Swede Midge Research Articles

Oviposition preference, larval distribution and impact of the swede midge, Contarinia nasturtii, on growth and yield of canola

The swede midge (Contarinia nasturtii) has become a significant economic pest of canola (Brassica napus L.) in Ontario and an emergent pest in the Prairie provinces. Determining yield impacts of swede midge damage and the growth stage(s) at which canola is most vulnerable or attractive to swede midge will contribute to the development of pest management recommendations throughout the growth of the crop. In four experiments, canola plants were exposed to specific densities of adult swede midge and measures of oviposition, damage and yield were collected. There was a significant positive relationship between female density and total oviposition per plant with a very high capacity for larval numbers on canola; up to ~ 4000. Given a choice of four growth stages, approximately 85% of oviposition occurred on seven-leaf and early bud canola. Given no choice, the high total oviposition on 3-leaf and flowering stages suggests that swede midge will oviposit on less favorable canola growth stages, if no others are present. Damage sustained on primary racemes remained relatively constant over time. However, damage ratings on secondary and tertiary racemes decreased over time in the highest treatment densities, suggesting compensation by the plant. All yield measures, except seed weight per pod, significantly decreased with increasing female density on primary and/or secondary racemes. A density of ~ 0.6 females per plant resulted in 10% reductions in the number of pods and seed weight produced on primary racemes. These results support recommendations for insecticide applications at, or just prior to, the early bud stage.

Efficacy of Biopesticides for Management of the Swede Midge (Diptera: Cecidomyiidae)

Management of the swede midge, Contarinia nasturtii Kieffer, in North American crucifer production relies on crop rotation and the timely application of synthetic insecticides, based on pheromone trap monitoring of local adult populations. Organically acceptable formulations of azadirachtin, pyrethrin, and spinosad, and a commercial biopesticide containing the entomopathogenic fungus, Beauveria bassiana, were evaluated for their effects on larval mortality and oviposition deterrence in the greenhouse, and on damage symptoms in the field. In greenhouse trials, pyrethrin and spinosad treatments applied up to 24 h prior to C. nasturtii exposure resulted in significant reductions in oviposition on host plants, whereas azadirachtin and B. bassiana only deterred oviposition when applied 2 h prior to exposure. Spinosad caused the highest larval reduction (∼96%) on cauliflower meristems, while azadirachtin, B. bassiana, and pyrethrin caused significant larval reduction when applied preoviposition and significant mortality when applied postoviposition. Field trials conducted with these insecticides on broccoli in 2011 produced no significant reductions in overall damage levels; however, B. bassiana treatments produced more marketable plants than did the control. In 2013, all treatments significantly reduced overall damage levels and all treatments, except B. bassiana, produced more uninfested and marketable plants than the control. Field applications of these alternative insecticides may be effective in protecting yields of broccoli and cauliflower, when combined with other tactics in an integrated pest management program.

Swede Midge, Diamondback Moth, and Imported Cabbageworm Control With Insecticides Allowed for Organic Production, 2014

This trial was conducted to evaluate insecticides approved for use in organic production. The trial was conducted on a field managed using practices allowed for organic production since 2008 at Cornell’s New York State Experiment Station in Geneva, NY. Broccoli ‘Belstar F1’ with 3–4 true leaves was transplanted on 2 Jun 2014. The transplants were set by hand using a Water Wheel transplanter (Rain-Flo Irrigation, Lancaster, PA) with a solution of 0.5oz/gal Fertrell fish oil emulsion into raised beds with 1.25 mil black polyethylene and drip irrigation tape. Annual ryegrass was seeded between the rows for weed control and mowed as needed. Six treatments and an untreated check were arranged in a RCB design with four replications. Each plot consisted of six plants spaced 12 inch apart with 7 ft between rows and 2 ft between treatments. Sprays (with the exception of Surround) were applied with a CO …

