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Sex Pheromone Receptor Specificity in the European Corn Borer Moth, Ostrinia nubilalis  [PDF]
Kevin W. Wanner,Andrew S. Nichols,Jean E. Allen,Peggy L. Bunger,Stephen F. Garczynski,Charles E. Linn Jr.,Hugh M. Robertson,Charles W. Luetje
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0008685
Abstract: The European corn borer (ECB), Ostrinia nubilalis (Hubner), exists as two separate sex pheromone races. ECB(Z) females produce a 97:3 blend of Z11- and E11-tetradecenyl acetate whereas ECB(E) females produce an opposite 1:99 ratio of the Z and E isomers. Males of each race respond specifically to their conspecific female's blend. A closely related species, the Asian corn borer (ACB), O. furnacalis, uses a 3:2 blend of Z12- and E12-tetradecenyl acetate, and is believed to have evolved from an ECB-like ancestor. To further knowledge of the molecular mechanisms of pheromone detection and its evolution among closely related species we identified and characterized sex pheromone receptors from ECB(Z).
Silent genes and rare males: A fresh look at pheromone blend response specificity in the European corn borer moth, Ostrinia nubilalis
Charles Linn Jr.,Marion O'Connor,Wendell Roelofs
Journal of Insect Science , 2003,
Abstract: The response of male moths from two pheromone races of the European corn borer, Ostrinia nubilalis, was measured in a flight tunnel assay to different ratios of structurally different compounds that comprise the sex pheromone of the Asian corn borer, Ostrinia furnacalis. For both O. nubilalis races, between 1 and 5% of the males completed upwind flights to two different blends of the O. furnacalis pheromone components (the 2:1 Z/E12-14:OAc female-produced blend, and a 97:3 Z/E mix), confirming that rare males exist in the O. nubilalis populations that can detect and respond to mixtures of the O. furnacalis pheromone components. Rare males that responded to the O. furnacalis blends also responded to their own O. nubilalis blends (97:3 or 1:99 Z/E11-14:OAc), indicating that rare O. nubilalis males are not preferentially sensitive to mixtures of the O. furnacalis compounds, but rather that they have a broad range of response specificity, which includes recognition of a wide range of conspecific female-produced ratios, and also recognition of heterospecific mixtures. The results support the hypothesis that saltational shifts in pheromone blend composition (Roelofs et al., 2002) can lead to the evolution of a new species-specific communication system, in part because the broad response specificity of some males includes the ability to respond in an agonistic manner to novel mixtures of compounds.
Zvjezdana Augustinovi?,Emilija Raspudi?,Marija Ivezi?,Mirjana Brme?
Poljoprivreda (Osijek) , 2005,
Abstract: European corn borer (Ostrinia nubilalis Hubner) is one of the major corn pest in the world and in Croatia. Former investigations of corn borer in Croatia covered mostly its Eastern region. In trials conducted in 1998 and 1999 the research was extended to the North Western part of Croatia too. Macro trials were carried out with corn hybrids of FAO groups 200-600 at three localities: Kri evci, Agricultural institute Osijek and at Belje PIK Karanac. In 1998 the intensity of the corn borer attack at the locality of Belje PIK Karanac was about 37.92% and in Agricultural institute Osijek 80.83%. In 1999 it varied between 37.08% at the locality of Agricultural Institute Osijek and 71.20% at the locality in Kri evci. The estimated number of holes per plant in all three localities in both years was higher than the number of caterpillars. Length of damage per plant was between 0.38 and 18.80 cm. The data showed significant differences in the intensity of damaging effects on different localities while no significant differences concerning various hybrids were found.The statistical data concerning yield in both years showed significant differences among hybrids, localities and their interactions.
European Corn Borer (Ostrinia nubilalis) Induced Responses Enhance Susceptibility in Maize  [PDF]
Nicole J. Dafoe, James D. Thomas, Paul D. Shirk, Michelle E. Legaspi, Martha M. Vaughan, Alisa Huffaker, Peter E. Teal, Eric A. Schmelz
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0073394
Abstract: Herbivore-induced plant responses have been widely described following attack on leaves; however, less attention has been paid to analogous local processes that occur in stems. Early studies of maize (Zea mays) responses to stem boring by European corn borer (ECB, Ostrinia nubilalis) larvae revealed the presence of inducible acidic diterpenoid phytoalexins, termed kauralexins, and increases in the benzoxazinoid 2-hydroxy-4,7-dimethoxy-1,4-benzoxazin-3?-one-glucose(HDMBOA-Glc) after 24 h of herbivory. Despite these rapidly activated defenses, larval growth was not altered in short-term feeding assays. Unexpectedly, ECB growth significantly improved in assays using stem tissue preconditioned by 48 h of larval tunneling. Correspondingly, measures of total soluble protein increased over 2.6-fold in these challenged tissues and were accompanied by elevated levels of sucrose and free linoleic acid. While microarray analyses revealed up-regulation of over 1100 transcripts, fewer individual protein increases were demonstrable. Consistent with induced endoreduplication, both wounding and ECB stem attack resulted in similar significant expansion of the nucleus, nucleolus and levels of extractable DNA from challenged tissues. While many of these responses are triggered by wounding alone, biochemical changes further enhanced in response to ECB may be due to larval secreted effectors. Unlike other Lepidoptera examined, ECB excrete exceedingly high levels of the auxin indole-3-acetic acid (IAA) in their frass which is likely to contact and contaminate the surrounding feeding tunnel. Stem exposure to a metabolically stable auxin, such as 2,4-dichlorophenoxyacetic acid (2,4-D), promoted significant protein accumulation above wounding alone. As a future testable hypothesis, we propose that ECB-associated IAA may function as a candidate herbivore effector promoting the increased nutritional content of maize stems.
