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1.
1 Short-snouted weevils, including Strophosoma spp. and related species, may damage tree seedlings. We investigated the damage caused by these weevils feeding on seedlings of seven tree species planted in clear-cuts and under shelterwoods with three densities (control, dense, and sparse).
2 There were no pronounced differences in damage caused by short-snouted weevils in the various shelterwood densities. Most feeding occurred in the clear-cuts during the first year, whereas more seedlings were damaged in the shelterwoods of all densities in the second year. In the third year, virtually no feeding occurred in either the clear-cuts or shelterwoods. We cannot explain this pattern of damage, but a fallow period of 2 years seems to prevent short-snouted weevil damage.
3 We determined the general feeding preferences for short-snouted weevils to be cherry, lime > beech, oak, spruce > maple, ash. However, although Strophosoma mellanogrammum [Correction added after online publication 8 December 2008: Strophosoma melanogrammum corrected to Strophosoma mellanogrammum ] was observed feeding on seedlings, no full short-snouted weevil inventory was conducted, so caution must be exercised when drawing conclusions from this study regarding weevil damage patterns and feeding preferences.
4 Short-snouted weevils can sometimes occur in large numbers and may destroy entire reforestation projects, but in our study their influence on seedling growth and survival was minor. 相似文献
2 There were no pronounced differences in damage caused by short-snouted weevils in the various shelterwood densities. Most feeding occurred in the clear-cuts during the first year, whereas more seedlings were damaged in the shelterwoods of all densities in the second year. In the third year, virtually no feeding occurred in either the clear-cuts or shelterwoods. We cannot explain this pattern of damage, but a fallow period of 2 years seems to prevent short-snouted weevil damage.
3 We determined the general feeding preferences for short-snouted weevils to be cherry, lime > beech, oak, spruce > maple, ash. However, although Strophosoma mellanogrammum [Correction added after online publication 8 December 2008: Strophosoma melanogrammum corrected to Strophosoma mellanogrammum ] was observed feeding on seedlings, no full short-snouted weevil inventory was conducted, so caution must be exercised when drawing conclusions from this study regarding weevil damage patterns and feeding preferences.
4 Short-snouted weevils can sometimes occur in large numbers and may destroy entire reforestation projects, but in our study their influence on seedling growth and survival was minor. 相似文献
2.
Previously, the combination of reduced rate of entomopathogenic nematodes (EPN) and fungus caused additive or synergistic mortality to third-instar black vine weevil (BVW), Otiorhynchus sulcatus. In this study, we examined this interaction in unheated glasshouses during winter and compared a combination of commercial formulation of a cold-tolerant EPN, S. kraussei (Nemasys L?) and fungus Metarhizium anisopliae strain V275 against overwintering third-instar BVW. The combination of M. anisopliae with S. kraussei at a rate of 1×1010 conidia+250,000 nematodes/growbag resulted in additive or synergistic effects, providing 100% control of overwintering larvae. 相似文献
3.
J. W. A. Scheepmaker F. P. Geels P. H. Smits L. J. L. D. Van Griensven 《Entomologia Experimentalis et Applicata》1997,83(3):323-327
Experiments were conducted to examine the location of oviposition by the phorid fly Megaselia halterata (Wood) (Diptera: Phoridae) in uncased and cased compost. Clearly, a majority of the gravid females choose oviposition sites directly after entering the top layer of the compost. In uncased compost, 60% of all adults emerged from the top of four compost layers of equal thickness. When the compost was covered by a casing layer which was still uncolonized by Agaricus bisporus, oviposition was further concentrated in the top compost layer. In this situation, 91% of all adults emerged from the top compost layer whereas only 1.5% emerged from the casing. When the casing layer was colonized by mushroom mycelium, 45% of all adults emerged from the casing layer and 53% emerged from the top compost layer. Further concentration in the top compost layer and the casing layer occurred as a result of upward migration of larvae. When compost was cased after oviposition, up to 43% of all adults emerged from the casing layer. We concluded that in the control of phorid infestations with insect pathogenic nematodes, applications in uncased compost can be restricted to the upper compost layer. When compost and casing are filled simultaneously, nematode applications in the casing layer only could be considered. 相似文献
4.
