Cereal leaf beetle
|Cereal leaf beetle|
The cereal leaf beetle (Oulema melanopus) is a significant crop pest, described by Carl Linnaeus in 1758.
One generation of this beetle is produced a year. Adults feed before winter and spend most of their overwintering time in protected areas such as wind rows, crop stubble, and tree bark crevices. Adults mate once the temperature warms to above 9-10 degrees Celsius (or 44.6 degrees F)  and females have a relatively long laying period (about 45–60 days), when they deposit eggs on the undersides of leaves. The larvae hatch in 7–15 days, and start the most damaging eating of the entire lifecycle. These larvae mature in 12–20 days. Larvae are the greatest threat to crops, as they eat the superficial layer of leaves, hindering the leaves' photosynthetic potential. According to Kon, Zabik, Webster, and Leavitt, a chemical factor attracts the beetles to leaves, and that chemical factor is directly related to hydrophobicity. Pupation occurs in soil, with the adults emerging in 20–25 days, ready to start the cycle again.
Eggs are cylindrical and round, about 0.9 mm long and 0.4 mm wide. Eggs are often laid along the midvein on the undersides of leaves. They are bright yellow at first and darken over time, and are partially black when the larvae emerge.
The larva appears white or yellow, is hump-backed, and has a black head and six small legs. It has a defense mechanism in which it smears excrement on its body to mask its vibrant color and to deter predators. This gives it a shiny black appearance, as opposed to yellow or white.
Adults, on average, are about 5 mm long and have dark-blue wing covers and red legs. Their thoraces range in color from red to orange to reddish brown. The biggest distinction between male and female O. melanopus is the difference in shape of the first abdominal segment. The male’s segment is more narrowly rounded and flat or concave, and it is more broadly rounded and convex in the female.
O. melanopus is native to Europe and Asia, but it has become much more common in the world. In North America, it was first spotted in Berrien County, Michigan, in 1962. Since then, it has spread through the Midwest to the East Coast, and is making its way westward. Significant populations are found in Virginia, North Carolina, Utah, Montana, North Dakota, and Missouri and Iowa. Environmental conditions such as temperature and humidity drastically affect the O. melanopus population for that year. A cold spring favors the host plant, whereas a warm spring favors the leaf beetle. An increase in the general temperature of the planet may allow O. melanopus to spread into Canada. More recent surveys have shown that O. melanopus has indeed arrived in Canada; in 2006, it was present in 11.1% of fields, and in 2009, in 33.3% of fields in southern Alberta.
Locally, adults spread to the exterior of fields during their overwinter. Larvae tend to stay on the outside of crop fields, but are also found in the center. Local populations are never homogenously distributed, hotspots and empty places occur in each field.
O. melanopus consumes nearly all cereal crops, but has a strong affinity for oats, barley, and rye, and its favorite host is wheat. Alternatives are corn, sorghum, and sudangrass for adults, and wild oats, quackgrass, timothy, canary grass, reed canary grass, annual and perennial ryegrass, foxtail, orchard grass, wild rye, smooth brome, and fescues for the whole lifespan. The physical symptoms of the plant caused by them are thin, long lines where the upper epidermis of the leaf has been eaten. Since the beetle is migratory when it eats, it is not consistent within a field. In Michigan, entire fields are rarely affected and the situation is most likely the same in the Midwest. A field of plants looks weathered and old, but is never completely destroyed. Damage is usually no more than 40% total.
When a herbivore consumes a plant, it releases volatile organic compounds (VOCs). Because VOCs are a chemical signal that attract some predators, the female O. melanopus is repelled by the chemicals for her own and the safety of her progeny. Males are deterred, but do not change eating habits .
To determine the eating habits of O. melanopus, scientists conducted an experiment using different media. They took agar gel infused with pea and barley extracts, and noted the resulting reaction. When used alone, both pea extract, which is not a desired food for the beetle, and barley extract, which is an alternate source, produced a weakening or halting of consumption. A combination of both, however, incited a small feeding response. Most likely, a secondary compound in barley incites an eating response, perhaps when a lack of desired food is present.
