Lepidopteran cereal stemborers and associated natural enemies on maize and wild grass hosts in Cameroon

Abstract:  In Cameroon, the noctuid Busseola fusca is the most important pest of maize. The braconid Cotesia sesamiae , which is the most common larval parasitoid of noctuid stemborers in eastern Africa, was absent on B. fusca attacking maize. Thus, it is planned to introduce several strains of the parasitoid from Kenya. Pre-release surveys were undertaken in major maize growing areas to catalogue stemborer species, and larval and pupal parasitoids on maize and four wild host plant species. On maize, B. fusca was the predominant borer in all ecozones except for the lowland coastal forest, usually accounting for 60–99%, followed by the pyralid Eldana saccharina in the forest zone and the crambid Chilo sp. in the mid-altitudes. Contrary to what was reported before, the noctuid Poeonoma serrata – and not B. fusca – was the predominant borer on elephant grass, constituting 70–96% of all borers. On wild sorghum in the forest zone, the noctuid Sesamia poephaga was the most abundant species, while on Panicum sp., Chilo sp. predominated. On Setaria megaphylla in the forest zone, Chilo sp. was the most abundant species followed by Busseola quadrata . Busseola fusca was scarce on all wild grass species, indicating that previous reports on the predominance of this pest species on wild host plants were the result of misidentifications. Three tachinid and 16 hymenopteran parasitoids were obtained, most of them from B. fusca and P. serrata , on maize and Pennisetum purpureum respectively. C. sesamiae was scarce and never recovered from B. fusca on maize. In view of the new findings, acceptability and suitability studies involving the different stemborer species identified from wild plant hosts are required to determine if they will form a reproductive sink or perennate C. sesamiae populations during the off-season when maize is scarce and B. fusca is diapausing.     

Long-term seasonal fluctuations of lepidopteran cereal stemborers and their natural enemies on maize and wild host plants in southern Benin

Abstract  The seasonal fluctuation of lepidopteran cereal stemborers on maize and wild host plants (i.e., grasses and a few sedges) was investigated in southern Benin from 1988 to 1998 by time series analysis and repeated-measures analysis of variance (ANOVA). In addition, a walk-in light trap was used to study the flight behavior of adult moths. On both cereals and grasses, the noctuid Sesamia calamistis was the predominant species, followed by the pyralid Eldana saccharina . The noctuid Busseola fusca was rare on both maize and wild host plants. In general, pest populations increased during the course of the year to reach peak densities during the second short rainy season, and then crashed to close to zero during the dry season. On wild host plants, egg masses and other immature stages were collected throughout the year but they were higher on wild grasses than maize during the off-season. Thus wild host plants can be considered as refuge for both borers and natural enemies during the off-season, when maize is not available. However, only four out of the eleven wild host species played a discernable role. S. calamistis egg densities appeared to be influenced by density-dependent factors, suggesting an effect of natural enemies. Temperature and rainfall had a negative effect on egg abundance. Larval parasitism by a Kenyan strain of the braconid Cotesia sesamiae , which was released in southern Benin in the early 1990s, and by the tachinid Sturmiopsis parasitica varied between seasons and years but there were no discernable patterns. For both parasitoids and borer host species, parasitism was positively correlated with trap catches of adult moths. The recovery of C. sesamiae during a 2-year period suggests that the parasitoid has established its population in southern Benin.     

Response of maize stemborers and associated parasitoids to the spread of grasses in the rainforest zone of Kisangani,DR Congo: effect on stemborers biological control

相似文献   

Recent advances in genetic transformation of forage and turf grasses

Summary Forage and turf grasses are critical to sustainable agriculture and contribute extensively to the world economy. Tremendous progress has been made in genetic transformation of forage and turf grasses in the past decade. The rapid advancement of cellular and molecular biology and transgenic technology provides novel methods to accelerate and complement conventional breeding efforts. This review summarizes the latest developments in genetic transformation methods and the applications of molecular techniques for the improvement of forage and turf grasses.     