- 1 Entomopathogenic nematodes are commercially available for inundative biological control of many insects, including the black vine weevil Otiorhynchus sulcatus (F.) (Coleoptera: Curculionidae). Currently, there is a lack of commercial application tests in field‐grown crops comparing the efficacy of different species of entomopathogenic nematodes.
- 2 Field trials were carried out under different growing conditions in Ireland and Norway to evaluate the efficacy of two commercially available nematode species on the market for control of the black vine weevil Heterorhabditis megidis and Steinernema kraussei.
- 3 Heterorhabditis megidis was evaluated not only at temperatures ideal for this species (soil temperatures above 10 °C), but also in the low temperature trials with S. kraussei as a ‘positive control’. Steinernema kraussei is sold as a cold active product and was therefore evaluated at low soil temperatures (below 10 °C).
- 4 The overall results indicated that H. megidis was effective as long as temperatures were optimum (not dropping below 10 °C). For S. kraussei, the results obtained were rather disappointing, where control barely reached 50% in the trial with the coldest temperature. Temperature and soil type appeared to be a major limiting factor for the efficacy of both nematode species.
- 5 On the basis of the results and experience obtained in these trials, the future implications for biological control of O. sulcatus with entomopathogenic nematodes in commercial field‐grown strawberry production are discussed.
5.
- Top‐down population regulation can influence the success of biological control agents when they are released into the field. Entomopathogenic nematodes (EPNs) are used commonly in biological control programmes, but their efficacy suffers from poor persistence. Although abiotic soil conditions have been shown to reduce EPN persistence, consumption of infected insects by scavengers and of infective juvenile (IJ) nematodes by predators may also regulate these populations. In the present study, the effects of different soil arthropods on EPNs in laboratory conditions were measured. It was hypothesised that arthropods commonly found in soil communities where EPNs are applied would consume cadavers of insects parasitised by the nematodes and the IJs themselves.
- Some species of scavengers consume EPN‐infected insects. Crickets (Gryllus bimaculatus De Geer), American cockroaches [Periplaneta Americana (Linnaeus)], ants [Tetramorium chefketi Forel and Pheidole pallidula (Nylander)], earwigs (Labidura riparia Pallas), mites (Sancassania polyphyllae Zachvatkin), and springtails (Sinella curviseta Brook and Folsomia candida Willem) have different responses to nematode‐killed insects. Results suggested that ants (T. chefketi), cockroaches, mites, and earwigs fed on Steinernema‐killed insects whereas neither crickets nor springtails consumed them.
- In the second part of the study, experiments were conducted to determine whether mites and springtails consumed IJ EPNs. Results showed that S. polyphyllae mites do not consume infective juveniles in soil, whereas both springtail species consumed significant numbers of the IJs.
- Top‐down regulatory processes can be a limiting factor for EPN populations under laboratory conditions. Both host cadavers and IJs are consumed (albeit by different arthropods), so these results may help explain the difficulties associated with the persistence of EPN application to soil.
6.
