Biology of the flea beetle,Altica carduorum [Col.: Chrysomelidae] on Canada thistle (Cirsium arvense) in South Dakota

A laboratory colony of 50 adults ofAltica carduorum Guérin-Méneville was established at South Dakota State University. Beetles reared in this colony had an average preoviposition period of 7 days when exposed to a regular cycle of 16 hr of light (24°C) and 8 hr of darkness (12.7°C). The laboratory reared females, whose longevity averaged 100 days, laid an average of 259.3±9.7 eggs. High temperatures and/or low RH are limiting factors to beetle survival. In the field eggs were laid throughout June on the underside of leaves along the edges of the veins. Adults fed throughout the summer and then over-wintered in the soil. Some of these beetles emerged the following spring and laid viable eggs. Factors limiting establishment in South Dakota, however, were high temperatures, low humidities, and the predators,Lebia viridis Say andHarpalus pennsylvanicus Degeer.A. carduorum originates from the Swiss Rhône valley where there is a relatively “continental” climate, but is limited to special habitats where comparatively high humidity occurs. South Dakota climate is characterized by cold winters, and hot, dry summers, therefore establishment would be most difficult.     

Biological control of creeping thistle (Cirsium arvense): Analysis of the releases ofAltica carduorum [Col.: Chrysomelidae] in Canada

Altica carduorum Guérin-Méneville, a biological control agent against creeping thistle (Cirsium arvense (L.)Scop.) was released in Canada on 2 climatically contrasting release sites. Predation at the southern site, aggravated by slow egg and larval development, and low temperatures at the northern site prevented establishment. Reports from other releases in Canada, Britain and South Dakota are discussed.

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Résumé Altica carduorum Guérin-Melville, ennemi naturel du chardon des champsCirsium arvense (L.)Scop. a été laché au Canada dans 2 régions de climat différent. Il n'y a pas eu d'acclimatation à cause de la prédation dans la localité méridionale; dans le site septentrional ce phénomène a été aggravé par un développement embryonnaire et larvaire lent et par de basses températures. Les données sur d'autres lachers faits au Canada, en Grande-Bretagne et dans le Dakota du Sud sont discutées.

     

Resource partitioning in a guild of aphid species associated with creeping thistle Cirsium arvense

Four aphid species (Aphis fabae cirsiiacanthoidis Scop., Brachycaudus cardui (L.), Capitophorus carduinus Walker and Uroleucon cirsii (L.)) feed on the creeping thistle Cirsium arvense. They utilize different parts of their host plant and at different times. A wide niche is typical of C. carduinus and U. cirsii, whereas A. f. crisiiacanthoidis and B. cardui, show narrower but overlapping niches. Morphological features such as stylet length and body size as well as colony size and density are associated with the choice of feeding site. C. carduinus, the smallest species with the shortest stylets was able to use leaf veins and lamina, while the other species mainly used the stem and peduncles. Within this group, A. f. cirsiiacanthoidis and B. cardui are restricted to the upper part of the stem because of their short stylets, but adult U. cirsii, the species with the longest stylets, can also feed at the base of the stem.

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Räumliche und zeitliche ressourcenaufteilung in der blattlausgilde an der ackerkratzdistel cirsium arvense

Zusammenfassung An der Ackerkratzdistel leben vier Blattlausarten (Aphis fabae cirsiiacanthoidis Scop., Brachycaudus cardui (L.), Capitophorus carduinus Walker und Uroleucon cirsii (L.)), die im Verlauf der Vegetationsperiode verschiedene Strukturen ihrer Wirtspflanze nutzen. Eine breite Nische ist für U. cirsii und C. carduinus typisch, während A. f. cirsiiacanthoidis und B. cardui engere Nischen besitzen, die sich nahezu überlappen. Die Nahrungsplatzwahl wird sowohl durch morphologische Parameter wie Stilettlänge und Körpergewicht als auch durch Koloniegröe und Dispersion innerhalb der Kolonie beeinflut. Die kleinste Art, C. carduinus, die auch das kürzeste Stilett besitzt, ist in der Lage, an Blattadern und auf der Blattspreite zu saugen. Die anderen Arten bevorzugen Stengel, Seitenstengel und Blütenstiele. Innerhalb dieser Gruppe können A. f. cirsiiacanthoidis und C. carduinus wegen ihrer kürzeren Stilette nur am oberen Teil des Stengels saugen, während adulte U. cirsii aufgrund ihrer längeren Stilette auch an der Stengelbasis leben können.

