繁育寄主对稻螟赤眼蜂寄生行为及寄生能力的影响

【目的】繁育寄主影响赤眼蜂的生物学特性,为明确米蛾 Corcyra cephalonica (Stainton)卵繁育的稻螟赤眼蜂 Trichogramma japonicum Ashmead是否和二化螟Chilo suppressalis (Walker)卵繁育稻螟赤眼蜂在防治二化螟上有差别,及田间用米蛾卵作为稻螟赤眼蜂续代寄主的可行性,本实验观察了羽化自不同寄主的稻螟赤眼蜂的寄主选择和寄生行为,研究了两种繁育寄主对稻螟赤眼蜂寄生能力的影响,为田间防治水稻螟虫提供参考信息。【方法】室内利用选择试验观察了由米蛾卵和二化螟卵繁育出的稻螟赤眼蜂对两种寄主的选择趋性及在两种寄主上的寄生行为和寄生能力,统计了羽化子代蜂的寿命。【结果】由二化螟卵繁育的稻螟赤眼蜂表现出了对二化螟卵的选择偏好,而米蛾卵繁育的稻螟赤眼蜂在米蛾卵和二化螟卵间没有表现出寄主选择偏好。寄主搜寻时间不受繁育寄主及供试寄主的影响,卵表探测时间和穿刺及产卵时间不受繁育寄主的影响,但同一寄主繁育的稻螟赤眼蜂在米蛾卵上的卵表探测时间显著长于在二化螟卵上的卵表检测时间。除二化螟卵繁育蜂寄生二化螟卵时的寄生率（36.95%）和羽化率（45.68%）较低外,米蛾卵繁育蜂寄生米蛾卵或二化螟卵以及二化螟卵繁育蜂寄生米蛾卵等3组处理间的寄生率、羽化率均无显著差异,各处理组间子代蜂寿命也无显著差异。【结论】繁育寄主影响稻螟赤眼蜂的寄主选择和寄生能力,但不影响寄生蜂搜寻寄主的能力和寄生行为。     

自然植物种群中病原菌与寄主植物相互作用的遗传学

在农业种群中,作物和菌病相互作用的遗传学已为人们所广泛研究,但对自然植物种群中病原菌与其寄主相互作用体系的某些重要现象却缺乏足够的重视。本文主要论述寄主与病原菌相互作用的遗传学本质;寄主抗性基因和病原菌毒性基因的获得代价及对各自适应力的影响;简单介绍了寄主-病原菌作用体系在种群水平上的遗传学内容及共进化的意义。     

转sck+cry1Ac基因水稻对二化螟及二化螟绒茧蜂存活和生长发育的影响

在实验室研究了转sck+cry1Ac基因水稻（MSB）对二化螟Chilo suppressalis (Walker)生长、存活以及经寄主对二化螟绒茧蜂Apanteles chilonis (Munakata)生物学特性的影响。连续取食转sck+cry1Ac基因水稻的二化螟, 体重下降、死亡率上升,从第2天开始,其体重显著低于取食明恢86的对照组;从第6天开始,死亡率极显著高于对照组。二化螟取食MSB 36 h后移至对照水稻上继续取食3、6、9、12天后,死亡率与对照差异都不显著;但体重均低于对照,其中第3天的体重差异达显著水平。二化螟绒茧蜂分别以取食MSB一定时间的3、4、5龄二化螟幼虫为寄主时,寄生率均低于以对照组,其中对4龄幼虫的寄生率差异显著;结茧率与对照差异均不显著;寄生在取食MSB的5龄二化螟幼虫体内的蜂、蛹期显著长于对照,而所结茧的茧长显著短于对照;但卵 幼虫历期、每茧块茧数、羽化率、雌性率、成蜂寿命和前翅长与对照无显著差异。结果表明转sck+cry1Ac基因水稻不仅对二化螟生长和存活有显著影响, 而且可经寄主二化螟影响到二化螟绒茧蜂的一些生物学特性。     