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

Abstract The swede midge is an invasive pest of crucifers in North America and exhibits temporal plasticity in diapause; diapause frequencies change throughout the growing season and spring emergence is typically bimodal. Factors controlling the timing of swede midge diapause events are not well understood. Pre‐diapause larval swede midge populations were isolated within cages in the field and tracked for emergence over 3 years. Diapause frequency was inversely correlated with photoperiod and absolute maximum air temperature, however photoperiod did not influence emergence timing. Emergence from diapause occurred in two large peaks, in mid‐June and early July, with a third, smaller peak in late August. Emergence phenotypes may correspond to different diapause durations from 236 to 296 days, or post‐diapause development requiring between 516 and 1449 degree days. Approximately 2% of swede midges overwintered for 2 years. Early control efforts would be most effective if they targeted the diapausing cohort (i.e. adults emerging June to July) to prevent damage by subsequent generations. Although few individuals overwintered for 2 years, prolonged diapause should be considered when crop rotation is employed for swede midge management.

Pheromone-Based Action Thresholds for Control of the Swede Midge, <I>Contarinia nasturtii</I> (Diptera: Cecidomyiidae), and Residual Insecticide Efficacy in Cole Crops

The swede midge, Contarinia nasturtii (Kieffer), is an invasive gall midge causing economic damage to cole crops (Brassica oleracea L.) and other crucifers in eastern Canada and United States. An effective decision-making tool for timing insecticide applications is a critical part of an integrated pest management program against C. nasturtii. Experiments were undertaken over 2 yr and at three locations in southern Ontario to develop pheromone-based action thresholds for C. nasturtii in cabbage and broccoli. An economic comparison between action threshold and calendar insecticide regimes was undertaken. The threshold approach was both economically viable and successful at minimizing swede midge damage for cabbage, and an action threshold of five males per trap per day with a minimum 7 d retreatment interval successfully reduced damage to acceptable levels. However, this approach was not successful with broccoli, which, unlike cabbage, is susceptible to damage by C. nasturtii through all plant stages, including heading. Acetamiprid and lambda-cyhalothrin both demonstrated approximately 7 d residual activity against C. nasturtii. Registration labels for both insecticides specify a minimum 7 d retreatment interval, which is supported by residual efficacy results. More effective insecticidal products may have longer residual efficacy and improve efficacy of the action threshold approach for broccoli and cabbage.

A method for induction and quantification of diapause entry in the swede midge (Diptera: Cecidomyiidae)

AbstractInduction of diapause under laboratory conditions is a valuable tool for the study of dormancy in economic pests such as the swede midge, Contarinia nasturtii Kieffer (Diptera: Cecidomyiidae). In the present study, diapause in larval swede midge was achieved via manipulation of rearing photoperiod and temperature. Frequency of diapause was assessed by sieve separation of diapause cocoons from pre-sifted peat substrate following emergence of pupating individuals. Mean diapause frequency for swede midge larvae reared under cool conditions with short day length or cool conditions with decreasing day lengths were 45.2% and 19.5%, respectively. Only 1.2% of swede midge reared under warm, long day length conditions entered diapause. A small percentage of larvae neither pupated nor entered diapause and remained in substrate long after other individuals had emerged as adults. This behaviour was more prevalent under cool and short or decreasing day length rearing conditions. Approximately 76% of the larvae used for diapause induction were recovered with the present larval and cocoon retrieval method, and premature (larval and pupal) mortality averaged 18.2%. Although diapause occurred in the present study, conditions resulting in higher diapause frequencies should be investigated and attempts should be made to improve survival and recovery of individuals.

Potential of Synthetic Sex Pheromone Blend for Mating Disruption of the Swede Midge, Contarinia nasturtii

The potential for pheromone-based mating disruption of the Brassica pest Contarinia nasturtii was tested, both in small-scale plots with Brussels sprouts and in commercial-scale fields with either broccoli or cauliflower. Experiments in the small-scale plots used laboratory-reared insects released into a previously uninfested area, whereas large-scale experiments used a high natural population of C. nasturtii. Effectiveness of mating disruption was evaluated by the reduction of male captures in pheromone traps, and by reduction of crop damage caused by C. nasturtii. Dental cotton rolls (small-scale experiment) and polyethylene caps (large-scale experiment), containing 50 μg (2S, 9S)-diacetoxyundecane, 100 μg (2S,10S)-diacetoxyundecane, and 1 μg (2S)-acetoxyundecane, spaced 2 m apart, served as dispensers in the test plots. In both experiments, mean catches of C. nasturtii males in pheromone traps were reduced to near zero in treated plots, with control plots averaging 71 males/trap. In the large-scale experiments, no males were caught in pheromone traps over a period of 41 days after mating disruption was applied; one male was caught from days 42-60. In the small-scale trials, crop damage was reduced by 59 %, compared to the untreated control plot. In the large-scale experiments, damage was reduced on average by 91 %. This study shows successful field application of the mating disruption technique for control of a member of the dipteran family Cecidomyiidae, and demonstrates that pheromone-based mating disruption has potential for management of C. nasturtii populations.

