Native Sunflower Research Articles

Oleosome interfacial engineering to enhance their functionality in foods

This study aimed to increase the physical stability of native sunflower oleosomes to expand their range of applications in food. The first objective was to increase the stability and functionality of oleosomes to lower pH since most food products require a pH of 5.5 or lower for microbial stability. Native sunflower oleosomes had a pI of 6.2. One particularly effective strategy for long-term stabilization, both physical and microbial, was the addition of 40% (w/w) glycerol to the oleosomes plus homogenization, which decreased the pI to 5.3 as well as decreasing oleosome size, narrowing the size distribution and increasing colloidal stability. Interfacial engineering of oleosomes by coating them with lecithin and the polysaccharides xanthan and gellan, effectively increased stability, and lowered their pI to 3.0 for lecithin and lower than 3.0 for xanthan. Coating oleosomes also caused a greater absolute value of the ζ-potential; for example, this amount was shifted to −20 mV at pH 4.0 for xanthan and to −28 mV at pH 4.0 for lecithin, which provides electrostatic stabilization. Polysaccharides also provide steric stabilization, which is superior. A significant increase in the diameter of coated oleosomes was observed with lecithin, xanthan and gellan. The oleosome sample with 40% glycerol showed high storage stability at 4 °C (over three months). The addition of glycerol also decreased the water activity of the oleosome suspension to 0.85, which could prevent microbial growth.

REMOVED: Oleosome interfacial engineering to enhance their functionality in foods

This study aimed to increase the physical stability of native sunflower oleosomes to expand their range of applications in food. The first objective was to increase the stability and functionality of oleosomes to lower pH since most food products require a pH of 5.5 or lower for microbial stability. Native sunflower oleosomes had a pI of 6.2. One particularly effective strategy for long-term stabilization, both physical and microbial, was the addition of 40% (w/w) glycerol to the oleosomes plus homogenization, which decreased the pI to 5.3 as well as decreasing oleosome size, narrowing the size distribution and increasing colloidal stability. Interfacial engineering of oleosomes by coating them with lecithin and the polysaccharides xanthan and gellan, effectively increased stability, and lowered their pI to 3.0 for lecithin and lower than 3.0 for xanthan. Coating oleosomes also caused a greater absolute value of the ζ-potential; for example, this amount was shifted to -20 mV at pH 4.0 for xanthan and to -28 mV at pH 4.0 for lecithin, which provides electrostatic stabilization. Polysaccharides also provide steric stabilization, which is superior. A significant increase in the diameter of coated oleosomes was observed with lecithin, xanthan and gellan. The oleosome sample with 40% glycerol showed high storage stability at 4°C (over three months). The addition of glycerol also decreased the water activity of the oleosome suspension to 0.85, which could prevent microbial growth.

Ginger and turmeric lipid-solubles attenuate heated oil-induced hepatic inflammation via the downregulation of NF-kB in rats

PurposeReusing deep-fried vegetable oils multiple times is a common practice to save costs, and their chronic consumption may cause hepatic dysfunction. In this investigation, we assessed the modulatory effects of ginger and turmeric lipid-solubles that may migrate to oils during heating on the hepatic inflammatory response in rats. MethodsMale Wistar rats were fed with; 1) control {native canola (N-CNO) or native sunflower (N-SFO)} oil, 2) heated (heated canola {(H-CNO) or heated sunflower (H-SFO)} oil, and 3) heated oil with ginger or turmeric {heated canola with ginger (H-CNO + GI) or heated canola oil with turmeric (H-CNO + TU), heated sunflower oil with ginger (H-SFO + GI) or heated sunflower oil with turmeric (H-SFO + TU)} for 120 days. Hepatic inflammatory response comprising eicosanoids, cytokines, and NF-kB were assessed. ResultsCompared to respective controls, feeding heated oils significantly (p < 0.05); 1) increased eicosanoids (PGE2, LTB4, and LTC4) and cytokines (TNF-α, MCP-1, IL-1β, and IL-6), 2) increased nuclear translocation of NF-kB in the liver, and 3) increased the hepatic expression of 5-LOX, COX-2, BLT-1, and EP-4. However, feeding oils heated with ginger or turmeric positively countered the changes induced by consumption of heated oils. ConclusionsConsumption of repeatedly heated oil may cause hepatic dysfunction by inducing inflammatory stress through NF-kB upregulation. Lipid-solubles from ginger and turmeric that may migrate to oil during heating prevent the hepatic inflammatory response triggered by heated oils in rats.