Scientists have had success in labs with a few types of nematode, Steinernema feltiae B30, S. carpocapsae C101, and Hetero-rhabditis bacteriophora D54. Nematodes attack the adults that overwinter in the soil, preventing them from reproducing in the spring. S. carpocapsae C101 was found to be the most effective, and even proved to be an effective alternative to pesticides. Each of the nematodes, however, was sensitive to temperature, implying that some strains would work better than others due to the temperature. Since the spread of O. melanopus is so great, a consistently important factor to consider is the temperature when selecting which strain is the most effective for the desired location.
Also, the hormone secreted by the males attracts the beetles into a trap, where they can be removed from the site.
Another biological control consists of larval parasites; Diaparsis carnifer, Lemophagus curtis, and Tetrastichus julis are wasps that do this  D. carnifer and L. curtis both consume the O. melanopus larvae, and T. julis lays eggs inside of the body of the O. melanopus larvae. Specifically, T. julis does not seem to pose too much risk to the crops themselves, but is extremely effective at dispatching large populations, around 90%. With all parasitic wasps in general, some experiments are proving that spraying a sugar solution on the fields encourages predators of O. melanopus to grow fast and hearty, so they can better kill off the population in the field.
Anaphes flavipes is an egg parasitoid that lays its eggs inside of the O. melanopus egg, killing it in the process. Effectiveness is around 90%. It is a good control agent because it is hearty and its lifecycle is synchronous with that of O. melanopus, the disadvantage being that it is not host-specific, and can cause other unforeseen deaths in other bugs, disrupting the balance of the ecosystem.>.
Even without human intervention, O. melanopus has experienced a decline in the United States due to general weather conditions such as drought or excessive rainfall. In the early days of outbreak in the United States, California experimented with quarantine as the first option. Any material suspected to contain O. melanopus was not allowed into California. O. melanopus populations traveling in hay can be suppressed by compressing the hay into bales.
Transgenic plants are still another option for control. Meissle et al. found that mortality of O. melanopus on Cry3Bb1 transgenic maize was double that of the wild type. Many transgenic plants seek to change the physical properties of the plant, making adhering eggs a difficult task.
In Europe, where the species is native, scientists have experimented with several pesticides. In one experiment, four pesticides belonging to two groups (organophosphates and pyrethroids) were tested to see their effects on the beetles' numbers. These were tested at several concentrations and mixtures. The chemical Vantex was superior, but the other pesticides were averaging 80% efficiency and were not to be counted out. With many pesticides, farmers must be cautious not to spray too early, because the eggs will not be affected much, and pesticide use may actually increase the numbers of O. melanopus because predators are killed. The optimum time to begin spraying is when about 50% of the eggs have hatched. An alternative is spraying when the adults are laying their eggs, which is also shown to be effective.
- Berchert, D.M.; Magarey, R.D.; Fowler, G.A. "PEST ASSESSMENT: Cereal Leaf Beetle, Oulema melanopus (L.), (Coleoptera:Chrysomelidae)" (PDF). www.nappfast.org. NC State University. Archived from the original (PDF) on 2011-07-27. Retrieved 10/06/13. Check date values in:
- DiFonzo, C. (2009). "Cereal Leaf Beetle". Michigan: Michigan State University Extension. Retrieved 09/10/2013. Check date values in:
- Herbert Jr., D.A.; Van Duyn, J.W. (2009). "Cereal Leaf Beetle: Biology and Management" (PDF). Virginia Tech. Retrieved 09/08/13. Check date values in:
- Blodgett, S.; Tharp, C.I.; Kephart, K. (2004). "Cereal Leaf Beetle" (PDF). Montana State University. Retrieved 10/12/13. Check date values in:
- Roberts, D. (2006). "Cereal Leaf Beetle". Oregon State University. Retrieved 10/07/13. Check date values in:
- Kon, R.T.; Zabik, M.J.; Webster, J.A.; Leavitt, R.A. (1978). "Cereal leaf beetle response to biochemicals from barley and pea seedlings. I. Crude extract, hydrophobic and hydrophilic fractions". Journal of Chemical Ecology. 4 (5): 511–522. doi:10.1007/bf00988915.
- White, R.E. (1993). "A Revision of the Subfamily Criocerinae (Chrysomelidae) of North America North of Mexico". Agricultural Research Service Technical Bulletin. United States Department of Agriculture. Retrieved 09/10/13. Check date values in:
- Laznik, Z.; Toth, T.; Lakatos, T.; Vidrih, M.; Trdan, S. (2009). "Oulema melanopus(L.) (Coleopters: Chrysomelidae) Adults are Susceptible to Entomopathogenic Nematodes (Rhabditida) Attack: Results From a Laboratory Study". Journal of Plant Diseases and Protection. Ulmer Journals. 117 (1): 30–32. Archived from the original on 2013-11-04. Retrieved 2013-09-16.