Biology of Synopeas myles, a parasitoid of the swede midge, Contarinia nasturtii, in Europe

Synopeas myles (Walker) (Hymenoptera: Platygastridae) is a parasitoid of the swede midge, Contarinia nasturtii (Kieffer) (Diptera: Cecidomyiidae), in Europe. We conducted the first thorough investigation of this parasitoid’s biology. Contrary to the biology reported for all platygastrids to date, exposure of late-instar host larvae to parasitism as opposed to eggs or early larvae yielded more S. myles offspring. Superparasitism was relatively common in the field and among groups of females in the laboratory, but was much less common among single females, providing preliminary evidence for self-discrimination. Observation of immature stages of S. myles inside living hosts revealed that supernumerary larvae in superparasitized hosts were probably eliminated by physical combat soon after hatching. With increasing levels of superparasitism, sex ratios of offspring became more female-biased and their mean development time increased. The probability that offspring would emerge from a host and the size of offspring were unaffected by increasing levels of superparasitism.

Identity, distribution, and seasonal phenology of parasitoids of the swede midge, Contarinia nasturtii (Kieffer) (Diptera: Cecidomyiidae) in Europe

The swede midge, Contarinia nasturtii (Kieffer) (Diptera: Cecidomyiidae) is an invasive gall midge of Eurasian origin that has recently become a pest of crucifer (Brassica oleracea L.) crops and canola (Brassica napus L.) in North America. In order to identify possible candidates for the classical biological control of this pest, we conducted an extensive survey of Europe to determine what species of parasitoids attack the swede midge. In addition, weekly monitoring of an oilseed rape plot in north western Switzerland allowed the observation of the seasonal phenological relationships between the swede midge and its parasitoids. Synopeas myles (Walker) (Hymenoptera: Platygastridae) and Macroglenes chalybeus (Haliday) (Hymenoptera: Pteromalidae) were found to be the two primary parasitoid species present throughout the surveyed range and, in Switzerland, attacking every generation of the swede midge. In the survey and the monitoring of the oilseed rape plot, total percent parasitism of samples ranged from 0% to 41%, but was typically quite low (<15%). Both S. myles and M. chalybeus have been reported to attack several other species of gall midges in Europe, casting doubt on their host specificity. However, before classical biological control of the swede midge in North America using its parasitoids from Europe can be ruled out, more research is needed to measure their importance as a mortality factor for natural swede midge populations and to properly assess their host specificity.

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.

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.

Insecticide Management Strategies for Control of Swede Midge (Diptera: Cecidomyiidae) on Cole Crops

Insecticide field trials were conducted in Ontario, Canada, and New York state to identify insecticides effective against the swede midge, Contarinia nasturtii Kieffer (Diptera: Cecidomyiidae), a new invasive pest in North America. Field trials indicated that foliar applications of lambda-cyhalothrin, permethrin, acetamiprid, chlorpyrifos, and dimethoate could provide control of C. nasturtii. Foliar insecticide applications were effective in keeping damage within marketable limits in all cabbage and some broccoli trials during the early phase of regional colonization by C. nasturtii (2001-2002). However by 2005-2006, treatments were rarely able to maintain damage levels within marketable limits. Low efficacy suggested the possibility of insecticide resistance in Canadian C. nasturtii populations, but laboratory assays revealed no evidence for resistance. Thus, eventual control failures on a season-long basis were apparently due to very high populations during later phases of colonization in Ontario. Early season applications (e.g., seed treatments, greenhouse plug tray drenches and/or band sprays) of neonicotinoid insecticides proved effective for 3-5 wk after transplanting in New York. These early season treatments would require supplemental control with foliar insecticides, but would reduce the number of foliar applications required and thus reduce insecticide usage. Our results suggest that acceptable control with foliar insecticides will be difficult where C. nasturtii populations are high, because of multiple and overlapping generations, and difficulty in achieving adequate spray coverage. An integrated pest management program that uses cultural control methods and host plant resistance, with judicious use of insecticides, is needed for sustainable management of this newly invasive pest.