二化螟绒茧蜂对二化螟及其寄主植物挥发物的趋性反应

利用Y-型嗅觉仪研究了二化螟绒茧蜂Cotesia chilonis对寄主植物（水稻或茭白）、二化螟Chilo suppressalis幼虫、虫粪及虫害苗挥发物的行为反应。健康植株、二化螟幼虫和虫粪的挥发物对二化螟绒茧蜂具有显著引诱作用。在虫害苗与健康苗挥发物之间,二化螟绒茧蜂显著地偏好虫害苗,但当去除虫害苗中的幼虫和虫粪后,寄生蜂对去虫苗与机械损伤苗的选择无显著差异;在虫害苗与有虫健康苗之间,寄生蜂显著趋向虫害苗,表明虫害苗本身释放的挥发物对二化螟绒茧蜂引诱作用与机械损伤苗无显著差异,但与二化螟幼虫或虫粪挥发物之间可能具有协同增效作用。水稻苗经机械损伤或损伤后以二化螟幼虫唾液处理,其挥发物对二化螟绒茧蜂的引诱作用无显著改变。二化螟绒茧蜂对不同为害程度水稻挥发物的选择无显著差异。二化螟绒茧蜂对两种寄主植物的健康苗、虫害苗、取食两种植物的幼虫及虫粪的挥发物的选择无显著差异。结果表明,二化螟绒茧蜂栖境定位和寄主选择过程中所利用的挥发物主要来自寄主植物、二化螟幼虫和虫粪以及虫害苗与幼虫和虫粪的协同作用。     

二化螟幼虫被二化螟绒茧蜂寄生后血淋巴的生理生化变化

二化螟Chila suppressalis幼虫被二化螟绒茧蜂Apanteles chilonis产卵寄生后,血细胞含量增加,在被产卵寄生后的第6—10天,血细胞数最比对照幼虫增加了1.53—2.79倍,但血细胞形成被囊的能力很弱,对于蜂卵和蜂幼虫形成被囊的百分率分别为0.34％和0.62％。绒茧蜂寄生后,对二化螟幼虫生理生化有一定的影响,在寄生前期和后期,寄主幼虫血淋巴蛋白质浓度显著下降,在寄生后第2天,血淋巴游离氨基酸总浓度明显上升,以后随蜂幼虫发育而逐渐下降。在16种氨基酸中,对苏、丝、赖、精氨酸的影响最大。此外,本文对二化螟绒茧蜂的营养生理和寄生后调节寄主的能力进行了探讨。     

二化螟幼虫被二化螟绒茧蜂寄生后血淋巴的生理生化变化

二化螟Chila suppressalis幼虫被二化螟绒茧蜂Apanteles chilonis产卵寄生后,血细胞含量增加,在被产卵寄生后的第6—10天,血细胞数最比对照幼虫增加了1.53—2.79倍,但血细胞形成被囊的能力很弱,对于蜂卵和蜂幼虫形成被囊的百分率分别为0.34%和0.62%.绒茧蜂寄生后,对二化螟幼虫生理生化有一定的影响,在寄生前期和后期,寄主幼虫血淋巴蛋白质浓度显著下降,在寄生后第2天,血淋巴游离氨基酸总浓度明显上升,以后随蜂幼虫发育而逐渐下降.在16种氨基酸中,对苏、丝、赖、精氨酸的影响最大.此外,本文对二化螟绒茧蜂的营养生理和寄生后调节寄主的能力进行了探讨.     

二化螟寄主种群及种群间生殖隔离形成机制研究

水稻和茭白是二化螟的两种主要寄主植物。经过长期的适应进化,二化螟已分化出水稻种群和茭白种群。国内外的大量研究表明,二化螟水稻种群和茭白种群在形态特征、交配行为、寄主选择性、寄主适应性、田间种群动态、越冬生物学、生理生化及遗传多样性等方面均存在一定差异。二化螟水稻种群和茭白种群的发生期差异、交配节律差异和交配后配子不亲合等可能造成了寄主种群的部分生殖隔离。目前认为,二化螟两寄主种群间仍存在基因交流,处于物种形成的早期阶段,但尚需从寄主种群鉴定、表型差异区分和种群间生殖隔离机制等方面开展深入研究来进一步明确,为理解昆虫同域物种形成机制提供参考。     

夹色姬蜂研究初报

<正> 夹色姬蜂Centetus alternecoloratus Cushman是二亿螟的主要寄生性天敌。1979年我们在水稻害虫天敌调查中发现,夹色姬蜂在山区对二化螟寄生率一般达50％左右,对二化螟的发展具有重要的自然控制效应。 为了进一步探讨夹色姬蜂的生物学特性和对二化螟的控制效能,1980年我们对夹色姬蜂进行了初步观察,现将所得结果整理如下。 一、寄主与寄生概况 寄主 据文献记载,夹色姬蜂除寄生二化螟外,同时还寄生甘蔗二点螟。 寄生概况 我们从田间采回各代二化螟蛹81—260只,经室内观察结果,夹色姬蜂对二化螟的寄生率是越冬代为15.8％、第一代为23.9％、第二代为37％,即一代高于一代。     

