Ceutorhynchus Napi Research Articles

Research on the Effectiveness of Some Fungicides and Insecticides in Combating of Some Diseases and Pests of Rape in Cristian Commune - Brașov County

In Romanian agricultural production, autumn rape is in present an indispensable component of crop rotations because helps to maintain soil fertility and contributes to sustainable production therefore. Behavior against fungal diseases and insect pests for modern rape varieties represents an essential agronomic property. Rape pest and disease control is a priority to minimize quantitative and qualitative production losses. In plant protection, fungicides and insecticides must to be used only when is necessary and at optimal times and doses. The notations were made during the vegetation period of 2020, 2021 and 2022. Both fungicides applied (125 g/l azoxistrobin + 125 g/l difenoconazol and 125g/l fluopiram + 125 g/l protioconazol) showed high efficacy against alternaria, black leg and powdery mildew, and in the variants where both fungicides were applied, the highest efficacy was 98.8% against black leg and 98.9% anti powdery-mildew. The effectiveness of the two insecticides applied (240 g/l tiacloprid and 5% lambda-cihalotrin) varied between 87.2 and 97.3 against Ceutorhynchus napi, C. assimilis, Phyllotreta atra, Ph. nemorum and Brevicoryne brassicae.

Intercropping Winter Oilseed Rape (Brassica napus L.) Has the Potential to Lessen the Impact of the Insect Pest Complex

Winter oilseed rape (Brassica napus) is a global major crop used for the production of vegetable oil. Typically sown in late summer and grown throughout winter and spring, it allows for interesting cultural practices, such as frost-sensitive intercropping with companion plants. This practice not only provides nitrogen resources much needed by the crop in the spring, but companion plants can also prevent weed growth in autumn, thereby reducing common herbicide use. Additionally, intercropping has the potential to protect the crop from insect pests. During winter 2019–2020, B. napus was grown alone (i.e., as a control) or intercropped with a mixture of faba bean (Vicia faba) and grass pea (Lathyrus sativus); because of the unusually clement weather conditions, the faba bean did not freeze, which allowed for the evaluation of the impact of these companion plants on the insect pest complex in spring. Insect damage by the beetles Psylliodes chrysocephala, Ceutorhynchus napi, and Brassicogethes aeneus was assessed in both treatments. The larval density of P. chrysocephala was significantly lower in the crop grown with service plants. Egg laying and damage by C. napi were significantly reduced when B. napus was intercropped, and the number of B. aeneus captured was significantly lower in the presence of service plants than in the control. Moreover, the yield from oilseed rape was significantly higher in the part of the field with service plants than in the pure crop control. The underlying mechanisms are only partially understood, but intercropping winter oilseed rape with frost-resistant service plants seems to be an ecologically sound practice with a very high level of potential to reduce insect pest pressure and increase crop yield. This may eventually reduce our reliance on chemical inputs in one of the most treated crops.

Control of cabbage stem weevil and pollen beetle with one insecticide application

Over the course of three years (2016–2018), the effects of insecticides on stem-mining weevils [(Ceutorhynchus pallidactylus (Marsham, 1802), Ceutorhynchus napi (Gyllenhal, 1837)] were assessed under field conditions. The dates for spraying were determined on the basis of the recorded percentages of weevil females carrying mature eggs in their ovaries (timing I: the first females with mature eggs present in yellow water traps; timing II: more than 50% of the females with mature eggs present). Delaying the first spring insecticide application till timing II made it possible to combine the control of the stem weevil along with the control of the pollen beetle, Brassicogethes aeneus (Fabricius, 1775). However, the poor effectiveness of the tested insecticides on the stem-mining weevils, regardless of the date they were sprayed, indicates it is impossible to successfully control the insect pests with one insecticide application during the seasons with prolonged egg-laying periods.

Phenology and suppression of stem weevils (Ceutorhynchus napi gyllenhal and Ceutorhynchus pallidactylus marsham) in oilseed rape in northern Serbia

