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1.
Species‐specific primers were developed for the pollen beetle (a pest in oilseed rape) for studies of predation by natural insect predators. Two forward and three reverse primers were designed within the mitochondrial COI gene and used in combination to amplify fragments in the size range of 163–290 bp. Remains of pollen beetle DNA were consistently detected in Pardosa spiders up to 24 h after ingestion but dropped drastically at 48 h. These primers will facilitate studies on biological control of this oilseed rape pest. Detection time was not correlated with fragment length as might be expected as the DNA gradually degrades into progressively shorter fragments over time. 相似文献
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1 Field studies were conducted in central Sweden to establish whether two host plants with high and low suitability for pollen beetles (Meligethes aeneus Fabr. [Coleoptera: Nitidulidae] and Meligethes viridescens Fabr.) affected the parasitoid Diospilus capito Nees [Hymenoptera: Braconidae]. 2 Samples of larvae were taken from fields with plots of white mustard, Sinapis alba L. and spring rape, Brassica napus L. in 1997 and 1998. Levels of parasitism and the survival and size of D. capito were measured to determine any influence of the host plant species. Survival and weights of pollen beetles from S. alba and B. napus were also measured. 3 Levels of parasitism between 8% and 29% were recorded. There was a significantly higher likelihood of being parasitized by D. capito for beetle larvae developing on S. alba than on B. napus. We argue that semiochemical or morphological properties of plant species could be responsible for differential parasitism by D. capito. 4 Neither survival of D. capito nor parasitoid size differed from hosts developing on S. alba or B. napus. Pollen beetle emergence was the same for both plant species, but beetles that developed on S. alba weighed less than those from B. napus. Results suggest that the partial resistance of S. alba to the pollen beetle will have no negative effects on the parasitoid D. capito. 相似文献
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Robin J. Blake Ben A. Woodcock Duncan B. Westbury Peter Sutton Simon G. Potts 《Agricultural and Forest Entomology》2013,15(1):77-85
- 1 Grass buffer strips have been widely sown to mitigate against intensive agricultural management practices that have negatively impacted on invertebrate and plant biodiversity in arable farming systems. Typically, such strips are floristically species poor and are dominated by grasses. In the present study, we developed management practices to enhance the floristic and structural diversity of these existing strips for the benefit of spiders, a key provider of natural pest control in crops.
- 2 Across three UK arable farms, we investigated the benefits of: (i) scarification to create germination niches into which wildflower seeds were sown and (ii) the effect of graminicide applications to suppress grass dominance. Spiders were sampled twice per year (July and September) during 2008 and 2009.
- 3 The combination of scarification with wildflower seeds, as well as graminicide, resulted in the greatest wildflower cover and lowest grass cover, with a general trend of increased abundance of adult and juvenile spiders. The abundance of Pachygnatha degeeri, Bathyphantes gracilis and juvenile wolf spiders of the genus Pardosa was positively correlated with wildflower cover, probably reflecting increased prey availability. Sward structure was negatively correlated with Erigone atra, Oedothorax fuscus and juvenile Pardosa abundance.
- 4 Management that utilizes existing commonly adopted agri‐environment options, such as grass buffer strips, represents a potentially important conservation tool for increasing the quantity and quality of invertebrate habitats. This can maximize opportunities for the provision of multiple ecosystem services, including pest regulation by predators such as spiders. These management practices have the potential to be incorporated into existing U.K. and European agri‐environment schemes.
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Alvin J. Helden Rodi Mckenzie Gail Cobbold Philip V. Grice Guy Q.A. Anderson Michael A. MacDonald 《Insect Conservation and Diversity》2015,8(3):272-281
- The cirl bunting (Emberiza cirlus L.) has been the subject of targeted and successful conservation efforts based on agri‐environment schemes (AES) in the UK since 1993. Recent work has suggested that although focused on a single species, there have been wider biodiversity benefits for plants and some invertebrates.
- In this study we investigated whether a similar pattern could be found for the Auchenorrhyncha (plant‐ and leafhoppers) within agricultural grasslands, where they form an important component of the herbivore community.
