Crop sequence effects on root maggot (Diptera: Anthomyiidae: Delia spp.) infestations in canola

Strong market demand for canola, Brassica napus L., has prompted some western Canadian producers to increase the frequency of this crop in rotations with other crop species, but the impact of this practice on canola insect pests has not been determined. Here, we investigate 12 cropping sequences involving canola over a 3-yr period (2008-2010 inclusive) at five locations across western Canada. Cropping sequences varied from continuous production of two herbicide-tolerant canola varieties, to production in two of 3 yr, to canola production in one of the 3 yr. Treatments analyzed were the frequency and timing of canola within the rotational sequence. Damage by larvae of root maggots (Diptera: Anthomyiidae: Delia spp.) to canola taproots increased as the study progressed, particularly in 2010 after canola had been grown continuously for 3 yr. Yield declined with continuous canola production, and differences were greatest in 2010. At mean canola crop prices for 2010, the yield reduction from continuous production amounted to economic losses of approximately Can$282-$377/ha. Crop quality, in terms of oil and protein concentrations of harvested seed, was affected more by crop variety than cropping sequence. Crop sequence effects for root maggot damage, yield, and seed quality were relatively stable in the presence of environmental (location) variation. Results of our study suggest that continuous canola production could be unsustainable over the long-term even though market forces currently provide incentive for this practice.     

Responses of the specialist biological control agent,Aleochara bilineata,to vegetational diversity in canola agroecosystems

Plant biodiversity is known to affect insect populations, both herbivores and their natural enemies, and as a consequence, habitat management through increased plant species composition and abundance can be exploited for sustainable pest management. In agroecosystems where crop monocultures are the routine production practice, plant biodiversity can be increased by maintaining small populations of weeds, with potential beneficial effects arising from concomitant increases in the abundance of predator and parasitoid populations. We manipulated weed populations in both species of canola, Brassica rapa L. and Brassica napus L., to investigate responses of adults of Aleochara bilineata Gyllenhal (Coleoptera: Staphylinidae), an important natural enemy of root maggots (Delia spp., Diptera: Anthomyiidae). Larval root maggots feed on canola taproots, disrupting the flow of water and nutrients within the plants, causing substantial yield reductions. Aleochara bilineata is a predator–parasitoid that attacks all root maggot pre-imaginal life stages. Activity density of A. bilineata increased as monocotyledonous weed biomass declined. Significant preferences between canola species were observed, with A. bilineata associated most frequently with B. rapa compared with B. napus. Our research suggests that improved management of root maggot infestations in canola through enhancement of populations of the A. bilineata predator–parasitoid could be accomplished by reducing weed infestations; however, such recommendations should consider other predators in the system and the role of weeds in reducing root maggot oviposition and damage.     

Ground beetle (Coleoptera: Carabidae) diversity, activity density, and community structure in a diversified agroecosystem

Diversity and abundance of ground beetles (Coleoptera: Carabidae) can be enhanced in vegetable and field intercropping systems, but the complexity of polycultures precludes the application of generalized assumptions of effects for novel intercropping combinations. In a field experiment conducted at Lacombe and Ellerslie, Alberta, Canada, in 2005 and 2006, we investigated the effects of intercropping canola (Brassica napus L.) with wheat (Triticum aestivum L.) on the diversity and community structure of carabid beetles, and on the activity density responses of individual carabid species. Shannon-Wiener diversity index scores and species evenness increased significantly as the proportion of wheat comprising total crop plant populations increased in one site-year of the study, indicating a positive response to enhanced crop plant species evenness in the intercrops, and in that same site-year, ground beetle communities in intercrops shifted to more closely approximate those in wheat monocultures as the percentage of wheat in the intercrops increased. Individual carabid species activity densities showed differing responses to intercropping, although activity densities of some potential root maggot (Delia spp.) (Diptera: Anthomyiidae) predators were greater in intercrops with high proportions of wheat than in canola monocultures. The activity density of Pterostichus melanarius (Illiger), the most abundant species collected, tended to be greater in canola monocultures than high-wheat intercrops or wheat monocultures. We conclude that intercrops of canola and wheat have the potential to enhance populations of some carabid species, therefore possibly exerting increased pressure on some canola insect pests.     