Stem weevils (Ceutorhynchus pallidactylus and Ceutorhynchus napi) are significant pests of oilseed rape that farmers regularly suppress by insecticide treatments intended against Brassicogethes aeneus. Recent studies have shown that in some regions of northern Serbia C. napi is dominant, while C. pallidactylus prevails in others. Increased damage from stem weevils has elicited an exploration of the situation and a study of their phenology and effects of insecticides in three differently managed fields: conventional, organic and integrated. New findings regarding the phenology of stem weevils show that both species were sporadically present in our experimental oilseed rape fields as early as during autumn (from the end of October 2010, BBCH 17-18). The main period of stem weevil settlement is the end of winter and early spring. Maximum flight of both weevil species was recorded on March 23 at the beginning of oilseed rape (OSR) stem elongation (BBCH 22-25), and one week later in the organic field. There were no significant differences in the number of settled weevils among the three differently managed fields. The insecticide treatment against C. napi was applied two weeks earlier than the usual treatment against B. aeneus and C. pallidactylus. Thus, it is clear that insecticide treatment directed against B. aeneus and C. pallidactylus is not effective against C. napi. In this way, such a practice can contribute to an increase in OSR damage, and density of the next generation of C. napi. A new generation of C. pallidactylus emerged from OSR fields in June 2011, while the majority of C. napi emerged in March of the following year.

Evaluation of nine genotypes of oilseed rape (Brassica napus L.) for larval infestation and performance of rape stem weevil (Ceutorhynchus napi Gyll.).

The rape stem weevil, Ceutorhynchus napi Gyll., is a serious pest of winter oilseed rape (Brassica napus L.) crops in Europe causing severe yield loss. In currently used oilseed rape cultivars no resistance to C. napi has been identified. Resynthesized lines of B. napus have potential to broaden the genetic variability and may improve resistance to insect pests. In this study, the susceptibility to C. napi of three cultivars, one breeding line and five resynthesized lines of oilseed rape was compared in a semi-field plot experiment under multi-choice conditions. Plant acceptance for oviposition was estimated by counting the number of C. napi larvae in stems. The larval instar index and the dry body mass were assessed as indicators of larval performance. The extent of larval feeding within stems was determined by the stem injury coefficient. Morphological stem traits and stem contents of glucosinolates were assessed as potential mediators of resistance. The resynthesized line S30 had significantly fewer larvae than the cultivars Express617 and Visby and the resynthesized lines L122 and L16. The low level of larval infestation in S30 was associated with a low larval instar and stem injury index. Low numbers of larvae were not correlated with the length or diameter of stems, and the level of stem glucosinolates. As indicated by the low larval infestation and slow larval development the resistance of S30 to C. napi is based on both antixenotic and antibiotic properties of the genotypes. The resynthesized line S30 should therefore be introduced into B. napus breeding programs to enhance resistance against C. napi.

Analysis of oilseed rape stem weevil chemical control using a damage rating scale.

Rape stem weevil (Ceutorhynchus napi Gyll.) and cabbage stem weevil (C. pallidactylus Marsh.) can cause significant yield losses to oilseed rape (Brassica napus L.), and chemical control is often needed to protect crops from these pests. The efficacy of six insecticides, chlorpyriphos + cypermethrin, bifenthrin, alpha-cypermethrin, pirimiphos-methyl, thiacloprid and tau-fluvalinate, was tested in a 4 year field trial. Besides the standard efficacy analysis expressed through the number of larvae per stem, a damage rating scale was introduced and modelled using a regression model for ordinal categorical data. Compared with the control, expressed through damage rating and larval number, treatments with chlorpyriphos + cypermethrin and bifenthrin, showed higher efficacy in the control of stem weevils compared with alpha-cypermethrin and pirimiphos-methyl. The lowest efficacy was observed in treatments with tau-fluvalinate and thiacloprid. This study showed that a combined efficacy evaluation expressed through both damage rating scale and the count of larvae, supported by an ordinal regression model for data analysis, is indispensable for obtaining accurate results. © 2017 Society of Chemical Industry.

Effects of insecticides intended for Ceutorhynchus napi Gyll. control in oilseed rape on ground beetles

The effects of insecticides that are commonly used for conventional and integrated oilseed rape (OSR) management on ground beetles were studied. Monitoring of harmful species showed that only insecticides intended against Ceutorhynchus napi should be applied. There were no differences in beetle numbers and phenology of settling of C. napi in the OSR fields that received different management practices. The type of OSR management has a primary and significant impact on ground beetles abundance. Early in the spring, ground beetles settled more massively on the non-tilled OSR field with abundant weed cover and mulch on soil surface. However, there were no significant differences in species richness between the OSR fields managed differently. A total of 22 species were recorded. Early in the spring, the granivorous ground beetles Amara aenea (47.3%) and Harpalus distinguendus (32.5%) were dominant. When insecticides were applied, immigration of ground beetles began, so that their adverse effect was minimal. In both management systems the number of ground beetles and their diversity increased after spraying. In conclusion, no significant harmful effects of the insecticides on ground beetles were detected in OSR fields managed in two different ways.