- Sweep netting was used to sample Auchenorrhyncha from AES pastures, on which no pesticide or fertiliser inputs are allowed, and from conventionally grazed and cut (silage) fields at 25 locations in south Devon UK, during 2008.
- Generalised linear mixed models and non‐metric multidimensional scaling were used to model abundance, species density, and community structure.
- AES fields had the highest abundance, followed by conventionally grazed and then cut fields. The same pattern occurred for species density, although there was no significant difference between conventionally grazed and cut fields. There was no difference in community structure between field types.
- Number of plant species, sward age, and nitrogen input were important covariates of field type, suggesting that the limitations on inputs resulting from AES are the likely drivers of the observed differences.
- The results add to the evidence base that suggests that increased agricultural intensity is inversely related to invertebrate biodiversity. They also provide evidence that AES designed for the cirl bunting have provided wider biodiversity benefits.
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Abstract. Small‐scale landscape elements, such as ditch banks, play an important role in preserving plant species richness in agricultural landscapes. In this study, we investigate whether the seed bank might be useful for restoring the above‐ground plant species richness. We studied the vegetation and seed bank composition at six species‐rich and six species‐poor ditch banks, where agri‐environment schemes are running to maintain and enhance ditch bank plant diversity. We show that the number of species in the seed bank was low, regardless of the number of species in the established vegetation. Moreover, the seed bank was always dissimilar to the established vegetation. Target species for nature conservation were occasionally present in the seed bank at both species‐poor and species‐rich sites, but rarely so if the species was absent from the established vegetation. We conclude that the potential use of the seed bank for restoration of ditch banks is minimal. At present, plant species richness seems to be largely controlled by germination opportunities; high biomass and competition appear to hamper germination at species‐poor sites. We recommend continued nutrient reduction at such sites. Soil disturbance measures and deliberate sowing should also be considered. 相似文献
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Two indigenous species ofTrichogramma were reared from natural populations of the blackheaded fireworm,Rhopobota naevana (Hübner) infesting cranberries in British Columbia, Canada. One was identified asTrichogramma sp. nr.sibericum Sorokina and the other wasTrichogramma minutum Riley. Percentage of parasitized hosts increased during the season in an abandoned field, but decreased in a commercial field
where pesticides were used. The potential ofTrichogramma as a biological control agent against the fireworm is discussed. 相似文献
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Amir Yazdanpanah Jaber Karimi 《Archives Of Phytopathology And Plant Protection》2013,46(13):1539-1548
The cabbage aphid, Brevicoryne brassicae is one of the most destructive pests in Cruciferaceae or Brassicaceae plant family around the world. According to this pest rapid resistance to insecticide, using the resistant cultivars should be evaluated. In the present study, the different canola cultivars resistance against the cabbage aphid and the population fluctuations in canola fields and also the natural parasitism are evaluated in Shahre-rey region. To evaluate the population fluctuations and its natural parasitism on the RGS003, SLMOO46, Karag2, Licord, Sarigol, Opera, Ocapi and Talaei canola cultivars were cultivated in four replications using the complete randomised block design. The population fluctuations studies showed that the pest is active during the canola growth period in studied region, but the peak of population and damage is found in 6 May month. The results showed that natural parasitism percentage of cabbage aphid on different canola cultivars has not significant difference, but the parasitism amount in different sampling dates was significantly different, so that the natural parasitism maximum observed in date 29 April. These results showed that the different canola cultivars have significant effects on cabbage aphid and parasitoids activity amount. Using the present results, the recognised cultivars in integrated pest management programmes can be used to grow the laboratory aphids as the parasitoids hosts. 相似文献
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Tim Diekötter Sabine Wamser Tanja Dörner Volkmar Wolters Klaus Birkhofer 《Agricultural and Forest Entomology》2016,18(2):167-173
- Organic farming not only increases plant diversity, but also simultaneously promotes biological weed control through provisioning of ample resources to seed predators.
- Harpalus affinis (Schrank, 1781) was collected from organically or conventionally managed winter‐wheat fields with high or low surrounding shares of organic fields, aiming to test the impact of agricultural management on its activity density, body size and nutritional condition. Body size and nutritional condition were then related to the arable weed seed predation of this granivorous carabid beetle.
