Seasonal development of an invasive exotic species, Contarinia nasturtii (Diptera: Cecidomyiidae), in Quebec

The seasonal development of the swede midge Contarinia nasturtii Kieffer was studied in Quebec in 2004 and 2005 using pheromone traps, emergence cages, and visual inspection in relation to degree-day accumulations (DD(7.2 degrees C)). Peak emergence of overwintering adults occurred between 344 and 731 DD(7.2 degrees C) (second half of June) during both seasons. The swede midge had three to four overlapping generations in Quebec based on adult captures in pheromone traps and abundance of larvae in the field. The level of infestation was higher in late transplants than in early transplants, with cauliflower and broccoli being more susceptible to damage than white or red cabbage under high pest population.     

Potential distribution and relative abundance of swede midge, Contarinia nasturtii, an invasive pest in Canada

The swede midge, Contarinia nasturtii (Kieffer) (Diptera: Cecidomyiidae), is a pest of most cultivated Brassicaceae such as broccoli, canola, cauliflower, cabbage, and Brussels sprouts. The species primarily has a Palaearctic distribution and occurs throughout Europe and southwestern Asia to the Caucasus. Between 1996 and 1999, producers of cruciferous vegetables in Ontario, Canada, reported crop damage that was consistent with damage symptoms characteristic of C. nasturtii feeding and in 2000, field studies confirmed that this damage was caused by C. nasturtii . A bioclimatic model was developed to predict potential range and relative abundance of C. nasturtii in Canada in order to determine the impact of the establishment and spread of C. nasturtii populations. Model output indicated that C. nasturtii could potentially become established in all provinces of Canada, with the risk being greatest in southwestern British Columbia, southern Ontario and Quebec, New Brunswick, Nova Scotia, and Prince Edward Island. Results indicated that C. nasturtii population growth in the Prairie Ecozone of western Canada would be greatest in years with above average precipitation.     

THE IDENTITY OF THE SWEDE MIDGE, WITH NOTES ON ITS BIOLOGY

A brief historical summary is given of the literature concerning Contarinia nasturtii Kieffer, C. torquens de Meijere and C. geisenheyneri Riibsaamen, three gall midges (Cecidomyidae) which have been associated respectively with leaf damage on Brassica spp. in England, identical malformation on the Continent and swollen and closed flowers of Brassica spp. in Europe.
Following the discovery in England of the true Contarinia nasturtii causing swollen and closed flowers oiRorippa amphibia, preliminary experiments have shown that midges from this source will also cause similar damage to swede flowers and that they are the same species as those attacking R. amphibia blossom in the Netherlands.
Further preliminary experiments have shown that swede midge derived from rape leaf axils will also cause identical damage to radish flowers in addition to breeding successfully on the leaves of turnip, swede, cabbage and radish.
Male midges derived from Rorippa blossom have been mated with females from rape leaf axils, and their offspring have been reared on Rorippa flowers and on turnip leaves.
This biological evidence confirms the previous supposition based on morphological grounds that the swede midge is Contarinia nasturtii Kieffer and will cause either flower or leaf damage. Consequently, C. torquens de Meijere and C. geisenheyneri Riibsaamen must remain synonyms.
The shortest time for a generation (from parent to first offspring midge) to develop was 24–39 days in an unheated open glasshouse during June-July in 1949 at Harpenden. Under the same conditions, the shortest time for the next generation from late July to August was 29–32 days. C. nasturtii is the first Contarinia species in which unisexual families have been discovered.     

Identifying sources and mechanisms of resistance in crucifers for control of cabbage maggot (Diptera: Anthomyiidae)

The cabbage maggot, Delia radicum (L.) is an important insect pest of eruciferous crops in upstate New York. This species causes considerable damage to seedlings and young plants by feeding on roots and stems, resulting in plant stand loss and yield loss. Five crucifer accessions (Brassica oleracea variety italica L.,'Green Comet'; B. oleracea L.,'Rapid Cycling' [Crucifer Genetics Cooperative 3-1 ]; B. oleracea variety botrytis L., a standard cauliflower cultivar'Amazing'; B. carinata L.; and Sinapis alba L., 'Cornell Alt 543') were evaluated to identify sources and mechanisms of resistance for D. radicum. Of the accessions tested, S. alba Cornell Alt 543 demonstrated reduced oviposition by D. radicum, reduced weights and survivorship of larvae, pupae or adults, and reduced damage to plants. Thus, S. alba Cornell Alt 543 could be a potential source for resistance to be bred into cruciferous crops for control of D. radicum.     