Assessment of the impact of natural enemies on stemborer infestations and yield loss in maize using selected insecticides in Mozambique

The effect of natural enemies on stemborer infestations and maize grain yields was estimated using an insecticide exclusion method. Field experiments were conducted at low, mid and high elevation zones, which vary in the stemborer species composition. Dimethoate was applied to exclude natural enemies and Cypermethrin to suppress stemborers, while other plots served as control. At all study sites more stemborer larvae and pupae were collected when natural enemies were excluded. Parasitism as well as maize grain weight in the unprotected plots were significantly higher than in the exclusion plots. Yield losses increased by 28.9 % in unprotected to 43.3 % in exclusion plots. The most abundant parasitoids of Chilo partellus (Swinhoe) (Lepidoptera: Crambidae) were Cotesia sesamiae (Cameron), Cotesia flavipes Cameron (Hymenoptera: Braconidae) and Dentichasmias busseolae Heinrich (Hymenoptera: Ichneumonidae). While for Busseola fusca (Fuller) (Lepidoptera: Noctuidae) they were C. sesamiae, Sturmiopsis parasitica (Curran) (Diptera: Tachinidae) and Porcerochasmias nigromaculatus Heinrich (Hymenoptera: Ichneumonidae). It was concluded that exclusion of natural enemies caused an increase in stemborer populations, thus, the parasitoids play an important role in suppressing stemborer infestations and increase maize yield.     

土壤因子对野生植物AM真菌的影响

1　引　　言关于生态因子对ＡＭ真菌发生和分布的影响 ,国内外均有报道[1,2 ,7] ,张美庆等[6] 比较系统地研究了我国东、南沿海七省ＡＭ真菌的生态分布 ;吴铁航[5] 报道了几种土壤因子对栽培作物根围内ＡＭ真菌分布的影响 .本文主要介绍土壤类型、质地、营养状况、ｐＨ等对野生植物根围ＡＭ真菌的侵染、孢子密度和种属分布的影响 .2　研究地区与研究方法2 1　研究地区概况山东省位于 33°2 5′～ 38°2 3′Ｎ ,114°36′～ 12 2°4 3′Ｅ之间 ,属暖温带大陆性季风气候 ,年平均气温 11～ 14℃ ,年平均降水量为 5 5 0～ 95 0ｍｍ .根据地貌不…     

湖北赛武当自然保护区野生珍稀植物优先保护定量研究

通过对湖北赛武当国家级自然保护区内的野生珍稀植物资源进行调查,运用濒危系数、遗传价值系数和物种价值系数,计算出物种优先保护值,以确定物种濒危等级和优先保护等级。结果显示：（1）该区内共有珍稀保护植物33种,隶属于26科33属,其中易危15种、近危11种、安全种7种;（2）该区珍稀植物优先保护值的范围为0.2631~0.6985,据此得出33种珍稀植物的优先保护等级为：Ⅰ级6种、Ⅱ级13种、Ⅲ级12种、Ⅳ级2种。（3）本研究结果与相关珍稀保护植物名录的濒危等级和优先保护级别存在较大差异,这可能是由于生境破碎化和人为干扰导致大部分植物在本区受威胁程度加重,因此应强化管理。     

Flowering calendar of grasses in Srinagar, Kashmir Himalaya (India)

Several grass pollens are important environmental bio-pollutants, causing various allergic disorders in susceptible persons. Therefore, it is essential to study the period and duration of the flowering of the plants growing in a particular region/area. For the area Srinagar (Kashmir Himalaya), a flowering calendar of grasses consisting of 57 species which fall under 35 genera has been compiled in order to provide an understanding of habit, period of pollen release and their dispersal from the flowers, pollen load in the atmosphere and the influence of meterological parameters. The main object of this research work is to provide an information regarding the frequency of grass pollen in atmosphere to the physicians, or medical practitioners. The maximum flowering period is recorded from July to September. This revised version was published online in June 2006 with corrections to the Cover Date.     