- Activity density of H. affinis was 3.5‐fold higher in organically compared with conventionally managed fields, if these were primarily surrounded by conventional fields. Body size was larger in fields surrounded by large proportions of organically managed land, independent of local management. The nutritional condition of beetles was unaffected by local or landscape scale farming. Per capita seed predation significantly increased with body size, whereas nutritional condition had no effect.
- The results of the present study suggest that organic farming at local and landscape scales enhances the potential of species to control arable weeds by increasing activity densities and intraspecific body size. Seed predation therefore not only depends on local and landscape effects on the community composition of local guilds of granivores, but also on the contribution of individual species to this important ecosystem service.
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J. J. Petersen 《Journal of nematology》1975,7(3):207-210
The susceptibility of 18 species of mosquitoes to the infective stage of the mermithid nematode Reesimermis nielseni was compared to that of Culex pipiens quinquefasciatus. Thirteen species were more susceptible, with three Anopheles species and Culiseta inornata the most susceptible. Aedes triseriatus, Culex territans, and Psorophora ferox were highly resistant. Resistance to R. nielseni appeared to be behavioral, physical, or physiological, and some host species exhibited one or more types of defense mechanisms. No noticeable differences were apparent in the degree of susceptibility of a native-and a laboratory strain of C. p. quinquqfasciatus to R. nielseni. 相似文献
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D. J. Warner L. J. Allen‐Williams S. Warrington A. W. Ferguson I. H. Williams 《Agricultural and Forest Entomology》2008,10(4):375-387
1 The spatio‐temporal distributions of predatory carabid beetles (Coleoptera: Carabidae) and their potential prey, the larvae of three coleopterous pests, Meligethes aeneus (Fabricius) and Ceutorhynchus spp. [Ceutorhynchus pallidactylus (Marsham), the cabbage stem weevil, and Ceutorhynchus assimilis (Paykull), the cabbage seed weevil], were studied within a crop of winter oilseed rape. The distributions of Collembola were recorded as potential alternative prey. Insect distributions were analysed and compared using Spatial Analysis by Distance Indices. 2 Mature larvae of the pests dropped from the crop canopy to the soil for pupation in temporal succession from May to early July. Their distributions within the crop were irregular and differed with species. 3 Adults of seven species or genera of carabid were abundant and active within the crop during May and June: Nebria brevicollis (Fabricius), Anchomenus dorsalis (Pontoppidan), Loricera pilicornis (Fabricius), Amara similata (Gyllenhal), Asaphidion spp., Pterostichus madidus (Fabricius) and Pterostichus melanarius (Illiger). 4 During May, N. brevicollis was spatially associated with peak numbers of M. aeneus larvae and with Collembola. Anchomenus dorsalis was spatially associated with Ceutorhynchus spp. larvae during two peaks in the abundance of the latter in early and late June. Nebria brevicollis and A. dorsalis coincided in both time and space with larvae of the three coleopterous pests when they were most vulnerable to predation by epigeal predators and are therefore good candidates for conservation biocontrol. 5 The importance of carabid beeetles in the natural enemy complex in winter oilseed rape and their potential for biocontrol of spring and summer pests are discussed in relation to husbandry practices for the crop and its adjacent areas which could be manipulated to promote carabid survival for integrated pest management. 相似文献
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A. Harbi F. Beitia B. Chermiti L. de Pedro F. Ferrara J. D. Asís C. Polidori J. Tormos B. Sabater‐Muñoz 《Journal of Applied Entomology》2018,142(8):755-764
The larval–pupal endoparasitoid Diachasmimorpha longicaudata (Hymenoptera: Braconidae) is currently the most commonly employed biological control agent against Tephritid fruit flies in the Americas. However, this parasitoid remains largely ignored and is not used in many regions, including the Mediterranean Basin. In this study, the potential of D. longicaudata as a biocontrol agent against the Mediterranean fruit fly (medfly) Ceratitis capitata (Diptera: Tephritidae) was addressed in an area of eastern Spain (the Valencian community). The parasitic activity of parasitoids and the effects of climatic conditions were evaluated throughout a 1‐year period in field‐cage experiments in which parasitoids were confined with apples artificially infested with