- Philips, C.R.; Herbert, D.A.; Kuhar, T.P.; Reisig, D.D.; Thomason, W.E.; Malone, S. (2011). "Fifty Years of Cereal Leaf Beetle in the U.S.: An Update on Its Biology, Managemente, and Current Research". Journal of Intregrated Pest Management. 2 (2): 1–5. doi:10.1603/ipm11014.
- Glogoza, P (2002). "North Dakota Small Grain Insects: Cereal Leaf Beetle" (PDF). North Dakota State University. Retrieved 2013-09-18.
- Hammond, R.B.; Michel, A.; Eisley, J.B. "Cereal Leaf Beetle" (PDF). FACT SHEET Agriculture and Natural Resources. Ohio State University. Retrieved 2013-10-13.
- Tooker, J. (2009). "Entomological Notes: Cereal Leaf Beetle". Pennsylvania State University. Retrieved 2013-09-19.
- Olfert, O.; Weiss, R.M.; Woods, S.; Phillip, H.; Dosdall, L. (2004). "Potential distribution and Relative Abundance of an Invasive Cereal Crop Pest, Oulema melanopus (Coleoptera: Chrysomelidae), in Canada". The Canadian Entomologist. Cambridge University Press. 136 (02): 277–287. doi:10.4039/n03-073.
- Reay-Jones, F.P.F. (2012). "Spatial Analysis of the Cereal Leaf Beetle (Coleoptera: Chrysomelidae) in Wheat". Environmental Entomology. Entomological Society of America. 41 (6): 1516–1526. doi:10.1603/en12103.
- Bailey, W.C.; Carlson, C.E.; Puttler, B.; Stoltenow, C.R. (1991). "Expansion of the Range of the Cereal Leaf Beetle, Oulema melanopus (L.) (Coleoptera: Chrysomelidae), in Missouri and Iowa". Journal of the Kansas Entomological Society. Allen Press on behalf of Kansas (Central States) Entomological Society. 64 (4): 455–457. ISSN 0022-8567. JSTOR 25085315. doi:10.2307/25085315.
- Gutierrez, A.P.; Denton, W.H.; Shade, R.; Maltby, H.; Burger, T.; Moorehead, G. (1974). "The Within-Field Dynamics of the Cereal Leaf Beetle (Oulema melanopus (L.)) in Wheat and Oats". Journal of Animal Ecology. British Ecological Society. 43 (3): 627–640. ISSN 0021-8790. JSTOR 3527. doi:10.2307/3527.
- Olfert, O.; Weiss, R.M. (2005). "Impact of Climate Change on Potential Distributions and Relative Abundances of Oulema melanupus, Meligethes viridescens and Ceutorhynchus obstrictus in Canada". Agriculture, Ecosystems & Environment. Saskatoon, SK, Canada: Science Direct. 113: 295–301. ISSN 0167-8809. doi:10.1016/j.agee.2005.10.017.
- Dosdall, L.M.; Cárcamo, H.; Olfert, O.; Meers, S.; Hartley, S.; Gavloski, J. (May 2011). "Insect invasions of agroecosystems in the western Canadian prairies: case histories, patterns, and implications for ecosystem function". Biological Invasions. Springer Netherlands. 13 (5): 1135–1149. ISSN 1387-3547. doi:10.1007/s10530-011-9951-8.
- Tanaskovic, S.; Madic, M.; Durovic, D.; Knezavic, D.; Vukajlovic., F. (2012). "Susceptibility of Cereal Leaf Beetle (Oulema Melanopa) in Winter Wheat to Various Foliar Insecticides in Western Serbia Region" (PDF). Romanian Agricultural Research. 29. ISSN 2067-5720. Retrieved 2013-09-13.
- Bieńkowski, A.O. (March 2010). "Feeding behavior of leaf beetles (Coleoptera, Chrysomelidae)". Entomological Review. SP MAIK Nauka/Interperiodica. 90 (1): 1–10. ISSN 0013-8738. doi:10.1134/S001387381001001X.