     

Biology and Ecology of Altica carduorum Chrysomelidae: Coleoptera from North-western China: A Potential Biocontrol Agent for Cirsium arvense Asteraceae in Canada

The biotype of the defoliating beetle, Altica carduroum, from Wusu Xinjiang, China was studied as a biocontrol agent for Cirsium arvense in Canada. At Wusu, the beetle is particularly damaging to C. arvense in irrigated crops and fallow fields. A release of 300 adult A. carduorum at Urumqi, Xinjiang, dispersed to cover an area with a radius of 600 m by the following year, where it destroyed almost 60 of C. arvense leaves and resulted in plant wilting at a density of 4.5 beetles plant. Laboratory studies of the beetle' s development of 2 C intervals from 15 to 27 C identified the optimum developmental temperature as 25.5 C. Beetles reared at this temperature laid an average of 245 eggs, with a 41-fold generation increase. Habitat comparisons between biotypes of A. carduorum from Wusu and Europe suggest that the Wusu biotype may be better suited as a biocontrol agent of C. arvense on the Canadian prairies.     

Sexual Dimorphism in Cirsium arvense (L.) Scop

Differences between males and females of Cirsium arvense (L.)Scop. in morphology and sexual performance are described. Nofunctional pollen was observed in females, and no pollen-sterileanthers were observed in males. The difference between the sexesin ovule functions is not absolute however: some males produceoccasional fruits. The number and distribution of fruits onboth sexes are described. The fruits borne on males are smallerand germinate less well than those borne on females, but theseedlings from the two sexes grow equally well. On the average,males contribute only 5.3 x 10^–4 as many genomes via ovulesas do females. The average male constancy, the proportion ofmale genes transmitted via pollen, is estimated as 0.9989. Theprimary sex index, a measure of the functional approach to strictdioecy (represented as 1.00) is 0.9995. C. arvense is describedas near-dioecious and varying from dioecy in a gynodioeciousmanner. The opinion expressed by Correns that the near-dioecyof C. arvense has been derived from hermaphroditism via gynodioecyis upheld.     

Effect of Herbivore Density, Timing of Attack and Plant Community on Performance of Creeping Thistle Cirsium arvense (L.) Scop. (Asteraceae)

Creeping thistle, Cirsium arvense (L.) Scop. (Asteraceae), is one of the most serious weeds in ecological compensation areas (within-field or border refugia) in Europe. Since conventional weed control measures are restricted in compensation areas, augmenting indigenous agents for biological control of the weed may be a feasible alternative. In this paper, we studied the effect of density of the shield beetle, Cassida rubiginosa Muller (Coleoptera, Chrysomelidae), and two vegetation types typical for ecological compensation areas, on the performance of creeping thistle plants in an open field experiment. Early-season larval feeding had no measurable effect on creeping thistle growth, while late-season feeding significantly reduced shoot growth. These findings were attributed to higher feeding rates of the herbivores at higher ambient temperatures late in the season. Defoliation had a strong effect on the above-ground performance of C. arvense plants, but not on the below-ground performance. In contrast, the plant community affected all below-ground performance parameters measured, but only some of the above-ground performance parameters of creeping thistle. A combination of high levels of plant competition and herbivory by C. rubiginosa larvae led to 50% mortality in C. arvense plants during the growing season. We conclude that augmentation of indigenous herbivores of C. arvense in combination with breaking up the root system by tillage and the establishment of a highly competitive plant community of beneficial herbs may be a feasible way to control this problematic weed in ecological compensation areas.     