Ginger and turmeric lipid-solubles attenuate heated oil-induced oxidative stress in the brain via the upregulation of NRF2 and improve cognitive function in rats.

In this study, we elucidated the modulatory potentials of lipid-solubles from ginger and turmeric that may migrate to oils during heating on the brain antioxidant defense and cognitive response in rats. Male Wistar rats were fed with control diet [including native canola oil (N-CNO), and native sunflower oil (N-SFO)], or experimental diets [including heated canola oil (H-CNO), heated sunflower oil (H-SFO), heated canola oil with ginger (H-CNO + GI), heated canola oil with turmeric (H-CNO + TU), heated sunflower oil with ginger (H-SFO + GI), heated sunflower oil with turmeric (H-SFO + TU)] for 90days. Memory parameters [Morris water maze, elevated plus maze, novel object recognition test, T-maze (spontaneous alteration)], locomotor skills (open field test and rotarod test), antioxidant defense enzymes, reactive oxygen species, NOS2, ICAM-1, and NRF-2 level in the brain were assessed. Compared to their respective controls, heated oil-fed rats, but not those fed oils heated with ginger or turmeric, showed significant (p < 0.05) reduction in the memory, motor coordination skills, antioxidant defense enzymes, and NRF-2 activation in the brain. Compared to their respective controls, the brain NOS-2 and ICAM-1 were significantly (p < 0.05) increased in heated oil-fed rats, but not those fed oils heated with ginger or turmeric. Chronic intake of repeatedly heated oil causes brain dysfunction by inducing oxidative stress through NRF-2 downregulation. Lipid-solubles from ginger and turmeric that may migrate to oil during heating prevent the oxidative stress and cognitive dysfunction triggered by heated oils in rats.

Ginger and turmeric lipid-solubles attenuate heated oil-induced cardio-hepatic oxidative stress via the up-regulation of nuclear factor erythroid 2-related factor 2 and decrease blood pressure in rats.

Deep-fried vegetable oils are reused multiple times to save costs, and their chronic consumption may cause organ dysfunction. In this study, we assessed the modulatory effects of lipid-solubles from ginger and turmeric that may migrate to oils during heating, on the cardio-hepatic antioxidant defence response and blood pressure in rats. Male Wistar rats were fed with: (1) control (native rapeseed (N-CNO) or native sunflower (N-SFO)) oil, (2) heated (heated rapeseed (H-CNO) or heated sunflower (H-SFO)) oil and (3) heated oil with ginger or turmeric (heated rapeseed oil with ginger (H-CNO + GI) or heated rapeseed oil with turmeric (H-CNO + TU), heated sunflower oil with ginger (H-SFO + GI) or heated sunflower oil with turmeric (H-SFO + TU)) for 120 d. Oxidative stress (OS) markers, antioxidant enzymes, nitric oxide synthase-2 (NOS-2), intercellular adhesion molecule-1 (ICAM-1), nuclear factor erythroid 2-related factor 2 (NRF-2), markers of hepatic and cardiac function and blood pressure were assessed. Feeding heated oils (H-CNO or H-SFO) (1) increased OS markers, NOS-2 and ICAM-1 expression; (2) decreased antioxidant enzyme activity and NRF-2 level; (3) increased marker enzymes of hepatic and cardiac function and (4) increased systolic and diastolic blood pressure significantly (P < 0·05), when compared with respective native oils (N-CNO or N-SFO). However, feeding oils heated with ginger or turmeric positively countered the changes induced by heated oils. Consumption of repeatedly heated oil causes cardio-hepatic dysfunction by inducing OS through NRF-2 down-regulation. Lipid-solubles from ginger and turmeric that may migrate to oil during heating prevent the oxidative stress and blood pressure triggered by heated oils in rats.

