Effective Sources Of Resistance Research Articles

Resistance to bean common mosaic potyvirus strains and its inheritance in some Indian land races of common bean

Evaluation of 397 common bean accessions of diverse origin revealed the presence of effective sources of resistance against bean common mosaic potyvirus strains prevalent in Himachal Pradesh, a north-western Himalayan state of India. 21 accessions viz., KR 7, KR 225, KR 295, KRC 4, KRC 7, KRC 11, KRC 12, KRC 13, KRC 16, KRC 22, Amanda, Black Turtle Soup, Contender, Hans, Great Northern UI 123, Improved Tender Green 40031, Jubila, Kentucky wonder, Monroe, Premier and Sanilac, were found resistant to NL-1n and NL-7n strains. Some of the genotypes showed strain specific resistance. Pattern of inheritance studied in Hans, Contender, KRC 4 and KRC 22 of Indian origin against strain NL-1n revealed that single dominant gene governed the resistance in Hans and Contender whereas single recessive gene determined the resistance in KRC 22 and KRC 4. SCAR marker SW13690 amplified a product of 690 bp in Hans and Contender, confirmed the presence of I gene in these cultivars. The implications of above genes in breeding for programme for BCMV resistance are discussed.

Evaluation of Fusarium Head Blight Resistance in Tetraploid Wheat (Triticum turgidum L.)

Durum wheat (Triticum turgidum L. subsp. durum) production in North America in recent years has been seriously threatened by epidemics of Fusarium head blight (FHB), caused mainly by Fusarium graminearum Schwabe [teleomorph Gibberella zeae (Schw.) Petch]. Deployment of FHB‐resistant cultivars has been considered the most effective and cost‐efficient strategy to combat this disease; however, progress in developing FHB‐resistant durum wheat cultivars has been hindered by a lack of effective sources of resistance. The objective of this study is to identify tetraploid wheat germplasm that could be used to enhance FHB resistance in durum wheat. We evaluated FHB reactions in 376 accessions of five cultivated subspecies of T. turgidum, including Persian wheat [T. turgidum subsp. carthlicum (Nevski) Á. Löve and D. Löve], cultivated emmer wheat [T. turgidum subsp. dicoccum (Schrank ex Schübler) Thell.], Polish wheat [T. turgidum subsp. polonicum (L.) Thell.], Oriental wheat [T. turgidum subsp. turanicum (Jakubz.) Á. Löve and D. Löve], and Poulard wheat (T. turgidum L. subsp. turgidum). We used point inoculation to evaluate resistance to the spread of infection over three greenhouse seasons and used the grain inoculum method of inoculation to evaluate putatively resistant accessions in two field locations. Preliminary evaluation data showed that 16 T. turgidum subsp. carthlicum and 4 T. turgidum subsp. dicoccum accessions consistently exhibited resistance or moderate resistance to FHB. These accessions likely carry genetic resistance to FHB and could be used directly in breeding programs to enhance FHB resistance in durum wheat.