外源BoCAL基因对花椰菜花球形态发生的调节及其遗传

花椰菜和结球甘蓝是芸薹属甘蓝种的两个变种,前者的BoCAL基因发生提前终止突变而失去了原有的功能,而后者的BoCAL基因具有完整的编码区。在农杆菌的介导下,我们获得了BoCAL转基因花椰菜。T2代的遗传研究表明,外源BoCAL基因转入后花椰菜转基因植株都没有形成花球,而是只形成松散的由花蕾组成的绿色花序。这一结果说明,花椰菜BobCAL被甘蓝BoCAL互补了,转基因花椰菜因此失去了形成花球的能力。这些转基因植株自交到T3代时花序的形态特征与T2代一致,为松散的绿色花序,但是花序出现的时间与T1代相比提早了15天。将转基因花椰菜与野生型花椰菜杂交,结果发现杂交后代的植株形成夹杂有花蕾的花球,且花序出现的时间大大推迟,在播种后135天后才形成花球。     

Components of resistance to the sorghum midge, Contarinia sorghicola

Studies were conducted on components of resistance to sorghum midge on four resistant (DJ 6514, AF 28, TAM 2566 and IS 15107) and two susceptible cultivars (CSH 1 and Swarna). Data were recorded on the numbers of eggs, larvae, emerged adults and grain damage in panicles of different genotypes infested with 60 midge females/panicle under no-choice conditions. The size of floral parts (glume, lemma, palea, lodicule, stigma, style, ovary and anther), rate of grain development and tannin content of grain were measured. The lengths of glume gl and 82, lemma L1 and L2, palea, lodicule, anther, style and stigma were positively associated with susceptibility to sorghum midge. Rate of grain development (between 3rd and 7th day after anthesis) was negatively associated with susceptibility to sorghum. Tannin content of grain was also negatively correlated with midge susceptibility, although there were distinct exceptions (e.g. DJ 6514 is highly resistant bur has a low tannin content).     

Molecular markers to differentiate two morphologically-close species of the genus Sitobion

The effect of allelochemicals from its host, the larva of the cabbage root fly, Delia radicum (L.) (Diptera: Anthomyiidae), and the host's food plant on the ovipositor probing response of the parasitoid Trybliographa rapae (Westw.) (Hymenoptera: Cynipidae) were investigated. Trybliographa rapae probed both cabbage root fly infested and uninfested swede (Brassica napus var. napobrassica), although significantly more wasps responded to infested swede. Antennal sensilla are likely to be the mediators of this response. The synomones and kairomones involved are extractable in water, diethyl ether and methanol. No response was observed to washed, starved cabbage root fly larvae. Wasps spent significantly longer searching infested swede than uninfested, although probing frequency remained constant. It is suggested that the initiation of probing in T. rapae is dependent on a threshold concentration of general synomones or host related synomones and kairomones, whereas time spent searching a particular area is dependent on the environment perceived by sensilla on the ovipositor.     

Resynthesized lines and cultivars of Brassica napus L. provide sources of resistance to the cabbage stem weevil ( Ceutorhynchus pallidactylus (Mrsh.))

