Wild Hop Research Articles

Relationship Among Volatile Organic Compounds and Sensory Properties in Craft Beer

Hops flowers are used to impart highly desirable hoppy aromas in beer. The emergence of craft brewing caused an increase in the popularity of intense hoppy beer determining a breeding trend for new hop flavour varieties that differ in terms of oil contents and compounds. The aim of this work is to examine the relationship between volatile organic compounds (VOCs) and sensory properties in an Italian craft beer brewed with 2 selected Italian wild hop varieties and a commercial one (Cascade) grown in 2 sites with different environmental condition. Since the beer aroma is represented by hop flowers and so they increase incise in the finished product. In this study, 6 beer samples produced by an Italian microbrewery using hop plants were collected and analysed for Volatile Organic Compounds (VOCs) profiles using a PTR-TOF-MS and a sensory evaluation (panel and consumer tests). Multivariate statistical analyses (PCA and CANOCO) showed as “Cascade commercial” sample marks with the highest intensity of taste in comparison to other samples. Results showed low interest for the aromas the hops imparted to the beers produced in relationships to the commercial variety grown and bought. In addition, the grown commercial cascade resulted to be interesting, producing a modified aroma profile when compared to its commercial counterpart. Finally, this study showed an initial contribution to screen other wild genotypes to identify new hops for direct use or breeding with new characteristics that can be used for the production of beer with a modified aroma.

Effect of different extraction solvents on phenolic compounds and antioxidant capacity of hop flowers (Humulus lupulus L.)

We investigated the potential of wild hop and determined the effects of different solvent extractions on quality and quantity of hop extracts. Three different solvents - aqueous-ethanol (75%), methanol and acetone - were applied to elicit the secondary metabolites of Humulus lupulus L. cones by automatic Soxhlet system, and extraction yield, total phenolic content, total flavonoid content and antioxidant capacity were compared. The antioxidant activity tests, DPPH, ABTS and FRAP, were used to analyze the antioxidant capacity of extracts. The crude extract obtained by aqueous-ethanol, methanol and acetone extraction were 98.65±5.2, 61.39±3.25, 69.28±4.1 mg g‑1 dry matter, respectively. The total phenolic content (TPC) as well as the total flavonoid content (TFC) of aqueous extracts exhibited the highest values. Also the antioxidant activity of extracts was different: the acetone extract had the highest value of IC(50) in the DPPH test, while the methanol extract has the highest antioxidant activity (1.79±0.25 mM Fe2+ g(‑1)) in the FRAP test, and the best result of percent inhibitors of ABTS (58.12±0.48) was observed for the aqueous-ethanol extract. In addition, ABTS value in aqueous-ethanol extract was 6.45±0.33 mmol Trolox equivalent g‑1 sample, significantly higher than others. No significant correlation was found among antioxidant measurement methods. Overall, 75% ethanol is suggested for the extraction of phenolic compounds from hop flowers due to its polarization diversity. Finally, the wild hop flowers have high antioxidant activity and a remarkable amount of phenolic compounds. They could be applied in food industries as a rich source of antioxidant activity. Characterization of the genetic diversity of wild hops is underway.

Identification and genetic structure of wild Italian Humulus lupulus L. and comparison with European and American hop cultivars using nuclear microsatellite markers

Nine genic SSR loci were used to evaluate the genetic diversity and identify accessions in wild Italian Humulus lupulus L., in comparison with widely cultivated European and U.S. commercial cultivars. A collection of 80 wild hop samples from Italy and 43 hop cultivars from Europe and U.S., were characterized. Allelic frequency analysis revealed 65 distinct Italian genotypes and differentiated all the commercial cultivars; moreover, specific alleles were observed for wild and cultivated hops. The number of alleles identified in the wild population were 104 and 123 within all the accessions. The maximum polymorphic information content was evidenced for locus HlGA23 in the Italian wild population and in the whole set of accessions (0.905 and 0.902 respectively). The dendrogram constructed from Euclidean distance with the UPGMA method showed two main clusters, one including commercial American and European accessions and one mostly composed by wild Italian accessions. Model-based clustering (Bayesian method) placed the accessions into five germplasm groups, one of which was characterized by Italian genotypes only. The study showed for the first time the great biodiversity present in Italy, and the remarkable differences with European and American hops. It was also found that within the population of north-central Italy a large genetic variability is present, suited to be studied and exploited; this genetic wealth could be used in future breeding programs in order to develop new hop varieties carrying characteristics useful for brewers.