Marija Ivezi?,Emilija Raspudi?
Poljoprivreda (Osijek) , 2001,
Abstract: European Corn Borer (ECB - (Ostrinia nubilalis Hübner) is one of the most important pest on corn in Croatia. In the last decade corn production was on over 400 000 ha, in Eastern Croatia. Although ECB is present every year, with no such a low intensity, their control is not implemented. Corn is grown in monoculture, at 40% of cornfields, which also has influence on spreading of ECB. In the last ten years average attack of ECB was 51.5%; been done three different kinds of trials for controlling ECB. First trials were carried out in DeKalb hybrids, and ECB was controlled by Biobit XL, on the base of Bacillus thuringiensis Berliner. Intensity of attack was decreased for 46%. Second trial was carried out in ten hybrids, in order to determine the tolerance of hybrids against ECB. It was identified that several domestic hybrids (OSSK 382, OSSK 664 and BC 462) are tolerant to ECB. The third trial was carried out with GM hybrids. Experiments included Pioneer hybrids Evelina Bt, and Landia Bt. Intensity of attack at Evelina standard was 52%, while in Evelina Bt, ECB wasn't present at all. At Landia standard ECB was present on 98%, while in Landia Bt, intensity of attack was 21%. At both Bt hybrids, number of larvae and tunnels was lower comparing to standard hybrids. Length of damage in Landia check was 20.66 cm, while in Landia Bt it was 0.45 cm. The yield was increased for 10.27% at Evelina Bt, and for 26.67% in Landia Bt comparing to their standards. This kind of experiments will be continued in the future, not only because of its agronomic importance, but also because of its ecological relevance.
Journal of Central European Agriculture , 2002,
Abstract: The influence of different doses of ultraviolet (UV) light on the pathogenicity of entomopathogenic fungus Beauveria bassiana (Balsamo) Vuillemin to the European corn borer, Ostrinia nubilalis Hbn., and radial growth of fungus was studied in laboratory conditions. The suspensions of B. bassiana isolate SK99 were exposed to UV light. Four different doses of UV light were used in the experiment. The distance between exposed suspensions and UV light source was 0.3 m. Exposure duration was 15, 30, 45 and 60 minutes (as A, B, C and D variants). Control variant SK99 and obtained variants SK99A, SK99B, SK99C and SK99D were cultivated 21 days on Sabourard-dextrose agar. The larvae of O. nubilalis were infected with dry powder consisted of mycelia and spores from fungus cultures. During 10 days, the mortality of infected larvae was evaluated. It was ascertained that UV light exposition significantly influenced the mortality effect of B. bassiana isolates to O. nubilalis larvae. Variant SK99C showed the highest level of infectivity. Radial growth of UV variants was slower with rising time of exposure. The best ability to grow possessed non-irradiated isolate SK99 and the worse variant SK99D. The difference between these two variants was significant.
Sex-Linked Pheromone Receptor Genes of the European Corn Borer, Ostrinia nubilalis, Are in Tandem Arrays  [PDF]
Yuji Yasukochi,Nami Miura,Ryo Nakano,Ken Sahara,Yukio Ishikawa
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0018843
Abstract: Tuning of the olfactory system of male moths to conspecific female sex pheromones is crucial for correct species recognition; however, little is known about the genetic changes that drive speciation in this system. Moths of the genus Ostrinia are good models to elucidate this question, since significant differences in pheromone blends are observed within and among species. Odorant receptors (ORs) play a critical role in recognition of female sex pheromones; eight types of OR genes expressed in male antennae were previously reported in Ostrinia moths.