Genetic diversity and population structure in four Cirsium (Asteraceae) species

The present study considers genetic diversity of 38 populations in 4 Cirsium species of the genus Cirsium Mill. (Asteraceae), occurring in different ecological regions and tries to compare degree of genetic variability among the species with wide geographical distribution versus endemic C. pyramidale showing confined geographical distribution. The results showed that the endemic species has similar value of genetic diversity parameters as the species with wider distribution. We also studied the possible admixture nature of these populations and tried to understand the relation between genetic changes, geographical distribution and polyploidy level and chromosome pairing in these species. ISSR analysis showed population difference in allele composition and frequency. Clustering and PcoA ordination produced different groupings in each species, while STRUCTURE and reticulation analyses revealed high degree of genetic admixture and gene exchange among populations as well as allelic rearrangement. No significant correlation was observed between geographical distance and genetic distance of the populations and AMOVA test revealed no significant difference among populations in each species studied. However, high amount of within population variation occurred in all 4 species indicating their cross-pollination nature and high genetic admixture. The populations also varied in chiasma frequency and chromosome pairing as well as the occurrence of heterozygote translocations all creating more variability to be used by plants for local adaptation.     

The internal cuticle of Cirsium horridulum (Asteraceae) leaves

Leaf internal cuticle has not previously been studied in detail, and yet its existence has profound implications for the path of water movement. The internal cuticle forms a uniform layer on the inner periclinal epidermal walls that border substomatal cavities. This cuticle is continuous with the external cuticle through the stomatal pores. The thickness of the internal cuticle on nonstomatal epidermal cells is approximately one-third that of the external cuticle on the same cells. On both the abaxial and adaxial sides of the leaf the internal cuticle forms irregularly shaped islands bordered by mesophyll cells. The size of the islands coincides with the epidermal area of the substomatal cavity. The internal cuticle remains intact and connected to the external cuticle after incubation in cellulytic enzymes. After treatment with sulfuric acid or chloroform, both cuticles remain intact. The autofluorescence of both cuticles is increased by staining with auramine O. These results indicate that large portions of the leaf epidermis are covered by both an internal and an external cuticle.     

Modelling and Mapping Geographic Ranges to Evaluate Weed Biocontrol Agents: A Case Study Using Altica carduorum (Coleoptera: Chrysomelidae) and Cirsium arvense (Asteraceae)

Leaf - feeding beetles , Altica carduorum, from a population in NW China have been identified as candidate agents for biocontrol of Canada thistle , Cirsium arvense. This paper assesses the potential of beetles from this population to establish on the Canadian prairies . A phenological model is applied to determine where sufficient heat accumulates to allow completion of at least one generation per year . The model was applied both with and without a submodel of adult thermoregulation . The model was driven using meteorological data from a grid covering the agricultural region of the Canadian prairies , i . e . ca . 670 000 km 2 , at a resolution of (50 50) km . In each grid square , the percentage of the years 1960 - 89 for which the model indicated that at least one generation could have been completed was calculated; these proportions were categorized (0 - 80%; 80 - 99% and 100%) and mapped . Maps of C. arvense density over the simulation region were also produced , and compared to the maps of predicted beetle distribution . The model suggests that A. carduorum could establish over much of the prairies . Without thermoregulation , the predicted range (i . e . the area in which one generation was completed in every year) is restricted to the warmer parts of the prairies , where C. arvense is generally sparse . Inclusion of thermoregulation almost doubled the predicted range to cover most of the range of C. arvense on the Canadian prairies , missing only the cooler peripheral areas . These results suggest that this strain of A. carduorum has potential to overlap the range of C. arvense on the Canadian prairies , and so has potential to control this weed .     