Characterization of host-dependent mutations of apple fruit crinkle viroid replicating in newly identified experimental hosts suggests maintenance of stem-loop structures in the left-hand half of the molecule is important for replication.

Apple fruit crinkle viroid (AFCVd) is a tentative member of the genus Apscaviroid, family Pospiviroidae. AFCVd has a narrow host range and is known to infect apple, hop and persimmon as natural hosts. In this study, tomato, cucumber and wild hop have been identified as new experimental herbaceous hosts. Foliar symptoms were very mild or virtually undetectable, but fruits of infected tomato were small, cracked and distorted. These symptoms resemble those observed on some AFCVd-sensitive apple cultivars. After transfer to tomato, cucumber and wild hop, sequence changes were detected in a natural AFCVd isolate from hop, and major variants in tomato, cucumber and wild hop differed in 10, 8 or 2 nucleotides, respectively, from the predominant one in the inoculum. The major variants in tomato and cucumber were almost identical, and the one in wild hop was very similar to the one in cultivated hop. Detailed analyses of the host-dependent sequence changes that appear in a naturally occurring AFCVd isolate from hop after transfer to tomato using small RNA deep sequence data and infectivity studies with dimeric RNA transcripts followed by progeny analysis indicate that the major AFCVd variant in tomato emerged by selection of a minor variant present in the inoculum (i.e. hop) followed by one to two host-dependent de novo mutations. Comparison of the secondary structures of major variants in hop, tomato and persimmon after transfer to tomato suggested that maintenance of stem-loop structures in the left-hand half of the molecule is critical for infection.

Clustering analysis of different hop varieties according to their essential oil composition measured by GC/MS

AbstractThis study describes the analysis of total hops essential oils from 18 cultivated varieties of hops, five of which were bred in Lithuania, and 7 wild hop forms using gas chromatography-mass spectrometry. The study sought to organise the samples of hops into clusters, according to 72 semi-volatile compounds, by applying a well-known method,

First report of Dahlia latent viroid and Potato spindle tuber viroid mixed‐infection in commercial ornamental dahlia in Japan

Dahlia (Asteraceae) has been cultivated since 1841 in Japan. Two viroids belonging to the family Pospiviroidae, Potato spindle tuber viroid (PSTVd) and Dahlia latent viroid (DLVd), were identified separately from dahlia plants in Japan and in the Netherlands, respectively (Tsushima et al., 2011; Verhoeven et al., 3). Because DLVd was characterised as a novel species, the findings drew attention towards the study of DLVd infection in dahlia and its potential risk in domestic dahlia cultivation. A total of four dahlia samples infected with PSTVd-dahlia (Tsushima et al., 2) were collected, and total RNA was extracted from approximately 200 mg of leaf tissue using TRIzol® reagent (Life Technologies, Carlsbad, USA) according to manufacturer's instructions. RNA was separated in 2-dimensional polyacrylamide gel (2D-PAGE) (Schumacher et al., 1) and two specific bands appeared, one corresponding to PSTVd infection and the other being unknown (Fig. 1). The unknown circular RNA samples were gel-excised and first tested with PSTVd-specific primers using a two-step reverse-transcription-polymerase chain reaction (RT-PCR) (Tsushima et al., 2), with, however, negative results. Therefore, a DLVd-specific primer set, DLVd-P1 (5'-GGGGCTCCTCAGAGAGTCTC-3') and DLVd-P2 (5'-GGGGCAACTCCGAGAGTGCTG-3') (Verhoeven et al., 3), was then used in two-step RT-PCR for the unknown viroid-like circular RNAs. The amplified DNA bands of the expected size (~340 bp) from these positive samples were purified, ligated to pGEM®-T easy vector (Promega, Madison, USA) and sequenced. Identical 342 bp sequences were obtained from all four dahlia isolates (GenBank Accession No. LC036322), corresponding with DLVd reported from the Netherlands (JX263426). Furthermore, a total of 78 dahlia leaf samples were collected from fields around Japan, irrespective of disease symptoms, and verified by two-step RT-PCR using the same DLVd-specific and pospiviroid-specific primers (Tsushima et al., 2). Of these samples, DLVd infection was detected in 38, suggesting that DLVd is widespread in Japan. New PSTVd infection was not found. To evaluate the pathogenicity of DLVd and PSTVd, these viroids were co-inoculated into wild hop (Humulus lupulus var. cordifolius) and dahlia seedlings. DLVd alone was inoculated into members of the Asteraceae family, Chrysanthemum pacificum, Tithonia rotundifolia, Helianthus annuus and Glebionis coronaria. Inoculated dahlia seedlings were positive for both DLVd and PSTVd, but wild hop and the remaining members of Asteraceae were negative. Dahlia seedlings that were positive for DLVd and PSTVd showed mild leaf curling in the early stage of growth (Fig. 2). To the best of our knowledge, this is the first report of DLVd infecting commercial dahlia in Japan and also of the mixed-infection of DLVd and PSTVd in commercial dahlia plants. A possible negative synergistic interaction of DLVd and PSTVd during dahlia cultivation must be considered. This work was supported in part by Japan Society for the Promotion of Science KAKENHI grant no. 24380026. TT received Research Fellowship of the Japan Society for the Promotion of Science.