The potential of resynthesized lines to provide resistance traits against rape stem weevil in oilseed rape

The rape stem weevil, Ceutorhynchus napi Gyll., is a serious pest of winter oilseed rape (Brassica napus L.) crops in Europe that causes stem distortion, severe disruption of stem growth, and significant yield loss. No resistance has been identified in current B. napus breeding material. Resynthesized lines of oilseed rape can be used to introduce genetic material from the parent species Brassica oleracea L. and B. rapa L. The susceptibility to C. napi of five resynthesized lines and three cultivars of oilseed rape was compared in a multi-choice field plot experiment. Morphological stem traits and stem levels of glucosinolates, carbon, and nitrogen were assessed as potential mediators of resistance. Eggs and larvae of C. napi in stems were counted weekly from the beginning of oviposition to larval maturation and stem pith degeneration in response to oviposition was assessed. Egg counts per stem were negatively dependent on stem length and positively dependent on the levels of five glucosinolates, glucobrassicanapin, glucoalyssin, glucobrassicin, neoglucobrassicin, and gluconasturtiin. The resynthesized line S30 was significantly more resistant to C. napi than the commercial cultivar Sollux, having fewer eggs and larvae. This resistance appeared to be largely antixenotic, due to the combination of a long stem and a paucity of the five key glucosinolates. We propose that resynthesized lines such as S30 should be used to introduce genes determining traits such as long stem length and glucosinolate profile into breeding programs to enhance resistance against C. napi in oilseed rape.

Assessing climate change impacts on the rape stem weevil, Ceutorhynchus napi Gyll., based on bias- and non-bias-corrected regional climate change projections.

Agricultural production is directly affected by projected increases in air temperature and changes in precipitation. A multi-model ensemble of regional climate change projections indicated shifts towards higher air temperatures and changing precipitation patterns during the summer and winter seasons up to the year 2100 for the region of Goettingen (Lower Saxony, Germany). A second major controlling factor of the agricultural production is the infestation level by pests. Based on long-term field surveys and meteorological observations, a calibration of an existing model describing the migration of the pest insect Ceutorhynchus napi was possible. To assess the impacts of climate on pests under projected changing environmental conditions, we combined the results of regional climate models with the phenological model to describe the crop invasion of this species. In order to reduce systematic differences between the output of the regional climate models and observational data sets, two different bias correction methods were applied: a linear correction for air temperature and a quantile mapping approach for precipitation. Only the results derived from the bias-corrected output of the regional climate models showed satisfying results. An earlier onset, as well as a prolongation of the possible time window for the immigration of Ceutorhynchus napi, was projected by the majority of the ensemble members.

Weevils of the genus Ceutorhynchus germ associated with oilseed rape in northern Serbia

Our research of the genus Ceutorhynchus associated with oilseed rape was conducted in northern parts of Serbia (Stari Zednik, Subotica). A specific assemblage of eight weevil species was found. The most numerous were stem weevils Ceutorhynchus napi with 81% of all trapped specimens, followed by C. pallidactylus with 18%. The remaining six weevil specimens were C. obstrictus, C.erysimi, C. minutus, C. picitarsis, C. sulcicollis and C. typhae, comprising 1% of all trapped insects. Stem weevils C. napi and C. pallidactylus began to immigrate into the oilseed rape fields in autumn, as early as November 10 (BBCH 17-18). The maximum flight was recorded at the beginning of oilseed rape stem elongation (BBCH 22-25) on March 23. A new generation of C. pallidactylus emerged from oilseed rape fields in June (BBCH 76-88), while individual specimens occurred during the autumn. The majority of C. napi emerged in March next year, sporadically until May 7. As a consequence of C. napi dominance insecticide treatment should be performed earlier than usual, i.e. when C. pallidactilus is the primary target.

Effect of flight activity of stem weevils (Ceutorhynchus napi, C. pallidactylus) and application time on insecticide efficacy and yield of winter oilseed rape

During 2010–2012, we monitored flight activity of male and female stem weevils (Ceutorhynchus napi, C. pallidactylus) using yellow water traps, the effectiveness of various application dates for the insecticide thiacloprid (72 g active ingredient/ha), and the influence on yield. The first occurrence of beetles in traps was recorded after soil temperature at 5 cm reached 8°C in all experimental years. In all years, males of C. pallidactylus dominated in the traps and the times of beetles’ first occurrence. The most effective applications of thiacloprid at the stated rate were 14 days (2010), 6 days (2011), and 1 day (2012) after peak flight. Females with eggs appeared in bowls in 2010 and 2012 at first flight, while in 2011 no females were recorded. After the most effective applications, yields increased significantly in 2010 (+5% vs. the control) and in 2011 (+4%), and insignificantly in 2012 (+2%).

