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1.
Lepidopteran stemborers are considered as the most important insect pests of cereal crops in Sub-Saharan Africa. However, limited information exists on stemborers and their parasitoids in the rain forest of the DR Congo. In order to enhance the understanding of the pest ecology, sampling in both cultivated and wild habitats has been recommended as a bottom line to any action aiming at the design of pest management measures. Following this recommendation, a survey was carried out in the rain forest of the DR Congo on maize and wild host plants. We collected eighteen stemborer and one earborer species belonging to 5 families. Five species were found feeding on maize while 18 species fed on wild host plants. Busseola fusca was the commonest species feeding on maize which accounted for 50.1%. At least 20 parasitoids species distributed as 15 species on maize and 16 species in the wild habitats were recovered during this study. Cotesia sesamiae, Enicospilus ruscus and Sturmiopsis parasitica accounted for 99.8% of interactions within parasitoid community. Out of nineteen wild host plants encountered, Pennisetum purpureum and Vossia cuspidata were the most speciose grasses in terms of both parasitoids and stemborers. The implications of such diversity and network structure are discussed.  相似文献   

2.
Samples taken from a ryegrass variety trial at the Grassland Research Institute, Hurley, and examined at the Welsh Plant Breeding Station, showed that the dominant stem borer species in the overwintering generation were Geomyza tripunctata Fall. and Oscinella frit L. The rate of parasitisation of stem borers, largely by species of Hymenoptera, ranged from 15 to 43%. There were differences in host plant selection by Geomyza compared with Oscinella spp. The numbers of both stem borer groups were significantly associated with the total number of tillers per sample; however, this relationship was found to differ markedly between varieties.  相似文献   

3.
The species of the genus Yponomeuta Latreille (Lepidoptera: Yponomeutidae) are known as ermine moths and can be found on various host plant species, sometimes appearing as pests. They are attacked by a wide range of parasitoids. We studied parasitoid complexes of several communities in Austria, Poland, Serbia, Slovenia and Sweden during 2014–2018. From four species, Yponomeuta cagnagella (Hübner), Yponomeuta evonymella (Linnaeus), Yponomeuta malinellus Zeller and Yponomeuta padella (Linnaeus), we reared 15 parasitoid species of seven hymenopteran and one dipteran family. In this study, the family Ichneumonidae is the most numerous, while Ageniaspis fuscicollis (Dalman) (Hymenoptera: Encyrtidae) was found in all four Yponomeuta species. Within reared parasitoids, A. fuscicollis is new record for Slovenia and Austria, Baryscapus evonymellae (Bouché) (Hymenoptera: Eulophidae) and Diadegma armillatum (Gravenhorst) (Hymenoptera: Ichneumonidae) are new records for Slovenia and Agrypon canaliculatum (Ratzeburg) (Hymenoptera: Ichneumonidae), Dolichogenidea dilecta (Haliday) (Hymenoptera: Braconidae), Elasmus steffani Viggiani (Hymenoptera: Eulophidae), Herpestomus brunnicornis (Gravenhorst) (Hymenoptera: Ichneumonidae), Trieces tricarinatus (Holmgren) (Hymenoptera: Ichneumonidae) and Mesochorus nuncupator (Panzer) (Hymenoptera: Ichneumonidae) are new records for Serbia. Also, Yponomeuta cagnagella is a new host record for Pteromalus semotus (Walker) (Hymenoptera: Pteromalidae) and Y. padella for E. steffani. Finally, we reviewed parasitoids of European Yponomeuta species and their associated host plants. In total 154 species are recorded from nine hymenopteran and one dipteran family.  相似文献   