Optimisation of the pheromone blend of the swede midge, Contarinia nasturtii, for monitoring

The swede midge, Contarinia nasturtii Kieffer, is a serious pest in crucifers. Its pheromone is a blend of (2S,9S)-diacetoxyundecane, (2S,10S)-diacetoxyundecane and (2S)-acetoxyundecane. The pheromone is used in monitoring traps, and this study examines possible ways to optimise the traps. Two dispenser types were compared: polyethylene dispensers and cotton dispensers. Polyethylene dispensers attracted male C. nasturtii for more than 6 weeks, whereas cotton dispensers were attractive for only 2 weeks. All three pheromone components were important for attraction of male midges in the field. The importance of the stereoisomeric compositions of the pheromone compounds was also tested-both in the wind tunnel and in the field. In the case of 2,9-diacetoxyundecane and 2-acetoxyundecane, the non-natural stereoisomers did not inhibit male C. nasturtii attraction, whereas one or both of the stereoisomers of 2,10-diacetoxyundecane did. Pheromone traps with the synthetic pheromone in a 1:2:0.02 ratio emitted from PE dispensers were highly effective and long lasting. As the mixture of stereoisomers of 2,10-diacetoxyundecane strongly inhibited attraction of male C. nasturtii while those of 2,9-diacetoxyundecane and 2-acetoxyundecane did not have any inhibitory effect, it is possible to produce traps that are effective and long lasting but cheaper to produce and maintain.

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

AbstractThe 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.

Seasonal Development of an Invasive Exotic Species, &lt;I&gt;Contarinia nasturtii&lt;/I&gt; (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 (DD7.2 degrees C). Peak emergence of overwintering adults occurred between 344 and 731 DD7.2 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.

Will climate change be beneficial or detrimental to the invasive swede midge in North America? Contrasting predictions using climate projections from different general circulation models

AbstractClimate change may dramatically affect the distribution and abundance of organisms. With the world's population size expected to increase significantly during the next 100 years, we need to know how climate change might impact our food production systems. In particular, we need estimates of how future climate might alter the distribution of agricultural pests. We used the climate projections from two general circulation models (GCMs) of global climate, the Canadian Centre for Climate Modelling and Analysis GCM (CGCM2) and the Hadley Centre model (HadCM3), for the A2 and B2 scenarios from the Special Report on Emissions Scenarios in conjunction with a previously published bioclimatic envelope model (BEM) to predict the potential changes in distribution and abundance of the swede midge, Contarinia nasturtii, in North America. The BEM in conjunction with either GCM predicted that C. nasturtii would spread from its current initial invasion in southern Ontario and northwestern New York State into the Canadian prairies, northern Canada, and midwestern United States, but the magnitude of risk depended strongly on the GCM and the scenario used. When the CGCM2 projections were used, the BEM predicted an extensive shift in the location of the midges' climatic envelope through most of Ontario, Quebec, and the maritime and prairie provinces by the 2080s. In the United States, C. nasturtii was predicted to spread to all the Great Lake states, into midwestern states as far south as Colorado, and west into Washington State. When the HadCM3 was applied, southern Ontario, Saskatchewan, and Washington State were not as favourable for C. nasturtii by the 2080s. Indeed, when used with the HadCM3 climate projections, the BEM predicted the virtual disappearance of ‘very favourable’ regions for C. nasturtii. The CGCM2 projections generally caused the BEM to predict a small increase in the mean number of midge generations throughout the course of the century, whereas, the HadCM3 projections resulted in roughly the same mean number of generations but decreased variance. Predictions of the likely potential of C. nasturtii spatial spread are thus strongly dependent on the source of climate projections. This study illustrates the importance of using multiple GCMs in combination with multiple scenarios when studying the potential for spatial spread of an organism in response to climate change.