Responses of the parasitoids of Delia radicum (Diptera: Anthomyiidae) to the vegetational diversity of intercrops

Several natural enemies regulate populations of root maggots (Delia spp.) (Diptera: Anthomyiidae) in canola (Brassica napus L.) in western Canada, among them the rove beetles Aleochara bilineata Gyllenhal and Aleochara verna Say (Coleoptera: Staphylinidae) and the hymenopteran Trybliographa rapae Westwood (Hymenoptera: Figitidae). Intercrops of canola and wheat (Triticum aestivum L.) can be part of an integrated pest management strategy to reduce damage by Delia spp. to canola. We investigated several intercropping regimes of canola and wheat to determine effects on parasitism of Delia radicum (L.) and activity densities of adult A. bilineata and A. verna. Studies were conducted over four site-years in central Alberta, Canada in 2005 and 2006. Mean parasitism rates of D. radicum puparia by A. bilineata ranged from 7.27% to 81.69%. Increasing proportions of wheat in intercrops significantly reduced parasitism by A. bilineata in one site-year. Parasitism of D. radicum by T. rapae was not affected by intercropping; mean parasitism rates were between 2.17% and 14.55%. In one site-year combined parasitism by all parasitoids significantly increased with increasing canola as a proportion of total crop plant populations. Pitfall trap collections of adult A. bilineata increased with increasing proportions of canola in some site-years. Collections of A. verna adults were low relative to A. bilineata and were largely unaffected by intercropping. Although canola–wheat intercrops do not appear to favour parasitism of D. radicum, reductions in canola root damage by Delia larvae in intercrops, reported previously, suggest that canola–wheat intercrops may nevertheless be favourable as a crop protection strategy.     

Effects of seeding date and canola species on seedling damage by flea beetles in three ecoregions

Flea beetles ( Phyllotreta striolata (Fabricius), Phyllotreta cruciferae (Goeze) and Psylliodes punctulata Melsheimer) (Coleoptera: Chrysomelidae) are chronic threats to canola seedling establishment throughout the Northern Great Plains of North America. We conducted field studies in AB, Canada, from 2001 to 2004 at Lethbridge, Lacombe and Beaverlodge in the southern, central and northern regions of the province, respectively, to assess the impacts of seeding date (fall, April, May), and canola species ( Brassica rapa L., Brassica napus L.) on flea beetle damage to canola. Flea beetle damage was generally low at Lacombe but reached economic threshold levels at other sites. Although our results were not consistent in all years, seeding date had opposite effects on flea beetle damage to canola seedlings at the southern and northern sites. In the south, both canola species planted in April escaped flea beetle damage unlike the May-seeded plots, which required insecticide spraying in 2003. The numbers of flea beetles on sticky cards sampled during the seedling stage of canola were also lower in early-planted plots than in those planted in May. In the north, flea beetle damage was lower in the May-planted plots compared with those planted earlier. To maximize yields, canola growers need to plant as early as possible in all agro-ecoregions; our study showed that crops in the central and northern regions will be at greater risk of flea beetle damage than in southern regions.     

Relay cropping cauliflower with lettuce as a means to manage first-generation cabbage maggot (Diptera: Anthomyiidae) and minimize cauliflower yield loss

First-generation cabbage maggot, Delia radicum (L.) (Diptera: Anthomyiidae), can cause extensive damage to newly transplanted brassica crops. This study investigated the use of relay cropping, a form of intercropping that involves overlapping two crops in the same field for a short period, as a means to 1) reduce first-generation D. radicum egg numbers by disrupting female host finding and 2) minimize yield loss by reducing the time that crops overlap. Because of the high incidence of two other Delia species, Delia platura (Meigen) and Delia florilega (Zetterstedt), treatment effects on these insects also were considered. In both years of the study (2003 and 2004), there were fewer D. radicum eggs collected from the base of cauliflower, Brassica oleracea variety botrytis, plants relay cropped with lettuce, Lactuca sativa L., than in monoculture. D. platura/D. florilega also laid fewer eggs on cauliflower in the relay crop than in monoculture in 2003, but in 2004 the opposite was true, there were more D. platura/D. florilega eggs laid on the relay-cropped cauliflower. After peak D. radicum oviposition, the lettuce was harvested. Cauliflower curd weights and diameters were comparable between treatments in both years. Plant loss because of D. platura/ D. florilega feeding in the 2004 relay-cropped plots resulted in reduced yields in these plots compared with the monoculture. Although further investigation is needed into the effects of relay cropping on other pests within this system, this is the first study to demonstrate that relay cropping can reduce egg laying by D. radicum at the scale studied while minimizing competition between component crops for key resources.     