4.
In general, it is difficult to evaluate host resource utilization of parasitoids by examining the biomass of concealed wood borers at parasitism, because the larval tissues of parasitized hosts observed in field surveys are often almost completely consumed. This work explored a precise and convenient method for evaluating the biomass of concealed wood-boring insect pests after they are parasitized. Allometric scaling laws were used to determine mathematical relationships between larval weight and other size variables in two host insects: the emerald ash borer [EAB], Agrilus planipennis Fairmaire, and the oak long-horned beetle [OLB], Massicus raddei (Blessig). These insects are hosts of the parasitoid Sclerodermus pupariae Yang et Yao (Hymenoptera: Bethylidae). Our results showed that body weight among different instars was significantly different for both host species, with greater overlap between neighboring instars. Mean larval weight had a highly significant exponential relationship with instar number. EAB larval weight showed a highly significant power relationship to body length and width, width of the prothoracic plate, peristoma width, urogomphus length, and anteriormost width of the urogomphus. Significant power relationships were also observed between OLB larval weight and body size parameters (including body length, length of the mesothoracic spiracle, width of the prothoracic plate, distance between the main ocelli, and mandible length). These findings indicated that host biomass could be easily calculated if any one size variable could be measured at the time of parasitism. Allometric methods provide a precise means of evaluating time-specific biomass of concealed wood borers.  相似文献   

5.
Studies were conducted during the years 2001–2003 to determine the parasitoids of Aphidoidea (Homoptera) species on weeds in Ankara province. Six genera and ten species of aphid parasitoids belonging to Braconidae were determined. The tritrophic associations of plant/aphid/parasitoid were analyzed. Forty-four associations of aphidiinae wasps, host aphids and host plants new to the Mediterranean region and 71 new associations for Turkish fauna were reported. http://www.phytoparasitica.org posting July 14, 2005.  相似文献   

6.
In Africa, Helicoverpa armigera (Hübner) (Lepidoptera, Noctuidae) is a key pest of cotton and vegetable crops, particularly tomato. Alternatives to insecticides to control this pest are needed such as conservation biological control. However, knowledge on the diversity and ecology of naturally occurring enemies of H. armigera is limited. A two-year field survey was conducted in a set of tomato farmer fields in the main vegetable-growing area in Senegal (Niayes) to assess the spatial and seasonal occurrence of indigenous parasitoids of H. armigera, and to evaluate the effect of insecticide use on biological control efficiency. No parasitoid emerged from H. armigera eggs. Incidence of larval parasitoids was generally moderate (20%) but highly variable (0%–100%) among fields, independently of host abundance, and negatively affected by the number of insecticide applications. Larval parasitism was largely dominated by the larval parasitoid Meteorus laphygmarum Brues (Hymenoptera, Braconidae), but a positive correlation was found between specific richness or Shannon diversity index of the parasitoid community and parasitism rate. This study is a first step toward development of research and extension programs for conservation of natural enemies in the framework of integrated management of the tomato fruitworm in Senegal.  相似文献   

7.
Lepidopteran stem borers are the main pests of cereals in Ethiopia. In recent years, habitat management techniques, which aim at increasing plant biodiversity through mixed cropping, have gained increased attention in stem borer control. In the present study, the profitability of mixed cropping of maize with haricot beans at different ratios and the effect on infestation of maize by stem borers, yield and borer parasitism were studied in Melkassa and Mieso, Ethiopia, in a field experiment under natural infestation. In Melkassa, pest infestations were too low for the cropping system to affect pests, plant damage and yields significantly, whereas in Mieso, where the pest densities were high, intercropping of maize with beans at ratios of 1:1 to 2:1 significantly decreased borer densities compared with pure maize stands. Chilo partellus (Swinhoe) and Cotesia flavipes. (Cameron) were the major stem borer and parasitoid species, respectively, recorded both at Melkassa and Mieso. Borer parasitism was higher at Mieso than at Melkassa and tended to increase with the increase of the haricot bean ratio in the intercropping system. Land equivalent ratios of >1 indicated higher land use efficiency in mixed compared with sole cropping, even if pest densities were low.  相似文献   