Manitoba Regional Meeting, 2006 The Canadian Phytopathological Society

Effects of mutations in a bacterial biocontrol agent,Pseudomonas chlororaphis PA23, on its root-colonization ability and production of volatile compounds. S.N.P. Athukorata, W.G.D. Fernando, T.R. de kievet, and K.Y. Rashid. Department of Microbiology, University of Manitoba, Winnipeg, MB R3T 2N2, Canada; and (K.Y.R.) Cereal Research Centre, Agriculture and Agri-Food Canada, Modern Research Station, Unit 100-101, Route 100, Modern, MB R6M 1Y5, Canada. Effects of bacterial and jasmonic acid treatments on insect pests of canola. K. Bergen, W.G.D. Fernando, and N.J. Holliday.Department of Plant Science, University of Manitoba, Winnipeg, MB R3T 2N2, Canada. The role of the stringent response in Pseudomonas spp. DF41 biocontrol. J. Brucal, W.G.D. Fernando, and T.R. de kievit. Department of Microbiology; and (W.G.D.F.) Department of Plant Science, University of Manitoba, Winnipeg, MB R3T 2N2, Canada. Population structure of the blackleg pathogen Leptosphaeria maculansfrom North America.Y.Chen, B. Fristensky, and W.G.D. Fernando. Department of Plant Science, 222 Agriculture Building, University of Manitoba, Winnipeg, MB R3T 2N2, Canada. New effective sources of resistance to crown rust [Puccinia coronata f.sp avenae] in Avena sterilis. J.Chong and G. Chen. Cereal Research Centre, Agriculture and Agri-Food Canada, 195 Dafoe Road, Winnipeg, MB R3T 2M9, Canada. Breeding for canola resistance against blackleg caused by PG3 and PG4 strains of Leptosphaeria amculans. M. Dusabenyagasani and W.G.D. Fernando.Department of Plant Science, 222 Agriculture Building, University of Manitoba, Winnipeg, MB R3T 2N2, Canada. The role of pycnidiospores as primary inoculum, and assessment of disease severity on canola or rapeseed (Brassica napus) Plants infected at different growth stages. k. Ghanbarnia and W.G.D. Fernando. Department of Plant Science, 222 Agriculture Building, University of Manitoba, Winnipeg, MB R3T 2N2, Canada. Prediction of deoxynivalenol in spring wheat based on cropping practices,Fusarium spores on a wheat head, and rainfall at the flowering stage. X.W. Guo, W.G.D. Fernando, H. Sapirstein, P. Bullock, and T. Nowicki.Department of Plant Science; (H.S.) Department of Food Science; (P.B.) Department of Soil Science, University of Manitoba, MB R3T 2N2, Canada; and (T.N.) Grain Research Laboratory, Canadian Grain Commission, 1404-303 Main Street, Winnipeg, MB R3C 3G8, Canada. Breaking the linkage between the Wsm1 gene for resistance to Wheat streak mosaic virus and the alien chromatin of its origin.S. Haber, M. Pradhan, and D. Somers.Cereal Research Centre, Agriculture and Agri-Food Canada; and (M.P.) Department of Botany, University of Manitoba MB R3T 2N2, Canada. The role of pyrolnitrin produced by Pseudomonas chlororaphis PA23 in the biological control of Sclerotinia sclerotiorum in canola. R. Habibian, T.R. de Kievet, and W.G.D. Fernando.Department of Plant Science; and (R.H., T.R.K.) Department of Microbiology, University of Manitoba MB R3T 2N2, Canada. Molecular and biochemical detection of Bacillus spp. producing fengycin and bacillomycin D, Antagonistic to fungal Pathogens of canola and wheat. R. Ramarathnam, S. Bo, Y. Chen, W.G.D. Fernand, and G. Xuewen.Department of Plant Science, 222 Agriculture Building, University of Manitoba, Winnipeg, MB R3T 2N2, Canada; and (S.B., G.X.) Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural university, No. 1 Weigang Road, Nanjing 210095, China.

Utilization of alien genes to enhance Fusarium head blight resistance in wheat – A review

Fusarium head blight (FHB) is a destructive disease of wheat worldwide. Sources of resistance to FHB are limited in wheat. Search for novel sources of effective resistance to this disease has been an urgent need in wheat breeding. Fusarium head blight resistance has been identified in relatives of wheat. Alien chromatin carrying FHB resistance genes has been incorporated into wheat through chromosome addition, substitution, and translocation. Relatives of wheat demonstrate a great potential to enhance resistance of wheat to FHB.

Genetic analysis of resistance to root‐lesion nematode (Pratylenchus thornei) in wheat

AbstractThe inheritance of resistance to root‐lesion nematode was investigated in five synthetic hexaploid wheat lines and two bread wheat lines using a half‐diallel design of F1 and F2 crosses. The combining ability of resistance genes in the synthetic hexaploid wheat lines was compared with the performance of the bread wheat line ‘GS50a’, the source of resistance to Pratylenchus thornei used in Australian wheat breeding programmes. Replicated glasshouse trials identified P. thornei resistance as polygenic and additive in gene action. General combining ability (GCA) of the parents was more important than specific combining ability (SCA) effects in the inheritance of P. thornei resistance in both F1 and F2 populations. The synthetic hexaploid wheat line ‘CPI133872’ was identified as the best general combiner, however, all five synthetic hexaploid wheat lines possessed better GCA than ‘GS50a’ The synthetic hexaploid wheat lines contain novel sources of P. thornei resistance that will provide alternative and more effective sources of resistance to be utilized in wheat breeding programmes.