The Draft Genome of Hop (Humulus lupulus), an Essence for Brewing.

The female flower of hop (Humulus lupulus var. lupulus) is an essential ingredient that gives characteristic aroma, bitterness and durability/stability to beer. However, the molecular genetic basis for identifying DNA markers in hop for breeding and to study its domestication has been poorly established. Here, we provide draft genomes for two hop cultivars [cv. Saazer (SZ) and cv. Shinshu Wase (SW)] and a Japanese wild hop [H. lupulus var. cordifolius; also known as Karahanasou (KR)]. Sequencing and de novo assembly of genomic DNA from heterozygous SW plants generated scaffolds with a total size of 2.05 Gb, corresponding to approximately 80% of the estimated genome size of hop (2.57 Gb). The scaffolds contained 41,228 putative protein-encoding genes. The genome sequences for SZ and KR were constructed by aligning their short sequence reads to the SW reference genome and then replacing the nucleotides at single nucleotide polymorphism (SNP) sites. De novo RNA sequencing (RNA-Seq) analysis of SW revealed the developmental regulation of genes involved in specialized metabolic processes that impact taste and flavor in beer. Application of a novel bioinformatics tool, phylogenetic comparative RNA-Seq (PCP-Seq), which is based on read depth of genomic DNAs and RNAs, enabled the identification of genes related to the biosynthesis of aromas and flavors that are enriched in SW compared to KR. Our results not only suggest the significance of historical human selection process for enhancing aroma and bitterness biosyntheses in hop cultivars, but also serve as crucial information for breeding varieties with high quality and yield.

Content of selected secondary metabolites in wild hop

AbstractWe focused on the determination of biologically active secondary metabolites in wild hops over the course of the vegetation period in four selected sites in Piešťany. Hop was collected in four collection periods in 2010. The objects of research were the leaves of male and female plants, and female cones. Analysis of the extracts from wild hop confirmed differences in total content of polyphenols, flavonoids between the localities and in the growing seasons over the vegetation period. The extracts from leaves from the first harvest in localities “gSládkovičova” and the river Vah showed higher levels of polyphenols (4.91–6.93 mg g−1 of dry mass), flavonoids (2.28–2.99 mg g−1 of dry mass) than the extracts from cones collected at the end of the vegetation period (polyphenols 3.63–5.33 mg g−1 of dry mass, flavonoids 1.86–2.16 mg g−1 of dry mass). The extracts from leaves from the first harvest from the “tennis court” site showed lower values of polyphenols and flavonoids. Our findings were that the leaves from the first harvest at the beginning of the growing season contained higher amounts of the secondary metabolites investigated than the cones at the end of the growing season. The content of α-bitter acids in wild hop cones ranged from 1.64 % to 2.91 %, in leaves from 0.11 % to 0.99%. Concentration of β-bitter acids in cones varied from 1.63 % to 1.93 % and in leaves from 0.02 % to 0.61 %.