The cabbage stem weevil (Ceutorhynchus pallidactylus (Mrsh.)) (Col., Curculionidae) is a serious pest of winter oilseed rape (Brassica napus L. var. oleifera Metzg.) in central and northern Europe. Although host-plant resistance is a key tool in integrated pest management systems, resistant genotypes are not yet available for this species. Resynthesized rapeseed lines (B. oleracea L.×B. rapa L.) are broadening the genetic diversity and might have potential as sources of resistance to pest insects. The host quality, of nine resynthesized rapeseed lines and six genotypes of B. napus to cabbage stem weevil, was evaluated in laboratory screening tests and in a semi-field experiment. In dual-choice oviposition tests, female C. pallidactylus laid significantly fewer eggs on five resyntheses and on swede cv 'Devon Champion' than on the moderately susceptible oilseed rape cv 'Express', indicating a lower host quality of these genotypes. Results of laboratory screenings were confirmed in a semi-field experiment, in which twelve genotypes were exposed to C. pallidactylus females. The number of larvae was significantly lower in two resyntheses and in cv 'Devon Champion' than in oilseed rape cv WVB 9. The total, as well as individual, glucosinolate (GSL) content in the leaves differed substantially among the genotypes tested. The amount of feeding by larvae of C. pallidactylus, as measured by a stem-injury coefficient, was positively correlated with the indolyl GSL compounds 3-indolylmethyl and 4-methoxy-3-indolylmethyl, and with the aromatic GSL 2-phenylethyl, whereas it was negatively correlated with 4-hydroxy-3-indolylmethyl. Thus, the composition and concentration of GSL compounds within the plant tissue might be a key factor in breeding for pest resistance in oilseed rape.     

MidgEmerge, a new predictive tool, indicates the presence of multiple emergence phenotypes of the overwintered generation of swede midge

The swede midge, Contarinia nasturtii (Kieffer) (Diptera: Cecidomyiidae), is a pest of cruciferous crops (Brassicaceae) in Europe and North America with high potential for economic impact. Effective timing of insecticide applications for swede midge control is difficult, in part due to a short adult lifespan. Predictive models are often used in integrated pest management programmes to facilitate the timing of control strategies. A European model, Contapré, for predicting adult swede midge emergence was shown to be inaccurate under Ontario field conditions. A new predictive model, MidgEmerge, was developed using DYMEX™ modelling software. MidgEmerge accurately predicts swede midge emergence in both Ontario and Québec. Observed emergence patterns cannot be explained without the presence of multiple emergence phenotypes. MidgEmerge indicates that there are two emergence phenotypes of the swede midge, each completing four generations per year in southern Ontario. A fifth generation of each may become possible with climate change. Evidence of a possible third emergence phenotype is presented. MidgEmerge has the potential to be an important predictive tool to inform and direct integrated pest management practices targeted against swede midge in North America.     

Patterns of diapause frequency and emergence in swede midges of southern Ontario

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Genetic control of immunity to turnip mosaic virus in winter oilseed rape (Brassica napus ssp. oleifera) and the effect of foreign isolates of the virus

Immunity to a UK isolate (UK 1) of turnip mosaic virus (TuMV) was studied in eight lines of oilseed rape selected from cv Rafal. Six of these lines were uniformly immune and two segregated. Segregation ratios in the F₂ generation of reciprocal crosses between two uniformly immune lines and two uniformly susceptible cultivars (Mikado and Yeoman) showed that immunity was controlled by a dominant nuclear allele. The immunity was confirmed by the inability to detect virus particles in mechanically inoculated plants by back inoculations, ELISA and ISEM tests. Plants were immune to repeated inoculations and aphid transmissions. The immunity was effective against one other UK isolate and two German isolates of TuMV. Another UK isolate (UK 3) and a Greek isolate partially overcame the immunity causing local infection and a Canadian and a Danish isolate overcame it completely causing systemic mosaic-type symptoms. When these immunity-breaking strains were tested against swede line 165 which is also immune to UK 1 TuMV, the Canadian isolate overcame the immunity whereas the Danish isolate did not. Using this swede line, one susceptible and one immune line of oilseed rape as differentials, four distinct groups of TuMV isolates could be identified. Selections of oilseed rape immune to UK TuMV isolates were more severely affected by the Canadian TuMV than UK TuMV susceptible selections. The gene determining immunity to TuMV had no pleiotropic effect on susceptibility to cauliflower mosaic virus. The implications on these findings in relation to breeding for virus resistance are discussed.     