Growth and development of larvae and galls of Urophora cardui (Diptera,Tephritidae) on Cirsium arvense (Compositae)

Summary The tephritid fly Urophora cardui induces a large multi-chambered gall within the stems of Cirsium arvense. Three distinct phases of gall development have been identified as initiation, growth, and maturation. During initiation the insect gains control of tissue development and during the gall's growth phase parenchyma cells proliferate rapidly surrounding the larvae with thick layers of cells. Patches of primary nutritive cells appear along the surface of larval chambers during the growth phase but few of these cells are consumed. In the gall's maturation phase, thick layers of secondary nutritive cells appear around the surface of larval chambers and the remaining gall parenchyma lignifies. Secondary nutritive cells are the primary food of U. cardui.The gall expands rapidly during the growth phase then abruptly slows at the beginning of the maturation phase. Rate of gall growth is dependent upon the number of larvae per gall but the number of larvae does not affect duration of this phase.Larvae remain in the second instar throughout the growth phase and grow slowly. Once the gall enters the maturation phase and the secondary nutritive cells appear, the larvae moult to the third instar and grow quickly. Larvace attain over 98% of their final weight during the maturation phase and consume all secondary nutritive cells.It is postulated that larvae do not feed extensively on primary nutritive cells since these cells play a key role in gall morphogenesis. The appearance of secondary nutritive cells stimulates larval feeding at a time when gall growth and development is finished.     

Canada thistle (<Emphasis Type="Italic">Cirsium arvense</Emphasis> (L.) Scop.) dynamics in young,postfire forests in Yellowstone National Park,Northwestern Wyoming

Canada thistle (Cirsium arvense (L.) Scop.) is an invasive, non-native plant in many terrestrial systems, often dominating plant communities, particularly in agricultural systems. Its invasion into forest systems is not well understood. Our objectives were to investigate the establishment, persistence, and abundance of C. arvense over a 7-year period following wildfire in a forest system, and to understand environmental factors related to variability in plant community composition. In 2006, we resurveyed 30 sites in young lodgepole pine (Pinus contorta Dougl. ex. Loud. var. latifolia Engelm. ex Wats.) stands that burned during 1988 in Yellowstone National Park, and that had been previously sampled in 1999. C. arvense disappeared from six of nine sites where it was present in 1999, persisting in the remaining three sites; it also established at 4 new sites since 1999. Notably, the relative cover of C. arvense and other non-native plant species decreased during the 7-year period. Important ecosystem measures (plant species diversity and richness, aboveground net primary productivity, and leaf area index) were all higher in sites where C. arvense was present, and its abundance was higher on more fertile substrates and at lower elevations. Plant community composition was strongly influenced by gradients of soil texture and bare ground, rather than the presence or absence of non-native plant species. This project demonstrates the dynamic nature of an invasive species 18 years following a major disturbance, and suggests that intensive management of this species in forested systems is probably unnecessary.     

Effects of variation in flower number on pollinator visits in Cirsium purpuratum (Asteraceae)

We examined the functional relationships between floral display and two types of bumble bee response, the visitation rate per plant and the number of flowers visited on a plant, in an artificially arranged field population of Cirsium purpuratum. To reduce the variance in data, we collected data for each day separately and adopted a Latin square design in selecting the focal plants within a day. We then tested several types of regressions to each set of data to find the best-fitting line accounting for the observed relationship between pollinator response and display size. We found that the visitation rate of bumble bees per plant was a decelerating function of floral display, and that the number of flowering heads visited on a plant increased linearly with display size. Predicted from the above two functions, the visitation rate per head was independent of floral display and nearly constant within each day. Our results suggest that conventional methods in collecting and analyzing data on pollinator visitation may yield large variance in data derived from temporal and spatial heterogeneity and that improved methods employed here are effective in reducing the variance and estimating patterns of pollinator response to floral display more accurately.     

