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At least 19 recordsLinked to original sources
PubMed2003

Cyromazine seed treatments to control onion maggot, Delia antiqua, on green onions.

Cyromazine seed treatments were evaluated for onion maggot control in green onion crops. The more tolerant to organophosphates of two populations of onion maggots was chosen for further research, based on the results of adult assays in a Potter spray tower. In the laboratory, first-instar mortality was compared between film-coated seed treatment and soil drench treatment. The LC50 for the film-coated seed treatment was approximately one fourth that of the soil drench treatment. In choice assays, no significant difference was observed between the number of eggs deposited on seedlings grown from film-coated seeds with cyromazine and film-coated seeds without cyromazine. Field studies demonstrated that all rates of cyromazine seed treatment resulted in protection of onion plants from onion maggot damage. Green onions may not require as high a rate of cyromazine for control of onion maggots as the rate established for use in dry onions for two reasons: the seeding rate is much higher for green onions resulting in more AI/ha for a given amount of AI/kg of seed, and a given percentage of stand loss is more difficult to detect in green onions than in dry onions.

Animals↗
PubMed2005

Evaluation of sampling methodology for determining the population dynamics of onion thrips (Thysanoptera: Thripidae) in Ontario onion fields.

Onion thrips, Thrips tabaci Lindeman, are an economic pest of alliums worldwide. In Ontario onion-growing regions, seasonal abundance and population trends of onion thrips are not well known. The objectives of this research were to investigate onion thrips population dynamics by using both white sticky traps and plant counts, to gain insight into flight height, and to determine the genus and sex of thrips fauna present in monitored fields. Adult thrips were captured on white sticky traps placed in two commercial onion fields in the Thedford-Grand Bend Marsh region as early as mid-May in 2001, 2002, and 2003. Thrips were not recorded on onion plants in these fields until late June and early July. A comparison of sticky trap captures to plant counts revealed a strong, positive correlation, indicating that sticky traps, which consistently detected thrips earlier than plant counts, could be used instead of plant counts early in the season to monitor onion thrips populations. Pole traps placed in onion and an adjacent soybean, Glycine max (L.) Merr., field revealed that regardless of crop type, most thrips were captured 0.7-0.95 m above the soil surface. During this study, 70% of 137,000 thrips captured on sticky traps and 89% of 1,482 thrips captured in pan traps were female onion thrips. No male onion thrips were identified in this study: most of the remaining thrips were Frankliniella spp.

Animals↗
PubMedDate not supplied

Suspended onion particles and potential corneal injury in onion harvesters.

The authors suspected that suspended onion particles contributed to corneal ulcers in onion harvesters in southern Taiwan. In the present study, the authors used manikins to study suspended onion particles in fields in an effort to simulate typical conditions experienced by onion harvesters. An animal eye-exposure simulation study was also performed by the authors, who impacted suspended soil grains or onion particles onto the corneas of guinea pigs via aerosol generated from the Palas dispersion nozzle. The average size of 25.9 pm for suspended particles collected during the digging of onions was the largest one of those for various harvesting activities. Some onion skin flakes were found in samples obtained from gathering and packing activities; the typical flake size was approximately 3.5 x 2.5 mm2. The results of the animal study indicated that the size of soil grains has a demonstrable effect on the severity of corneal injury (p = .009). With respect to onion skin flakes, wind velocity was also associated significantly with the occurrence of corneal injury (p = .0004). A wind velocity threshold of 7 m/sec is recommended for the maintenance of safety, and if the wind speed exceeds this threshold level, workers should not engage in harvesting activities. Furthermore, use of appropriately designed goggles is necessary for the protection of onion harvesters who work in high-wind conditions.

Agricultural Workers' Diseases↗
PubMed2003

Regional and temporal variation in susceptibility to lambda-cyhalothrin in onion thrips, Thrips tabaci (Thysanoptera: Thripidae), in onion fields in New York.

