genus Lecanicillium) infects the aphid and may control it.
References
Etzel, R.W. and Petitt, F.L. 1992. Association of Verticillium lecanii with population reduction of red rice root aphid (Rhopalosiphum rufiabdominalis) on aeroponically grown squash. Florida Entomologist 75: 605-606.
Jedlinski, H. 1981. Rice root aphid, Rhopalosiphum rufiabdominalis, a vector of barley yellow dwarf virus in Illinois, and the disease complex. Plant Disease 65: 975-978.
Kindler, D., Hesler, L., Elliott, N., Shufran, K. and Springer, T. 2004. Cereal and grass Hosts of the rice root aphid, Rhopalosiphum rufiabdominalis (Sasaki), and a description of an efficient greenhouse rearing technique. Journal of Agricultural and Urban Entomology 21: 51–59.
Rawlings, M.R. 2006. Effects of the rice root aphid, Rhopalosiphum rufiabdominalis (Sasaki), on wheat growth and yield. M.Sc. thesis, Oklahoma State University, pp. 75.
Swirski, E., Wysoki, M. and Izhar, Y. 2002. Subtropical Fruit Pests in Israel. Fruit Board of Israel (in Hebrew with an English summary).
Tsai, J.H. and Liu, Y.H. 1998. Effect of temperature on development, survivorship, and reproduction of rice root aphid (Homoptera: Aphididae). Environmental Entomology 27: 662-666.