Resistance in cultivated barleys to Pyrenophora teres f. teres and prospects of its utilisation in marker identification and breeding

Net type net blotch (NTNB) is a prevalent disease in Australia, causing significant losses in barley yield and quality. Its impact can be reduced with the identification and utilisation of effective sources of resistance. Sixty-nine cultivated barley lines were screened as seedlings against 9 isolates of Pyrenophora teres f. teres from Australia, and in the field in Western Australia. Resistance expressed in seedlings was frequently expressed in adult plants in the field, indicating that these sources are potentially useful for resistance breeding. Of these lines, 24 with the best overall resistance were identified, which could be used against virulence diversity present in P. teres f. teres in Australia.As a prelude to the evaluation of established mapping populations in the Australian Barley Molecular Marker Program, 42 parental lines were screened against a range of Australian isolates of P. teres f. teres. Variation in net blotch responses was observed among parents of the mapping populations. Ten principal mapping populations appear to provide opportunities to map resistances and identify molecular markers linked to NTNB resistance genes effective against Australian pathotypes.

Selections from barley landrace collected in Libya as new sources of effective resistance to powdery mildew (Blumeria graminis f.sp. hordei)

Powdery mildew on barley (Hordeum vulgare L.) caused by the pathogen Blumeria graminis f.sp. hordei occurs worldwide and can result in severe yield loss. Because agronomical methods to control the disease are not completely effective, cultivars with genetic resistance are needed. Therefore, there is a need to describe new sources of genes that confer resistance to barley powdery mildew. This study was conducted to determine the genetic basis of resistance to powdery mildew in three selections 995-1-1, 995-1-2, 995-1-3 from barley landrace 995 (ICB 112840) collected in Al Aziziyah district, Tripolitania, Libya. Landrace originated from InternationalCenter for Agricultural Research in the Dry Areas – ICARDA, Aleppo, Syria. To determine the number of genes, the types of genes action and the gene loci in tested lines two types of crosses were made: (1) the lines were crossed to the susceptible cultivar Pallas, (2) the lines were crossed with Pallas isoline P22 carrying gene mlo5. The parents and progeny F2 were evaluated with isolate R303.1 for the powdery mildew resistance. Based on segregation ratios we found that resistance in these three selections was determined by a single recessive gene allelic to the Mlo locus occurring in Pallas isoline P22. In addition tested lines showed resistance reaction type 0(4) characteristic only for genes mlo. The value of new identified sources of highly effective powdery mildew resistance to breeding programs and barley production is discussed.

Current Virulence of Pyrenophora teres on Barley in Western Australia.

Studies on variation, occurrence, and distribution of virulence in Pyrenophora teres are helpful to identify effective sources of resistance that can be used for barley breeding in Western Australia. Seventy-nine isolates of Pyrenophora teres were collected from different barley fields of Western Australia in 1995-96. Seventy-four induced net type symptoms (P. teres f. teres) and five induced spot type symptoms (P. teres f. maculata). Net type isolate responses on 47 barley lines were similar to the range of responses induced by nine historical isolates collected in the region between 1975 and 1985. These net type isolates were classified into two distinct groups based on virulence to the cultivar Beecher. Isolates were further classified into eight groups based on minor pathogenic variation among the population. The virulence phenotype present in an eastern Australian isolate was not observed in any isolates collected from Western Australia. An analysis of variance on a subset of 12 net type isolates indicated a significant line × isolate interaction (P < 0.001), with the interaction term variance component four times larger than the error variance. Based on these studies, the virulence among net type isolates has remained stable in Western Australia for the last 19 years. Spot type isolates were collected from a wider geographic area than previously reported and varied in virulence based on response to barley line Herta. Variation in spot-type isolates is reported for the first time from the region. The results from this study are being used in the development of resistant varieties.

RESISTANCE TO POWDERY MILDEW IN BARLEY LANDRACES FROM MOROCCO

A total of 44 accessions of barley landraces from Morocco were screened for resistance to powdery mildew. Nineteen of the tested landraces showed resistance reactions and 45 lines were selected. Sixteen of these lines were tested at the seedling stage with 17, and another 29 lines with 23 differential isolates of powdery mildew respectively. Six lines (170-1-3, 172-3-2, 173-1- 2, 181-3-5, 201-3-2, 201-3-3) were identified that have resistance to all the prevalent European powdery mildew virulence genes. It was postulated that 3 different resistance alleles (Mlat, Mla6, and Mla14) are present in the tested lines either alone or in combination. Among the tested lines 8 (18.0%) had one specific gene for resistance and 37 (82.0%) had a combination of different genes for resistance. Among specific resistance alleles the most common was Mlat whose presence was postulated in 20 (44.4%) of the tested lines. The distribution of reaction type indicated that about 79.0% of all reaction types observed were classified as powdery mildew resistance (scores 0, 1 and 2). The majority (65.0%) of resistance reaction types observed in the tested lines was intermediate reaction type 2. The use of new effective sources of resistance from Moroccan barley landraces for diversification of resistance genes for powdery mildew in barley cultivars is discussed.