- Delaney, K. J.; Wawrzyniak, M.; Lemanczyk, G.; Wrzesinska, D.; Piesik, D. (May 2013). "Synthetic cis-jasmone exposure induces wheat and barley volatiles that repel the pest cereal leaf beetle, Oulema melanopus L". J Chem Ecol. 39 (5): 620–9. ISSN 1573-1561. PMID 23588742. doi:10.1007/s10886-013-0281-4.
- Piesik, D.; Lemnczyk, G.; Skoczek, A.; Lamparski, R.; Bocianowski, J.; Kotwica, K.; Delaney, K. J. (2011). "Fusarium infection in maize: Volatile induction of infected and neighboring uninfected plants has the potential to attract a pest cereal leaf beetle, Oulema melanopus". Journal of Plant Physiology. 168 (13): 1534–1542. ISSN 0176-1617. doi:10.1016/j.jplph.2011.01.032.
- Piesik, D.; Panka, D.; Delaney, K. J.; Skoczek, A.; Lamparski, R.; Weaver, D. K. (2011). "Cereal crop volatile organic compound induction after mechanical injury, beetle herbivory (Oulema spp.), or fungal infection (Fusarium spp.)". Journal of Plant Physiology. 168 (9): 878–886. ISSN 0176-1617. doi:10.1016/j.jplph.2010.11.010.
- Rao, S.; Cosse, A.A.; Zilkowski, B.W.; Bartelt, R.J. (2003). "Aggregation Pheromone of the Cereal Leaf Beetle: Field Evaluation and Emission From Males in the Laboratory". Journal of Chemical Ecology. 29 (9): 2165–2175. doi:10.1023/a:1025698821635.
- Evans, E.W.; Karren, J.B.; Israelsen, C.E. (2006). "Interactions over time between cereal leaf beetle (Coleoptera : Chrysomelidae) and larval parasitoid Tetrastichus julis (Hymenoptera : Eulophidae) in Utah". Journal of Economic Entomology. 99 (6): 1967–1973. ISSN 0022-0493. doi:10.1603/0022-0493-99.6.1967.
- Evans, E.W.; Bowling, P.D.; Anderson, M.R. (2010). "Targeted sugar provision promotes parasitism of the cereal leaf beetle Oulema melanopus [electronic resource]". Agricultural and Forest Entomology. Oxford, UK : Blackwell Publishing Ltd. 12 (1): 41–47. ISSN 1461-9555. doi:10.1111/j.1461-9563.2009.00448.x.
- California Department of Food and Agriculture (2003). "Cereal Leaf Beetle". California Department of Food and Agriculture. Archived from the original on 2013-12-21. Retrieved 2013-09-13.
- Yokoyama, V.Y. (2011). "Approved Quarantine Treatment for Hessian Fly (Diptera: Cecidomyiidae) in Large-Size Hay Bales and Hessian Fly and Cereal Leaf Beetle (Coleoptera: Chrysomelidae) Control by Bale Compression". Journal of Economic Entomology. 104 (3): 792–798. ISSN 0022-0493. doi:10.1603/ec10339.
- Meissle, M.; Knecht, S.; Waldburger, M.; Romeis, J. (2012). "Sensitivity of the cereal leaf beetle Oulema melanopus(Coleoptera:Chrysomelidae) to Bt maize-expressed Cry3Bb1 and Cry1Ab" (6): 203–211.
- Buntin, G.D.; Flanders, K.L.; Slaughter, R.W.; DeLamar, Z.D. (2004). "Damage loss assessment and control of the cereal leaf beetle (Coleoptera : chrysomelidae) in winter wheat". Journal of Economic Entomology. 97 (2): 374–382. ISSN 0022-0493. doi:10.1603/0022-0493-97.2.374.
- Buntin, G.D. (2000). "3". In Robert K.D. Peterson and Leon G. Higly. Biotic Stress and Yield Loss (PDF). Boca Raton: CRC Press. pp. 34–52. ISBN 0-8493-1145-4.
- Ruppel, R.F. (1974). "A Test of Insecticides against the Cereal Leaf Beetle (Coleoptera: Chrysomelidae)". Journal of the Kansas Entomological Society. Allen Press on behalf of Kansas (Central States) Entomological Society. 47 (3): 412–415. ISSN 0022-8567. JSTOR 25082669. doi:10.2307/25082669.