Herbivore‐induced plants do not affect oviposition but do affect fitness of subsequent herbivores on canola

The diamondback moth (DBM), Plutella xylostella (L.) (Lepidoptera: Plutellidae), is oligophagous on plants in the Brassicaceae, and is considered one of the most significant insect pests of canola (Brassica napus L.), a major oilseed crop grown in the Prairie Provinces of Canada. The bertha armyworm (BAW), Mamestra configurata Walker (Lepidoptera: Noctuidae), is a generalist herbivore that preferentially feeds on canola plants. In the canola growing season in the Prairie Provinces of Canada, DBM feeding occurs prior to BAW herbivory. In this study, we test the effect of DBM herbivory on subsequent host use by BAW. Oviposition by female BAW was not influenced by previous DBM‐herbivory or mechanical damage of canola plants. Bertha armyworm larvae were deterred from feeding on canola previously damaged by DBM and larvae developed into lighter pupae when reared on DBM‐damaged plants. Bertha armyworm pupae that developed from larvae fed on mechanically damaged plants had similar pupal weights to those fed undamaged plants. Adult BAW reared on canola with previous DBM feeding damage had marginally smaller wings than moths reared on canola treated differently. The combination of these results suggests that herbivory by the brassicaceous specialist, DBM, negatively influences host use and larval performance by the generalist, BAW, on canola.     

Spatio-temporal ecology and management of cabbage maggot

This study analyzes the spatio-temporal dispersion patterns of the cabbage maggot (Delia radicum L.) (Diptera: Anthomyiidae) infestation in rutabagas and turnips in Oregon and suggests ways to exploit the spatial and temporal ecology of the cabbage maggot to improve management of the pest. The patchy distribution of cabbage maggots arises from a combination of first-order effects driven by spatial heterogeneity and second-order effects driven by spatial autocorrelation. The intensity of cabbage maggot infestations varied from year to year. Within a given year, damage rates tended to be higher in rutabagas than turnips, in crops planted earlier in the season, and in fields near nurseries and houses. Nonsignificant first-order effects included soil texture, distance from river, proximity to maggot sources (other than cultivated fields), type of vegetation on field borders, field manager, field area, and perimeter. Second-order effects were processes intrinsic to the population and would give rise to patchiness even in a homogeneous environment. For example, adults may be attracted to others of their species or eggs may be deposited in batches. The locations of patches arising from second-order effects cannot be predicted from knowledge of environmental covariates. However, cabbage maggot does not tend to disperse far, and existing patches tend to give rise to other patches nearby at a later time. We found elevated damage rates in spring fields planted near fields that were heavily damaged the previous fall and in fields planted late in the season near fields that had heavy damage early in the season.     

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.     

Suppression of Plutella xylostella and Trichoplusia ni in cole crops with attracticide formulations

The three key lepidopteran pests of cole, Brassica oleracea L., crops in North America are diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae); cabbage looper; Trichoplusia ni (Hübner) (Lepidoptera: Noctuidae); and imported cabbageworm, Pieris rapae (L.) (Lepidoptera: Pieridae). Two species-specific pheromone-based experimental attracticide formulations were evaluated against these pests: LastCall DBM for P. xylostella and LastCall CL for T. ni. No LastCall formulation was available against P. rapae. Laboratory toxicity experiments confirmed the effectiveness of each LastCall formulations in killing conspecific males that made contact. In replicated small plots of cabbage and collards in central Alabama, over four growing seasons (fall 2003, spring 2004, fall 2004, and spring 2005), an attracticide treatment receiving the two LastCall formulations, each applied multiple times at the rate of 1,600 droplets per acre, was compared against Bacillus thuringiensis. subspecies kursatki (Bt) spray at action threshold and a negative untreated control. Efficacy was measured by comparing among the three treatments male capture in pheromone-baited traps, larval counts in plots, and crop damage rating at harvest. LastCall provided significant reductions in crop damage comparable to Bt in three of the four seasons. Efficacy of LastCall was dependent upon lepidopteran population densities, which fluctuated from season to season. In general, reduction in crop damage was achieved with LastCall at low-to-moderate population densities of the three species, such as typically occurs in the fall in central Alabama, but not in the spring when high P. rapae population pressure typically occurs in central Alabama. Significant reductions in pheromone trap captures did not occur in LastCall plots, suggesting that elimination of males by the toxicant (permethrin), rather than interruption of sexual communication, was the main mechanism of effect.     