Sources of powdery mildew resistance in barley landraces from morocco

A total of forty eight accessions of barley landraces from Morocco were screened for resistance to powdery mildew. Twenty two (46%) of tested landraces showed resistance reactions and thirty four single plant lines were selected. Eleven of these lines were tested in seedling stage with seventeen and another twenty three lines with twenty three isolates of powdery mildew respectively. The isolates were chosen according to the virulence spectra observed on the ‘Pallas’ isolines differential set. Line 229–2–2 was identified with resistance to all prevalent in Europe powdery mildew virulence genes. Lines 230–1–1, 248–1–3 showed susceptible reaction for only one and lines 221–3–2, 227–1–1, 244–3–4 for only two isolates respectively. Three different resistance alleles (Mlat, Mla6, and MLA14) were postulated to be present in tested lines alone or in combination. In thirty (88%) tested lines it was impossible to determine which specific gene or genes for resistance were present. Most probably these lines possessed alleles not represented in the ‘Pallas’ isolines differential set. The distribution of reaction type indicated that about 71% of all reaction types observed were classified as powdery mildew resistance (scores 0, 1 and 2). Majority (79%) of resistance reaction types observed in tested lines was intermediate resistance reaction type two and twenty three lines (68%) showed this reaction for inoculation with more than 50% isolates used. The use of new effective sources of resistance from Moroccan barley landraces for diversification of resistance genes for powdery mildew in barley cultivars was discussed.

Civil Society and the "Art of Association"

Civil Society and the “Art of Association” William A. Galston (bio) The past two decades have witnessed an explosion of interest in “civil society” on the part of both scholars and political activists. There are four principal reasons for this development. In the first place, events in the former Soviet-bloc nations of Central Europe dramatized the ways in which civil associations—labor unions, networks of dissident intellectuals, and churches, among others—could serve as effective sources of resistance to oppressive governments. Second, “nongovernmental organizations” emerged throughout the world as fora for previously unheard voices addressing issues of transnational significance such as the environment, population, the status of women, human rights, and even disarmament. (Witness the Rio, Cairo, and Beijing conferences, the influence of Amnesty International, and the anti-land mine treaty.) Third, the concept of civil society—a realm of nonprivatized collective action that is voluntary rather than compulsory and persuasive rather than coercive—provided a basis for criticizing the excesses of both the state and the market. The Left, sobered by the limits of centralized governmental action, began looking to voluntary associations as an alternative way of fostering civic engagement and promoting public purposes. Conservatives, troubled by the amorality of the market and by its corrosive effects on social institutions, turned to voluntary associations as sources of stability and virtue. (Remarkably, the leading contenders for the Democratic and Republican presidential [End Page 64] nominations in the United States in the year 2000 have both called for an expanded role for voluntary associations—including faith-based institutions—as partners with government.) Finally, the concept of civil society responded to the anxiety throughout the advanced industrialized world (and especially in the United States) that the traditional sources of socialization, solidarity, and active citizenship were becoming dangerously weak. Robert Putnam’s “Bowling Alone,” published in these pages five years ago, 1 touched precisely this nerve of concern, sparking a conceptual, empirical, and political debate that rages unabated today. 2 Not surprisingly, this upsurge of interest in voluntary associations has coincided with renewed attention to the writings of Alexis de Tocqueville, who is seen (not without reason) as the locus classicus for this subject. After all, it was Tocqueville who declared that “in democratic countries the science of association is the mother of all science. . . . If men are to remain civilized or to become so, the art of associating together must grow and improve among them in the same ratio in which the equality of conditions is increased” (II, 110). Although no noncontemporary writer is more frequently cited by American academics and politicians, Tocqueville is more often quoted than understood. I will try here to place Tocqueville’s discussion of voluntary associations in Democracy in America in what I believe to be its proper context and to examine its relevance for contemporary politics. Political Associations Tocqueville begins his discussion of voluntary organizations in democracies with politics rather than civil society (I, ch. xii). His analysis of political association is less well-known than that of civil association but, as we shall see, it is no less important. Tocqueville distinguishes three types (or phases) of free political association—aggregations of shared belief arising from free public speech, especially through organs of mass communication such as newspapers; freedom of assembly; and most significantly, formal conventions organized around political parties or burning national issues. Free political associations serve as counterweights both to directly coercive concentrations of political power and to the more subtle (but no less significant) threat to democratic liberty that he famously labels the “tyranny of the majority.” Perhaps most surprising to contemporary readers is Tocqueville’s emphasis on the threat posed by freedom of political association, or by its abuse. At one point he declares that “unlimited freedom of association cannot be entirely assimilated to the liberty of the press. The one is at the same time less necessary and more dangerous than [End Page 65] the other. A nation may confine it within certain limits without forfeiting any part of its self-directing power; and it may sometimes be obliged to do so in order to maintain its own authority” (I, 193). Our surprise abates when we appreciate the context of...