Growth and Yield of Carrot (Daucuscarota L.) as Affected by Different Irrigation Frequency, Organic Soil Amendments and Inorganic Fertilizer

Growth and yield of carrots exposed to different irrigation frequency, organic soil amendments and inorganic fertilizer was investigated using 2x4 factorial experiment designs to find out the effects of those variables. The frequency of irrigation were two (F1) and four days intervals (F2), and the different organic soil amendments were the mushroom spent, chicken dung and native sunflower leaves. The inorganic fertilizer was the ammonium phosphate, urea and muriate of potash (S0). Statistical analysis showed that he length of leaves at 31, 38, 52, 66, 80 and 88 days after emergence and irrigated 2 days interval was highly significant, but the number of leaves, diameter of root, and texture of root were not significant. The root length, weight and number of marketable root, were significantly affected by irrigation at two days interval with the highest yield of 22.06 t/ha, and irrigation at four days interval resulted to lowest yield of 13.84 tons/ha. While no significant interaction were noted on the effects of the two factors on the length of foliage at different days after sowing. https://doi.org/10.26803/ijhss.11.4.2

Preference of Pen-Reared Northern Bobwhite Among Native Plant Seeds of the Sand Sagebrush-Mixed Prairie

Adult northern bobwhites (Colinus virginianus) are largely granivorous, primarily eating seeds produced from grasses and forbs. Our objective was to determine northern bobwhite preference among seeds of 45 plant species associated with sand sagebrush (Artemisia filifolia)–mixed prairie. A preference existed among the 45 plant species by weight of seed consumed and percentage of seed in diet (P ≤ 0.05) and on the basis of a cluster analysis of these variables. Five species were categorized into most preferred for food. These included, in order of preference: switchgrass (Panicum virgatum), Rocky Mountain bee plant (Peritoma serrulata), annual sunflower (Helianthus annuus), sand lovegrass (Eragrostis trichodes), and false sunflower (Heliopsis helianthoides). Thirteen plants were categorized into intermediately preferred for food, and 27 species were categorized into least preferred for food. The sand sagebrush–mixed prairie community supports a broad range of plants and animals. Improving rangeland conditions by employing conservative grazing management, especially during drought, or by planting a greater variety of native grasses, sunflowers, shrubs, forbs, and legumes, when reestablishing marginal crop lands, would improve the habitat and diet quality for northern bobwhite and other wildlife species.

Sunflower Stem Weevil and Its Larval Parasitoids in Native Sunflowers: Is Parasitoid Abundance and Diversity Greater in the U.S. Southwest?

Classical biological control programs often target a pest's region of origin as a likely source for new biological control agents. Here, we use this approach to search for biological control agents of the sunflower stem weevil (Cylindrocopturus adspersus LeConte), an economically important pest of commercial sunflower. We conducted surveys of weevil natural enemy diversity and abundance across a transect running from the northern Great Plains to the southwestern U.S. (the presumed area of endemism of annual sunflower species in the genus Helianthus). Accordingly, natural enemy diversity and abundance were expected to be greater in the southwestern U.S. C. adspersus and their larval parasitoids were collected from stems of four native sunflower species (Helianthus annuus, H. nuttallii, H. pauciflorus, and H. petiolaris) from 147 sites across eight states. Native H. annuus constituted the majority of the sunflower populations. Mean weevil densities were significantly higher in sunflower stalks that were larger in diameter. Mean weevil densities within sites did not differ across the range of longitudes and latitudes sampled. After accounting for the effects of stalk diameter and location, weevil densities did not differ among the four sunflower species nor did they differ as a function of elevation. C. adspersus in H. annuus and H. petiolaris were attacked by seven species of parasitoids. No parasitoids were found attacking C. adspersus in H. nuttallii or H. pauciflorus stalks. C. adspersus were twice as likely to be attacked by a parasitoid when feeding on H. petiolaris than H. annuus. Furthermore, the likelihood that C. adspersus would be parasitized decreased with increasing elevation and increasing stem diameters. All parasitoid species have been previously reported attacking C. adspersus larvae in cultivated sunflower. Species richness was less diverse in these collections than from previous studies of cultivated sunflower. Our findings suggest that the species of larval parasitoids attacking C. adspersus in native sunflowers have successfully made the transition to cultivated sunflower.