ISSR and SCoT for evaluation of hereditary differences of 29 wild plants in Al Jubail Saudi Arabian

This survey is concerned with the hereditary differences of 29 wild plants collected from fifteen different regions in Al Jubail, Saudi Arabia using two molecular marker systems, viz. inter simple sequence repeat (ISSR) and start codon targeted (SCoT) molecular markers. Ten ISSR and ten SCoT primers amplified a total of 142 and 163 bands with a 87% and 84% polymorphism, respectively. The average number of polymorphic bands for each pair of ISSR and SCoT primers combinations was 12.4 and 13.7, respectively. The highest genetic similarity for ISSR (0.97) and SCoT (0.90) were recognized between Zygophyllum qatarense-22 and Juncus rigidus-23, and between Zygophyllum qatarense-28 and Zygophyllum qatarense-29, whereas the lowest was (0.59) differentiated between Zygophyllum qatarense-6 and Salsola imbricate-18 for ISSR and between Cyperus conglomeratus-7 and Halopeplis perfoliata-14 for SCoT. This considers confirmed the value of molecular techniques such as ISSR and SCoT to assess the hereditary differences among the selected 29 weeds for hereditary preservation and plant enhancement.     

The role of wild grasses in the management of lepidopterous stem-borers on maize in the humid tropics of western Africa

Sites in the humid forest of Cameroon and the derived savanna of Benin were selected to evaluate the effect of planting border rows of wild host plants on lepidopterous stem-borer infestations and on maize yield. Grass species were chosen that in surveys and greenhouse trials were highly attractive to ovipositing female moths but with offspring mortality of close to 100%, thus acting as trap plants. In Cameroon, elephant grass Pennisetum purpureum Moench significantly lowered infestations of Busseola fusca (Fuller), Sesamia calamistis Hampson and Eldana saccharina Walker and increased yields of maize though the differences were not significant during all three cropping seasons. In 1998 in Benin, the only grass tested, Pennisetum polystachion L., significantly increased parasitism of mainly S. calamistis eggs by Telenomus spp. and larvae by Cotesia sesamiae Cameron and reduced numbers of the cob-borer Mussidia nigrivenella Ragonot. In 1999, three grass species; P. polystachion, Sorghum arundinaceum (Desv.) Stapf and Panicum maximum Jacq. were tested. Panicum maximum was the most efficient species for suppressing S. calamistis and M. nigrivenella infestations and enhancing egg and larval parasitism. In the Benin trials, with the exception of M. nigrivenella damage to cobs, the grass species tested had no beneficial effect on yield because pest densities were too low and also rodent damage to maize was enhanced with grasses in the vicinity of the crop. By contrast, stand losses due to Fusarium verticillioides Sacc. (Nirenberg), were significantly reduced by border rows of grasses.     

Effect of nitrogen fertilizer level on infestations of lepidopterous stemborers and yields of maize in Zanzibar

The effect of nitrogen levels of 0, 60, 120, and 250 kg/ha and insecticide treatment (Furadan) on population densities and parasitism of lepidopteran stemborers, and maize yields were studied in Zanzibar during 2004/05. Chilo partellus (Swinhoe) (Lepidoptera: Crambidae) dominated by 3-fold over Sesamia calamistis Hampson (Lepidoptera: Noctuidae) and 42 fold over Chilo orichalcociliellus Strand (Lepidoptera: Crambidae). Stemborer density per plant and parasitism by Cotesia flavipes (Cameron) (Hymenoptera: Braconidae) increased with nitrogen application level. Percentage of bored internodes per plant caused by stemborer decreased with N levels during the short rainy season. Pesticide application reduced densities of all stemborer species during the short rainy season, when infestations were high. Maize yield increased 2 to 8 times with N level, compared to the zero treatment, but the effect was less pronounced in the protected plots.     

中国野生植物保护管理的政策、法律制度分析和建议

中国是全球生物多样性最丰富的国家之一.最近40年,中国的植物多样性保护取得了巨大成就,实施了多项政策和法律,尤其是《野生植物保护条例》和《国家重点保护野生植物名录》先后颁布,奠定了中国植物保护的法律和政策框架,就地保护和迁地保护网络基本形成.但与生态文明建设的要求相比,野生植物保护依然存在许多不足.本文系统回顾了中国野...     