斑痣悬茧蜂对不同寄主密度斑块的选择和最优搜寻行为

在圆柱形透明有机玻璃罩内,观察了斑痣悬茧蜂对不同寄主密度斑块的选择和滞留时间,并用Cox比例风险模型分析了寄主密度、产卵次数和搜寻特征对斑痣悬茧蜂在斑块上的驻留时间及其影响因素.结果表明:斑痣悬茧蜂对高密度寄主斑块的初次选择次数、访问次数均高于低密度寄主斑块,导致在高密度斑块上具有更高的寄生率;斑痣悬茧蜂在各斑块的驻留时间随寄主密度的增加而增加.Cox模型分析结果显示,斑块内寄主密度和产卵数均对其离开斑块的倾向起消极作用,即随寄主密度和产卵数的增加而倾向于留在斑块上;而寄主密度与产卵数的互作反而对寄生蜂离开斑块倾向具有促进作用,这两种作用可使寄生蜂利用寄主斑块获得最大适合度.     

多寄主型寄生性天敌昆虫的寄主适应性及其影响因素

寄生性天敌昆虫对不同寄主资源的适应能力是其存活和繁殖的必要条件,它们的寄主选择行为则是其重要的适应结果。多寄主型寄生性天敌昆虫虽然对某种特定寄主资源的利用效率可能不如单寄主型寄生蜂,但却有利于拓展更宽的寄主范围,因此对环境的适应能力更强,更容易在自然界维持其种群的生存。统计结果也表明多寄主型天敌的生物防治效果往往比专食性天敌更高。有时生物防治成功的关键可能并不在于所利用的天敌种类的不同,而在于天敌的不同生物型或地理宗。总结了多寄主型寄生性天敌昆虫的寄主适应能力及其影响因素。寄生性天敌昆虫不仅因地理隔离产生种群分化,也可能因寄生不同的寄主产生种群内的分化,从而更加适应寄主的生活特性和栖境条件。寄主种类、寄主发育阶段、寄主大小、寄主营养、寄主免疫反应、寄主逃避反应、其它天敌的竞争、寄主共生或共栖生物的存在、寄主植物、天敌自身的学习能力及其共生微生物等多种因素对寄生性天敌昆虫的寄主适应性可产生影响。展望了多寄主型寄生性天敌昆虫对新寄主资源的拓展利用能力和适应性在生产上的可能应用前景和途径,以期为明确天敌与寄主间的互作关系,人工驯化寄生性天敌昆虫增强对靶标害虫的控制作用,合理利用天敌提高生物防治效率提供新的思路和理论支持。     

The effects of sowing date and planting method on stem borer damage in dauro millet

In field trials conducted at Samaru, Nigeria in 1983, 1984 and 1985, damage to dauro millet by the millet stem borer, Coniesta ignefusalis Hampson (Lepidoptera: Pyralidae), varied between years and dates of planting. The crop was almost completely destroyed by the stem borer during 1984. Based on 1983 and 1985 data, the period between 10 July and 2 August appears to be best for planting dauro millet at Samaru for least stem borer damage while planting between 11 and 30 July appears to be optimum for grain yields. The direct sown crop suffered more damage than the transplanted crops in all years but only in 1985 was the difference significant. There was no significant difference between slant and upright transplanting in terms of stem borer damage and grain yield. It is concluded, therefore, that the choice of planting method would depend on its convenience to the farmer.     

Effect of transgenic Bacillus thuringiensis rice lines on mortality and feeding behavior of rice stem borers (Lepidoptera: Crambidae)

