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.     

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.     

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.     

Evaluation of insecticides and application methods against Contarinia nasturtii (Diptera: Cecidomyiidae), a new invasive insect pest in the United States

The midge Contarinia nasturtii (Keiffer), a serious gall-forming insect pest of cruciferous plants in Europe and southwestern Asia, was first reported in the United States in summer 2004. It had not been recorded in North America until its discovery in Ontario, Canada, in 2000. Efficacy of 20 insecticides belonging to 12 different classes was evaluated by using a foliar spray, soil drench, or seed treatment method. The broccoli cultivar 'Packman' was used in all tests at the suitable stage of four to five true leaves. Results indicated that foliar sprays of lambda-cyhalothrin, acephate, acetamiprid, chlorpyrifos, and methomyl reduced C. nasturtii larval populations by 96.7-100%. Except for acetamiprid, the other four insecticides also were effective against adults and provided 100% mortality after 24 h. When applied by drench, acetamiprid, imidacloprid, and thiamethoxam provided 100% control of C. nasturtii larvae, and the duration of efficacy lasted at least 7 wk. When applied as seed treatment, clothianidin and thiamethoxam provided 100% control of larvae and did not significantly affect seed germination. Imidacloprid also provided 100% control but the percentage of germination after treatment was only 62% (96.9% in check). These results indicate that several insecticides may significantly reduce midge populations. The nicotinoid class of insecticides, which has strong systemic activity, is likely to be the first choice. It is necessary to explore and develop other control methods such as cultural control and host resistance to develop an effective integrated pest management system.     

Simulated crop rotation systems control swede midge, Contarinia nasturtii

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. Many counties in Canada and the USA, 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. Alternative management strategies against C. nasturtii are sorely needed in order to protect crucifers. Under controlled laboratory conditions, the effectiveness on C. nasturtii control by 11 simulated cauliflower-sweet corn and cauliflower-kidney bean crop rotation systems was evaluated, with and without the presence of cruciferous weeds as alternative hosts. Our results indicated that when soil was infested with C. nasturtii pupae, the emergence pattern from the soil was very similar regardless whether the soil was later planted to host or non-host plants. As emergence was not affected, we examined whether manipulating host availability for oviposition through crop rotation would be effective. Our results indicated that the simulated cauliflower-sweet corn and cauliflower-kidney bean rotation systems provided full control of C. nasturtii . The effectiveness of one cycle of non-host crop rotation was reduced when cruciferous weeds were present. However, the C. nasturtii population in a one-cycle non-host rotation system with cruciferous weeds present was significantly lower than that in a non-rotation system. Two consecutive cycles (simulating a cropping season) of non-host plant crop rotations provided full control of C. nasturtii , regardless of the presence of the cruciferous weeds. The importance of cruciferous weed management and how to implement a successful crop rotation in fields to control C. nasturtii are discussed.     

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.     

Relative abundance and flight phenology of two pheromone types of Acrobasis nuxvorella (Lepidoptera: Pyralidae)

Two synthetic sex pheromones have been developed and are currently used to detect the flight of the pecan nut casebearer, Acrobasis nuxvorella Neunzig, the most damaging pest of pecan [Carya illinoinensis (Wangenh.) K. Koch]. One pheromone (referred to as standard) is attractive to moths in the southern United States, but not in Mexico. The other pheromone (referred to as Mexican) is attractive to moths in the southern United States and in Mexico. These two pheromones have been implemented by producers as an important tool in monitoring the activity of this pest and have allowed for more efficient pesticide use. In the future, these pheromones could be used as a means of population reduction through pheromone based control methods. Trapping data taken over a 3-yr period were used to determine if phenological differences exist between pheromone types of pecan nut casebearer. The relative abundance of each pheromone type at several locations in the United States also was evaluated. Results of this study indicate that no phenological differences exist between the two pheromone types studied in the United States and that significantly more males are attracted to field-deployed pheromone traps baited with the standard pheromone than to traps baited with the Mexican pheromone.     

Discovery of the oldest record of Nitellopsis obtusa (Charophyceae,Charophyta) in North America

Studies of the colonization and spread of invasive species improves our understanding of key concepts in population biology as well as informs control and prevention efforts. The characean green alga Nitellopsis obtusa (starry stonewort) is rare in its native Eurasian range but listed by the United States Geological Survey (USGS) as an aggressive invasive in North America. First documented in North America in 1978 from New York, United States, it has since been reported from numerous inland lakes from Minnesota to Vermont, and from Lake Ontario and inland lakes in southern Ontario, Canada. While the ecological impacts of N. obtusa are not clearly understood in its invasive range, initial results show negative environmental effects. We have discovered a liquid‐preserved herbarium specimen that predates the 1978 records by at least 4 years, and is the first confirmed record of N. obtusa in Québec.     