Plum sawflies are among the most damaging pests of European plum. Current control strategy implies insecticide application. Three species of entomopathogenic nematodes (EPN), Steinernema feltiae Filipjev, S. carpocapsae Weiser and Heterorhabditis bacteriophora Poinar were tested under laboratory and field conditions to assess effectiveness against larval and adult stages. Laboratory tests resulted in up to 100% mortality of last instar larvae before construction of a cocoon. However, the nematodes were not able to penetrate the cocoon. Foliar application did not result in plum sawflies larvae infestation by EPNs. Under field conditions, the nematodes reduced the number of emerging adults by application against sawfly larvae in the previous year before migration into the soil for overwintering by 62%–92%. Application of the nematodes against adults just before their anticipated emergence resulted in reduction of fruit infestation up to 100%. Mean results of 5 trials using caged trees were 47.8% with S. feltiae, 56.3% with S. carpocapsae and 62.9% with H. bacteriophora. In open field trails, control of adults obtained with S. feltiae at 0.5 million nematodes/m2 was 98.2 and 67.8% and at 0.25 million m−2 41.7 and 41.2%. Forecasting adult emergence and optimal soil moisture conditions are essential for success of the nematode application. 相似文献
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Héctor A. Cárcamo Carolyn E. Herle Jennifer Otani Sean M. McGinn 《Entomologia Experimentalis et Applicata》2009,133(3):223-231
The cabbage seedpod weevil, Ceutorhynchus obstrictus (Marsham) (Coleoptera: Curculionidae), is a serious pest of brassicaceous crops in temperate regions and a chronic member of the pest complex that attacks canola in Canada. We conducted several laboratory and field experiments to quantify winter survival and its role in the population dynamics of this insect. We estimated the supercooling point of the weevil at ?7 °C and its survival over 8 weeks decreased significantly at ?5 °C relative to 5 °C, but extending the overwintering period at 5 °C to 18.5 weeks had no effect on mortality. Cumulative sub‐freezing degrees estimated from air temperature, and especially from soil temperature, were highly correlated with weevil survival. Our linear regression model predicted poor survival of the weevils in typical winters in northern Alberta. Our results indicate that if milder winters prevail, as predicted by global warming, there is potential for the weevils to establish and become a serious pest in northern canola‐growing regions of Canada. 相似文献
8.
Inge Armbrecht & Maria Cristina Gallego 《Entomologia Experimentalis et Applicata》2007,124(3):261-267
Soil‐dwelling ants, many of which are generalist predators, are more diverse in shaded than in sun coffee plantations without trees. We compared ant predation on the coffee berry borer, Hypothenemus hampei (Ferrari) (Coleoptera: Curculionidae: Scolytinae) in three shaded and three sun coffee plantations in Apía, Colombia, in both the wet and the dry seasons. We found that H. hampei adults exposed to ants for 5 days suffered higher removal in shaded plantations and in the wet season. In the laboratory, we observed that ants killed 74–99% of H. hampei adults over the course of 5 days. Ants appear to be important predators of H. hampei, particularly in shaded coffee plantations and in the wet season. 相似文献
9.
Norikuni Kumano Futoshi Kawamura Dai Haraguchi & Tsuguo Kohama 《Entomologia Experimentalis et Applicata》2009,130(1):63-72
The effect of irradiation on the dispersal ability of males and females of the flightless West Indian sweetpotato weevil, Euscepes postfasciatus (Fairmaire) (Coleoptera: Curculionidae), a major sweet potato pest, was examined in the field using mark–release–recapture techniques. To evaluate the dispersal ability of the weevil, we released 7 619 weevils in two replicates (July and August 2007). Each replicate lasted 5 days from release to sampling and consisted of one weevil release and two weevil samplings. Thirty-two traps were placed in lines corresponding to eight compass directions and in four distance classes (8, 12, 16, and 20 m) in each replicate. We captured 709 (9.3%) weevils in the two replicates. Weevils dispersed at least 20 m from the release point in 2 days, regardless of sex or irradiation. Dispersal was strongly affected by wind direction, and in both replicates most weevils were recaptured in upwind directions. The mean dispersal distance for non-irradiated weevils was about 11 m per 2 days. Although there were some differences between sexes in recapture rate and dispersal distance, there was no consistent difference between irradiated and non-irradiated weevils in dispersal distance. We conclude that irradiation does not affect the dispersal ability of flightless E. postfasciatus in the field. 相似文献
10.