8.
The South American tomato leafminer, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), is a major threat to tomato (Solanum lycopersicum L.) crops. After its first detection in Spain in 2006, it spread rapidly through the Western Palaearctic region, arriving in Tunisia 2 years later. The aim of this research was to assess whether generalist indigenous parasitoids are adapting to this exotic host in Tunisian tomato crops. For this, we conducted a survey in four Tunisian tomato-growing areas by sampling infested leaves of tomato and solanaceous weeds and exposing artificially infested sentinel plants. Two ectoparasitoid species were found attacking and developing on T. absoluta: Bracon sp. (Hymenoptera: Braconidae) and Necremnus sp. nr artynes (Hymenoptera: Eulophidae), whereas no egg or pupal parasitoids were found. The eulophid wasp was the most abundant with a peak of apparent parasitism rate of 25.5%. It emerged from parasitized T. absoluta young larvae in exposed sentinel plants and in sampled infested tomato leaves, both in greenhouse and open field cultivations. Bracon sp. showed a gregarious development on T. absoluta mature larvae and it was collected only on sentinel plants exposed in the Ragueda (Kiarouan) site, with 10.23% of estimated parasitism. Although further research is still needed to assess properly the ecological role of these parasitoids in the biological control of T. absoluta, this study represents the first step toward establishing the scientific basis for including these parasitoids in the Tunisian IPM and biological programs against this pest.  相似文献   

9.
Inoculation     
Terpenes and biogenically related phenols commonly found in plant essential oils are known to be toxic to insect pests. Accordingly thymol was tested for acute toxicity via topical application to diamondback moth, Plutella xylostella L. (Lepidoptera: Plutellidae) and its parasitoid, Cotesia plutellae (Kurdjunov) (Hymenoptera: Braconidae under laboratory conditions. Topical application to adult female parasitoids versus second instars of P. xylostella showed that thymol was about 62 times less toxic to the parasitoid than to the host larvae with 24 h LD50 of 0.052 and 0.0008M, respectively. Although thymol was less toxic to the parasitoid, some biological parameters of the progeny at sublethal doses of surviving parasitoids were impaired such as rate of emergence and development time of larvae and pupae. The impact on detoxification enzymes was also studied and there was no significant induction in cytochrome P450 and carboxylesterase activities in both treated male and female wasps. Results obtained suggest that parasitoid is able to withstand the impact of thymol significantly.  相似文献   

10.
The pyralid Mussidia nigrivenella, a pest of cotton, maize and Phaseolus bean in West Africa, has never been reported as a crop pest in East and Southern Africa, although reportedly it exists in the wild. It is hypothesized that the difference in pest status of M. nigrivenella between western and eastern Africa was either due to differences in natural enemy compositions or that there exist several populations and/or species of Mussidia, which vary in their host plant range. Thus, a catalogue of parasitoids of Mussidia spp. was established through surveys in mid-altitude and coastal Kenya, between 2006 and 2007. Mussidia spp. eggs, larvae and pupae were collected from fruits of plants known to host Mussidia spp. and were examined for parasitoid-related mortality. The trichogrammatid Trichogrammatoidea sp. nr. lutea was obtained from eggs of Mussidia fiorii. A braconid egg-larval parasitoid, Phanerotoma sp., was reared from the larvae of unknown species of Mussidia (which we are referring to as Mussidia “madagascariensis”, Mussidia “quanzensis”) and M. fiorii, while the bethylid Goniozus sp. and the braconid Apanteles sp. were obtained from Mussidia nr. nigrivenella. Moreover, the ichneumonid larval parasitoid Syzeuctus sp. was obtained from M. fiorii, while the tachinid Leskia sp. was obtained from Mussidia “madagascariensis”. Overall, mortality caused by parasitoids was negligible; hence they were not considered key mortality factors in the population dynamics of the Mussidia spp. in Kenya.  相似文献   