Shifted migration of the rape stem weevil Ceutorhynchus napi (Coleoptera: Curculionidae) linked to climate change

A multi-model ensemble of 15 climate change projections from regional climate models was used to assess the impact of changes in air temperature and precipitation on the phenology of pest species in agriculture. This allowed the bandwidths of expected changes in both meteorological variables to be calculated, forming the basis for assessing and clearly communicating the uncertainties related to the model results. More specifically, we investigated the potential impact of regional climate change effects on the crop inva- sion of the rape stem weevil, Ceutorhynchus napi Gyllenhal (Coleoptera: Curculionidae), in Central Europe (Luxembourg). Multisite and perennial data from field observations were used to choose a biological model from the literature, based on daily maximum air temperature and daily totals of precipitation to describe the migration of C. napi. Based on this statistical relation, we were able to reproduce the observed crop invasion with a mean root mean squared error (RMSE) of 10 days. Daily values of projected maximum air temperatures and daily totals of precipitation of the multi-model ensemble were used as input data for the threshold-based biologi - cal model that projects the immigration of this pest species into oilseed rape crops (Brassica napus L.). We examined three thirty-year timespans, the near (2021 to 2050) and the far future (2069 to 2098) and compared them to a reference timespan (1961 to 1990). The projections showed a significant shift of crop invasion to an earlier onset for the near (14 days) and far future (21 days) compared to the reference period. In addition, the timespan in which the potential crop invasion will take place increased from 53 days in the reference timespan to 73 days in the near and 65 days in the far future based on the ensemble median values. It could be expected that a shifting of the immigration period will increase the risk of missing the appropriate time frame for an insecticide application. A depletion of stored nutrient resources, leading to starvation after diapause, can be eliminated for C. napi under climate change effects, as this species hibernates motionless as an adult in earth cocoons until emergence in early springtime driven by temperature.

Carabid beetle condition, reproduction and density in winter oilseed rape affected by field and landscape parameters

AbstractThe carabid beetles Amara similata and Poecilus cupreus are abundant in Central European winter oilseed rape (OSR) fields and potential antagonists of OSR pests. Therefore, they were investigated in 29 OSR fields relative to the influence of field and landscape parameters on their nutritional condition, reproductive potential and activity density. Nutritional condition was measured by a condition factor (CF). Fecundity of female beetles was expressed by the number of ripe oocytes in the ovaries. Activity density comprised the number of individuals caught with pitfall traps during their peak of reproductive period. Soil productivity and pest abundance (as a proxy of local prey availability) were considered as field parameters. Landscape parameters comprised the distance to the next fallow and the percentage of crop area around each study field. In eight of ten cases, pest abundance proved to be the most important factor explaining carabid characteristics, indicating that P. cupreus and A. similata consume insect pests in OSR fields. Pest abundance influenced the CF of both species and sexes positively. Oocyte numbers of A. similata were negatively related to the distance to the next fallow. Oocyte numbers of P. cupreus tended to increase with increasing pest abundance. Activity density of female A. similata was negatively influenced by soil productivity. Activity density of male A. similata and of female and male P. cupreus was negatively influenced by pest abundance. When analysing exclusively the influence of severe OSR pests (Meligethes aeneus, Ceutorhynchus napi and Dasineura brassicae), abundance of larval M. aeneus and C. napi was most important in explaining the CF and activity density of male A. similata, and male and female P. cupreus. M. aeneus and C. napi could be an essential prey for the carabids studied which may reduce the pests, thereby contributing to the protection of OSR from pest herbivory.