Populations of onion thrips, Thrips tabaci Lindeman, from commercial onion fields in New York were evaluated for their susceptibility to the commonly used pyrethroid, lambda-cyhalothrin (Warrior T), using a novel system called the Thrips Insecticide Bioassay System (TIBS). To use TIBS, thrips are collected directly from the plant into an insecticide-treated 0.5-ml microcentrifuge tube that has a flexible plastic cap with a small well into which 0.08 ml of a 10% sugar-water solution with food colorant is deposited. The solution is sealed into the well with a small piece of stretched parafilm through which the thrips can feed on the solution. Thrips mortality is assessed after 24 h with the help of a dissecting stereoscope. In 2001, onion thrips populations were collected from 16 different sites and resistance ratios were >1,000 in five populations. Percent mortality at 100 ppm, a recommended field rate, varied from 9 to 100%, indicating high levels of variation in susceptibility. Particular instances of resistance appeared to be the result of practices within an individual field rather than a regional phenomenon. In 2002, we also observed large differences in onion thrips susceptibility, not only between individual fields but also between thrips collected in a single field at mid season and late season, again suggesting that insecticide-use practices within an individual field caused differences in susceptibility. Additional tests indicated no differences in susceptibility between adult and larval onion thrips populations and only relatively minor differences between populations collected from different parts of the same field. Using TIBS, several populations of onion thrips with different susceptibilities to lambda-cyhalothrin were identified and then subjected to lambda-cyhalothrin-treated onion plants. There was a highly significant positive relationship between percent mortality of thrips from TIBS and percent mortality from the treated onion plants, indicating that results from TIBS could be used to predict spray performance. These data suggest that use of TIBS for evaluating susceptibility to particular insecticides could be instrumental for developing a resistance management strategy for onion thrips.

Animals↗
PubMed1978

Exposure to onion taste in mother's milk leads to enhanced preference for onion diet among weanling rats.

Five mothers of 50 newborn rat pups were maintained on either standard lab chow or a diet composed of the same chow with onion powder added. Taste preference tests administered during weaning indicated that the pups whose mother was fed the onion chow showed a preference for onion diet, but that such preference dissipated across the five day testing period. A control group of pups who were exposed to any onion diet cues available through channels other than the mother's milk did not show a preference for onion diet. It was concluded that exposure to onion taste in mother's milk was responsible for an initial preference for onion diet.

Animal Feed↗
PubMed1998

Field Persistence Studies on Pendimethalin Residues in Onions and Soil after Herbicide Postemergence Application in Onion Cultivation.

Field studies were undertaken to evaluate the fate of pendimethalin residues in spring and dry onions, after postemergence application of the herbicide in a clay soil onion planting in central Greece, at rates of 1.32 and 2.0 kg of active ingredient (ai)/ha. Residues were determined with capillary GC-ECD after onion extraction with 2-propanol/toluene and extract cleanup in a AgNO(3-)coated alumina column; the recovery of pendimethalin from spiked onions was found to be 82-99% and the limit of determination 0.007 mg/kg. Pendimethalin residues were found to decline rapidly, and it was estimated that 7 days after the treatment only half of the initial concentrations remained for both the low recommended dose (LRD) and the high recommended dose (HRD) experiments. In all cases the residues in dry bulb onion were well below the lowest maximum residue limit (MRL) set by European countries, which is 0.05 mg/kg. Residues in spring onions at harvest time were also below this level when treated at the LRD and were only slightly above in case of the HRD. The pendimethalin concentration in planting soil for the investigated period declined with half-lives of 37 and 39 days for the LRD and the HRD experiments, respectively.

Journal Article↗
PubMed2006

Patterns of insecticide resistance in onion thrips (Thysanoptera: Thripidae) in onion fields in New York.

To develop an insecticide resistance management program for onion thrips, Thrips tabaci Lindeman (Thysanoptera: Thripidae), on onions (Allium spp.), we surveyed populations in commercial onion fields in New York and evaluated their susceptibility to the two most widely used classes of insecticides plus two new insecticides during 2003-2005. All insecticide evaluations were conducted using the Thrips Insecticide Bioassay System (TIBS). As in our surveys conducted during 2002-2003, there were large temporal and spatial variations in susceptibility to the pyrethroid lambda-cyhalothrin (Warrior) across onion-growing regions in 2003. New data indicate that the field rate of methomyl (Lannate LV) still provides control but that the genes for resistance to methomyl are present in some populations. Tests with the two new insecticides, acetamiprid (Assail 70 WP) and spinosad (SpinTor 2CS), indicated they provided > 85% mortality at the field rate. To determine the spatial variation in insecticide susceptibility within a region, a series of systematic assays were conducted with lambda-cyhalothrin and methomyl. In 2004 and 2005, our data indicated that the within-region spatial variation in susceptibility to lambda-cyhalothrin was not large at the field rate or for the 100 ppm rate of methomyl. In 2005, a year in which T. tabaci densities in most fields were much higher than in 2004, growers were unable to control T. tabaci in particular fields and attributed this lack of control to resistance. Yet, we found similar levels of high susceptibility in all fields when using TIBS. This finding suggests that resistance had not developed and that variation in control may have been due to other factors, such as localized higher populations, poor spray coverage, too much time between spray applications, or different onion varieties.