Swede midge (Diptera: Cecidomyiidae), ten years of invasion of crucifer crops in North America

The Swede midge, Contarinia nasturtii Kieffer (Diptera: Cecidomyiidae), a common insect pest in Europe, is a newly invasive pest in North America that constitutes a major threat to cruciferous vegetable and field crops. Since its first identification in Ontario, Canada, in 2000, it has rapidly spread to 65 counties in the provinces of Ontario and Quebec and has recently been found in canola (one of two cultivars of rapeseed, Brassica napus L. and Brassica campestris L.) in the central Prairie region where the majority of Canada's 6.5 million ha (16 million acres) of canola is grown. The first detection of Swede midge in the United States was in 2004 in New York cabbage (Brassica oleracea L.), but it has now been found in four additional states. Here, we review the biology of Swede midge, its host plant range, distribution, economic impact, pest status, and management strategies. We provide insight into this insect's future potential to become an endemic pest of brassica crops in North America. We also proposed research needed to develop tactics for handling this invasive pest in brassica crops.     

Potential resistance of crape myrtle cultivars to flea beetle (Coleoptera: Chrysomelidae) and Japanese beetle (Coleoptera: Scarabaeidae) damage

Field and laboratory studies were conducted to identify potential resistance among crape myrtles, Lagerstroemia spp., to Japanese beetle, Popillia japonica Newman and to flea beetles, Altica spp. Damage ratings revealed variation among cultivars in susceptibility to beetle feeding. Cultivars with Lagerstroemia fauriei Koehne in their parentage exhibited the least amount of damage in choice and no-choice experiments, with few exceptions. The data indicate that both beetle species cause more feeding damage on certain cultivars of Lagerstroemia indica L., such as 'Country Red', 'Twilight', and 'Carolina Beauty' than interspecific cultivars with L. fauriei in their parentage, such as 'Natchez', 'Tonto', and 'Muskogee'. When comparing the effect of parentage on all of the major pests of crape myrtle, L. faurei confers resistance to all pests except crape myrtle aphid. No correlation was found between leaf toughness, leaf color, and leaf nutrients in estimating flea beetle cultivar preference. With this information, growers can more effectively target scouting measures to the most susceptible cultivars. and breeders can select plants that will require the fewest chemical inputs.     

Effects of cultivar on oviposition preference, larval feeding and development time of diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae), on some Brassica oleracea vegetables in Victoria

Abstract We studied oviposition preference of Plutella xylostella for four cultivars of cabbage, broccoli and cauliflower in the field. There were no differences in the number of eggs found on the various cultivars of broccoli or cauliflower. Significantly more eggs were laid on cultivar Savoy King than any of the other cabbage cultivars tested. We then compared the development time and feeding damage of larvae reared on Savoy King and Green Coronet cabbages. Larvae developed more rapidly and fed more and for longer on Green Coronet than Savoy King. Thus, while Savoy King is more attractive to oviposition in the field, net impacts on the crop may be lessened to some degree through lower feeding proficiency of the larvae on that cultivar.     

The effect of plant density on populations of the cabbage root fly on four cruciferous crops

To study the effects of plant density on populations of the cabbage root fly (Erioischia brassicae), cabbage, cauliflower, Brussels sprout and swede were each planted in plots with twenty-four concentric circles of plants at spacings ranging from 10 to 90 cm between the individual plants. Plants treated with a root drench of chlorfenvinphos and untreated plants were each sampled at ten plant densities which ranged from 1–5 to 68-3 plants/m². In the absence of insecticide, the numbers of overwintering cabbage root fly pupae produced ranged from c. four per m² at the lowest plant density to 200 per m² at the highest. The number of pupae per m² was proportional to plant density to the powers 0–98,0-77,0–69 and o-6i for the swede, cauliflower, cabbage and Brussels sprout crops, respectively. The magnitude of each cabbage root fly population was determined mainly by plant density but also by the cultivar used as host plant. The results suggested that, in a given locality, when changing from low to high plant density crops during a growing season it should be unnecessary to apply insecticide to control cabbage root fly; conversely, a change from high to low plant densities would necessitate an extremely efficient application of insecticide.     