Seroprevalence of Toxoplasma gondii in wild boars (Sus scrofa leucomystax) and wild sika deer (Cervus nippon) in Gunma Prefecture, Japan

The ingestion of undercooked meat from wild animals can be a source of Toxoplasma gondii infection in humans and other animals. In this study, we determined the seroprevalence of T. gondii infection in 175 wild boars (Sus scrofa leucomystax) and 107 wild sika deer (Cervus nippon) hunted in 2004–2007 in Gunma Prefecture, Japan, by using a commercial latex agglutination test (LAT). Antibodies (LAT, 1:64 or higher) to T. gondii were found in 6.3% of wild boars and 1.9% of sika deer. This is the first record of T. gondii infection in wild deer in Japan, and deer and wild boar meat should be cooked well before human consumption.     

Endophyte-mediated disease resistance in wild populations of perennial ryegrass (Lolium perenne)

Twelve wild, endophyte-infected populations of perennial ryegrass were tested for resistance against artificial infection of Drechslera siccans and Fusarium spp. Plants with identified endophyte presence (E+), together with plants free from endophytes (E−), were inoculated with serious turf grass pathogens: D. siccans (cause of brown blight) and a mixture of Fusarium species (cause of Fusarium blight). For both diseases, the positive effect of endophyte presence on plant resistance was observed. In the case of a few ecotypes, endophyte infection increased resistance against both diseases, which is of practical importance for disease control.     

中国、老挝野生动植物边境贸易现状及加强管理的建议

通过对中国、老挝边境地区野生动植物贸易的资料收集和调查研究,结果表明,中老野生动植物年贸易额超过1000万美元,合法贸易额约500万美元,其中有380.63万美元是经过西双版纳州边贸局或勐腊海关登记的。常见的野生植物种类有51种,其中有35.3%野生植物是老挝禁止出口种类,43.14%的种类是属限量贸易种类;常见的野生动物种类134种,其中哺乳类56种,鸟类45种,爬行类31种,鱼类和两栖类各1种。交易的动物种类中,有71种动物是国际上禁止贸易种类, 属于〖WTBZ〗CITES规定的一级保护种类有19种,二级保护种类有32种。在野生动植物合法贸易中,从采集者到老挝集镇的一级商贩,价格提高20%～70%,到达中国云南省勐腊,价格一般为原价的2.7倍,到达云南省以外市场,价格增加到原价的约3.6倍,非法贸易的价格变化幅度是同级合法贸易的2.7～4.5倍。动植物贸易的主要获利者是中间商贩,采集者的获利相对较小,但采集的劳动日收益仍达0.6～2.8美元/天,比当地种水稻和旱稻收益高。文章针对该地区野生动植物贸易的有效管理提出若干建议。     

Effects of fertilization and herbicides on growth of young loblolly pine and infestations of Nantucket pine tip moth（Lepidoptera： Tortricidae）

A 2-year-old pine plantation was selected to receive treatments of fertilizers and herbicides to evaluate effects on Nantucket pine tip moth infestations and the tree growth parameters of height, diameter and volume increment. Nitrogen and phosphorus fertilizers, and hexazinone and sulfometuron methyl herbicides were used in creating six treatments： （i） control; （ii） phosphorus; （iii） nitrogen and phosphorus; （iv） phosphorus and herbicide; （v） nitrogen, phosphorus and herbicide; and （vi） herbicide. Treatments were applied in 1987 and 1988. In 1987, trees treated with nitrogen, phosphorus and herbicide had significantly greater height, diameter and volume growth than trees not receiving fertilizer treatments, but did not have significantly higher tip moth infestations than control trees. Treatments receiving phosphorus only had much lower tip moth infestation rates than other treatments except nitrogen and phosphorus. In 1988, tip moth infestations were uniformly low, with no differences in treatment effects observed.     