Animals↗
PubMed2003

Hypoglycaemic and antioxidant effects of onion, Allium cepa: dietary onion addition, antioxidant activity and hypoglycaemic effects on diabetic rats.

The purpose of the present study was to discover the relative potency of onion, Allium cepa, with respect to its hypoglycaemic and hypolipidaemic effects on the diabetic situation, and the association of these effects with the potential against oxidative stress. Male Wistar rats were divided into four groups. A normal control (group A), and a non-diabetic group (group B) were treated daily with 1 ml A. cepa solution (0.4 g A. cepa/rat). Groups C and D were made diabetic by an intraperitoneal injection of streptozotocin (STZ) (60 mg/kg body weight) in citrate buffer (pH 6.3). These animals (groups C and D) were the STZ diabetic control and STZ diabetic rats with onion intake, respectively. Onion increased the fasting serum high-density lipoprotein levels, and demonstrated alleviation of hyperglycaemia in STZ diabetic rats. The hypoglycaemic and hypolipidaemic actions of A. cepa were associated with antioxidant activity, since onion decreased superoxide dismutase activities while no increased lipid hydroperoxide and lipoperoxide concentrations were observed in diabetic rats treated with A. cepa.

Alanine Transaminase↗
PubMed2006

Onion maggot (Diptera: Anthomyiidae) resistance to chlorpyrifos in New York onion fields.

A larval immersion bioassay was developed to identify susceptibility of onion maggot, Delia antiqua (Meigen) (Diptera: Anthomyiidae), to chlorpyrifos and to determine whether this assay could be used to predict control in onion fields. Laboratory colonies were established from larvae collected in New York onion fields during 2003 and 2004, providing us with test insects to use in bioassays. The larval assay effectively determined susceptibility of D. antiqua to chlorpyrifos, and results were congruent with an adult bioassay. However, use of similar-aged larvae (4 d old) in the assays was critical because larvae became more tolerant to chlorpyrifos as they aged. In a field survey, six of the 13 populations had LC50 values above the recommended field rate of 3,600 ppm (range 4,031-6,869). Over two successive seasons in the same field, susceptibility of D. antiqua to chlorpyrifos decreased in two of three fields (by 45 and 42%) and remained the same in another field, indicating that resistance is not predictable from year to year. Based on the relationship between damage in the field and LC50 values from 11 of the populations mentioned above, all five populations that had LC50 values above the field rate caused unacceptable levels of damage, whereas five of six populations that had LC50 values below the field rate did not cause serious damage.

Age Factors↗
PubMed1987

Antiasthmatic effects of onions. Inhibition of platelet-activating factor-induced bronchial obstruction by onion oils.

Lyophilized onion extract and ether extracts of onions were separated by chromatographic methods into several subfractions and tested for their effects on asthmatic reactions of guinea pigs to allergen, histamine, acetylcholine and platelet-activating factor (PAF) inhalation as well as on thromboxane biosynthesis of human platelets and lung fibroblasts. Onion oils are counteracting the bronchial obstruction due to PAF inhalation.

Allium↗
PubMed1996

Coat protein gene sequences of garlic and onion isolates of the onion yellow dwarf potyvirus (OYDV).

Partial genomic sequences from an unknown garlic potyvirus and from an onion isolate of the onion yellow dwarf potyvirus (OYDV) were obtained. Comparison of the deduced amino acid sequences showed a similarity of 88% between the respective viral coat proteins. The garlic potyvirus coat protein was expressed in E. coli cells, purified, and subjected to Western blot analysis using antibodies raised against different garlic-infecting viruses. The expression protein was consistently recognised by anti-OYDV antibodies and did not react with antibodies specific for leek yellow stripe potyvirus (LYSV), garlic common latent carlavirus (GCLV) and shallot latent carlavirus (SLV). Besides, the garlic potyvirus coat protein was obtained as a fusion protein and used as antigen to produce polyclonal antibodies. These antibodies reacted with purified OYDV virions, but failed to recognise LYSV particles. In the light of this evidence the garlic potyvirus was identified as the garlic strain of OYDV.

Amino Acid Sequence↗
PubMed2004

Polyphasic characterization of xanthomonads isolated from onion, garlic and Welsh onion (Allium spp.) and their relatedness to different Xanthomonas species.