Screening of wild helianthus species for resistance to high virulent Orobanche cumana Wallr., affecting sunflower in the Rostov region of the Russian Federation

SUMMARY During the last years in Rostov region of Russian Federation highly virulent biotypes of broomrape have propagated, affecting both hybrids of foreign breeding, and the native sunflower assortment, which used to be resistant earlier. Apart from that, the resistance of some known European sunflower types to broomrape races had disappeared, which testifies about the presence of the races F, G, H in the region at least. Consequently, the search of the sources of resistance is urgent. 14 samples of annual and 27 of perennial wild sunflower from the collection of Kuban experimental station VIR were tested for resistance to the most virulent broomrape population. From the annual species only H. petiolaris had weak degree of affection (1-3 tubercles/plant), while the other were affected to a high degree. The majority of perennial sunflower samples have shown the immunity. Perennial wild species of the sunflower of the same name that were used earlier in the research of Ruso et al . (1996) as resistant species against the Spanish populations of broomrape, show resistance also to high virulent O. cumana , which had propagated in the Rostov region of the Russian Federation. The immunity to broomrape of the studied wild perennial sunflower samples is not related to the absence of stimulating effect of root exudations on the seeds of the parasite. The immunity is more likely connected to physiologicalbiochemical features of cortex root cells.

Effect of dietary fat sources on fatty acid deposition and lipid metabolism in broiler chickens

The hypothesis tested was that dietary vegetable fats rich in saturated fatty acids, when compared with a vegetable oil rich in linoleic acid, increase fat deposition in broiler chickens and affect synthesis or oxidation, or both, of individual fatty acids. Diets with native sunflower oil (SO), a 50:50 mix of hydrogenated and native SO, palm oil, and randomized palm oil were fed to broiler chickens. Intake of digestible fat and fatty acids, whole body fatty acid deposition, hepatic fatty acid profile, and hepatic enzyme activities involved in fatty acid oxidation and synthesis were measured. The fat deposition:digestible fat intake ratio was significantly lower for the SO group in comparison with the groups fed the vegetable fats rich in saturated fatty acids. The difference between digestible intake and deposition of C18:2, reflecting its maximum disappearance rate, was highest for the SO group and lowest for the palm oil- and randomized palm oil-fed birds. The calculated minimal rate of de novo synthesis of monounsaturated fatty acids (MUFA), calculated as deposition minus digestible intake, was more than 50% lower for the SO group than for the other 3 dietary groups. Based on the fatty acid profiles in the liver, it would appear that increasing contents of C18:2 decrease the desaturation of saturated fatty acids into MUFA. It is concluded that a diet rich in C18:2 in comparison with different kinds of vegetable saturated fatty acids decreases the deposition of fat, especially of MUFA. It appears to be caused by a higher β-oxidation and a reduced de novo synthesis of MUFA, but this conclusion is not fully supported by the measured activities of enzymes involved in fatty acid synthesis and oxidation.

Application of Enzymatic Hydrolysis on Sunflower Lecithin Using a Pancreatic PLA2

Journal of the American Oil Chemists' SocietyVolume 88, Issue 3 p. 443-446 Letter to the Editor Application of Enzymatic Hydrolysis on Sunflower Lecithin Using a Pancreatic PLA2 D. M. Cabezas, D. M. Cabezas Centro de Investigación y Desarrollo en Criotecnología de Alimentos (CIDCA), CCT La Plata, CONICET, Facultad de Ciencias Exactas, Universidad Nacional de La Plata (FCE, UNLP), 47 y 116 (1900), La Plata, ArgentinaSearch for more papers by this authorR. Madoery, R. Madoery Cátedra de Química Orgánica, Facultad de Ciencias Agrarias, Universidad Nacional de Córdoba (FCA, UNC), Ciudad Universitaria S/N, Córdoba, 5000 ArgentinaSearch for more papers by this authorB. W. K. Diehl, B. W. K. Diehl Spectral Service GmbH Laboratorium für Auftragsanalytik, Emil Hoffman Str. 33, Cologne, 50996 GermanySearch for more papers by this authorM. C. Tomás, Corresponding Author M. C. Tomás [email protected] 54-221-425485354-221-4890741 | Fax: 54-221-4249287 Centro de Investigación y Desarrollo en Criotecnología de Alimentos (CIDCA), CCT La Plata, CONICET, Facultad de Ciencias Exactas, Universidad Nacional de La Plata (FCE, UNLP), 47 y 116 (1900), La Plata, Argentina [email protected]Search for more papers by this author D. M. Cabezas, D. M. Cabezas Centro de Investigación y Desarrollo en Criotecnología de Alimentos (CIDCA), CCT La Plata, CONICET, Facultad de Ciencias Exactas, Universidad Nacional de La Plata (FCE, UNLP), 47 y 116 (1900), La Plata, ArgentinaSearch for more papers by this authorR. Madoery, R. Madoery Cátedra de Química Orgánica, Facultad de Ciencias Agrarias, Universidad Nacional de Córdoba (FCA, UNC), Ciudad Universitaria S/N, Córdoba, 5000 ArgentinaSearch for more papers by this authorB. W. K. Diehl, B. W. K. Diehl Spectral Service GmbH Laboratorium für Auftragsanalytik, Emil Hoffman Str. 33, Cologne, 50996 GermanySearch for more papers by this authorM. C. Tomás, Corresponding Author M. C. Tomás [email protected] 54-221-425485354-221-4890741 | Fax: 54-221-4249287 Centro de Investigación y Desarrollo en Criotecnología de Alimentos (CIDCA), CCT La Plata, CONICET, Facultad de Ciencias Exactas, Universidad Nacional de La Plata (FCE, UNLP), 47 y 116 (1900), La Plata, Argentina [email protected]Search for more papers by this author First published: 01 October 2010 https://doi.org/10.1007/s11746-010-1684-9Citations: 6Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Citing Literature Volume88, Issue3March 2011Pages 443-446 RelatedInformation