Pyrethroid sensitivity monitoring in Germany of oilseed rape pest insects other than pollen beetle

Pyrethroid resistant pollen beetles (Meligethes aeneus) are widely distributed in Germany and other European countries. Other insect pests on oilseed rape are also exposed to pyrethroids which often have more than one application per season. In spite of this scarce information about the sensitivity of other oilseed rape pest insects is available. To address this monitoring of pyrethroid sensitivity of different oilseed rape pest insects has been carried out since 2005. Laboratory experiments were conducted using an adult‐vial‐test design with samples collected in different areas of Germany.Most samples of Ceutorhynchus napi, C. assimilis, C. pallidactylus, Dasineura brassicae, Phyllotreta spp. and Psylliodes chrysocephala tested from 2005–2007 showed 100% mortality at 0.003 and 0.015 µg/cm2 lambda‐cyhalothrin used as reference test pyrethroid. Some samples especially of C. pallidactylus, C. napi and C. assimilis showed a lower mortality with alive and healthy beetles at 0.015 µg/cm2 lambda‐cyhalothrin. For all samples tested from 2005–2007 100% mortality was found only at higher rates of 0.0375 or 0.075 µg/cm2 lambda‐cyhalothrin.To date, no clear pyrethroid resistance has been detected in other oil seed rape pest insect populations in Germany.

Interactions between the stem‐mining weevils Ceutorhynchus napi Gyll. and Ceutorhynchus pallidactylus (Marsh.) (Coleoptera: Curculionidae) in oilseed rape

Abstract 1 The rape stem weevil Ceutorhynchus napi Gyll. and the cabbage stem weevil Ceutorhynchus pallidactylus (Marsh.) share the same habitat and food resource within the stems of oilseed rape, Brassica napus L. var. oleifera. Interactions occurring between these two sympatric species on this host were studied under both field and laboratory conditions.2 The oviposition preference of C. pallidactylus and the within‐plant distribution of eggs and larvae were examined in field plots of oilseed rape. Female C. pallidactylus tended to lay their eggs in plants already infested by eggs and larvae of C. napi rather than in uninfested plants. The within‐plant distribution of the egg batches of C. pallidactylus did not differ significantly between uninfested plants and those preinfested by C. napi. Ovipositing females of C. napi and C. pallidactylus generally showed a significant preference for plants with larger stem diameter.3 Laboratory choice tests provided further evidence for the oviposition preference of C. pallidactylus. Females laid significantly more eggs in leaves of plants that had been previously infested by C. napi than in leaves of previously uninfested plants.4 Larvae of C. pallidactylus showed a significant shift of their feeding niche towards the stem base when feeding in individual plants attacked by both species. This possibly indicates ressource partitioning between C. pallidactylus and C. napi. The within‐plant distribution of C. napi larvae was not affected by the simultaneous attack of C. pallidactylus.5 The size of the head capsule of full‐grown larvae of C. napi and C. pallidactylus was not significantly correlated with the diameter of the stem of their host plant or with the number of conspecific larvae within individual plants.

Differences in flight activity of pests on winter and spring oilseed rape

For 6 years the flight activity of pests on winter and spring oilseed rape was studied from spring till harvest, using yellow traps. In all years the flight intensity was higher in winter rape than in spring rape. The dominant insect pests of winter oilseed rape were Ceutorhynchus obstrictus, C. napi, C. pallidactylus, Dasineura brassicae, Meligethes aeneus, Phyllotreta atra and Ph. nigripes; subdominant were Athalia rosae, Brevicoryne brassicae and Psylliodes chrysocephala. In spring rape the dominant species were Brevicoryne brassicae, Ceutorhynchus obstrictus, Dasineura brassicae, Meligethes aeneus, Phyllotreta atra and Ph. nigripes; subdominant were Athalia rosae, Ceutorhynchus napi, C. pallidactylus and Psylliodes chrysocephala. Dasineura brassicae was not evaluated from trap catches. The damage by D. brassicae is higher to pods on axillary branches than on the main inflorescence. The occurrence of pests on spring rape was tied to a unsuitable phenophase of the plants at the time of flight activity and to the suitability of food. Winter rape requires a higher intensity of chemical treatment against pests than spring rape.

CEUTORHYNCHUS NAPI OR CEUTORHYNCHUS RAPÆ

In the report of the Commissioner of Agriculture for 1888, p. 136, Miss Mary E. Murtfeldt gives some notes on the development of Ceutorhynchus napi, Gyll., which had worked serious injury to cabbage in Missouri, the species having been determined, as stated by Miss Murtfeldt, by the late Dr. C. V. Riley, at that time United States Entomologist. Prior to the publication of Miss Murtfeldt's notice, she had informed me of her “find,” and on my writing to ask her if there was not a mistake, and if she did not refer to rapæ, she replied that she, too, had not felt sure of the correctness of the determination until she had written Dr. Riley a second time with reference to the species, and the determination had been reaffirmed. This appeared to settle the matter, and I was satisfied that napi must be correct, though not before known to occur in North America.