Phenotypic and alpha-acid content diversity of wild hop populations in Croatia

An ecogeographical survey of wild hop populations was conducted in the northwest of Croatia in two consecutive years. A total of 121 plants was documented on eight locations. Along with the passport data, the data on three phenotypic traits (no. of leaflets, cone shape, aroma) were gathered during collection, while the content of α<i>-acids in hop cones was determined by lead conductance</i>. Shannon’s information index was calculated for each phenotypic trait and was used as a measure of intra- and inter-population diversity. For all analyzed traits, most of the total phenotypic diversity was attributable to differences among plants within populations. The differences in proportions of individuals having a particular trait state between all pairs of populations in the case of leaflet number and cone shapes were non-significant. Four out of 28 pairwise comparisons for aroma were proven significant, indicating the existence of differences in proportions of individuals across populations recorded to have ‘typical hoppy’, ‘fine hop’ or ‘rough’ aroma. No significant differences were observed for α-acids content among populations. Plants exhibiting elongated cone shape had significantly higher α-acids content than those having oval or round cone shapes. Similarly, plants categorized as ‘rough’ aroma hop cones had the highest content of α-acids compared with those categorized as ‘typical hoppy’ or ‘fine hop aroma’ hop cones.

APHID TOLERANCE OF DIFFERENT HOP GENOTYPES: FIRST ATTEMPTS TO DEVELOP A SIMPLE BIOTEST FOR HOP BREEDING BY THE USE OF PHORODON HUMULI

A keystone of future pest management in hops is the breeding of cultivars (cvs.) that are tolerant or resistant to Phorodon humuli infestation. During 2006 and 2007 first attempts were made for the development of a biotest concerning the aphid susceptibility of different hop genotypes. We chose for these tests the susceptible cvs. 'Hallertauer Magnum' (HM) and 'Herkules' (HS), the aphid-tolerant or -resistant cvs. 'Spalter Select' (SE) and 'Boadicea' (BO), and two apparently resistant genotypes from our germplasm - the male accession 38 and the wild hop Jena 49. Aphid cages were mounted to leaves taken from potted greenhouse plants of these six genotypes, and each cage was equipped with an aphid larva with known day of birth. The leaves (12 replications per genotype) were stored in a climate chamber, and the 72 cages opened three times a week to count and remove all newborn larvae. The mother aphids stayed in their cages until the death of the last aphid marked the end of a series. Altogether eight series were conducted. The cumulative alive offspring of one aphid was highest on HM, with an overall mean number of 66.2 larvae, and lowest on 38, with 14.9 larvae. However, overall means of the other cvs. were not significantly lower - 59.7 on HS, 59.6 on SE and 57.6 on BO. The maximum number of larvae produced by one aphid was 115 on HM. The lifespan of the aphids was longest on HM, with an overall mean of 39.8 days, and shortest on 38, with 24.4 days. The other genotypes produced similar lifespans from 31.7 to 34.3 days. The record holder survived on HM for 69 days. These results, especially concerning the aphid-tolerant cvs. BO and SE, demonstrate that for the development of a practical, simple aphid biotest there is still a long way to go.

Variability of Volatiles of Wild Hops (Humulus lupulus L.) Growing in Eastern Lithuania

Wild hop (Humulus lupulus L.) cones were collected in 12 localities of Eastern Lithuania. α-Humulene (11.1–33.4%) dominated in seven oils, myrcene (15.7–21.1%) in four oil samples and γ-elemene (14%) in one oil. The other most prominent constituents of the essential oils were α-humulene (14.2–16.2%), myrcene (7.7–19.3%), β-caryophyllene (7.6–14.5%), (E)-β-farnesene (7.8–10.4%),γ-curcumene (15.8%), ar-curcumene (10.4%), zingiberene (8.4%) and β-bisabolol (11.8–13.5%). Sesquiterpene hydrocarbons comprised the largest group of oil constituents (45.6–73.7%). One hundred and twenty identified compounds made up 83.4–99.5% of the oils.

