insect-damaged wheat: suni bug, cereal bug, sunn pest, wheat bug, shield bug, shell bug
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DESCRIPTIONWheat quality can be defined in terms of inherent quality attributes those under genetic control and seasonal quality attributes. One of the parameters of wheat quality is insect-damage.
- 1. Digital Re-print -September | October 2012Insect-damaged wheat: suni bug, cereal bug, sunnpest, wheat bug, shield bug, shell bug Grain & Feed Milling Technology is published six times a year by Perendale Publishers Ltd of the United Kingdom. All data is published in good faith, based on information received, and while every care is taken to prevent inaccuracies, the publishers accept no liability for any errors or omissions or for the consequences of action taken on the basis of information published. Copyright 2010 Perendale Publishers Ltd. All rights reserved. No part of this publication may be reproduced in any form or by any means without prior permission of the copyright owner. Printed by Perendale Publishers Ltd. ISSN: 1466-3872 www.gfmt.co.uk
2. FEATUREInsect-damaged wheat: suni bug, cereal bug, sunn pest, wheat bug, shield bug, shell bugby Prof. Dr. M. Hikmet Boyacioglu, Group R&D Director-Cereal Foods Institute Director, Doruk Group Holding, Turkey This article was derived from the presentation made in 4th International Mhlenchemie Symposium, September 8-9, 2011.Wheat quality can be defined In New Zealand, Nysius huttoni is thought to time of ripening of wheat, or a combinationin terms of inherent qualitybe the cause of the problem (Lorenz andof these factors.attributes those under geneticMeredith, 1988). According to Paulian and Popov (1980)control and seasonal quality attributesThis article reviews the economical some 10-15 million hectares (25-37 million(Table 1, 2). One of the parameters importance and varietal susceptibility ofacres) of cereal cultivation are at risk, andof wheat quality is insect-damage.insect damage, methods for the predictionin certain years chemical treatments may beof damage, effects on baking quality, suni bug applied to seven million hectares (about 17It is widely accepted that insect-damaged management and improvement of breadmillion acres) in an attempt to limit the dam-wheat contains a bug salivary proteinase, quality. age, especially if the crop is wheat.which causes rapid relaxation of dough A report prepared and published in 1993and, consequently, results in the productionEconomical importanceby FAO/ICARDA authorities, states thatof loaves with poor volume and texture The economical importance of the cereal about 1.3 million acres field is inflicted by E.(Cressey, 1987, Every et al., 1996). Damage bug E. integriceps on the wheat plant con- integriceps, and a part of 582.000 acres areto wheat and its baking quality, due to pre-centrates on two main points of negativeharvest insect attack, has been reportedeffects. First of all, the bite of only oneacross the world including Germany, Spain,mature insect, which survives under the Table 1: Inherent Quality AttributesHungary, Italy, Turkey, Iran, Iraq, and New winter conditions, is more than enough to Protein type and quality (extensibility, stabilityZealand amongst others. kill the plant body. Yield losses attributableto mixing),Damage to the wheat crop in Syria,to direct feeding typically range between 50Potential to produce grain with proteinwhere nearly the whole harvest in a relativelyand 90 percent. content in a given range (either high or low),small area was affected, caused a loss of 24 Secondly, five nymph generations feedingGrain hardness,million Francs in 1924. The affected area on the ear of the plant have completed theirPotential to produce grain having a highdoubled in 1925 and was six-fold in 1926, larva era, but are still not mature insectsmilling yield (high milling release),but damage decreased in 1927 and 1928,or the young bugs increase the rate andalthough the insect damage covered a larger number of bitten kernels, which in turn Resistance to weather damage-dormancy.area. Part of Ukraine also suffered severeresult in a sharp decline in the quality ofdamage in 1901 and 1909. In Turkey, insectbread.damage to wheat, first time, was reportedIf immature grain is attacked in the field Table 2: Seasonal Quality Attributesin 1932 and 1937. The damage caused byby insects, there is damage to the mature Soundness and maturity,bugs to the New Zealand crop is usually low,grain. The dough made from this grain isPlumpness and hence actual milling yield,but its incidence varies from year to year. very weak, owing to the action of a proteaseThere have been five major outbreaks of bug presumably injected by the insect. BecauseActual protein content,damage in New Zealand, since the problemof the severe results on dough formationWeather damage,was first reported in 1936. The problem and baking quality, bug-damaged grain isContent of broken, shriveled, dry green, orregained importance after the 1980s inseverely downgraded, generally warranting frosted grains,Afghanistan, Iran, Iraq, Syria, Russia, Bulgaria, only feed grade prices (Wrigley and Batey,Contamination of foreign seeds,and Romania as well as in Turkey (Lorenz. 