11.
Infestation levels and parasitism of lepidopteran stemborers on maize were assessed in four agroecological zones (AEZ) in Uganda. The indigenous noctuidBusseola fusca Fuller (Noctuidae) and the invasiveChilo partellus Swinhoe (Crambidae) were the most important stemborers recorded.C. partellus represented 77% of the stemborers in the Eastern AEZ whileB. fusca was dominant in the other AEZs, accounting for 60–79%. The proportion of infested plants was between 16% and 45% and borer density between 0.2 and 1.0 borers per plant. There was no clear relationship between damage and stem tunneling, which is often used to estimate yield loss.Telenomus busseolae Gahan (Scelionidae), the only egg parasitoid recovered, caused parasitism of up to 46% onB. fusca eggs. Several larval and pupal parasitoid species were recorded. The most common were the indigenous braconidCotesia sesamiae and the introducedCotesia flavipes, which are larval parasitoids ofB. fusca andC. partellus, respectively. Mean parasitism by the indigenousC. sesamiae ranged between 2.0% and 29.4% onB. fusca and from 0 to 13% onC. partellus. C. flavipes was recovered at most locations with parasitism of 0–30.5% onC. partellus and 0–12% onB. fusca; the latter was probably the result of multiparasitism as laboratory studies have shown that it was not a suitable host forC. partellus. Results indicated further that the parasitoid has not attained equilibrium 5 years after its introduction. http://www.phytoparasitica.org posting Nov. 20, 2006. Teddy Matama-Kauma died suddenly in an accident on Dec. 10, 2006, while this paper was in press.  相似文献   

12.
为明确浙江省不同地区以及不同寄主植物上的烟粉虱Bemisia tabaci寄生蜂种类,更好地利用寄生蜂对烟粉虱进行生物防治,通过对浙江省8个地区进行田间烟粉虱末期若虫或伪蛹采样,并将其带回实验室内饲养直至寄生蜂成蜂羽化进行形态学鉴定。结果表明,在浙江省8个地区共采集到3 490头烟粉虱寄生蜂,其中蒙氏桨角蚜小蜂Eretmocerus mundus Mercet、狄氏桨角蚜小蜂Eretmocerus debachi RoseRosen和浅黄恩蚜小蜂Encarsia sophia(GiraultDodd)的数量最多,比例分别达到了53.0%、27.8%和9.9%;在温州发现的寄生蜂种类最多,共有10种;在20种寄主植物种类或品种上共发现10余种烟粉虱寄生蜂,其中17种寄主植物上共有的烟粉虱寄生蜂有蒙氏桨角蚜小蜂、12种寄主植物上共有的是浅黄恩蚜小蜂、10种寄主植物上共有的是狄氏桨角蚜小蜂;表明这3种寄生蜂是浙江省广泛分布的优势种类。  相似文献   

13.
The Citrus Leafminer (CLM) Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae) is considered an important pest of citrus, damaging mainly nursery plants. In Greece it was first recorded on the island of Rhodes in 1995 and rapidly spread to all citrus growing areas of the country. Due to its wide expansion and damage, efforts were initiated to control this pest with biological control agents. For this purpose, a number of exotic parasitoids, such as Citrostichus phyllocnistoides (Narayanan), Quadrastichus sp. Girault and Semielacher petiolata (Girault) (Hymenoptera: Eulophidae), were introduced, reared in insectaries and released in several regions of Greece. The species composition and the seasonal abundance of the native parasitoids, as well as the recovery of the released parasitoids, were investigated in weekly samplings during 1998 and 1999 in a citrus orchard in Argolis district. Results showed that among the released parasitoids, only C. phyllocnistoides was recovered. Among the native parasitoids, Neochrysocharis formosa (Westwood), Pnigalio pectinicornis (L.) and Cirrospilus sp. Westwood (Hymenoptera: Eulophidae) were identified. The most abundant parasitoid species was the exotic C. phyllocnistoides. The highest percent of parasitism in 1999 increased approximately by 46% compared with that of the previous year. The percent of parasitism increased to its maximum level during November, at the end of the sampling period in both years, when the population density of C. phyllocnistoides was high.  相似文献   

