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Digitale Medien

BIOLOGY AND MANAGEMENT OF ECONOMICALLY IMPORTANT LEPIDOPTERAN CEREAL STEM BORERS IN AFRICA (2002)

Kfir, Rami ; Overholt, W. A. ; Khan, Z. R. ; [weitere]

Palo Alto, Calif. : Annual Reviews

Annual Review of Entomology 47 (2002), S. 701-731

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ISSN: 0066-4170

Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff

Thema: Biologie

Notizen: Abstract Cereals (maize, sorghum, millet, rice) are extremely important crops grown in Africa for human consumption. Of the various insect pests attacking cereal crops in Africa, lepidopteran stem borers are by far the most injurious. All 21 economically important stem borers of cultivated grasses in Africa are indigenous except Chilo partellus, which invaded the continent from India, and C. sacchariphagus, which has recently been found in sugarcane in Mozambique. C. partellus is competitively displacing indigenous stem borers in East and southern Africa. A parasitoid, Cotesia flavipes, was introduced from Pakistan for biological control of C. partellus and caused a 32-55% decrease in stem borer densities. This article is an attempt to summarize the status of knowledge about economically important cereal stem borers in Africa with emphasis on their distribution, pest status and yield losses, diapause, natural enemies, cultural control, host plant resistance, and biological control. Special attention is given to Busseola fusca and C. partellus, the most important pests of maize and grain sorghum.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1146/annurev.ento.47.091201.145254

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Digitale Medien

Modulation of phototactic behavior of first-instar larvae of rice leaffolder by plant factors (1991)

Ramachandran, R. ; Khan, Z. R.

Springer

Entomologia experimentalis et applicata 58 (1991), S. 149-157

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ISSN: 1570-7458

Schlagwort(e): Rice leaffolder ; Cnaphalocrocis medinalis ; orientation ; movement ; phototaxis ; plant factors ; rice volatiles

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie

Beschreibung / Inhaltsverzeichnis: Résumé Au laboratoire et en plein champ, avec la lumière venant d'en haut, les larves du premier stade de la pyrale du riz C. medinalis s'orientent vers le bars lorsqu'elles se trouvent sur une feuille de riz tenue verticale, et elles s'orientent vers le haut lorsqu'elles sont sur du papier filtre. La direction d'orientation sur les deux substrat s'inverse lorsque la lumière provient du bas. Ces différences d'orientation par rapport à la source de lumière, sur la feuille de riz et sur le papier filtre, se maintiennent même lorsque le substrat est horizontal. Lorsque l'expérience est effectuée dans l'obscurité, l'intensité de la réaction d'orientation vers le haut sur du papier filtre tenu verticalement se réduit, et l'orientation vers le bas sur la feuille de riz disparaît. Sur des substrats horizontaux (feuille de riz et papier filtre), les larves ne s'orientent pas dans l'obscurité. On n'observe pas de différence dans le comportement d'orientation entre des larves issues d'œufs pondus sur des plants de riz ou sur des substrats non végétaux, ou entre des larves exposées aux substances volatiles du riz ou à de l'air pur. Le comportement d'orientation des larves du premier stade sur des variétés de riz susceptibles ou résistantes est similaire, mais sur des graminées non-hôtes on n'observe pas d'orientation significative vers le haut ou vers le bas. En traitant les feuilles de riz avec de l'hexane pour enlever les cires de surface, on réduit l'intensité de la réaction d'orientation; cependant, l'application de cires de surface sur du papier filtre ne modifie pas significativement le comportement des larves. Sur une feuille de riz séchée, l'orientation est similaire à celle observée sur papier filtre, mais est d'une intensité plus faible. Les substances volatiles du riz extraites par distillation à la vapeur et appliquées sur une feuille de riz séchée causent une perte d'orientation à 500 pm, tandis que leur application sur du papier filtre cause une décroissance dose-dépendante de l'intensité de l'orientation vers le haut. Ces résultats indiquent que les larves du premier stade de C. medinalis sont positivement phototactiques et que des substance volatiles et d'autres substances jusqu'ici non identifiées et présentes dans les plants de riz causent une inversion ans la phototaxie, ce qui résulte en une orientation vers le bas sur les feuilles de riz.

