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Delaying sowing until after the peak autumn flight can reduce virus incidence in winter cereals. Early maturation of winter barley crops provides some resistance to M. dirhodum via drying out of the leaves (Howard and Dixon, 1995).
Significant differences in the resistance of winter wheat varieties have been reported (Auclair, 1989), and the ancient variety Einkorn (Triticum monococcum) has shown antibiotic resistance to M. dirhodum (Sotherton and Lee, 1988). Maize cultivars Blask and Bulat were identified as the most resistant in a study on the susceptibility of 12 maize hybrids to M. dirhodum in Poland (Pienkosz et al., 2005).
A study by Clayson et al. (2014) showed evidence of synergy between resistance in wheat cv. Rapier and the susceptibility of M. dirhodum to malathion, raising the possibility of using reduced concentrations of pesticides to control aphids on resistant crop cultivars.
Biological control has been attempted in a number of countries recently invaded by M. dirhodum. Aphidius ervi and members of the Aphidius rhopalosiphi/A. uzbebistanicus complex were introduced into southern Chile from France in 1976-1977, from where they may have spread to Brazil and Argentina (Botto and Hernandez, 1982). The establishment of Aphidius spp. was confirmed during the spring following their introduction, and levels of parasitism reached peaks of 14.7% (Norambuena, 1981). Similarly, stocks of the A. rhopalosiphi group were introduced into New Zealand (in 1985) and Australia (in 1986) (Stufkens and Farrell, 1987; Carver, 1989). In 1988-1989, the rate of parasitism by A. rhopalosiphi was estimated at Lincoln, near Canterbury, New Zealand, to be about 50% in winter barley and 100% in spring barley at the time of peak aphid numbers (Farrell and Stufkens, 1990).
In Australia, M. dirhodum was rapidly subjected to parasitism by Erynia neoaphidis and by A. ervi (Carver, 1989). However, artificially introduced E. neoaphidis was found by Wilding et al. (1990) to be too slow and unpredictable in its action to be likely to form a practical alternative to conventional insecticides for cereal aphid control in the UK.
In Brazil, the braconids Aphidius ervi, A. rhopalosiphi, A. uzbekistanicus and Praon volucre have successfully been used for the biological control of wheat aphids M. dirhodum and Sitobion avenae since the 1970s (Alves et al., 2005; Sampaio, 2009).
In field studies in wheat in Argentina, the coccinellid predator Eriopis connexa showed a linear increase in numerical response to an increase in the density of aphids (including M. dirhodum) and was higher in higher plant diversity (HPD) plots with refuge strips than in lower plant diversity (LPD) plots without refuge strips (Tulli et al., 2013).
In a population dynamics model devised to provide a tool for integrated pest management in winter wheat, it was estimated that fungal diseases accounted for 75% of the reduction in peak density of aphids (Sitobion avenae, Rhopalosiphum padi and M. dirhodum) in western France and were the key factor acting on aphid dynamics in this region (Plantegenest et al., 2001).
Due to the variable regulations around (de-)registration of pesticides, we are for the moment not including any specific chemical control recommendations. For further information, we recommend you visit the following resources:
M. dirhodum is one of the most economically significant insect pests of wheat in Washington, USA (Pike and Tanigoshi, 1996) and was described by Feng et al. (1991) as abundant in a field survey of dryland and irrigated crops of small grains in Montana, USA.
In Chile, M. dirhodum population levels have exceeded those in its native (i.e. European) region, causing relatively severe outbreaks of Barley yellow dwarf virus on cereal crops (Sylvester, 1989).
Severe infestations of M. dirhodum develop on cereals in some years as a result of favourable climatic conditions and the absence of natural enemy control (Cannon, 1986; Dixon, 1987). Significantly higher populations of M. dirhodum are associated with nitrogen applications, although it is not clear whether this is a direct or indirect effect, for example due to changes in canopy structure (Duffield et al., 1997). In a field study in the UK, longevity of M. dirhodum was unaffected by five levels of nitrogen fertilization (from 50 to 250 kg N/ha). Aphid intrinsic rate of increase and fecundity increased with each level applied to 200 kg N/ha but there was a significant decrease in fecundity for the highest rate of fertilization of 250 kg N/ha (Gash, 2012).
In addition to the direct damage caused by a drain of nutrients by phloem-feeding (and the development of saprophytic fungi on honeydew excretions, which accelerates the ageing of the plants), indirect damage occurs as a result of the transmission of viruses. In particular, persistent Barley yellow dwarf virus (BYDV), which typically produces symptoms of yellowing and dwarfing. In Italy, M. dirhodum is able to transmit BYDV from maize (on which it produced no symptoms), or wild grasses, and pass it on to wheat and barley (Suss and Colombo, 1982; Guglielmone and Caciagli, 1996). M. dirhodum was recorded as a vector of isolate BYDV-PAS (but not usually as a vector of isolate BYDV-PAV) on cereals and grasses in the Czech Republic (Jarošová et al., 2013) and as a vector of isolate BYDV-PAV on wheat and oats in Brazil (Parizoto et al., 2013).
M. dirhodum was found to transmit a Spanish isolate of Sugarcane mosaic virus in a non-persistent manner (Angeles Achón et al., 2003). M. dirhodum is also a vector of Potato virus Y (Schröder and Krüger, 2014) and an inefficient vector of Zucchini yellow mosaic virus (Katis et al., 2006). M. dirhodum is an occasional inefficient vector of Plum pox virus (Gildow et al., 2004a,b) and was also found to be a vector of a new virus called rose spring dwarf associated virus (RSDaV) (Salem et al., 2008).
Holt et al. (1984) determined the effect of crop growth stage (G.S.) on yield reductions of winter wheat caused by M. dirhodum. Yield losses at early (G.S. 30-41), middle (G.S. 41-65) and late (G.S. 65-77) stages of crop growth were 5, 8 and 27%, respectively. Yield reductions of barley attributed to feeding by M. dirhodum in the Irish Republic were estimated at 0.32, 0.48 and 0.43 t/ha (5.2, 5.6 and 5.7%) in 1997, 1999 and 2000 (Kennedy and Connery, 2005).