韭菜根蛆的发生危害及综合防治技术研究——公益性行业(农业)科研专项“作物根蛆类害虫综合防治技术研究与示范”进展

针对我国根蛆类害虫严重危害葱蒜类蔬菜作物,特别在韭菜上问题突出的现状,项目开展了根蛆的生物学和生态学、种群规律、单项防治技术及综合防治技术的研究与示范工作。明确了我国大部分地区韭菜上的根蛆主要是韭菜迟眼蕈蚊Bradysiaodoriphaga Yang et Zhang,在甘肃和辽宁地区的优势种为异迟眼蕈蚊B.difformis Frey。采用黄板诱集成虫结合挖根查幼虫的方法,明确了华北、东北、西北和华东地区根蛆在田间的发生规律。根蛆不耐高温耐低温,春、秋和冬季发生严重,在夏季有转主危害的趋势,冬季以老熟幼虫在0~5 cm土层中越冬。蕈蚊成虫对黑色和棕色趋性最强,研发出特异性的黑色粘虫板。覆盖50~60目防虫网对根蛆的防效最佳,且对韭菜生长有促进作用。建立了蕈蚊成虫的优势捕食性天敌——瘦弱秽蝇Coenosia attenuata的饲养技术和田间应用技术,筛选出了对蕈蚊幼虫高致病力的昆虫病原线虫和Bt菌株,田间防效达60%以上。研发出保护地灌溉臭氧水、减量施药和喷淋施药等轻简化的根蛆防治技术10项。根据不同地区韭菜的种植习惯和根蛆的发生特点,在辽宁、河北、山东、甘肃等地建立了区域性的根蛆类害虫综合防治技术,建立核心示范区10个,进行技术培训5 000人次,取得了一定的经济、社会和生态效益。     

Native Vaccinium spp. and Gaylussacia spp. infested by Rhagoletis mendax (Diptera: Tephritidae) in the Great Lakes Region: a potential source of inoculum for infestation of cultivated blueberries.

In this study, we addressed the question of whether or not native stands of blueberry (Vaccinium spp.) and/or huckleberry (Gaylussacia spp.) support populations of blueberry maggot, Rhagoletis mendax Curran, in the Great Lakes region. Infestation of commercial blueberries by the blueberry maggot, R. mendax, is a serious problem in many areas where blueberries are grown. In the past 10-20 yr, commercial bighbush blueberry, Vaccinium corymbosum L., production has expanded into places such as southern Ontario and southern Quebec where blueberry maggot had not previously been reported. In the mid-1990s, isolated infestations of commercial highbush blueberry were reported in southern Ontario. Because R. mendax was not considered endemic to that area, it was widely assumed that the pests had come into the fields via movement from exotic localities. Here we present an alternative hypothesis, that the blueberry maggots infesting newly established highbush plantations are derived from native blueberries growing in the vicinity. To test this hypothesis, in 1997-1999, we sampled potential native hosts for R. mendax (Vaccinium spp. and Gaylussacia spp.) from 31 localities in the Great Lakes region, primarily in Michigan and Ontario. R. mendax was reared from fruits of native hosts collected at four sites in Michigan and one site each in Ontario, Indiana, and Ohio. V. corymbosum was the predominant host infested, with infestation of this host observed at five of the seven sites. However, two huckleberry species [Gaylussacia baccata (Wangenheim) K. Koch, and Gaylussacia dumosa (Andersson) Torrey & Gray] had the highest rates of infestation that we observed (25.4 and 17.6%, respectively). These data represent the first published reports of R. mendax infesting native host plants in the Great Lakes region, and support the hypothesis that infestations observed in commercial fields may have originated from infested native host plants.     

Nonwoven fiber barriers for control of cabbage maggot and onion maggot (Diptera: Anthomyiidae).