WILD HUMULUS GENETIC RESOURCES AT THE U.S. NATIONAL CLONAL GERMPLASM REPOSITORY

During the past 23 years the Humulus genetic resource collection at the U. S. Department of Agriculture (USDA), Agricultural Research Service (ARS), National Clonal Germplasm Repository (NCGR) in Corvallis, Oregon, has greatly benefited from many international plant collecting trips. Significant contributions from North America include several private and USDA sponsored expeditions to Arizona, Colorado, Iowa, Kentucky, Manitoba, Minnesota, Missouri, Montana, Nebraska, New Mexico, New York, North Dakota, Saskatchewan, and Wisconsin. In addition, USDA-sponsored foreign expeditions to Albania, Armenia, China, Kazakhstan, and Russia, have also expanded the representation of global Humulus diversity. More than 199 wild hop accessions are preserved at the NCGR from these expeditions. Locality information from the plant collecting expeditions is loaded to the publicly accessible Germplasm Resource Information Network (GRIN) database. Seed from these accessions are inventoried, labeled, and stored at -20 o C. Germination protocols are being reviewed and revised. Seedlings from these accessions are being evaluated for disease resistance, morphological traits and chemical and genetic profiles. Genotypes with specific quality traits are being preserved as plants growing in screened enclosures, protected from virus or other pathogen infection. Specific genotypes are cultured in vitro. These tissue cultures are preserved at 4°C for up to 2 years. Meristems from tissue cultures are cryopreserved and stored at a remote location for long-term, back-up preservation. Plant propagules including stem cuttings, rhizomes, tissue cultures, or seeds, are available for distribution to international researchers upon request.

Microsatellite variability among wild and cultivated hops (HumuluslupulusL.)

Hop (Humulus lupulus L.) is a dioecious perennial plant native to the northern hemisphere cultivated for its use in the brewing industry. To investigate the genetic diversity present in wild hop accessions in comparison with cultivated hops, microsatellite marker variation was assessed at four loci in 124 accessions of wild (from Europe, Asia and from North America) and cultivated (varieties and breeding lines) hops. A total of 63 alleles were identified, with an average of 15.7 alleles per locus and an average PIC of 0.64 over four loci. The average number of alleles per locus in groups of accessions ranged from 5.75 to 8.30, with the highest number detected in groups of wild hops either of European (EU) or North American (NA) origin. Accessions from NA revealed the highest number of unique alleles indicating the high diversity present in this gene pool. Cluster analysis based on the D(D) or D(sw) distance matrix divided accessions into 10 different clusters, which reflect the relationship among geographically diverse wild accessions and hop cultivars. The highest genetic differences were found between NA wild accessions, forming one distant cluster, and all the other accessions. The differentiation between European wild and cultivated accessions was revealed by PCoA based on the D(D) distance matrix and by AMOVA results. Cultivated hops differ significantly from wild ones, although most of the variability was found within groups. The molecular variances within groups of cultivated and wild hops were homogeneous, suggesting that a similar level of molecular variability is found in both groups of accessions. The analysis of allele polymorphism and of allele sequences showed that hop germplasm can be differentiated to NA and EU geographic types according to the differences of allele sizes at three loci or by the specific microsatellite repeat type at one locus. The analysis also indicates the different evolutionary dynamics and complex mutations of microsatellite sequences within loci that can be followed in the two biogeographically separated germplasms.

Structure and inheritance of ribosomal DNA variants in cultivated and wild hop, Humulus lupulus L.

Genetic variation was assessed among cultivated and wild hop, Humulus lupulus, by restriction fragment length polymorphisms (RFLPs) of the ribosomal RNA genes (rDNA). Two rDNA length variants of 10.3 and 9.3 kbp represented by three phenotypes designated A, B and C were detected with XhoI. Restriction-site mapping showed that hop rDNA is structurally similar to those of most higher plants. A high level of homogeneity existed in rDNA repeat lengths among the diverse hop genotypes. Generally, phenotype A was predominant in wild and cultivated European and Asian genotypes; phenotype B in North American cultivars; while phenotype C was present only in native North American hop, providing a potential molecular marker for the identification of this germ plasm. The rDNA data provided genetic evidence for the separation of native and cultivated American genotypes and supports the hypothesis that North American hop cultivars are of hybrid origin from European and native American genotypes. The segregation of rDNA phenotypes in four F1 families suggests that a single locus with two co-dominant alleles controls genetic variability for rDNA variants in hop.

Structure and inheritance of ribosomal DNA variants in cultivated and wild hop, Humulus lupulusL.

Structure and inheritance of ribosomal DNA variants in cultivated and wild hop, Humulus lupulusL.

Biology of the hop cyst nematode Heterodera humuli

SUMMARY Heterodera humuli inhibited plant growth in pot experiments when the nematode population exceeded 500 eggs g‐1 of soil; below this density there was evidence of stimulated growth. The development of H. humuli was tested on seven hop cultivars. No differences were found in the numbers of newly produced cysts on different cultivars but the sizes of the cysts differed significantly. The biggest cysts were found on a wild hop and the smallest on the cultivar ‘OR/55’. The nematode and the fungus, alone or in combination, did not affect the bine length of cvs Northdown or Target. The growth of nematode infested plants of a wilt susceptible hop cultivar was significantly reduced when the plant pathogenic fungus Verticillium albo‐atrum was also present. Verticillium did not significantly influence the reproduction of H. humuli under either laboratory or field conditions although hatching of juveniles in the field was delayed by two weeks and more juveniles were found in the soil during late summer around the roots of fungus infected plants in the field.