medfly larvae. The following parameters were calculated and related statistically to several environmental conditions: the parasitism rate, the induced mortality and progeny sex ratio. The results show that D. longicaudata is able to parasitize medfly larvae throughout the year under semi‐natural conditions. Important fluctuations in the parasitism rate (from almost zero to 42%) and the induced mortality (from 6% to 80%) were partially influenced by climatic conditions. The parasitism rate increased with mean temperature and decreased with mean relative humidity, while the induced mortality decreased with minimum relative humidity. The optimal climatic conditions for the activity of the parasitoid were a mean temperature of 16–24°C combined with a relative humidity of 45%–60%. Overall, these results suggest that reduction in the medfly population due to D. longicaudata activity is feasible and provide information about the optimal time period for parasitoid release in the field. In conclusion, D. longicaudata has a significant potential to control C. capitata in the Mediterranean region. 相似文献
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DAVID KLEIJN HANS SCHEKKERMAN WIM J. DIMMERS RUUD J. M. VAN KATS DICK MELMAN WOLF A. TEUNISSEN 《Ibis》2010,152(3):475-486
Agricultural intensification is one of the main drivers of farmland bird declines, but effects on birds may be confounded with those of climate change. Here we examine the effects of intensification and climate change on a grassland breeding wader, the Black‐tailed Godwit Limosa l. limosa, in the Netherlands. Population decline has been linked to poor chick survival which, in turn, has been linked to available foraging habitat. Foraging habitat of the nidifugous chicks consists of uncut grasslands that provide cover and arthropod prey. Conservation measures such as agri‐environment schemes aim to increase the availability of chick foraging habitat but have not yet been successful in halting the decline. Field observations show that since the early 1980s, farmers advanced their first seasonal mowing or grazing date by 15 days, whereas Godwits did not advance their hatching date. Ringing data indicate that between 1945 and 1975 hatching dates advanced by about 2 weeks in parallel with the advancement of median mowing dates. Surprisingly, temperature sums at median mowing and hatching dates suggest that while the agricultural advancement before 1980 was largely due to agricultural intensification, after 1980 it was largely due to climate change. Examining arthropod abundance in a range of differently managed grasslands revealed that chick food abundance was little affected but that food accessibility in intensively used tall swards may be problematic for chicks. Our results suggest that, compared with 25 years ago, nowadays (1) a much higher proportion of clutches and chicks are exposed to agricultural activities, (2) there is little foraging habitat left when chicks hatch and (3) because of climate change, the vegetation in the remaining foraging habitat is taller and denser and therefore of lower quality. This indicates that for agri‐environment schemes to make a difference, they should not only be implemented in a larger percentage of the breeding area than the current maxima of 20–30% but they should also include measures that create more open, accessible swards. 相似文献
15.
The major physiological theories of the control of the flowering process are first presented and their inferences tested in the long-day plant Sinapis alba. Then, the genetic analyses of the control of flowering time in Arabidopsis thaliana are also summarized with a brief overview of the several pathways, each including several genes, identified. Clearly, both the experimental data of physiological experiments and the multiplicity of interacting genetic pathways best support the theory of the multifactorial control of flowering. This is further shown by the fact that a critical gene expressed in the shoot meristem at floral transition in S. alba, MADS A (orthologous to A. thaliana SOC1), can be upregulated by a single dose of a cytokinin or a gibberellin, without leading to flowering. This indicates that the floral shift requires upregulation of other genes by other factors. 相似文献
16.
Gabriella J. Kietzka James S. Pryke Michael J. Samways 《Insect Conservation and Diversity》2015,8(3):229-237
- Ecological networks (ENs) are able to mitigate the negative effects of commercial forestry on terrestrial biodiversity, yet this remains untested for the aquatic fauna. Understanding the anthropogenic and natural variables that drive dragonfly diversity at the landscape and habitat scales, allows the design and implementation of ENs that minimise biodiversity loss across production landscapes.
