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Plantwise Technical Factsheet

oat leaf beetle (Oulema melanopus)

Host plants / species affected
Avena sativa (oats)
Elymus (wildrye)
Elymus repens (quackgrass)
Festuca arundinacea (tall fescue)
Hordeum vulgare (barley)
Phalaris canariensis (Canarygrass)
Phleum pratense (timothy grass)
Secale cereale (rye)
Setaria italica (foxtail millet)
Triticum aestivum (wheat)
Zea mays (maize)
List of symptoms/signs
Leaves  -  external feeding
Adults and larvae of O. melanopus feed on the adaxial leaf surface of host plants. Feeding is usually from the tip of the blade to the base, consuming the chlorophyll-containing mesophyll cells but leaving the lower epidermis intact. Feeding occurs between the leaf veins, causing a longitudinal feeding scar. In heavy infestations, when seen from a distance, damage appears to be injury by frost as a result of larval feeding that result in the tips of the leaves being whitened. Adult damage can be distinguished by the leaf being completely chewed through, creating narrow slits.
Prevention and control
Cultural Control

Hodson (1929) mentions the use of ploughing stubble immediately after harvest as a means of controlling O. melanopus. In North America, this tactic is not feasible. Hodson (1929) also mentions premature cutting of the grain crop as a green fodder of animals as a method of reducing beetle populations.

Research has shown that O. melanopus populations are increased by fertilization (Sokolov and Nikitina, 1991) and compost (Koteles et al., 1997).

Biological Control

Haynes and Gage (1981) reviewed the biological control efforts in North America. Four European parasites, Anaphes flavipes, Tetrastichus julis, Diaparsis temporalis and Lemophagus curtus, have been successfully established. Failure of the parasitoids to spread with O. melanopus, unsuccessful adaptation to new environments and changes in farming practices have reduced the success of the programme. Montgomery and DeWitt (1975) illustrated the immature stages of the three European larval parasitoids established in North America. Tetrastichus julis was also established in Canada and was outstandingly successful in Ontario, by contrast to Michigan, as a result of differing climate and cultural practices (Kelleher and Hulme, 1984).

Host-Plant Resistance

Papp (1992) reviewed the literature on host-plant resistance in wheat. The major factor in resistance in wheat is trichome length and density, whereas silicon deposits in the leaves are the most important factor in barley resistance (Guslits, 1990). The principal behavioural component was non-preference for oviposition and deterrence of early instar larval feeding activity. Webster and Smith (1983a) outlined a system for a resistance breeding and testing programme. Dubbut and Tscharntke (1997) found that O. melanopus did not distinguish between Festuca arundinacea lines with and without endophytes.

Chemical Control

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:

Integrated Pest Management

IPM programmes are being devised and implemented in North America (Haynes and Gage, 1981) and Europe (Hausammann, 1996).

In the absence of natural enemies, O. melanopus may cause considerable damage to crop plants. Yield losses as high as 55% in spring wheat and 23% in winter wheat have been reported from heavily infested fields. In oats and barley, yields have been reduced by as much as 75%.

O. melanopus has been shown to vector Brome mosaic virus (Gaborjanyi and Szabolcs, 1987), Maize chlorotic mottle virus (Nault et al., 1978), Barley yellow dwarf virus (Papp, 1992), Cocksfoot mottle virus (Benigno and A'Brook, 1972) and phleum mottle virus (Benigno and A'Brook, 1972). Gaborjanyi and Szabolcs (1987) found that adult O. melanopus could transmit virus after 1 day of feeding on infected plants but would lose infectivity after feeding on healthy plants for 1 day.

Related treatment support
External factsheets
Pennsylvania State University Insect Pest Fact Sheets, The Pennsylvania State University, 2009, English language
Virginia Cooperative Extension - Agricultural Insects Pests, Virginia Polytechnic Institute and State University, 2009, English language
Kentucky IPM Scout Info Factsheets, University of Kentucky, 2005, English language
CIMMYT Plant Pest and Disease Factsheets, Centro Internacional de Mejoramiento de Maiz y Trigo (CIMMYT) (International Maize and Wheat Improvement Center), English language
AAFC Sustainable Crop Protection Factsheets, Agriculture and Agri-Food Canada (AAFC), 2015, English language
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