We investigated the use of nonwoven fiber barriers for control of cabbage maggot, Delia radicum (L.), and onion maggot, D. antiqua (Meigen). The barriers consist of arrangements of minute fibers loosely intertwined in "web" form. Results from a greenhouse experiment showed that manually applied graphite fibers placed at the base of broccoli plants reduced the number of D. radicum eggs by 64-98%, and that efficacy increased with greater fiber density. Using a melt extrusion process, we devised a method for on-site creation of nonwoven fibers of ethylene vinyl acetate (EVA). In field trials with broccoli and onion plants, EVA fibers significantly reduced the number of cabbage and onion maggots infesting plants. Fiber barriers provided comparable control to standard insecticide applications. The addition of blue, yellow, red, or black pigments, as well as optical brighteners that absorb UV light did not enhance fiber efficacy. Incorporation of capsaicin olfactory repellent to EVA also did not enhance fiber efficacy. Nonwoven fiber barriers may offer an alternative to insecticides for control of cabbage maggot and onion maggot and possibly other insect pests. Additional research is needed to improve the application process and to identify economically feasible and biodegradable compounds for fibers.     

Two seed coat-specific promoters are functionally conserved between <Emphasis Type="Italic">Arabidopsis thaliana</Emphasis> and <Emphasis Type="Italic">Brassica napus</Emphasis>

Canola is one of the most important cash crops in Canada, and a national project named “Designing Oilseeds for Tomorrow’s Market” was undertaken to improve seed meal quality of this strategically important crop. As a part of this project, our group is focusing on identifying seed coat-specific promoters for canola (Brassica napus). These promoters will be used to genetically modify canola seed coat to reduce or eliminate anti-nutritional components from the meal. The Arabidopsis thaliana BAN promoter (AtBANpro) and δVPE promoter (AtδVPEpro) were isolated and fused to GUS reporter gene to generate transgenic canola plants. These plants were analyzed by GUS staining and microtome sectioning which showed that both promoters are seed coat-specific in canola: AtBANpro in inner seed coat layer and AtδVPEpro in outer seed coat layer. Therefore, the two Arabidopsis promoters can be used to modify genes in seed coat of canola for further improving its seed qualities.     

Phyllotreta cruciferae and Phyllotreta striolata responses to insecticidal seed treatments with different modes of action

The strategy used most commonly in western North America to protect seedlings of canola (Brassica rapa L. and Brassica napus L.) from attack by adults of the flea beetles Phyllotreta cruciferae (Goeze) and Phyllotreta striolata (Fabricius) (Coleoptera: Chrysomelidae) involves planting seed coated with insecticide for systemic activity. Previous research determined that the two beetle species responded differently to the most commonly used neonicotinoid seed dressings. However, other insecticides that exploit different modes of action have commercial potential for managing infestations of these pests, but no information exists on their efficacies for these flea beetle species. Studies were conducted to compare effects of the neonicotinoid compounds, thiamethoxam and imidacloprid, to spinosyn and fipronil as systemic seed treatments for reducing feeding damage to canola seedlings and increasing mortality of P. cruciferae and P. striolata. Phyllotreta cruciferae experienced greater mortality and caused less feeding damage than P. striolata to seedlings treated with the neonicotinoid compounds. Mortality increased and feeding damage decreased significantly when beetles fed upon seedlings treated with fipronil, indicating its potential usefulness for control of these pests. However, spinosyn seed treatment was relatively ineffective against either beetle species. Higher rates of P. striolata mortality with fipronil than thiamethoxam suggest that fipronil may provide improved flea beetle control over hundreds of thousands of hectares in western North America where flea beetle populations are dominated by P. striolata, and control with thiamethoxam has been suboptimal.     

Efficacy of Fluensulfone in a Tomato–Cucumber Double Cropping System

Vegetable crops in the southeastern United States are commonly grown on plastic mulch with two crop cycles produced on a single mulch application. Field trials were conducted in 2013 and 2014 in two locations to evaluate the efficacy of fluensulfone for controlling Meloidogyne spp. when applied through drip irrigation to cucumber in a tomato–cucumber double-cropping system. In the spring tomato crop, 1,3-dichloropropene (1,3-D), fluensulfone, and a resistant cultivar significantly decreased root galling by 91%, 73%, and 97%, respectively, compared to the untreated control. Tomato plots from the spring were divided into split plots for the fall where the main plots were the spring treatment and the subplots were cucumber either treated with fluensulfone (3.0 kg a.i./ha. via drip irrigation) or left untreated. The fall application of fluensulfone improved cucumber vigor and reduced gall ratings compared to untreated subplots. Fluensulfone reduced damage from root-knot nematodes when applied to the first crop as well as provided additional protection to the second crop when it was applied through a drip system.     