Esterase activity and associated insecticide resistance in the damson-hop aphid,Phorodon humuli(Schrank) (Hemiptera: Aphididae)

AbstractPhorodon humuli(Schr.) was obtained from both wild and cultivated hop plants, cultured, and bioassayed using seven different foliar spray insecticides, and the results were assesssed by probit analysis to determine LC50s and LC95s. The wild aphids and their progeny were highly susceptible to the insecticides, whereas those from cultivated hops were generally resistant to them. The level of resistance was related to the source of the original aphid population and the insecticide used. Clones of insecticide-resistant and susceptible aphids were maintained under identical conditions, and individual adult apterae were assayed for total esterase and esterase isoenzyme activities. Total esterase activity was appreciably higher in resistant aphids than in susceptible ones. Resistant aphids were associated with high esterase isoenzyme activity of complex bands II–V, while in susceptible aphids these bands were virtually missing. An insecticide-resistant clone ofP. humuliwas selected for low esterase activity and a susceptible clone was selected for high esterase activity, over eight generations. Selection pressure was then reversed for a further eight generations. The resistant clone lost its esterase activity by generation six and it remained low thereafter, whereas that of the control stock remained high. By contrast, the esterase activity of the susceptible clone remained unaltered by selection. The resistant clone also lost its resistance to both methomyl and methidathion.

Insecticide resistance in damson‐hop aphid, Phorodon humuli in commercial hop gardens in Kent

SUMMARYFrom 1966 to 1976, samples of Phorodon humuli were collected annually from five commerical hop gardens in Kent and from other hop gardens where problems in control occurred. A susceptible stock was obtained from wild hop growing in northern England in 1969. The samples were cultured in isolation on potted hops and bioassayed against insecticides in common use. The level of resistance to demeton‐S‐methyl was c. 10X in 1966 after 10 yr use, and more than doubled from 1968–1974 apparently due to the spread of a more resistant type; there was a further increase to c. 50X in 1975–1976. There was also resistance of C. 20–30X to omethoate, 2–7X to methidathion and 4–8X to methomyl. Assays and field results show an increased resistance to methidathion and less certainly to methomyl after 5 yr use. There was no clear change in response to endosulfan. The LC50's estimated from a single dose and a mean probit slope were found to agree satisfactorily with the LC50's calculated from serial doses and so should be adequate for monitoring trends in resistance.

Sex Chromosomes in the Hop Humulus lupulus

STUDIES of meiosis in male plants of the hop Humulus lupulus have resulted in conflicting reports on the nature of the sex chromosomes. Winge1 and Jacobsen2 have described an unequal pair of sex chromosomes which Jacobsen also identified in the somatic cells of male and female plants. Sinoto3 found no heteromorphic pair, but described a chain of four sex chromosomes which he designated X 1 Y 1 X 2 Y 2. No evidence was put forward in support of this interpretation. Ono4, however, demonstrated in H. lupulus var. cordifolius (the wild hop of Japan) that a quadrivalent occurred in meiotic divisions in the male, but not in the female plant. More recently5 he has described the occurrence, in a number of male varieties, of five different sex chromosome types, one of which is a homomorphic pair, two are heteromorphic pairs with different length ratios, and two are complexes of four chromosomes, also with differing length ratios.

The European Corn Borer, Pyrausta Nubilalis (Hubn.), and Its Principal Host Plant. I. Orientation and Feeding Behavior of the Larva on the Corn Plant1

The European corn borer is a non-host-specific insect, and has been reported feeding on over 200 different plant species (Caffrey and Worthley 1927, Hodgson 1928, and others). The borer's native Eurasian host was probably wild hop or one of the larger grasses, such as millet (Caffrey and Worthley 1927). Corn, being of American origin, could not have been the native host, but has proved to be the preferred host wherever the geographical distributions of the plant and insect coincide. The broad range of possible host plants is of considerable significance to the study of the relationships between the borer and the corn plant. It indicates that the plant characteristics required for successful borer establishment and growth are present in a large number of plant species and are not peculiar to corn alone.