Variation in Courtship Ultrasounds of Three Ostrinia Moths with Different Sex Pheromones  [PDF]
Takuma Takanashi,Ryo Nakano,Annemarie Surlykke,Haruki Tatsuta,Jun Tabata,Yukio Ishikawa,Niels Skals
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0013144
Abstract: Moths use ultrasounds as well as pheromones for sexual communication. In closely related moth species, variations in ultrasounds and pheromones are likely to profoundly affect mate recognition, reproductive isolation, and speciation. The European corn borer, Ostrinia nubilalis, and its Asian congeners, Ostrinia furnacalis and Ostrinia scapulalis, exhibit within-species and between-species variation in their pheromone communication. Recently, we reported ultrasound communication in O. furnacalis; however, variations in ultrasounds in the three congeners have not been addressed to date. Here we investigated features of ultrasound production and hearing in O. nubilalis and O. scapulalis, and compared them with those of O. furnacalis. As in O. furnacalis, males of O. nubilalis and O. scapulalis produced ultrasounds during courtship by rubbing specialized scales on the wings against scales on the thorax. The covering of these scales with nail polish muffled the sounds and significantly reduced mating success in O. nubilalis, showing the importance of ultrasound signaling in mating. The ultrasounds produced by O. nubilalis and O. scapulalis were similar, consisting of long trains of pairs of pulses with a main energy at 40 kHz, but distinctly different from the ultrasound produced by O. furnacalis, consisting of groups of pulses peaking at 50 kHz and with substantially more energy up to 80 kHz. Despite overall similarities, temporal features and patterns of amplitude modulation differed significantly among the geographic populations of O. nubilalis and O. scapulalis, which differed in pheromone type. In contrast, no significant difference in hearing was found among the three species with regard to the most sensitive frequencies and hearing threshold levels. The patterns of variations in the songs and pheromones well reflected those of the phylogenetic relationships, implying that ultrasound and pheromone communications have diverged concordantly. Our results suggest that concordant evolution in sexual signals such as courtship ultrasounds and sex pheromones occurs in moths.
A Δ11 desaturase gene genealogy reveals two divergent allelic classes within the European corn borer (Ostrinia nubilalis)
Kerry A Geiler, Richard G Harrison
BMC Evolutionary Biology , 2010, DOI: 10.1186/1471-2148-10-112
Abstract: The Δ11 desaturase gene genealogy does not differentiate O. nubilalis pheromone strains. However, we find two distinct clades, separated by 2.9% sequence divergence, that do not sort with pheromone strain, geographic origin, or emergence time. We demonstrate that these clades do not represent gene duplicates, but rather allelic variation at a single gene locus.Analyses of patterns of variation at the Δ11 desaturase gene in ECB suggest that this enzyme does not contribute to reproductive isolation between pheromone strains (E and Z). However, our genealogy reveals two deeply divergent allelic classes. Standing variation at loci that contribute to mate choice phenotypes may permit novel pheromone mating systems to arise in the presence of strong stabilizing selection.The origin of novel sex pheromone signaling systems may play an important role in insect speciation. Insect sex pheromones are volatile compounds or mixtures of such compounds, used in many species for mate location, species recognition, and mate choice [1]. In many moths, females produce species-specific chemical cues, and males exhibit species-specific responses (both physiological and behavioral) that are important in mate finding. Males may also produce pheromones that are used by females in exercising mate choice (e.g., [2]). These chemical cues are often blends of long-chain hydrocarbons with acetate, alcohol, or aldehyde functional groups. Because pheromone biosynthetic pathways have been well characterized [3,4], it is now possible to examine how changes at the level of protein sequence or gene expression affect pheromone phenotype, patterns of mating, and ultimately, the nature and origin of barriers to gene exchange.Pheromone signaling systems are described as "highly canalized" because changes in production or response are opposed by strong selection against novel phenotypes [5,6]. Only if the same genes control signal and response (pleiotropy), or if the genes controlling these traits are tigh
Journal of Central European Agriculture , 2003,
Abstract: The investigations were made in 2002 in the outskirts of two settlements: Balatonmagyaród (Zala county) and Várda (Somogy county). In the corn fields Jermy’s light- and Arco-Pheron MZ pheromone traps were placed in order to follow up the course of flight. From the material collected the corn borer specimens were isolated, then separated by sex. The generation number of the populations appearing on the respective areas, and the characteristics of the flight were determined. The meteorological data of the areas obtained from Keszthely and Kaposvár for the period concerned were compared woth the data of flight. In that way the effect of the different meteorological elements on the flight and on the trend of the female ratio could be established. The results showed the presence of two-generation corn borer populations in both places. In Balatonmagyaród the first- while in Várda the second generation proved larger. The meteorological elements significally influenced the possibility of trapping in the case of both sexes. As for the female sex ratio close correlations were found with the minimum (P=100%; r=0.297)-, maximum (P=99.9%; r=0.267)-, average (P=100%; r=0.308) temperature and precipitation (P=98.2%; r=0.187) data. Considerable asynchrony was observed between the data obtained with the two prognostic means that we ascribed to the unreliability of the pheromone trap.
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