Mating interactions between coexisting dipoloid, triploid and tetraploid cytotypes ofHieracium Echioides (Asteraceae)

Experimental crosses between diploids, triploids and tetraploids ofHieracium echioides were made to examine mating interactions. Specifically, cytotype diversity in progeny from experimental crosses, intercytotype pollen competition as a reproductive barrier between diploids and tetraploids, and differences in seed set between intra- and intercytotype crosses were studied. Only diploids were found in progeny from 2x × 2x crosses. The other types of crosses yielded more than one cytotype in progeny, but one cytotype predominated in each cross type: diploids (92%) in 2x × 3x crosses, tetraploids (88%) in 3x × 2x crosses, triploids (96%) in 2x × 4x crosses, triploids (90%) in 4x × 2x crosses, tetraploids (60%) in 3x × 3x crosses, pentaploids (56%) in 3x × 4x crosses, triploids (80%) in 4x × 3x crosses and tetraploids (88%) in 4x × 4x crosses. No aneuploids have been detected among karyologically analyzed plants. Unreduced egg cell production was detected in triploids and tetraploids, but formation of unreduced pollen was recorded only in two cases in triploids. Triploid plants produced x, 2x and 3x gametes: in male gametes x (92%) gametes predominated whereas in female gametes 3x (88%) gametes predominated. Cytotype diversity in progeny from crosses where diploids and tetraploids were pollinated by mixture of pollen from diploid and tetraploid plants suggested intercytotype pollen competition to serve as a prezygotic reproductive barrier. No statistically significant difference in seed set obtained from intra- and intercytotype crosses between diploids and tetraploids was observed, suggesting the absence of postzygotic reproductive barriers among cytotypes.     

Host finding and recognition by Altica carduorum, a defoliator of Cirsium arvense

Altica carduorum Guer. (Coleoptera: Chrysomelidae) populations aggregate on vigorously growing stands of its host, the thistle Cirsium arvense (L.) Scop. (Asteraceae). The beetle needs contact to recognize a Cirsium species and biting to distinguish its host C. arvense. Feeding or mechanical damage on C. arvense, but not other Cirsium species, aggregates the beetles. Also feces from feeding on C. arvense, but not other Cirsium species, aggregates the opposite sex. Adults also aggregate on larval feces. We suggest that initial host location in the spring depends on random encounter by beetles overwintering in a stand of C. arvense. The beetles commonly make short flights after feeding and either land on another C. arvense plant, which establishes a secondary aggregation centre, or return to the original one. In this manner beetles released on a stand of C. arvense in China spread a radius of 600 m in a year, but those released 35 m away from their host failed to find it. Altica carduorum will develop on any Cirsium species to which it is confined, but is monophagous in the field because host finding is dependent on aggregation to wound and feces substances that are specific to C. arvense.     

Molecular cloning and characterization of procirsin,an active aspartic protease precursor from Cirsium vulgare (Asteraceae)

Typical aspartic proteinases from plants of the Astereaceae family like cardosins and cyprosins are well-known milk-clotting enzymes. Their effectiveness in cheesemaking has encouraged several studies on other Astereaceae plant species for identification of new vegetable rennets. Here we report on the cloning, expression and characterization of a novel aspartic proteinase precursor from the flowers of Cirsium vulgare (Savi) Ten. The isolated cDNA encoded a protein product with 509 amino acids, termed cirsin, with the characteristic primary structure organization of plant typical aspartic proteinases. The pro form of cirsin was expressed in Escherichia coli and shown to be active without autocatalytically cleaving its pro domain. This contrasts with the acid-triggered autoactivation by pro-segment removal described for several recombinant plant typical aspartic proteinases. Recombinant procirsin displayed all typical proteolytic features of aspartic proteinases as optimum acidic pH, inhibition by pepstatin, cleavage between hydrophobic amino acids and strict dependence on two catalytic Asp residues for activity. Procirsin also displayed a high specificity towards κ-casein and milk-clotting activity, suggesting it might be an effective vegetable rennet.The findings herein described provide additional evidences for the existence of different structural arrangements among plant typical aspartic proteinases.     