The parasitoid Microctonus hyperodae Loan (Hymenoptera: Braconidae) was introduced into New Zealand to control the weevil Listronotus bonariensis (Kuschel) (Coleoptera: Curculionidae), a major pest of graminaceous plants. Four experiments were conducted to investigate the effects of various pesticides that are commonly used in the pastoral environments of L. bonariensis and M. hyperodae. Topical applications of aqueous solutions prepared from commercial formulations of five herbicides were not toxic, but the surfactant Silwett L‐77 increased M. hyperodae mortality relative to the water‐treated controls. Laboratory assays showed that M. hyperodae adults were susceptible to chlorpyrifos residues on pasture foliage following application of the insecticide to field plots at ≥5 g a.i. ha?1. Maintenance of L. bonariensis on ryegrass in the laboratory showed that treatment of the food plants with chlorpyrifos at ≥96 g a.i. ha?1 reduced L. bonariensis survivorship and ultimately reduced M. hyperodae prepupal emergence from those hosts. Initially, mortalities of non‐parasitized L. bonariensis were significantly greater than for parasitized L. bonariensis. Maintenance of parasitized L. bonariensis on diflubenzuron‐treated ryegrass plants arrested M. hyperodae larval development in the host and ultimately reduced prepupal emergence of M. hyperodae from those hosts. Despite the arrested development of M. hyperodae, the mortality of L. bonariensis hosts was increased. Adult M. hyperodae successfully reared from hosts maintained on diflubenzuron (12.5 g a.i. ha?1) treated food plants had reduced reproductive potential. The consequences of pasture management strategies that employ pesticides are discussed in relation to biocontrol of L. bonariensis by M. hyperodae. 相似文献
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Mark A. Boetel Ayanava Majumdar Stefan T. Jaronski Richard D. Horsley 《Biocontrol Science and Technology》2012,22(11):1284-1304
The sugarbeet root maggot, Tetanops myopaeformis (Röder), is a major North American pest of sugarbeet, Beta vulgaris L. Previous research suggests that moderate T. myopaeformis control is possible with the entomopathogen Metarhizium anisopliae (Metch.) Sorok. We conducted a three-year (2002–2004) experiment to assess impacts of oat, Avena sativa L. and rye, Secale cereale L., cover crops on persistence of corn grit-based granular or spray formulations of M. anisopliae isolate ATCC 62176 (i.e. MA 1200) applied at 8×1012 viable conidia/ha in sugarbeet. More colony forming units (CFUs) were detected immediately after application [0 days after treatment (DAT)] in spray plots than granule-treated plots. However, 76–92% declines in CFUs per gram of soil occurred in spray plots within 30 DAT. Substantially (i.e. 83–560%) more rainfall occurred in June 2002 than during June of any other year. Subsequently, 71–670% increases in CFU concentrations occurred by 60 DAT in M. anisopliae granule-treated plots with oat or rye cover crops that year. CFU density increases were higher in cover crops in 2002, but no significant cover crop effects were detected. Conidia persisted for up to 30 DAT in M. anisopliae spray plots and 60 DAT in granule-treated plots in 2002; however, no increases occurred in the years with less June rainfall. Trends suggest that M. anisopliae aqueous sprays result in greater conidia concentrations than granules at sugarbeet plant bases in June during T. myopaeformis oviposition and larval establishment on host plants. Increases are possible when delivering conidia via granules, but high post-application rainfall could be necessary for conidia production. 相似文献
14.
Juliana Jaramillo Christian Borgemeister & Mamoudou Setamou 《Entomologia Experimentalis et Applicata》2006,119(3):231-237
Superparasitism by Phymastichus coffea LaSalle (Hymenoptera: Eulophidae), a parasitoid of adults of the coffee berry borer, Hypothenemus hampei (Ferrari) (Coleoptera: Curculionidae: Scolytinae), was recorded under field conditions in a coffee plantation in Colombia. Parasitoid adults were released 1, 5, and 9 days after artificial infestations of 90‐, 150‐, and 210‐day‐old coffee berries with H. hampei females. The position of the beetle inside the berry and the number of P. coffea larvae per female host were assessed 10 days after each parasitoid release. Under laboratory conditions, P. coffea usually lays two eggs per host, one female and one male. In our studies, we often recorded more than six P. coffea larvae in an individual host and mean numbers of larvae per host ranged from two to 4.45. Superparasitism by P. coffea under field conditions was influenced by the age of the coffee berries, which is the most important factor determining the speed of penetration by H. hampei, and therefore the time the beetles are exposed to a P. coffea attack. The number of parasitoid larvae in each H. hampei female gradually decreased with the age of the berry, and also linearly decreased with the time of parasitoid release. Age‐dependent effects of coffee berries that alter the ratio of available hosts to searching parasitoids by providing refuges to the herbivore, largely determine the extent of superparasitism of H. hampei by P. coffea under fields conditions in Colombia. 相似文献
15.