Bacterial blight is an emerging disease that affects primarily onion, but also garlic and Welsh onion. The present study was undertaken to characterize the causative xanthomonad(s) by a polyphasic approach using a worldwide collection of 33 bacterial strains. Analysis of 16S rRNA gene sequence similarities indicated that the causal agent belongs to the campestris core in the genus Xanthomonas, which is in agreement with results of phenotypic characterization (analyses of carbon source utilization and fatty acid methyl esters). However, DNA-DNA hybridization, thermal stability of DNA reassociation and fluorescent amplified fragment length polymorphism analysis allowed the causal agent to be identified as a pathovar of Xanthomonas axonopodis.

Allium↗
PubMed2003

Testing the efficacy of different insecticides to control onion thrips (Thrips tabaci Lindeman, Thysanoptera, Thripidae) in onion crops.

Onion thrips (Thrips tabaci) has become important pest in onion crops in Slovenia. Because it is a polyphagous species, it causes damage also in vegetable production in general (leek, cabbage, ornamentals etc.). The group of efficient insecticides for thrips control in Slovenia is limited, because its misusage in the past caused the development of resistance of this pest. In 2002, eight different insecticides based on four active substances was tested in Goriska region. The results of field experiments showed the highest efficiency of active substances Spinosad and Abamectine for control of Thrips tabaci. Unfortunatelly, they are not registrated in Slovenia for this purpose as yet.

Animals↗
PubMed1993

Acute and subacute toxicity tests of onion coat, natural colorant extracted from onion (Allium cepa L.), in (C57BL/6 x C3H)F1 mice.

The toxicity test of onion coat colorant (OC), a food colorant extracted from onion (Allium cepa L.), was undertaken using (C57BL/6 x C3H)F1 mice of both sexes for the safety assessment of this product. The acute toxicity test was performed by administration of OC suspended in corn oil by gavage at doses of 2500, 5000, 7500, and 10,000 mg/kg body weight to groups of 5 or 6 males and 6 or 7 females, maintained for 14 d. Six of 12 females dosed at 10,000 mg/kg body weight and 3 of 11 females dosed at 7500 mg/kg body weight were dead before the end of the study, indicating that the tolerated dose of OC was between 7500 and 5000 mg/kg body weight. The subacute toxicity test of OC was examined using 123 mice of both sexes (62 males and 61 females) by feeding a diet mixed with OC at concentrations of 5, 2.5, 1.25, 0.6, and 0.3% for 90 d. All mice tolerated these doses of OC well. The body weight gains of male and female mice were not affected by the treatment. Histopathological examinations showed that hyperplastic changes in the esophagus, forestomach, pancreas, cervix, and endometrium of mice were found in treated and control mice. However, their incidences were not related to the dose of OC. Moreover, only a spontaneous ovarian teratoma was found in an OC-treated mouse. These results suggest that OC has no acute and subacute toxic effects in mice.

Administration, Oral↗
PubMed2004

Gold color in onions (Allium cepa): a natural mutation of the chalcone isomerase gene resulting in a premature stop codon.

Unusual gold-colored onions were selected from a F3 family originating from a cross between US-type yellow and Brazilian yellow onions. HPLC analysis showed that the gold onions contained a significantly reduced amount of quercetin, the most abundant flavonoid in onions. This result indicated that an early step in the flavonoid biosynthesis pathway might be abnormal in these onions. The expression of flavonoid synthesis genes isolated from onions was examined in gold onions and compared to that in onions of other colors by RT-PCR. The results showed that all genes were transcribed in gold onions as in red onions. In order to identify any critical mutations in flavonoid synthesis genes encoding enzymes involved in early steps of the pathway, the genomic sequence of chalcone isomerase (CHI) was obtained. A premature stop codon and a subsequent single base-pair addition causing a frameshift were identified in the coding region of the CHI gene in the gold onions. Co-segregation of the mutant allele of the CHI gene and the gold phenotype was investigated in the original F2 segregating population. Genotyping of three color groups (red, yellow and gold) of F2 onions revealed perfect co-segregation of the mutant CHI allele with the gold phenotype. All tested gold F2 onions were homozygous for the mutant CHI allele. This perfect co-segregation implies that the presence of a premature stop codon in the gold CHI gene results in an inactive CHI. Inactivation of CHI results in a block in the flavonoid biosynthesis pathway and the accumulation of chalcone derivatives, including a yellow pigment which might be responsible for the gold color in onions.

Amino Acid Sequence↗