Uraba lugens (Lepidoptera: Nolidae) in New Zealand: pheromone trapping for delimitation and phenology

A synthetic sex pheromone trapping survey of the leaf skeletonizer Uraba lugens Walker (Lepidoptera: Nolidae) demonstrated the unexpectedly widespread distribution of the insect across > 40,000 ha of urban Auckland, New Zealand. A survey of eucalyptus trees planted in parks and other public areas showed a significant spatial correlation between trap catch and breeding populations, validating the trap survey results. Traps in trees showing damage had four-fold higher catches than traps placed in undamaged or nonhost trees, and < 1% of damaged trees with traps failed to catch adult moths. Damage by larval feeding was correlated with male trap catch in the previous generation, offering good prospects for a pest management decision support system, provided that an economic threshold is developed. Catches increased by 3.4-fold in the same georeferenced trapping grid between November and December 2003 and between March and April 2004 across two generations, over the summer. A vertical transect showed that catches increased with height up to the top trap at 13 m (60% of mean tree height). Options for managing the insect will need to overcome the high rate of increase, the rate of spread, and the vertical distribution of the insect on tall eucalyptus trees.     

Female Ascetics in Hinduism; The Graceful Guru: Hindu Female Gurus in India and the United States; Offering Flowers, Feeding Skulls: Popular Goddess Worship in West Bengal

Female Ascetics in Hinduism. Lynn Teskey Denton. Albany: State University of New York Press, 2004. 218 pp.
The Graceful Guru: Hindu Female Gurus in India and the United States. Karen Pechilis, ed. Oxford: Oxford University Press, 2004. 260 pp.
Offering Flowers, Feeding Skulls: Popular Goddess Worship in West Bengal. June McDaniel. Oxford and New York: Oxford University Press, 2004. 356 pp.     

Phenology and field biology of black cutworm (Lepidoptera: Noctuidae) in Ontario no-till corn

Black cutworm, Agrotis ipsilon (Hufnagel), is an occasional corn, Zea mays L., pest that is attracted to no-till fields. Understanding the phenology of black cutworm in Ontario no-till corn, particularly the time of arrival of adults in relation to the onset of crop damage and the stages of larvae that coincide with vulnerable corn seedling leaf stages, is important for their effective control. Pheromone and blacklight trap captures of moths first occurred in early April, whereas significant influxes did not occur until mid- to late April. Males and females were often captured simultaneously, in contrast to findings in Iowa and Illinois where males were captured in pheromone traps on average 3 wk ahead of females or males in blacklight traps. This may be a reflection of a more mature source population for the influxes into Ontario because first captures also were later than in the United States. Females arrived mated and corn seedling cutting occurred within 137 degree-days (DD) (base 10.4 degrees C) of first capture in Ontario corn. Cutworms were present in cornfields before planting, and the mean age of larvae increased along with corn leaf stage, suggesting that no new recruitment took place after planting. The apparent synchrony between corn and cutworm phenology in the northern areas of corn production seems more related to the availability and quality of food for young larvae relative to the development of the crop then the time of arrival of moths.     

Typification of Crataegus crus-galli L. (Rosaceae) and nomenclatural notes on some related species of hawthorn

Lectotypification of Crataegus crus-galli permits the common ten-stamened entity of the northern United States and adjacent Canada to retain its name. The correct name for the related 20-stamen form, usually called C. fontanesiana, is C. tenax. Crataegus persimilis, lectotypified here, is shown to occur in Ontario as well as New York, having been previously misidentified as C. ?bushii and C. prunifolia in Ontario. A horticultural taxon usually (but improperly) called C. prunifolia is provided with a new cultivar name.     