Impact of Soil Type, Moisture, and Depth on Swede Midge (Diptera: Cecidomyiidae) Pupation and Emergence

Impact of Soil Type, Moisture, and Depth on Swede Midge (Diptera: Cecidomyiidae) Pupation and Emergence

Impact of Soil Type, Moisture, and Depth on Swede Midge (Diptera: Cecidomyiidae) Pupation and Emergence

Contarinia nasturtii (Kieffer) (Diptera: Cecidomyiidae), a common insect pest in Europe and a new invasive pest in North America, causes severe damage to cruciferous crops. Currently, many counties in Canada and the United States in which C. nasturtii has not been previously reported are at risk of being infested by C. nasturtii. Effectiveness of chemical control is limited, especially under high population pressure in fields, because the cryptic habits of C. nasturtii protect them from insecticidal sprays. Alternative management strategies against C. nasturtii that are needed to protect crucifers and soil management for the pupal stage were studied as one option. Six different types of soils (loam fine sand, fine sand, clay loam, muck, Chenango shale loam, and silt loam soil) were collected from commercial cabbage fields in New York and studied in the laboratory for their impact on C. nasturtii pupation and emergence. The results indicated that extremely wet or dry soils significantly hindered C. nasturtii emergence, regardless of soil type, suggesting that soil type alone may not be a major factor regulating C. nasturtii abundance. Optimal moisture content for C. nasturtii emergence varied for different soils. Most C. nasturtii pupated within the top 1 cm of soil. Furthermore, we found that >5 cm of soil cover effectively reduced the emergence number and delayed the time of emergence. Based on these results, we suggest that soil manipulation (moisture content and cultivation practices) should be considered as an important component in an overall integrated pest management program for C. nasturtii.

Monitoring and detection of the swede midge (Diptera: Cecidomyiidae)

AbstractIn 2002, two types of light traps were compared against sticky yellow cards for efficiency and selectivity in capturing adult swede midge Contarinia nasturtii (Kieffer) (Diptera: Cecidomyiidae). Incandescent light traps were more efficient at capturing swede midge than were sticky traps. Incandescent light traps were more selective than blacklight traps and required less time for processing of samples and identification of captured midges. Emergence (2003 and 2004) and pheromone (2004) traps were used to assess swede midge population dynamics. Captures from emergence traps indicate up to five overlapping emergence events for swede midge each year. Emergence traps captured swede midge earlier in the season than pheromone traps, but pheromone-trap captures continued later in the season than those in emergence traps. Pheromone traps are small and portable, easy to maintain, and capture significantly more swede midge than emergence traps.

Efficiency of natural enemies against the swede midge Contarinia nasturtii (Diptera: Cecidomyiidae), a new invasive species in North America

The swede midge, Contarinia nasturtii Kieffer (Diptera: Cecidomyiidae), a widespread pest of cruciferous crops in Europe, has been recently found in Canada. A 2-year survey in Quebec yielded no specialized natural enemies. Two polyphagous coccinellid predators ( Harmonia axyridis (Pallas) and Coccinella septempunctata L) were field collected for further evaluation. In laboratory experiments, these two coccinellid species fed on swede midge larvae, and H. axyridis showed a higher voracity than C. septempunctata. Late larvae and adults of H. axyridis were shown to consume more swede midge larvae than young larvae, while the adults of H. axyridis showed no preference between swede midge larvae and the green peach aphid Myzus persicae. However, H. axyridis adults were not able to prey on swede midge larvae on potted infested broccoli plants. The susceptibility of swede midge larvae to three species of entomopathogenic nematodes ( Steinernema feltiae, Steinernema carpocapsae, and Heterorhabditis bacteriophora) was also evaluated. H. bacteriophora was the only species that caused significant mortality to swede midge larvae. At a concentration of 1000 IJs/larva, H. bacteriophora caused 90–100% mortality to swede midge larvae in loam, sandy loam, clay and muck soils.