Notizen: Abstract First-instar larvae of the rice leaffolder Cnaphalocrocis medinalis (Guenńe) oriented upwards on a vertically inclined filter paper and downwards on a rice leaf when the light source was from above. The direction of orientation was reversed when the light source was from below. The opposite directions of orientation on these substrates persisted when the substrates were held horizontal with light source from the sides. No difference was observed in the magnitude of reaction on susceptible and resistant rice varieties or when the rice leaf was held with its distal end pointing down. On non-host grasses, however, the directional orientation was lost. Dipping rice leaves in hexane decreased the magnitude of reaction. On dried rice leaf, the reaction was similar to that on filter paper but was of a lower magnitude. Application of rice plant volatile extracts on a filter paper decreased the intensity of upward orientation while 500 ppm of the volatile extracts applied on dried leaf caused a loss of oriented movement. Application of a mixture of seven volatile chemicals, identified from rice, decreased the magnitude of reaction significantly. It is concluded that rice plant volatiles along with some other hitherto unidentified rice plant factor cause a reversal of phototaxis, leading to downward orientation on the rice leaf.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00164939

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Digitale Medien

Feeding site selection of first-instar larvae of Cnaphalocrocis medinalis on susceptible and resistant rice plants (1991)

Ramachandran, R. ; Khan, Z. R.

Springer

Entomologia experimentalis et applicata 60 (1991), S. 43-49

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ISSN: 1570-7458

Schlagwort(e): Rice leaffolder ; neonate larval ; feeding site ; movement ; whorl leaf ; mature leaf ; resistance ; varieties

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie

Notizen: Abstract More first-instar larvae of the rice leaffolder, Cnaphalocrocis medinalis (Guenée), were recovered from susceptible IR36 and Roxoro rice varieties than resistant TKM6 and Oryza perennis, 24 h after infestation. Within a rice plant, a higher proportion of larvae was recovered from young whorl leaf, followed by mature leaves and leafsheaths on all the four rice varieties tested. However, differences were observed between susceptible and resistant varieties in the distribution of larvae on these three plant parts. In laboratory choice tests, first-instar larvae preferred to settle on the young leaves of IR36 and TKM6 when presented with their respective mature leaves. No such preference was observed in tests with Rexoro and O. perennis. Larval survival was similar on young and mature leaves of Rexoro. Young leaves of IR36 and TKM6 were more suitable for survival in comparison with their respective mature leaves while the reverse was true for O. perennis. Larval movement was slower on the mature leaves and larvae took longer to reach the whorl leaf of TKM6 than on IR36. The density of trichomes of the abaxial surface of TKM6 was higher than that of the other varieties tested. Adaptive significance of feeding in the leafwhorl to young larvae is discussed.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00164958

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4

Digitale Medien

Olfactory sensitivity of two sympatric species of rice leaf folders (Lepidoptera: Pyralidae) to plant volatiles (1990)

Ramachandran, R. ; Khan, Z. R. ; Caballero, P. ; [weitere]

Springer

Journal of chemical ecology 16 (1990), S. 2647-2666

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ISSN: 1573-1561

Schlagwort(e): Cnaphalocrocis medinalis ; electroantennogram ; green leaf volatiles ; host-plant resistance ; Lepidoptera ; Marasmia patnalis ; olfaction ; plant volatiles ; Pyralidae ; rice leaf folder

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie , Chemie und Pharmazie

Notizen: Abstract Electroantennograms (EAGs) were recorded from male and female moths of two sympatric leaf folder species,Cnaphalocrocis medinalis (Gue-née) andMarasmia patnalis Bradley (Lepidoptera: Pyralidae) to 91 volatile chemicals of plant origin. Responses of both leaf folder species were similar to all compounds except to three monoterpenes-β-myrcene, menthone, and isomenthone- and two sesquiterpenes-cis-nerolidol and isophytol. Response ofM. patnalis, an oligophagous leaf folder, to these compounds was higher compared with that of polyphagousC. medinalis. EAG responses of males to saturated and unsaturated aliphatic aldehydes were significantly higher than those of conspecific females in both species. A higher response ofC. medinalis males also was observed for 1-nonanol, 3-nonen-2-one, andtrans, trans-2,6-dimethyl-2,4,6-octatriene. In contrast, females of both species responded more to monoterpenes, borneol, isoborneol, and fenchyl alchohol. Response ofC. medinalis female was higher for terpinen-4-ol, carveol, dihydrocarveol, (−)-myrtenal, and perillaldehyde. In both species and sexes, high EAG responses were recorded for compounds of the green leaf odor complex. EAG responses to nonanal and hexanal were maximum among the aliphatic aldehydes while 1-hexanol elicited the highest response among the alcohols tested. EAG responses to terpene compounds-citronellal,α-terpineol, and (−)-myrtenal-were equal to the response to 1-hexanol. While all compounds tested elicited a negative potential, thymol and carvacrol elicited a positive EAG potential. The EAG data are discussed with regard

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00988076

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5

Digitale Medien

Mechanisms of resistance in wild riceOryza brachyantha to rice leaffolderCnaphalocrocis medinalis (Guenée) (Lepidoptera: Pyralidae) (1991)

Ramachandran, R. ; Khan, Z. R.