Fecundity, longevity and establishment of Otiorhynchus sulcatus (Fabricius) and Otiorhynchus ovatus (Linnaeus) (Coleoptera: Curculionidae) from the Pacific North-west of the United States of America on selected host plants

1 The fecundity, longevity and establishment of Otiorhynchus sulcatus and Otiorhynchus ovatus from the Pacific North‐west U.S.A. was studied on five selected host plants: Picea abies‘Nidiformis’, Picea glauca‘Conica’, Taxus baccata, Rhododendron catawbiense‘Boursault’ and Fragaria×ananassa‘Totem’. 2 Teneral adults were used to study adult longevity and reproductive success. Leaves of these host plants were used for sustenance for 9 months. Larval establishment was studied by infesting potted host plants with eggs. 3 Fragaria×ananassa‘Totem’ produced the longest survival, shortest preoviposition time, the greatest number of eggs, and the highest fertility for adults of both species. Picea spp. were not good adult hosts for O. sulcatus. Taxus was a good adult host for O. sulcatus, but was a nonhost for adults and larvae of O. ovatus. 4 Adult hosts did not affect preoviposition time or egg viability with O. ovatus adults. With O. sulcatus, preoviposition time was greatly increased and egg viability was < 50% on Picea spp. 5 The best larval host was F.×ananassa‘Totem’ for O. sulcatus and P. glauca‘Conica’ for O. ovatus. Rhododendron was a poor larval host for both species. 6 When all of the studies on these two pests are considered, O. sulcatus appears to have varying host preferences from among its many geographical areas of occurrence whereas O. ovatus has a more universal host selection.     

Mechanical limitations on feeding by meadow spittlebugs Philaenus spumarius (Homoptera: Cercopidae) on wild and cultivated host plants

Abstract. 1. Field observations on the distribution of Philaenus spumarius (L.) on pearly everlasting (Anaphalis margaritacea) and alfalfa (Medicago sativa) showed that the range of feeding sites exploited increased with instar. Development of trichomes, depth of xylem elements, and tissue hardness were measured as possible factors determining the suitability of sites on food plants.
2. Spittlebugs caged outside their normal feeding sites experienced difficulty feeding. Experimental removal of trichomes showed that trichomes prevented younger instars from feeding on the stem. The depth of the xylem elements and tissue hardness were not significant barriers to feeding near the stem apex.
3. By caging fourth and fifth instar nymphs at increasing distances below the terminal bud on A.margaritacea stems, we showed feeding ability declined with distance below the apex, and feeding was more restricted in fourth compared to fifth instars. A similar decline was demonstrated in experiments with fifth instars on M.sativa.
4. On A.margaritacea, this restriction was associated with increasing tissue hardness of the stem with distance from the apex and the presence of trichomes in regions with hard tissues. On M.sativa the associated barriers were a combination of tissue hardness and reduction in the availability of xylem vessels in the penetrable region of the stem. Although the tissues impeding stylet penetration differed in the two hosts, the critical factor in both species was the increase in the amount of lignification of those tissues at increasing distances from the terminal bud.     

Mechanism of salt tolerance in wild rice (Oryza coarctata Roxb)

Summary Oryza coarctata, a highly salt-resistant wild rice species, is commonly found on the banks of coastal rivers in India. This species can also withstand saline water (20 to 40 dSm⁻¹ E.C) submergence for quite a long period. It was revealed thatO. coarctata has some special unicellular salt hairs (trichomes) on the adaxial surface of the leaves, by which they efficiently maintain a low concentration of toxic salts in the plant tissue. Sodium and chloride were the dominant ions in the excreted material but they also excrete potassium, magnesium and calcium. With the increase in soil salinity sodium, magnesium and chloride excretion increased.O. coarctata maintained the optimum mineral concentration in its tissues. Maximum accumulation of potassium was observed in the leaves. With the increase in salt stress total biomass production and osmotic potential increased over control but there was no change in the moisture percentage of leaves.