Optimizing mirid control on cocoa farms through complementary monitoring systems

Mirids (Sahlbergella singularis and Distantiella theobroma) are the most important insect pests affecting cocoa production across West Africa. Understanding the population dynamics of mirids is key to their management; however, the current recommended hand‐height assessment method is labour intensive. The objective of the study was to compare recently developed mirid sex pheromone trapping and visual hand‐height assessment methods as monitoring tools on cocoa farms and to consider implications for a decision support system. Ten farms from the Eastern and Ashanti regions of Ghana were used for the study. Mirid numbers and damage were assessed fortnightly on twenty trees per farm, using both methods, from January 2012 to April 2013. The mirid population increased rapidly in June, reached a peak in September and began to decline in October. There was a significant linear relationship between numbers of mirids sampled to hand‐height and mirid damage. High numbers of male mirids were recorded in pheromone traps between January and April 2012 after which there was a gradual decline. There was a significant inverse relationship between numbers of trapped adult mirids and mirids sampled to hand‐height (predominantly nymphs). Higher temperatures and lower relative humidities in the first half of the year were associated with fewer mirids at hand‐height, but larger numbers of adult males were caught in pheromone traps. The study showed that relying solely on one method is not sufficient to provide accurate information on mirid population dynamics and a combination of the two methods is necessary.     

Variability in thermal responses among Furia gastropachae isolates from different geographic origins

The effect of temperature ranging from 5-30 degrees C on in vitro vegetative growth and conidial germination of isolates of the entomophthoralean fungus Furia gastropachae was investigated. Eleven isolates were used for growth studies; two from Maryland, six from New York, and three from Ontario. A subset of four isolates, one each from Maryland and New York and two from Ontario, were used in conidial germination experiments. Growth and germination were significantly associated with temperature for all isolates, occurring throughout the range 5-30 degrees C, though both processes were inhibited to varying degrees at upper and lower extremes. Temperature optima for growth ranged from 20 to 27 degrees C, and for germination from 20 to 25 degrees C. Although significant variability was observed among isolates in growth at temperatures above 13 degrees C, temperature optima were not significantly different among isolates, and variability did not appear to relate to the geoclimatic origins of the isolates. In contrast, germination responses to temperature did appear to be related to geographic origin. Furia gastropachae isolates from New York and Maryland germinated more slowly at 10 degrees C than did Ontario isolates, although the percentage of conidia ultimately germinating at each temperature was the same for all isolates. The New York and Maryland isolates performed much better at 30 degrees C, with significantly greater overall germination and secondary conidial discharge, than the Ontario isolates. Compared with other isolates at 30 degrees C, Ontario isolates were the least active, often failing to successfully discharge any secondary conidia.     

New Silurian cooksonias from dolostones of north-eastern North America

New specimens of Cooksonia and Hostinella are described from the Bertie Group of Ontario and New York State, which is dated by faunas as latest Silurian (Přídolí). The rare plant fossils are unusual in that they are preserved in fine-grained, slightly argillaceous dolostones ('waterlime') rather than clastic rocks. At least two species of Cooksonia are present, one with ± globular sporangial morphology close to C. hemisphaerica Lang. Those with ellipsoidal/discoidal sporangia are compared with C. pertoni Lang, C .  paranensis Gerrienne et al . and C. bohemica Schweitzer, the latter represented by a single specimen from the Přídolí of the Czech Republic. However, the paucity of specimens, which prevents assessment of taphonomic influences on shape, combined with the absence of any anatomical features and the gross morphological simplicity of the fossils, precludes specific assignment. Specimens of Hostinella include one in which apices and a lateral basal structure resembling a root are preserved. It is concluded that the Laurentian assemblage of Ontario and New York State is less diverse and disparate than coeval assemblages, which are also preserved in marine rocks. Its preservation in limestones may have been facilitated by the hypersalinity inferred from various sedimentary features, which would restrict the activity of many decomposers.  © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society , 2004, 146 , 399–413.     

Effects of two pheromone trap densities against banana weevil, Cosmopolites sordidus, populations and their impact on plant damage in Uganda

Abstract:  An on-farm study to evaluate the effect of pheromone trap density on the population of the banana weevil, Cosmopolites sordidus (Germar) (Col., Curculionidae) was conducted in Masaka district, Uganda. The pheromone used was Cosmolure+, a commercially available weevil aggregation pheromone. Forty-two farms were assigned to one of three treatments: 0, 4 and 8 pheromone traps/ha. Pheromone lures were changed monthly at which time the traps were moved to a different location within the stand. Adult weevil population densities were estimated by using mark and recapture methodology at 0, 6, 12, 18 and 21 months, while damage to the banana corm was assessed at 0, 3, 6, 12, 18 and 21 months since the start of the experiment. Pheromone trap captures were generally low: about 10 weevils per trap per month. There were no significant differences in mean catches of C. sordidus per trap per month except for February 2002 when doubling the pheromone trap density decreased weevil catches. Although not significant, decreased efficiency was also the trend in higher trap densities over all the data sets. Doubling the number of traps increased the number of weevils caught per hectare per month from 0.4 to 0.6%. There was no significant difference in plant damage between the pheromone treatments in low- compared with high-trap densities. There were generally no significant differences in weevil populations and plant damage between pheromone-treated and control farms. Possible reasons for the low-trap efficacy in this study are discussed.     