Influence of Viscosity Ratio on Droplets Formation in a Chaotic Advection Flow

The efficiency of liquid/liquid dispersion is an important sake in numerous sectors, such as the chemical, food, cosmetic and environmental industries. In the present study, dispersion is achieved in an open-loop reactor consisting of simple curved pipes, either helically coiled or chaotically twisted. In both configurations, we investigate the drop breakup process of two immiscible fluids (W/O) and especially investigate the effect of the continuous phase viscosity, which is varied by the addition of different fractions of butanol in the native sunflower oil. The global Reynolds numbers vary between 40 and 240, so that the flow remains laminar while the Dean roll-cells in the bends develop significantly. Different fractions of butanol are added to the oil in each case to examine the influence of the continuous phase viscosity on the drop size distribution of the dispersed phase (water). When the butanol fraction is decreased, the dispersion process is intensified and smaller drops are created. The Sauter mean diameters obtained in the chaotic twisted pipe are compared with those in a helically coiled pipe flow. The results show that chaotic advection intensifies the droplet breakup until there is a 25% reduction in droplet size.

Terpenoids from &lt;i&gt;Tithonia diversifolia&lt;/i&gt;

The air-dried flowers of Tithonia diversifolia , commonly known as native sunflower, afforded tagitinin C ( 1 ), fatty acid esters of faradiol ( 2 ), squalene ( 3 ), and a mixture (1:2) of stigmasterol ( 4 ) and sitosterol ( 5 ). The structure of 1 was elucidated by extensive 1D and 2D NMR spectroscopy, while the structures of 2 to 5 were deduced by a comparison of their 1 H and 13 C NMR spectral data with those found in the literature. Antimicrobial tests on 1 indicated that it was moderately active against S. aureus and C. albicans ; slightly active against E. coli , P. aeruginosa , and T. mentagrophytes ; and inactive against B. subtilis and A. niger .

Importance of Native Seeds in White‐Winged Dove Diets Dominated by Agricultural Grains

ABSTRACT Agricultural intensification is a key factor in the decline of many avian populations throughout the world, yet the exact mechanisms that contribute to these declines are relatively unresolved, especially for seed‐eating species. We tested the hypothesis that forage quality, particularly protein content, limits productivity in birds consuming diets dominated by agricultural grains and lacking in native forages. We used white‐winged doves (Zenaida asiatica) because columbids are highly granivorous and white‐winged doves have declined in areas dominated by grain agriculture. We randomly assigned 52 pairs of captive doves to 1 of 2 treatments: we fed one treatment sorghum (Sorghum bicolor) and the second sorghum plus native seeds (croton [Croton sp.] and native sunflower [Helianthus sp.]). Birds with access to native seeds fledged 123% more young per pair, with young weighing 32% more at fledging than those fed only sorghum. Doves with access to native seeds selected a diet consisting of 43% sorghum, 32% croton, and 25% sunflower. We conclude that agricultural grains, which typically have high metabolizable energy and low to moderate protein concentrations, are not sufficient for normal productivity of white‐winged doves. The lack of native forages with sufficient metabolizable energy and protein content may be a factor in the declining productivity of white‐winged doves in the lower Rio Grande Valley of Texas, USA, as well as other species in regions dominated by agriculture.