2003; Trissi, 2006).Presence of unmillable material, e.g. chaff,and Meredith, 1988). In recent years, it has The damage caused by the cereal bugwhite heads,reappeared in Black Sea region. shows important differences which are influ-Presence of moldy, insect damaged, orThe insects which cause the damage have enced by a number of criteria such as cli-infested grain,been identified a Eurygaster integriceps andmate and weather conditions, availability ofMoisture content.Aelia rostrata in Europe and in the Near East.water, characteristics of the wheat type, and22 | September - october 2012Grain&feed millinG technoloGy 3. FEATUREthus treated with pesticides. The calculatedcost for the treatment of one acre withpesticides is about US$10, making a total ofUS$5,870,000.In a report prepared by specialists aboutthe cereal bug problem in Turkey, it wasstated that should no plant protection meas-urement and precautions be taken againstthe insect during plague years, the damagecould reach a ratio of 90 percent to as muchas 100 percent. Moreover, if sufficient pre-cautions are taken against the plague, savingswith an amount of US$40,000,000 could beachieved (Knac, 1994).Varietal susceptibilityMany researchers have noted that thegenetic quality of the insect-damaged vari-ety influences the degree of quality dete-and the soft type breeding line WW378 is much less (Knac, 1994).rioration (Cressey et al, 1987). Paulian andwas clearly the most susceptible to NysiusPopov (1980) reported that hard wheatsinfestation.Effects on baking qualityare attacked more severely by the insect E. A similar study performed in Turkey byIn 1931, wheat producing a slimy glutenintegriceps than soft wheats. Knac (1994) has proven that the cereal bugwas reported by Berliner. This wheat wasAlso, in New Zealand, the semi-hard E. integriceps prefers to attack white, softcompletely unsuitable for processing intowheat cultivar Karamu has shown moreand/or semi-hard wheats and it is astonish- bread because doughs formed from the floureffects and the soft, white wheat cultivaring that the first priority of the insect is to quickly relaxed, becoming very sticky andArawa has fewer effects of bug damage thanselect those high quality kernels. The same difficult to mould.other cultivars (Every et al, 1996). In a study study showed that E. integriceps rarely attacks Loaves of bread baked from these doughsto investigate the susceptibility of varioushard wheats. The latest genotypes of wheattypically had low volume, coarse texture, andNew Zealand wheat cultivars and breed-which the bug preferred to attack were hard knobbly tops. Gluten was washed out of theing lines to attack by N. huttoni, Every et alred wheats. Also it was observed that the flour with difficulty, and instead of having the(1996) stated that the hard wheat cultivardensity of the cereal bug among wheat hav-normal elastic properties; it was slimy orDomino was clearly the least susceptibleing thick, hard and tightly adhered seed coatsrotten (Lorenz and Meredith, 1988).Grain &feed millinG technoloGy September - october 2012 | 23 4. FEATUREDough made from flour stinkbug-damagedwheat has lost much of its elasticity and issticky or slimy.A review of several overseas studies(Nuorteva and Veijola, 1954) indicates thatin general a level of two to five percentaffected grain is necessary before bakingquality is degraded.Meredith (1970) claimed that three tofour bug-damaged grains per thousand couldseriously affect baking quality.Effects of attack by suni bug were studiedon the size of Russian grains and percentof damaged grain was found to be higherin smaller fractions; the proportion of fully Figure 1. Farinogram, based on Brabender Farinograph Standarddestroyed grains and the degree of damage Procedure, shows 2.6% insect damage on wheat on the whole sample set both increased in Courtesy of DORMAR Flour Mills, Turkey.smaller fractions (Yakovenko, 1985).The influence of wheat infestation by sunibug on bread making properties of Bulgarianwheat was investigated and results showedthat suni bug infestation had a marked impacton bread making properties, with even onepercent infestation affecting bread quality(Vasileva et al., 1998).Methods for the prediction ofdamagePhysical Tests - Currently, the most widelyused method to determine insect damagein wheat is the visual method. Wheat bugdamage to wheat kernels can be examinedvisually since they are recognised as pale,Figure 2. Extensigram, based on Brabender Extensigraph Standard slightly elevated patches, often with one or Procedure, shows 2.6% insect damage on wheat more black dots considered to be the marks Courtesy of DORMAR Flour Mills, Turkey.of bug stylet punctures. No such damagecan be found in uninfested samples.Chemical and Biochemical Tests - Theprediction of the extent of insect-damageto wheats prior to milling has gained impor-tance as the enzyme secreted by cereal bugsresults in the production of runny and stickydough and, subsequently, a low quality ofbread.Most of the test methods determinethe qualit