Pilar Morera‐Margarit Davide Bulgarelli Tom W. Pope Robert I. Graham Carolyn Mitchell Alison J. Karley 《Entomologia Experimentalis et Applicata》2019,167(3):186-196
Otiorhynchus sulcatus (Fabricius) (Coleoptera: Curculionidae), commonly known as black vine weevil or simply vine weevil, is an important pest of soft fruit and ornamental crops. This species is endemic to temperate areas of Europe but has spread to many other areas over the last century, including North America and Australasia. The ability of vine weevils to adapt to such different environments is difficult to reconcile with the parthenogenetic reproduction strategy, which is likely to underpin a low genetic diversity. It is therefore tempting to hypothesize that weevil adaptation to different environments is mediated, at least partly, by the microbial communities inhabiting these insects. As a first step towards testing this hypothesis we characterized the composition of the bacterial microbiota in weevils from populations feeding on strawberry plants across four geographically separate locations in the UK. We performed 16S rRNA gene Illumina amplicon sequencing, generating 2 882 853 high‐quality reads. Ecological indices, namely Chao1 and Shannon, revealed that the populations used for this study harboured a low diversity and an uneven bacterial microbiota. Furthermore, β‐diversity analysis failed to identify a clear association between microbiota composition and location. Notably, a single operational taxonomic unit phylogenetically related to Candidatus Nardonella accounted for 81% of the total sequencing reads for all tested insects. Our results indicate that vine weevil bacterial microbiota resembles that of other insects as it has low diversity and it is dominated by few taxa. A prediction of this observation is that location per se may not be a determinant of the microbiota inhabiting weevil populations. Rather, other or additional selective pressures, such as the plant species used as a food source, ultimately shape the weevil bacterial microbiota. Our results will serve as a reference framework to investigate other or additional hypotheses aimed at elucidating vine weevil adaptation to its environment. 相似文献
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Thomas Bawin Fawrou Seye Slimane Boukraa Jean-Yves Zimmer Fara Nantenaina Raharimalala Quentin Zune 《Biocontrol Science and Technology》2016,26(5):617-629
The spore productivity and insecticidal activity of two opportunistic insect pathogenic Aspergillus species (namely: Aspergillus clavatus Desmazieres and Aspergillus flavus Link (Ascomycota: Eurotiales, Trichocomaceae)) were compared to Metarhizium anisopliae sensu lato (Metchnikoff) Sorokin (Ascomycota: Hypocreales, Clavicipitaceae) for mosquito (Diptera: Culicidae) control. The production of aerial spores on wheat bran and white rice was investigated in solid-, semi-solid-, and liquid-state media supplemented with a nutritive solution. Wheat bran-based media increased the spore yield in solid-state from three to sevenfold: A. clavatus produced 48.4?±?5.2 and 15.7?±?1.6?×?108 spores/g, A. flavus produced 22.3?±?4.1 and 3.1?±?2.5?×?108 spores/g, and M. anisopliae produced 39.6?±?6.5 and 13.1?±?2.6?×?108 spores/g of wheat bran or white rice, respectively. A. clavatus, A. flavus and M. anisopliae spores harvested from wheat bran-based solid-state media showed lethal concentrations (LC50) of 1.1, 1.8, and 1.3?×?108 spores/ml against Culex quinquefasciatus Say larvae in 72?h. Because A. clavatus and M. anisopliae displayed similar features when cultured under these conditions, our results suggest that insect pathogenic Aspergillus species may be as productive and virulent against mosquito larvae as a well-recognised entomopathogenic fungus. 相似文献
17.
Abstract
- 1 Natural control of apple blossom weevil, Anthonomus pomorum (L.), deserves attention, as the pest is regaining importance with the declining use of non‐selective pesticides in apple and pear orchards. In this study the biology of Centistes delusorius (Förster), a specific parasitoid of adult apple blossom weevil, is investigated.
- 2 The parasitoid hibernates as young larva in an adult weevil, and juvenile development is resumed in early spring. The fully grown parasitoid larvae leave their hosts during full bloom at the end of April and early May, to pupate. The adults emerging in May oviposit into the newly emerged weevils, which initially feed on apple leaves.