- Here, we determine the relative contribution of anthropogenic disturbances and natural environmental variables to dragonfly assemblages within ENs. Sixty sites, of various freshwater body types, were sampled for adult dragonflies across ENs in a commercial forestry landscape.
- Overall, species richness was significantly influenced by river width, water turbidity, water depth and the presence of invasive plants. Nevertheless, overall species composition was influenced by water body type, flow rate and substrate type. Further differences were found when analyses were conducted separately for Anisoptera and Zygoptera.
- Counter‐intuitively, anthropogenic disturbances had less effect on dragonfly species richness and composition than did natural environmental variables, emphasising the importance of conserving natural heterogeneity. Overall, dragonfly diversity can be successfully conserved in ENs provided that conservation planning incorporates appropriate local scale variables. These results also suggest that impacts on water quality and dragonfly diversity are minimised by well‐designed ENs within this production landscape.
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Ceci LR Volpicella M Rahbé Y Gallerani R Beekwilder J Jongsma MA 《The Plant journal : for cell and molecular biology》2003,33(3):557-566
The mustard trypsin inhibitor, MTI-2, is a potent inhibitor of trypsin with no activity towards chymotrypsin. MTI-2 is toxic for lepidopteran insects, but has low activity against aphids. In an attempt to improve the activity of the inhibitor towards aphids, a library of inhibitor variants was constructed and cloned into the pRlac3 phagemid vector. The library of 9.3 x 107 independent colonies was created by randomisation of a stretch of five consecutive codons in the reactive site. Repeated selection rounds against bovine trypsin and chymotrypsin allowed the identification of novel, MTI-2 derived, antitrypsin and antichymotrypsin inhibitors. Chy8, the selected variant with highest affinity for bovine chymotrypsin (Ki = 32 nm versus >1000 nm for the wild-type) represents the strongest known recombinant chymotrypsin inhibitor of the MTI-2 family. It is highly toxic to nymphs of the aphid Acyrthosiphon pisum, and moderately toxic to nymphs of Aphis gossypii and Myzus persicae. The LC50 of 73 microg ml-1 towards A. pisum is the lowest value known among chymotrypsin inhibitors. The aphicidal activity of Chy8 was improved eightfold compared to the wild-type inhibitor. This demonstrates, for the first time, that bovine chymotrypsin provides a useful template to select engineered proteins highly toxic against these aphids. The selected gene will allow the development of transgenic crops that are protected against sucking insect pests. 相似文献
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M. K. Agbodzavu Z. O. Lagat M. Gikungu I. Rwomushana S. Ekesi K. K. M. Fiaboe 《Journal of Applied Entomology》2018,142(7):646-653
Cotesia icipe Fernandez‐Triana & Fiaboe is a solitary koinobiont larval endoparasitoid, recently discovered in Kenya and new to science, that parasitizes select lepidopteran herbivores of amaranth. We investigated its host range on five commonly encountered amaranth lepidopteran defoliators. Cotesia icipe accepted, successfully and aggressively parasitized the amaranth noctuid defoliators Spodoptera littoralis (Boisduval) and Spodoptera exigua (Hübner), but failed to parasitize Herpetogramma bipunctalis (F.), Spoladea recurvalis (F.) and Udea ferrugalis (Hübner) all in Crambidae family. On S. littoralis, C. icipe was highly efficient, with 95% of females successfully ovipositing during 2 hr of exposure. Parasitism rate and larval and pupal non‐reproductive mortalities were significantly higher at higher parasitoid density. A single female of C. icipe parasitized 42.99 ± 2.66% of the 50 exposed larvae for oviposition in 24 hr, whereas a cohort of five females of C. icipe conferred 85.59 ± 1.46% parasitism rate. The efficiency ratio per female was much higher in single releases than in cohort releases while a balanced sex ratio was obtained in F1 offspring regardless of the density of female released. The potential use of C. icipe for conservation and augmentative biological control of S. littoralis in amaranth as well as its potential use against other Noctuid moths and in other commodities is discussed. 相似文献