Case study of host-pathogen interaction: tomato (Lycopersicon spp.)–tomato powdery mildew (Oidium lycopersici) – a review

The present paper tries to demonstrate progress and gap of knowledge in plant pathology through the tomato - tomato powdery mildew host-pathogen interaction as a model. Tomato powdery mildew (Oidium lycopersici) has caused serious damages on glasshouse tomato (Lycopersicon esculentum) crops during the last approximately 15 years. Although the absence of tcleomorph stage did not allow exact taxonomic classification of the pathogen, comparative morphological studies using light and scanning electron microscopy revealed that Oidium lycopersici might be included to the Erysiphe sect. Erysiphe (close to Erysiphe aqui­ legiae var. ranunculi). Effective resistance sources to 0. lycopersici were found mainly in wi ld Lycopersicon hirsutum and L. penne/lii (confirmed by testing with four different 0. lycopersici isolates). Available information on the pathogenic variability of 0. lycopersici is given; host range experiments revealed considerable differences in abi lity of different 0. lycopersici isolates to infect cucumber and tobacco. postulating existence of different pathotypcs lformae specialist of pathogen. Similarly, some Lycopersicon spp. genotypes showed remarkable differential reactions with pathogen isolates, indicating existence of different pathogen races. Information regarding recently detected mechanisms and basis of resistance in Lycopersicon spp. are also men­ tioned. However, more research based on classical, biochemical and molecular approaches is also needed.

Evaluation of commercial Lycopersicon esculentum hybrids for resistance to tomato spotted wilt tospovirus (TSWV) in Spain

SummaryThe recent commercialization of tomato hybrids resistant to tomato spotted wilt tospovirus (TSWV) in Spain by different seed producer companies has reduced the economic losses caused by this virus. However, the presence of TSWV-infected plants or fruits showing peculiar ring spots in commercial fields planted with these hybrids have prompted this study. A comparative assay of mechanical inoculation and natural infection by thrips of TSWV provided different results. The assays carried out using different hybrids, supposedly resistant to TSWV, have shown that the presence of the SW-5 gene from cultivar `Stevens' is the only effective source of resistance; although a low proportion of susceptible plants can be found in the seed lots. In some of them, the virus partially overcame this resistance, although no changes in infectivity of virus isolates has been detected; in other cases there is a typical infection of the virus by absence of SW-5 gene. However, its presence seems to be more important in the field assay of ring spots caused by TSWV on some tomato fruits produced by apparently healthy plants containing the SW-5 gene. The evidence presented here indicated that the probably the cause is the feeding of viruliferous thrips, which implies new epidemiological considerations because the time of infection and the economic losses with respect to infectious process of susceptible tomato crops are different and the control measures would need to be modified.

New Resistance to Virulent Root‐Knot Nematodes Linked to the Rk Locus of Cowpea

Screening of cowpea [Vigna unguiculata (L.) Walp.] germplasm for additional resistance to the root‐knot nematodes, Meloidogyne incognita (Kofoid and White) Chitwood and M. javanica (Treub) Chitwood, revealed an accession (IT84S‐2049) from Africa with resistance to diverse populations of both root‐knot species. The resistance was effective against nematode isolates that are virulent to the resistance gene Rk present in commercial cowpea cultivars, in addition to isolates of gene Rk‐avirulent populations. This study was conducted to elucidate the inheritance of a newly identified, highly effective source of resistance, and to determine its relationship to gene Rk in existing cultivars. Egg mass production on root systems of plants in growth pouches was used to assess susceptibility‐resistance of F1, F2, F3, BC1F1, BC1F2, and TC1 populations generated from crosses of IT84S‐2049 with California Blackeye no. 3 (CB3, susceptible), CB5, or CB46 (both possessing Rk). Segregation of resistance to gene Rk‐virulent M. incognita in progenies from IT84S‐2049 × CB3 showed that resistance in IT84S‐2049 is governed by one dominant nuclear gene. No susceptible recombinants were found among 1206 F2 and 1144 TC1 progeny from IT84S‐2049 × CB5 or CB46 and inoculated with Rk‐avirulent M. incognita (used to detect both resistance phenotypes). Resistance in IT84S‐2049 is conferred by an additional dominant allele of the Rk locus, or by another gene locus very tightly linked to Rk within 0.17 map units. We propose the symbol Rk2 to designate this new resistance factor in IT84S‐2049. Thus, Rk may be a complex nematode resistance locus, analogous to those reported for other plant pathogen‐host combinations.