Host Specificity of Altica carduorum Guer. Chrysomelidae: Coleoptera , a Defoliator of Cirsium arvense L. Scop. Asteraceae from North-western China

Traditionally, insects are not approved for release in North America as agents for the biological control of weeds if the larvae complete development on desirable plants in no-choice tests. This criterion excludes the use of the leaf-feeding beetle Altica carduroum Guer. since it can complete development on all Cirsium spp., including rare North American species, although in nature it is only known from the target weed Cirsium arvense. Host suitability is the result of a sequence of selection factors, and this study shows that most discrimination between thistle species is the result of host finding and egg production, and not larval developmental ability. In no-choice tests, the larvae completed development on 18 Cirsium species in five sections of the genus that were tested and on Silybum marianum, but not on other genera in the tribe Cardueae or more distantly related Asteraceae. The adult food consumption on C. arvense was two to eight times greater than on other Cirsium species, many of which, such as C. pitcheri and C. drummondii, received no feeding by over 50 of the beetles in the first 24 h. The best North American thistle for egg production was C. scariosum, but this was only 28 of that on C. arvense. The preference for C. arvense in multiple-choice tests increased with the size 2 of the arena. In the largest, an area of 6 m , 80 of the beetles and eggs were found on C. arvense and none were found on plants outside the subtribe Carduineae. Thus, as theory predicts, host discrimination between thistle species takes place at earlier stages than suitability for larval development, and this should be considered when determining the safety of candidate agents.     

Combined effects of folivory and neighbor plants on <Emphasis Type=Italic>Cirsium altissimum</Emphasis> (tall thistle) rosette performance

Predicting how herbivory and neighbor plant interactions combine to affect host plants is critical to explaining variation in herbivores’ impact on plant population dynamics. In a field experiment, we asked whether the combined effects of neighbor plants and folivores upon performance of tall thistle (Cirsium altissimum), a monocarpic perennial, can be predicted as the product of their individual effects (i.e., effects of neighbor plants and folivores act independently in suppressing tall thistle performance). Alternately, the combined effects of neighbor plants and folivores might be greater, indicating a synergistic interaction, or less, indicating an antagonistic interaction, than the product of their individual effects. Our experiment involved a neighbor plant clipping treatment and a folivory reduction treatment in a factorial design with manipulations applied to naturally occurring tall thistle rosettes in restored tallgrass prairie. Clipping neighbors at the soil surface within 40 cm of tall thistle rosettes increased light availability to rosettes, rosette growth, and the transition rate of 2007 rosettes to reproductive adults in 2008. Folivores’ and neighbor plants’ effects acted independently upon rosette growth. By contrast, folivory reduced the rate at which 2007 rosettes transitioned to reproductive adults in 2008 only where neighbor plants were unclipped, indicating a possible synergistic interaction of neighbor plants and folivores in suppressing tall thistle performance. Our results suggest that (1) promoting neighbor plant aboveground biomass should suppress rosette-forming weeds, and (2) folivory, which reduces light acquisition by rosettes, may generate synergistic herbivory × neighbor plant interaction effects on rosettes in grasslands, where light often limits rosettes.     

Altered patterns of growth, physiology and reproduction in invasive genotypes of Solidago gigantea (Asteraceae)

Introduced plants may leave their specialized herbivores behind when they invade new ranges. The Evolution of Increased Competitive Ability (EICA) Hypothesis holds that this escape from herbivory could lead to reduced investment in defenses, thereby freeing resources for growth and reproduction. We tested the prediction that introduced genotypes of Solidago gigantea would outperform native genotypes when grown in the absence of herbivores, and examined whether tolerance to insect herbivory has changed in introduced genotypes. S. gigantea is native to North America and an exotic invasive in Europe. Insect damage reduced plant growth and biomass for both native and exotic genotypes. While there was no evidence that continent of origin influenced the degree to which plants compensated for herbivory, the mechanisms contributing to recovery differed for native and exotic plants. Damaged US plants showed enhanced photosynthetic rates to a greater extent than damaged European plants, while damaged European plants carried more leaves than damaged US plants. At the end of the season, leaf mass of European plants was significantly greater than that of US plants. Contrary to the predictions of the EICA hypothesis, US plants were more likely to flower than European plants. European plants invested significantly more of their total reproductive biomass into rhizomes rather than flowers than US plants. While other work with S. gigantea has supported some aspects of the EICA hypothesis, the results reported here generally do not. We conclude that multiple factors influence the success of introduced plants.