外源BoCAL基因对花椰菜花球形态发生的调节及其遗传

花椰菜和结球甘蓝是芸薹属甘蓝种的两个变种,前者的BobCAL基因发生提前终止突变而失去了原有的功能,而后者的BoCAL基因具有完整的编码区。在农杆菌的介导下,我们获得了BoCAL转基因花椰菜。T_2代的遗传研究表明,外源BoCAL基因转入后花椰菜转基因植株都没有形成花球,而是只形成松散的由花蕾组成的绿色花序。这一结果说明,花椰菜BobCAL被甘蓝BoCAL互补了,转基因花椰菜因此失去了形成花球的能力。这些转基因植株自交到T_3代时花序的形态特征与T_2代一致,为松散的绿色花序,但是花序出现的时间与T_1代相比提早了15天。将转基因花椰菜与野生型花椰菜杂交,结果发现杂交后代的植株形成夹杂有花蕾的花球,且花序出现的时间大大推迟,在播种后135天后才形成花球。     

Contributions of climate and Brassica oleracea cultivar to gastropod abundance and assemblage in southeastern Brazil

1. Terrestrial gastropods (slugs and snails, Mollusca: Eupulmonata) are destructive pests of brassica crops. These organisms defoliate plants and contaminate the harvest, leading to reduced crop yield and marketability. Losses caused by molluscs have escalated in recent years in Brazil.
2. We aimed to determine the seasonal activity of gastropods in brassica fields and unravel the environmental variables associated with these dynamics. Gastropod abundance, assemblage and within-plant distribution were also compared among Brassica oleracea cultivars (broccoli, cabbage and cauliflower).
3. Mild temperatures and rainy periods were found to coincide with gastropod peaks. Regression analyses confirmed a positive association of rainfall and humidity with gastropod abundance, whereas gastropod abundance increased with decreasing temperature. Deroceras laeve (Müller) (Agriolimacidae) and Bradybaena similaris (Férussac) (Bradybaenidae) were the most constant species. Mollusc abundance and assemblage differed amid B. oleracea cultivar; cabbage had the highest abundance and its species composition differed from broccoli and cauliflower. Slugs and snails were more concentrated on lower plant portions, regardless of the cultivar.
4. Management efforts should be reinforced in mild-temperature and rainy periods to reduce damage by gastropods, and cabbage should be monitored more closely than other cultivars.

     

十字花科蔬菜基因组含量的测定与分析

以我国14种重要十字花科蔬菜为材料,利用流式细胞术测定基因组合量.其中青苤蓝、乌塌菜、雪里蕻、芥蓝的基因组含量属首次报道.本试验数据与国外文献提供的相关数据对比,发现青萝卜、结球甘蓝、青花菜和根用芥菜的基因组含量与已报道数值基本吻合,而大白菜、花椰菜的基因组含量值与报道数据存在差异.造成同一物种基因组含量值差异的因为可能是品种的不同,也可能与生长环境或测定时参考标准选用等因素不同有关.     

Effect of insect density, plant age, and residue duration on acetamiprid efficacy against swede midge

The Swede midge, Contarinia nasturtii Kieffer (Diptera: Cecidomyiidae), a common insect pest in Europe, is a newly invasive pest in North America that constitutes a major threat to crucifer vegetable and field crops. Chemical control of Swede midge with synthetic insecticides under laboratory conditions indicated that insecticides generally could provide very effective control; however, insecticide treatments in the field were rarely able to maintain damage levels within marketable limits. In the current study, factors affecting insecticide efficacy were investigated using a neonicotinoid insecticide, acetamipird, as a foliar spray on cauliflower plants. Our results indicated that Swede midge density did not affect the efficacy of acetamirpid, although it significantly increased the subsequent Swede midge population on the unsprayed cauliflower plants. Additionally, cauliflower plant age did not significantly affect spray coverage and acetamipird efficacy on Swede midge. However, acetamiprid only provided 6-d control of Swede midge and its efficacy was reduced by up to 50% 9 d after spraying. Implications of our results on the development of an overall integrated pest management (IPM) program for Swede midge also are discussed.