- 3 Centistes delusorius was detected in six out of 15 host‐weevil infested orchards, but was only common in two with larger apple trees standing in grass. There, parasitism levels of around 30% were usual in hosts taken from treebands in winter.
- 4 The delicate larva is vulnerable, and the thin cocoon provides little protection against either desiccation or drowning on a weedless orchard floor. Observations indicate that successful pupation of C. delusorius demands stable humid conditions and some shelter, such as that found in grass or woodland soils.
- 5 Parasitoid females, provided with honey, lived for a mean of 6.3 ± 2.1 days under outdoor conditions in June. Their life span was similar whether they had access to and oviposited in hosts, or not. The species is pro‐ovigenic, and potential fecundity is about 40 eggs. Oviposition usually takes a few seconds. Parasitized female hosts do not reproduce.
- 6 Up to 95% of the parasitoid eggs laid in May develop into a second generation, the adults of which appear in July, when the host has entered aestivation. Older (British) records of C. delusorius outside orchards suggest that some parasitized hosts, like the healthy ones, leave the orchard prior to aestivo‐hibernation, so that the latter do not escape parasitoid attack in July.
- 7 A trapping sample in late June, when most non‐parasitized weevils have gone into aestivo‐hibernation, is probably the most efficient method to detect parasitized weevils.
- 8 The (near‐)absence of C. delusorius in many orchards is probably due not only to pesticide side‐effects, or scarcity of its host, but also to the absence of suitable pupation sites for the wasp.
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Plants and herbivorous insects can each be dramatically affected by temperature. Climate warming may impact plant invasion success directly but also indirectly through changes in their natural enemies. To date, however, there are no tests of how climate warming shifts the interactions among invasive plants and their natural enemies to affect invasion success. Field surveys covering the full latitudinal range of invasive Alternanthera philoxeroides in China showed that a beetle introduced for biocontrol was rare or absent at higher latitudes. In contrast, plant cover and mass increased with latitude. In a 2‐year field experiment near the northern limit of beetle distribution, we found the beetle sustained populations across years under elevated temperature, dramatically decreasing A. philoxeroides growth, but it failed to overwinter in ambient temperature. Together, these results suggest that warming will allow the natural enemy to expand its range, potentially benefiting biocontrol in regions that are currently too cold for the natural enemy. However, the invader may also expand its range further north in response to warming. In such cases where plants tolerate cold better than their natural enemies, the geographical gap between plant and herbivorous insect ranges may not disappear but will shift to higher latitudes, leading to a new zone of enemy release. Therefore, warming will not only affect plant invasions directly but also drive either enemy release or increase that will result in contrasting effects on invasive plants. The findings are also critical for future management of invasive species under climate change. 相似文献
20.
病原线虫对桔小实蝇种群的控制作用 总被引：15，自引：2，他引：15
通过室内和田间实验研究了昆虫病原线虫对桔小实蝇Bactrocera (Bactrocera) dorsalis (Hendel)的控制作用。室内实验结果表明,供试的3种线虫的4个品系（小卷蛾斯氏线虫Steinernema carpocapsae All品系与A24品系,夜蛾斯氏线虫Steinernema feltiae SN品系和嗜菌异小杆线虫Heterorhabditis bacteriophora H06品系）,以小卷蛾斯氏线虫All品系对桔小实蝇的侵染力最强,其3天的LD50和LD95分别为35.0和257.1条/cm2土壤。按300条/cm2土壤的量施用,小卷蛾斯氏线虫All品系对当代桔小实蝇的控制效果为86.3%。用以虫期作用因子组建的生命表方法评价了小卷蛾斯氏线虫All品系对田间桔小实蝇下代种群的控制作用,结果表明,按300条/cm2土壤的量施用线虫,对照杨桃园的桔小实蝇种群趋势指数为105.9,而处理杨桃园的桔小实蝇种群趋势指数下降为15.5;小卷蛾斯氏线虫All品系对桔小实蝇的干扰控制指数为0.146,即线虫处理果园的下代种群密度仅为对照果园的14.6%。 相似文献