Springer

Journal of chemical ecology 17 (1991), S. 41-65

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ISSN: 1573-1561

Schlagwort(e): Wild rice ; Oryza brachyantha ; rice ; Oryza sativa ; host plant ; resistance ; antixenosis ; attractants ; deterrents ; silica ; rice leaffolder ; Cnaphalocrocis medinalis ; Lepidoptera Pyralidae

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie , Chemie und Pharmazie

Notizen: Abstract A wild rice,Oryza brachyantha, was rated as highly resistant to rice leaffolder,Cnaphalocrocis medinalis (Guenée), while its F1 hybrid from a cross with a high-yielding, leaffolder-susceptible rice, IR31917-45-3-2, was rated resistant in a standard screening test. In comparison with IR31917-45-3-2,O. brachyantha and the F1 hybrid were unsuitable for oviposition, survival, and growth ofC. medinalis. However, growth and survival of larvae in artificial diets containing lyophilized leaf powder of IR31917-45-3-2 andO. brachyantha were comparable. Studies on the feeding and settling preference of the larval stages suggested that the mechanism of resistance ofO. brachyantha is that of antixenosis type. Olfactometer tests with first-instar larvae and electroantennogram responses of adults indicated a lack or low levels of volatile attractants inO. brachyantha and the F1 hybrid in comparison with IR31917-45-3-2. Bioassays of sequential solvent extracts of these plants indicated that larval preference for IR31917-45-3-2 and nonpreference forO. brachyantha and the F1 hybrid were due partly to chemical factors present in hexane and methylene chloride extractables. Closer arrangement of silica cells in the epidermal layer ofO. brachyantha and a higher mandibular wear in larvae reared onO. brachyantha suggested that physical resistance due to silica may be an additional cause of resistance. It was hypothesized that the high levels of resistance observed inO. brachyantha may be due to an additive or synergistic action of the absence of attractants or feeding stimulants, the presence of deterrents, and the physical resistance offered by silica. The significance of these results to a successful wide hybridization program aimed at transferring resistance factors from wild rice to cultivated rice is discussed.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00994421

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Digitale Medien

Occurrence and significance of precipitating antibodies against thermophilic actinomycetes in the sera of dairy herd workers, Nangali, Delhi (1991)

Gangwar, Madhurama ; Khan, Z. U. ; Gaur, S. N. ; [weitere]

Springer

Antonie van Leeuwenhoek 59 (1991), S. 167-175

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ISSN: 1572-9699

Schlagwort(e): precipitating antibodies to thermophilic actinomycetes ; Faenia rectivirgula ; Saccharomonospora viridis ; dairy herd workers ; Ouchterlony's double diffusion test ; counterimmunoelectrophoresis ; enzyme-linked immunosorbent assay

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie

Notizen: Abstract The study was prompted by the lack of information on the role of thermophilic actinomycetes in hypersensitivity pneumonitis in India. It reports the occurrence of precipitating antibodies against clinically important thermophilic actinomycetes in the sera of a population sample of dairy herd workers, Nangali, Delhi. Of 112 workers investigated, 28 (25%) showed precipitins againstFaenia rectivirgula, 4 (3.2%) againstSaccharomonospora viridis, 2 againstThermoactinomyces thalpophilus and one each againstT. vulgaris andT. sacchari. The results of enzyme-linked immunosorbent assay (ELISA) indicated that IgG antibody activity againstF. rectivirgula was significantly higher in the symptomatic group than in the asymptomatic group (p〈0.05) of workers and the controls (p〈0.01). Significant difference inF. rectivirgula IgG activity was also obtained between the precipitin-positive symptomatic group and the precipitin-positive asymptomatic group (p〈 0.05). In strong contrast, the IgG antibody activity againstT. thalpophilus was found to be uniformly low. A limited aeromicrobiological sampling of the dairy farm revealedS. viridis (55.8%) to be the commonest species followed byT. vulgaris (19.2%),T. thalpophilus (18.5%),F. rectivirgula (5%) andT. sacchari (15%). On the basis of suggestive clinical and laboratory findings, farmer's lung disease was suspected in four dairy herd workers. A comprehensive clinical evaluation including pulmonary function studies on the dairy herd workers and their long-term follow-up is indicated to determine the extent of respiratory morbidity caused byF. rectivirgula, S. viridis, T. thalpophilus, T. sacchari andT. vulgaris in India.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00580656

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7

Digitale Medien

Cyanobacteria in rice soils (1994)

Khan, Z. U. M. ; Tahmida Begum, Z. N. ; Mandal, R. ; [weitere]

Springer

World journal of microbiology and biotechnology 10 (1994), S. 296-298

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ISSN: 1573-0972

Schlagwort(e): Cyanobacteria ; diazotrophs ; rice field ; soil

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung

Notizen: Abstract Cyanobacteria were recovered from each of 38 soil samples collected from local rice fields. Of the 84 species belonging to 31 genera that were isolated, 42 were heterocystous diazotrophic species belonging to 14 genera and the remaining were non-heterocystous. Fischerella, Nostoc and Calothrix were widespread.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00414867

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