Comparison of female attractiveness and male response among populations of Choristoneura rosaceana (Harris) in western and eastern U.S. apple orchards

Female obliquebanded leafrollers, Choristoneura rosaceana (Harris), collected from Oregon, Michigan, and New York were deployed in delta traps in Michigan apple orchards to compare their relative attractiveness to Michigan males of the same species. Females originating from Oregon attracted more males than females originating from New York during both generations of leafroller flight in Michigan. Also, females from Oregon attracted more males in Michigan than did "native" Michigan females during the first generation of flight. Analysis of gland extracts from the three populations revealed significantly more of each pheromone component in females originating from Oregon (approximately nine-fold more pheromone per female overall) than those from Michigan. However, there were no significant differences in the relative amounts of each pheromone component between Oregon and Michigan females. A 100:4:5:2 blend of Z11-14:OAc, E11-14:OAc, Z11-14:OH, and Z11-14:Ald was optimal for catching males in Michigan with no added or detrimental effect of Z11-14:Ald, confirming previous studies. However, 100:1 ratios of Z11-14:OAc relative to either E11-14:OAc or Z11-14:OH (also containing 2% Z11-14:Ald) captured more males in Oregon apple orchards compared with 100:4 and 100:10 ratios of Z11-14:OAc relative to either E11-14:OAc or Z11-14:OH. Addition of increasing amounts of Z11-14:Ald relative to Z11-14:OAc (range, 0-8:100) into a blend also containing 4% E11-14:OAc and 5% Z11-14:OH increased male catch in Oregon but not in Michigan. Our results suggest that pheromone blend quantity rather than blend quality may explain greater attractiveness of western compared with eastern female C. rosaceana to males in Michigan. Also, an optimized generic blend for monitoring male C. rosaceana across North America should contain Z11-14:Ald as has been previously shown, but should not exceed 4:100 ratios of both E11-14:OAc and Z11-14:OH relative to Z11-14:OAc for optimized catch of males in the western United States.     

Suitability of commercially available insect traps and pheromones for monitoring dusky sap beetles (Coleoptera: Nitidulidae) and related insects in Bt sweet corn

Two trap types and pheromone sources for the dusky sap beetle, Carpophilus lugubris Murray (Coleoptera: Nitidulidae), were compared in Bacillus thuringiensis (Bt) and non-Bt sweet corn fields over a 3-yr period. Overall, commercial traps and pheromones were equally effective as experimental traps and pheromones used previously for capturing C. lugubris and other sap beetle species. The commercial trap often caught significantly more Glischrochilus quadrisignatus Say than the experimental trap that had been used in previous studies. Bt corn significantly reduced caterpillar damage to ears compared with the non-Bt isoline and did not adversely affect levels of Orius sp., the most common insect predator. Sap beetle damage was the most common insect damage to Bt sweet corn ears. Sap beetles were detected by traps at population levels below that which are likely to cause economic concern, indicating commercially available traps and pheromone lures for monitoring sap beetles should be suitable for detecting them under commercial growing conditions.     

危害茄科蔬菜的外来入侵害虫——马铃薯甲虫

马铃薯甲虫是世界著名的入侵害虫,是我国的重要检疫性有害生物,主要危害马铃薯、茄子和西红柿等茄科蔬菜。该甲虫目前分布于美洲、欧洲和亚洲等30多个国家和地区,于1993年入侵我国新疆,到2010年扩散到36个县市,最前沿为木垒县。该文介绍了马铃薯甲虫的扩散历史、危害情况、发生规律以及防治措施,指出我国在西北方向遭受新疆马铃薯甲虫入侵内地威胁的同时,也在东北方向遭受俄罗斯滨海边区马铃薯甲虫对黑龙江及东北地区入侵的严重威胁,应加强防范。     

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

Climate 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.