14.
Valid identification of a novel pest species and clarifying its origin are the primary steps in understanding population structure and development of biocontrol programs. In this study geographical populations of Conicofrontia sesamoides Hampson (Lepidoptera: Noctuidae) collected during surveys conducted in the years 2009, 2014 and 2015 were morphologically identified and their genetic diversity was analysed by using sequences of the mitochondrial cytochrome-c oxidase I (COI) gene in an attempt to examine host plant, or/and altitude associated differences among populations and determine the source of the newly recorded population of this species in the South African sugarcane. The C. sesamoides specimens in this study were collected from Miscanthus capensis (Nees) (Poaceae) and sugarcane (Saccharum officinarum L.) (Poaceae) in Eastern Cape and KwaZulu-Natal Provinces of South Africa. Analysis of Molecular Variance showed a moderate to highly significant genetic differentiation between C. sesamoides populations from different host plants (FST?=?0.115, p?=?0.14) and altitudinal range (FST?=?0.159, p?=?0.18). This result was however, contradictory to outcomes of phylogenetic analyses, haplotype networking and uncorrected sequence divergence (0.0–1.54%) which revealed no detectable genetic differentiation between populations from different host plants and altitudes. As it is difficult to measure FST accurately without a large data set, the very small sample used in the analysis might have resulted in inflation of the FST value in this study. After evaluation of the results, it was concluded that the sugarcane population of C. sesamoideshas originated from the population residing in wild host plants in the Eastern Cape and/or KwaZulu-Natal provinces of South Africa. Possible reasons for the host plant expansion and its implications to commercial sugarcane production in the country are discussed.  相似文献   

15.
Myzus persicae (Sulzer) is an economically important agricultural pest with over 500 known host plants in the world. The present study recorded the major parasitoids found parasitizing M. persicae on sweet pepper (Capsicum annuum [L.]) crops in greenhouses in Himachal Pradesh, India. Three species of hymenopteran parasitoids were reared from M. persicae from this source: Aphelinus asychis Walker (Aphelinidae), Aphidius matricariae Haliday (Braconidae), and Aphidius ervi (Haliday) (Braconidae), with parasitism rates per sample date ranging from 2.3–38.6%, 4.8–58.2%, and 2.9–28.4%, respectively, during 2011–2012. This is the first report of parasitoids associated with M. persicae in greenhouse environments in India. The present findings suggest that the management of M. persicae could be possible with the addition of augmentative releases of these parasitoids, which should help reduce pesticide use in Indian vegetable production greenhouses.  相似文献   

16.
Parasitoids are known to be an important factor in the population density regulation of bark beetles. In our study of the parasitoid complex of spruce bark beetles in 2011 and 2012, we collected bark samples from trees infested with I. typographus from spruce stands in the altimontane belt of Slovenia. The samples were taken at different altitudes: 450, 700 and 1230 m above sea level. A total of 9 bark beetle species and 12 parasitoid species was found. Ips typographus was most abundant, with 93% of all species of scolytids. The parasitoid species that were found belonged mainly to the Pteromalidae and Braconidae families. By far the most abundant and frequent species was Roptrocerus xylophagorum, which represented 84% of all parasitoids and was present in all study samples. Differences in species composition, parasitoid species diversity, species abundance and parasitism rate were confirmed between locations and also between both years of our study.  相似文献   

17.
Factors affecting overwintering mortality in the Mediterranean corn stalk borer,Sesamia nonagrioides Lefebvre (Lepidoptera: Noctuidae), were investigated under field conditions in the southeast Mediterranean region of Turkey. During two consecutive years larvae and pupae were sampled from December to April in maize plots sown on three different dates. Field-collected larvae and pupae were reared and the emerged parasitoids were recorded. An effect of sowing date on total numbers ofS. nonagrioides was found with reduced populations in the early sown plots. Larval parasitism did not significantly affect overwintering mortality.Habrobracon hebetor (Say) (Hymenoptera: Braconidae) caused 11% parasitism and was found only in the first year of the study. Pupal parasitoids were predominantlyIchneumon sarcitorius caucasicus Meyer,Barichneumon sp. andPimpla spuria Gravenhorst (Hymenoptera: Ichneumonidae) and the parasitism level was 11% in both years of the study.  相似文献   