Preceding crop and phosphorus fertilization affect cadmium and zinc concentration of flaxseed under conventional and reduced tillage

Field studies were conducted over 4 years at two locations in Manitoba, Canada to evaluate effects of preceding crop, tillage and phosphorus (P) fertilization on Cd and Zn concentration in oilseed flax (linseed—Linum usitatissimum L.). Canola (Brassica napus L.) and spring wheat (Triticum aestivum L.) were grown under conventional and reduced tillage with three rates of monoammonium phosphate. Flax was seeded the year following the spring wheat or canola, with or without P fertilizer, and Cd and Zn concentration and accumulation were determined in the flax tissue at 5 weeks and in the mature seed. Flax following canola had lower Zn concentration and accumulation and higher Cd concentration and Cd:Zn ratio in the tissue and seed relative to flax following wheat. Phosphorus fertilization tended to increase Cd concentration and Cd:Zn ratio and decrease Zn concentration in the tissue and seed. Effects of tillage and interactions among tillage, preceding crop, and P fertilization were inconsistent. Changes in flax Cd and Zn concentration may be due to changes in mycorrhizal colonization or by the high concentration of Cd in the decomposing canola residue. Crop sequence and P management can be used to improve flaxseed food quality, by increasing Zn and decreasing Cd concentration.     

Effect on radish pests by application of insecticides in a nearby spring oilseed rape field

Chemical control of insect pests is often necessary to ensure high yields of field crops. The aim of the present study was to study whether field pesticide use influences amount of pest damage in neighbouring garden crops. Spring oilseed rape, OSR (Brassica napus L.), was established in Southern Sweden as an example of an agricultural field crop. One half of the OSR field was treated with insecticides to control flea beetles (Phyllotreta spp., Chrysomelidae) and pollen beetle (Meligethes aeneus Fab., Nitidulidae). Radish (Raphanus sativus L.) was used as an example of a common garden crop and it was sown as four replications at three different distances and on four occasions during the season. Care was taken to protect the radish plots from pesticide due to wind drift during applications. Damage to the radish by flea beetle and cabbage root fly (Delia radicum L., Anthomyiidae) along with unspecified leaf damage was recorded. Significantly lower damage by flea beetles was found on cotyledons of radish adjacent to the insecticide treated side of the OSR field compared to the untreated side in radishes from the first sowing. Unspecified damage to true leaves was also less abundant on radishes at the treated side of the OSR field as compared to the untreated side, in all three of the radish harvests analysed. However, radish plot distance from the OSR field did not influence leaf damage. Root fly damage rates in radish did not differ significantly between those adjacent to the treated and untreated sides of the OSR. Damage rates were, however, higher in the radish plots closest to the OSR field in the first sowing, which coincides with the appearance of the first ovipositing females after overwintering as pupae elsewhere. Generally, insecticide treatment in the agricultural field appeared to influence overall damage in the neighbouring garden crop, despite the fact that the garden crop was protected against wind drift of the insecticides during applications.     

Pod shatter-resistant Brassica fruit produced by ectopic expression of the FRUITFULL gene

Arabidopsis has proven to be extremely useful as a reference organism for studies in plant biology, and huge efforts have been employed to unravel various mechanisms of Arabidopsis growth. A major challenge now is to demonstrate that this wealth of knowledge can be used for global agricultural and environmental improvement. Brassica species are closely related to Arabidopsis and represent ideal candidates for model-to-crop approaches as they include important crop plants, such as canola. Brassica plants normally disperse their seeds by a pod-shattering mechanism. Although this mechanism is an advantage in nature, unsynchronized pod shatter constitutes one of the biggest problems for canola farmers. Here, we show that ectopic expression of the Arabidopsis FRUITFULL gene in Brassica juncea is sufficient to produce pod shatter-resistant Brassica fruit and that the genetic pathway leading to valve margin specification is conserved between Arabidopsis and Brassica . These studies demonstrate a genetic strategy for the control of seed dispersal that should be generally applicable to diverse Brassica crop species to reduce seed loss.     

An investigation into the variations in the fine surface details of the eggs of five species of Delia (Diptera: Anthomyiidae)

The eggs of five species of Delia have been examined for the external chorionic patterning, the size and shape of the micropyle and the number, characteristics and distribution of the aeropyles using the scanning electron microscope. The species concerned are the cabbage root fly Delia radicum , the onion fly Delia antiqua , the seed corn maggot Delia platura , the wheat bulb fly Delia coarclata and the turnip fly Delia floralis.
Each species has its own clear characters and this, coupled with a significant difference in egg size, enables one species to be distinguished from another.