Powdery Mildew Resistance in Winter Wheat: I. Gene Number and Mode of Inheritance

Few widely effective sources of resistance to powdery mildew, caused by Blumeria graminis (DC.) E. O. Speer f. sp. tritici Em. Marchal, have been identified in wheat (Triticum aestivum L.), and the identity of resistance genes in many cultivars is unknown. Ten winter wheat lines selected from the 1982 International Winter Wheat Mildew and Rust Nurseries were studied to characterize gene number and mode of inheritance of resistance to powdery mildew. Each of the lines were crossed to the susceptible cultivar Chancellor. Seedlings of the parental lines, F1, F2, BC1 (Chancellor × F1), and F3 populations were inoculated with isolate 127 of B. graminis in the greenhouse and evaluated for powdery mildew reaction. All parents were resistant, except for ST1‐25, which had an intermediate reaction type. Genetic analyses revealed that resistance in C39 and SI5 is conferred by three dominant genes, and resistance in A55‐2, R107, GO4779, OK75R3645, and Bulk PV63‐6 is governed by single partially dominant genes. Data from F2, F3, and BC1 populations, derived from crosses between ‘Armada’ and Chancellor, were inconsistent but indicated that Armada has at least one dominant gene for resistance, which likely is Pm4b us previously postulated. Resistance in VPM1 and ST1‐25 is governed by one recessive gene in each fine. Three to 11 different resistance genes are represented among the 10 parents.

Cluster analysis as a method for evaluation of genetic similarity in specific host — parasite interaction (Lactuca sativa — Bremia lactucae)

In gene-for-gene systems, specificity of hostparasite interactions is most often estimated qualitatively using the symbols +, −, (i.e. susceptibility and/or resistance). In large sets (interaction patterns) it becomes impossible to analyze numerous data by mere comparison. This is overcome by application of cluster analysis. In our experiments the methods in question were used to estimate the data obtained in a study on interactions between more than 220 Lactuca sativa cultivars and 12 Bremia lactucae physiological races (isolates) of Czechoslovak origin. The matrix of similarity coefficients was analyzed by hierarchical clustering. Similarity and/or dissimilarity of host R-genotypes was graphically expressed using the method of two principal components. The results obtained are related to genetic constitution of race specific resistance of the host and the possibility of predicting effective resistance sources.

Sources of resistance to Mayetiola Destructor in breadwheat and durum wheat in Morocco

Grain yield reductions of both breadwheat (Triticum aestivum L.) and durum wheat (Triticum turgidum L. var. durum) caused by attacks of Hessian fly (Mayetiola destructorSay) are second perhaps only to those caused by inadequate soil moisture in Morocco. To identify effective sources of resistance, 817 entries of common wheat and durum wheat reported to be resistant to Hessian fly were evaluated under natural infestations in Morocco. A large number of genes conferring virulence are present in populations of Moroccan Mayetiola. The genes H1, H2, H3, h4, H6, H7, H8, H9, H10, H11, H14, H15, and H16 as well as the ‘Marquillo’, ‘Kawvale’ and PI 94587 resistance sources are not useful for cereal improvement in North Africa. ‘Luso’, which has the gene H12, also appeared susceptible in limited testing. Genotypes having the genes H5 and H13 were identified as significantly reducing larval survial in natural populations of Mayetiola. Of 11 resistant breadwheats identified with unknown genes, seven were from Portugal and three were from the Soviet Union. Although none of the durums tested had high levels of reistance, the two most promising durums were from Portugal. It is proposed that initially H5 be deployed in durum wheats and H13 be used in common wheat improvement. Leaf pubescence appears of little use in reducing the larval survival of Mayetiola.