18.
Conspecific and heterospecific associations of aphid parasitoids (Hymenoptera, Braconidae, Aphidiinae) were used to determine the interactions between crops forming the main arable crop ecosystem (wheat, alfalfa, isogenic and [Bt Bacillus thuringiensis] transgenic maize) in an irrigated area in Catalonia, Spain. Species composition and instars of parasitized aphids (mummies) were used to detect the parasitoid population movements between the crops and proved interactions (alternation) between the crops, including transgenic maize. Parasitoid interactions were species-dependent, appearing in the movements between alfalfa-wheat-maize in the individual species. Aphidius ervi Hal., A. rhopalosiphi DeSt.-Perez, A. uzbekistanicus Luzh., Lysiphlebus testaceipes (Cress.) and Praon volucre (Hal.) were classified as key-stone species in the target agroecosystems in the area. No differences were found in aphid-parasitoid associations on Bt transgenic maize and isogenic maize for aphid species composition and associated parasitoid guild.  相似文献   

19.
Survey studies of Aleurothrixus floccosus (Maskell) (Homoptera, Aleyrodidae) and its parasitoid Cales noacki Howard (Hymenoptera, Aphelinidae) were made in 4 provinces; namely Adana, Mersin, Hatay and Osmaniye, which are the main citrus growing areas of the East Mediterranean region of Turkey. Inoculative parasitoid releases were made in regions where no or low natural parasitism occurred after obtaining preliminary results on presence of the parasitoid. The population dynamics of A. floccosus and C. noacki were examined in Silifke (Mersin), Dörtyol (Hatay) and Yüreir (Adana), where the A. floccosus population was remarkably high at the beginning of the study in 1999. However, after parasitoid release, the pest population declined in all the sites and did not attain the same high levels again. Five predators, three parasitoids and one entomopathogen species were determined as natural enemies of A. floccosus. In addition, seven plant species, six of them belong to Rutaceae, were found as host plants for A. floccosus.  相似文献   

20.
Recognizing the potential significance of using nuclear techniques in biological control, investigations were conducted on the rearing of parasitoids of the peach fruit-fly, Bactrocera zonata (Saunders) (Diptera: Tephritidae) to lead to a greater flexibility in the use of irradiated hosts. For improving mass production of the biological control agents, the use of irradiated fruit-fly larvae at the dose of 15 Gy proved useful for enhancing the parasitism and adult emergence of the larval parasitoid, Trybliographa daci (Weld) (Hymenoptera: Eucoilidae) due to no negative repercussions on parasitoid development. Overall, parasitism by the parasitoid increased with age of the host larvae; however, significantly higher parasitism occurred on 4 d-old irradiated larvae of B. zonata compared to those aged 5 d. The female parasitoids preferred the irradiated larvae, and significantly higher numbers of larvae were parasitized compared with non-irradiated larvae. There was no significant difference in adult parasitoid emergence with respect to the sex of the host. A radiation level of 80 Gy was the best dose for rearing of the pupal parasitoid, Dirhinus giffardii (Silvestri) (Hymenoptera: Chalcididae) owing to broad tolerances in the use of irradiation for the rearing of fruit-fly's parasitoids. Percentage parasitism by D. giffardii varied with host pupal age, and the preference of the female parasitoid was lower on 48 h old host pharate pupae due to optimum size and mass of host. Present findings further revealed that the 24 h old host pupae of B. zonata were relatively more suitable for the maximum parasitism and progeny production of D. giffardii. Parasitisms by D. giffardii and T. daci were significantly higher on B. zonata host when parasitoids were released at a density of 3000 individuals per acre (7500 per hectares) than the other release rates of parasitoids for the management of fruit-flies in mango orchards. The implementation of these findings ought to help improve the mass production of parasitoids and the effectiveness of releases of biocontrol agents for control of B. zonata in mango plantations.  相似文献   

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