Results of a European inter-laboratory comparison study on the determination of EU priority polycyclic aromatic hydrocarbons (PAHs) in edible vegetable oils

A collaborative study on the analysis for 15 + 1 EU priority PAHs in edible oils was organised to investigate the state-of-the-art of respective analytical methods. Three spiked vegetable oils, one contaminated native sunflower oil, and one standard solution were investigated in this study. The results of 52 laboratories using either high-performance liquid chromatography with fluorescence detection or gas chromatography with mass-selective detectors were evaluated by application of robust statistics. About 95% of the laboratories were able to quantify benzo[a]pyrene together with five other PAHs included in the commonly known list of 16 US-EPA PAHs. About 80% of the participants also quantified seven additional PAHs in most samples, two of which were benzo[b]fluoranthene and benzo[k]fluoranthene, which were also known from the EPA list. Only about 50% of the participants quantified cyclopenta[cd]pyrene, benzo[j]fluoranthene, and benzo[c]fluorene. The robust relative standard deviations of the submitted results without discrimination between the methods applied ranged between 100% for 5-methylchrysene in spiked olive oil and 11% for the same analyte in spiked sunflower oil. The results clearly showed that for these analytes the methods of analysis are not yet well established in European laboratories, and more collaborative trials are needed to promote further development and to improve the performances of the respective methods.

Effects of Host-Plant Distribution on Genetic Structuring of Two Tortoise Beetles (Coleoptera: Chrysomelidae: Cassidinae) in the Northern Great Plains

Physonota helianthi Randall feeds exclusively on a native sunflower, Helianthus grosseserratus Martens, in southeastern South Dakota. Helianthus grosseserratus populations are highly fragmented by agriculture and their patchy distribution presents the hypothesis that host-plant fragmentation results in genetic structuring in P. helianthi. In contrast, another cassidine beetle, Chelymorpha cassidea F., feeds on common bindweeds (Convolvulus arvensis L. and Calystegia sepium (L.) R. Br.) and therefore may not exhibit such genetic structuring. We sampled patches of host plants for P. helianthi and C. cassidea. Families were reared in the laboratory through adult emergence and assayed with starch-gel electrophoresis. Genetic variability within and among beetle families from different patches was compared for both species. For P. helianthi, 15 loci were used to evaluate allele frequencies in 30 families from five sites. For C. cassidea, we assayed 13 loci from 25 families from five sites. We determined the relative magnitude of genetic variance within a hierarchy that included families, patches, and total sample. For P. helianthi, slightly more genetic variation existed within families from the same patch than among families from different patches, but overall, variability was low (x̄ heterozygosity = 0.048). Paternity of individual egg masses was more than one in most cases. Chelymorpha cassidea was more variable (x̄ heterozygosity = 0.072) but showed less differentiation among patches. Multiple paternity was less frequent in this species than in P. helianthi. Differences in genetic structuring of these two species are likely because of their contrasting host-plant distributions and mating structure.

Abundance of a Native MothHomoeosoma electellum(Lepidoptera: Pyralidae) and Activity of Indigenous Parasitoids in Native and Agricultural Sunflower Habitats

Insect herbivores have been assumed to be more abundant in agricultural habitats than in native habitats; however, this hypothesis is rarely tested explicitly by comparing field populations of domesticated plants and their wild ancestors. This study examined the abundance of the sunflower moth, Homoeosoma electellum (Hulst), and its parasitism by natural enemies in agricultural and native sunflower habitats. Nutrient levels and plant population factors in the two habitat types were measured to identify factors associated with the patterns of herbivory and parasitism. Adult male and larval H. electellum were consistently more abundant in agricultural habitats. In contrast, parasitism of H. electellum was 6–10 times higher in native sunflower habitats than in agricultural habitats. Also, fewer parasitoid species were found in agricultural habitats, and parasitism by individual parasitoid species was reduced by 90%. Larval densities per flower head were higher on agricultural plants, but parasitoids failed to respond to the higher densities. The relationship between flower age and larval infestation differed between agricultural and wild flowers; larval age tracked agricultural flower age, but on wild flowers, larvae moved from older to younger flowers. Among the three nutrients sampled, only nitrogen was positively correlated with habitat differences. These results indicate that patterns of trophic interactions varied by habitat type and were related to plant phenotypic changes and environmental habitat factors such as crop domestication, nitrogen fertilization, and plant phenology.

