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Rice root aphid, Red rice root aphidOn this page: Identification & Distribution Other aphids on the same host Damage & Control
Identification & Distribution
Adult apterae of Rhopalosiphum rufiabdominale on the primary host (not pictured) are reddish-brown or greenish-brown with bluish-white mealy wax on the sides of the body and forming dorsal cross-bands. Apterae on the secondary host are dark green or brownish with a rusty-red suffusion about the bases of the siphunculi (see pictures below - note they are of immatures). The hairs on antennal segment III (see first clarified mount below) are markedly longer than the basal diameter of that segment; on the secondary host the longest hairs are 3-5 times the basal diameter (cf. Rhopalosiphum nymphaeae and Rhopalosiphum padi, which has the hairs on antennal segment III shorter than or equal to the basal diameter of that segment). Marginal tubercles are usually only present on abdominal tergites I and VII (cf. Rhopalosiphum nymphaeae, which has marginal tubercles on tergites I-VII). The siphunculi are less than 0.3 mm long, or 1.7-1.8 times longer than the cauda, and with no discernible subapical swelling (cf. Rhopalosiphum nymphaeae, which has siphunculi more than 0.3 mm long and swollen proximal to the subapical constriction). The body length of adult Rhopalosiphum rufiabdominale apterae is 2.0-2.6 mm.
First image above by permission, copyright Sunil Joshi & Poorani, J. Aphids of Karnataka (accessed 12/2/20).
Alatae on the secondary host are dark green with a rusty suffusion around the bases of the siphunculi. They usually have 5-segmented antennae (see second clarified mount below) with 3-35 secondary rhinaria on antennal segment III, and 0-4 on segment IV.
Clarified mount images above copyright Brendan Wray, AphID, USDA APHIS PPQ, Bugwood.org
Rhopalosiphum rufiabdominale is native to east Asia where it host alternates from Prunus species, including Japanese apricot (Prunus mume) and Chinese plum (Prunus salicina), to the roots of various grasses (Poaceae), sedges (Cyperaceae), potatoes / nightshades (Solanaceae), and cannabis (Cannabaceae). It has also been found overwintering in Europe on domestic plum (Prunus domestica) and apricot (Prunus armeniaca). Rhopalosiphum rufiabdominale is found in warmer climates, or glasshouses, in much of the rest of the world as anholocyclic populations on the secondary hosts. It is a major pest of rice in east Asia and of cannabis in hydroponic cultivation.
Other aphids on the same host
Rhopalosiphum rufiabdominale has been recorded from 17 different species of Prunus (Prunus armeniaca, Prunus avium, Prunus cerasoides, Prunus domestica, Prunus glandulosa, Prunus ishidoyana, Prunus jamasakura, Prunus japonica, Prunus lannesiana, Prunus mume, Prunus nakaii, Prunus persica, Prunus pseudocerasus, Prunus sachalinensis, Prunus salicina, Prunus tomentosa, Prunus yedoensis).
Rhopalosiphum rufiabdominale has been recorded from more than 22 plant families - including many different grass & cereal species (Poaceae), especially rice (Oryza sativa), as well as from various Solanaceae and Cannabinaceae.
Damage and control
CABI Plantwise Knowledge Bank provide a useful summary of the information on damage by, and control of, this polyphagous pest. Rhopalosiphum rufiabdominale is an economically important pest of upland rice, particularly in Japan, but is not a pest of irrigated rice anywhere in the world. Injury to upland rice can be severe in Japan, with losses of up to 50-70%. Occurrence is related to the cultivars of upland rice in China, with aphids causing light damage at the seedling stage and heavy damage at the tillering stage. Generally, all aphids cause more serious damage during the early growth stages.
Rhopalosiphum rufiabdominale infests the roots of a range of other crops worldwide, including barley in Turkey, wheat in India, North America and Africa, aubergines in Spain, cotton in Africa and the USA, seed potatoes in India and sugarcane in Japan and India. It is probably frequently overlooked, especially in cereals. The record of overwintering on apricot Prunus armeniaca and common plum (Prunus domestica) in northern Italy (Rakauskas et al., 2015), indicates an increased threat of the aphid to cereal crops, and possibly stone fruits, in temperate Europe.
Rhopalosiphum rufiabdominale has become a pest of plants grown in hydroponic systems in greenhouses, in the USA and elsewhere, and under these circumstances can infest plants outside its usual host range. In 2004-2005 Rhopalosiphum rufiabdominale was first reported infesting greenhouse tomatoes and sweet peppers in Ontario, Canada - and greenhouse potatoes in Syria in 2007. In recent years it has become well known as a pest of cannabis (Cannabis sativa grown in hydroponic systems.
Rhopalosiphum rufiabdominale is also a vector of several plant viruses, including Barley yellow dwarf virus (BYDV) and Cereal yellow dwarf virus (CYDV), which contributes to its economic importance as a pest of barley in Turkey and North America. There is also evidence of it being a vector of Maize mosaic virus in India. Rhopalosiphum rufiabdominale has also been reported to transmit Sugarcane mosaic virus (SCMV) in India and is thought to be a non-persistent vector of Cucumber mosaic virus, which causes serious damage to tobacco in some areas in Taiwan.
Control of rice root aphid in rice fields is problematic. One of the few trials of insecticidal control was carried out by Barwal (2003) in India. Different formulations of insecticides were evaluated for efficacy and for effects on natural enemies. Four systemic insecticides, phosphamidon, monocrotophos, formation, thiometon and one contact insecticide, endosulfan, were found effective against the aphid without adversely affecting the parasitoids.
In greenhouses in Florida, the fungus Verticillium leucanii has been used to successfully control Rhopalosiphum rufiabdominale on squash (Cucurbita pepo), Etzel & Petitt (1992). An increase in the population of rice root aphids was observed following replacement of squash plants in a greenhouse in Florida during 1991. Aphids infected with Verticillium lecanii were introduced to the greenhouse in February. Fungal sporulation was observed 6 days after inoculation and a decrease in the population was observed after 2 weeks. Within a month of inoculation most of the aphids were dead. This procedure was subsequently routinely implemented for the control of Rhopalosiphum rufiabdominale. LaChapell in rice root aphid management and life cycle has proposed other mycopesticides including Botanigard (Beauveria bassiana) and PFR 97 (Isaria fumosorosea) for root aphid control, as well as Neem (azadirachtin) and Pyrethrin.