Biology and Seasonal Abundance of Parasitoids of the Banded Sunflower Moth (Lepidoptera: Tortricidae) in Sunflower

Mortality, parasitization, and overwintering development through pupation of the banded sunflower moth, Cochylis hospes Walsingham, larvae and two of its endoparasitoids, Glypta prognatha Dasch and Chelonus phaloniae Mason, were followed over a 2-year period (1987 to 1989). Development of parasitoids in the field was determined for each species by examination of moth eggs and larvae during the 1989 season. Parasitoids of C. hospes, recovered from cultivated sunflower, Helianthus annuus L., from North and South Dakota and Minnesota in 1994 and 1995, parasitized 24 and 17% of larvae, respectively. Species of Hymenoptera collected included G. prognatha and Trathala sp. (Ichneumonidae), C. phaloniae and Macrocentrus ancylivorus Rohwer (Braconidae), and Perilampus robertsoni Crawford (Pteromalidae). The most abundant parasitoid was G. prognatha. In 1994 and 1995, C. phaloniae, an egg-larval parasitoid, emerged earlier but was less abundant than the later occurring larval parasitoid G. prognatha. Species of parasitoids collected from cultivated sunflower and five species of native sunflowers were similar. An additional parasitoid, Mastrus sp. (Ichneumonidae), was recovered only from the native sunflowers H. annuus and H. tuberosus L. Results from 1994 and 1995 showed that parasitization rates for the total season by the two most abundant parasitoids were similar in fields using three planting dates. These results suggest that altering planting date could be successfully used as a pest management strategy without disrupting the biological control of the banded sunflower moth. Conservation of these parasitoids in the sunflower agroecosystem is needed since they play an important role in the management of C. hospes.

Antioxidative effectiveness of some natural antioxidants in sunflower oil.

Sunflower oil has been oxidized at 25 and 100 degrees C in the presence and in the absence of 0.01, 0.02 and 0.05% 3,4-dihydroxybenzoic acid, caffeic acid, esculetin and fraxetin. 3,4-Dihydroxybenzoic acid shows no antioxidative activity at either temperature. Esculetin possesses a relatively low effectiveness at 100 degrees C (stabilization factor F = 1.3 for 0.05% esculetin), and at 25 degrees C it does not improve the oxidative stability. Sunflower oil is more easy to stabilize at 100 degrees C: F = 3.0 for 0.05% fraxetin, and F = 1.9 for 0.05% caffeic acid. Native sunflower oil is much more difficult to stabilize than are its kinetically pure triacylglycerols.

Resistance of Native Sunflowers (Asterales: Asteraceae) to the Banded Sunflower Moth (Lepidoptera: Cochylidae)

Six native sunflower, Helianthus , species were evaluated for resistance to the banded sunflower moth, Cochylis hospes Walsingham, a pest of cultivated sunflower in the northern Great Plains. Larval survival and oviposition preference by female C. hospes on the capitula (heads) of the native sunflowers H. annuus L., H. petiolaris Nuttall, H. maximiliani Schrader, H. tuberosus L., H. pauciflorus Nuttall ssp. subrhomboideus (Rydberg) Spring & Schilling, and H. nuttallii ssp. rydbergii (Britton) Long were evaluated in the field and laboratory, respectively. Larval development occurred on the capitula of all sunflowerspecies tested. Larval survival was higher on H. annuus than on any other species. The lowest larval survival, based on the percentage of capitula infested, occurred on H. maximiliani , H. pauciflorus , and H. tuberosus . More eggs were laid on the capitula of H. annuus than on other species in multiple-choice trials. In 2-choice tests, H. tuberosus received significantly fewer eggs than H. annuus . Both larval antibiosis and oviposition antixenosis resistance were evident in the perennial sunflower species H. pauciflorus , H. tuberosus , and H. maximiliani . Incorporating germplasm from these species into commercial hybrids could be helpful in reducing costs for the control of the banded sunflower moth.