Ten transgenic Bacillus thuringiensis Bt rice, Oryza sativa L., lines with different Bt genes (two Cry1Ac lines, three Cry2A lines, and five Cry9C lines) derived from the same variety Minghui 63 were evaluated in both the laboratory and the field. Bioassays were conducted by using the first instars of two main rice lepidopteran insect species: yellow stem borer, Scirpophaga incertulas (Walker) and Asiatic rice borer, Chilo suppressalis (Walker). All transgenic lines exhibited high toxicity to these two rice borers. Field evaluation results also showed that all transgenic lines were highly insect resistant with both natural infestation and manual infestation of the neonate larvae of S. incertulas compared with the nontransformed Minghui63. Bt protein concentrations in leaves of 10 transgenic rice lines were estimated by the sandwich enzyme-linked immunosorbent assay. The cry9C gene had the highest expression level, next was cry2A gene, and the cry1Ac gene expressed at the lowest level. The feeding behavior of 7-d-old Asiatic rice borer to three classes of Bt transgenic rice lines also was detected by using rice culm cuttings. The results showed that 7-d-old larvae of Asiatic rice borer have the capacity to distinguish Bt and non-Bt culm cuttings and preferentially fed on non-Bt cuttings. When only Bt culm cuttings with three classes of different Bt proteins (CrylAc, Cry2A, and Cry9C) were fed, significant distribution difference of 7-d-old Asiatic rice borer in culm cuttings of different Bt proteins also was found. In the current study, we evaluate different Bt genes in the same rice variety in both the laboratory and the field, and also tested feeding behavior of rice insect to these Bt rice. These data are valuable for the further development of two-toxin Bt rice and establishment of appropriate insect resistance management in the future.     

Diversity and abundance of lepidopteran stem borers and their host plants in Ethiopia

Lepidopteran stem borers are among the most important insect pests of maize, sorghum and sugarcane in sub‐Saharan Africa. Except for Chilo partellus, the other stem borer pests in Ethiopia are indigenous to Africa and are assumed to have coevolved with some native grasses and sedges in the natural habitat. In addition to pest species, natural habitats harbour diverse non‐economic stem borer species, some of which are new to science. However, with the growing threats to natural habitats, some non‐economic stem borer species may switch or expand their host ranges to include cultivated crops and evolve as “new” pests. Besides host switch, some of the unknown species currently limited to natural habitats may disappear. We examined the diversity, abundance and interactions of lepidopteran stem borers and their wild host plants in five different vegetation mosaics in Ethiopia. The stem borer species diversity varied among vegetation mosaics and host plants. Forty‐four stem borer species belonging to 14 different genera in the families of Noctuidae, Crambidae, Pyralidae and Tortricidae were recorded from 34 wild host plants and through light trap. Among these families, Noctuidae was the highest in species richness in which 31 species were identified, out of which 15 species and two genera were new to science. This paper discusses the ecological interpretation of host plant–stem borer species interactions, particularly in relation to habitat disturbances.     

Influence of maize/lablab intercropping on lepidopterous stem borer infestation in maize

Lepidopterous stem borers seriously affect production of maize, Zea mays L., in sub-Saharan Africa. Intercropping maize with legumes such as lablab, Lablab purpurens (L.), is one of the effective systems to control stem borers. Sole culture maize and maize/lablab intercrop system of different lablab densities were planted at two locations to investigate the effects of intercrop system on incidence and severity of stem borers with particular reference to Chilo partellus (Swinhoe) (Lepidoptera: Pyralidae). Stem borer infestation was found to be more severe in sole culture maize than maize in maize/lablab intercrop. There was a significantly negative relationship between lablab densities and maize grain yields, suggesting a possible competition for resources between the two crops. It was concluded that density of lablab and date of planting of lablab in maize/lablab intercropping have significant affects on stem borer populations and maize grain yields.     

A review of sugarcane stem borers and their natural enemies in Asia and Indian Ocean Islands: an Australian perspective

This paper provides a review on lepidopteran stem borer pests of graminaceous crops in Asia and Indian Ocean Islands which have the potential to invade Australia. Information on the geographical distribution, host plants and potential of invading Australia is provided for 36 stem borer species. A literature review of all natural enemies of 18 key pest species is provided. A knowledge of possible biological control options is essential to determine which natural enemies are to be considered for introduction following an incursion. The Braconid, Cotesia flavipes Cameron (Hymenoptera: Braconidae), stands out as a promising candidate for introduction into Australia following a borer incursion. Studies are currently being conducted on a native Cotesia species in Australia, which may be able to parasitize larvae of exotic borers, therefore minimizing the need for other parasitoids introductions.     

Species diversity of lepidopteran stem borer parasitoids in cultivated and natural habitats in Kenya

Field surveys were conducted during 2005 to 2007 to assess the species diversity of stem borer parasitoids in cultivated and natural habitats in four agroecological zones in Kenya. In total, 33 parasitoid species were recovered, of which 18 parasitized six stem borer species feeding on cereal crops, while 27 parasitized 21 stem borer species feeding on 19 wild host plant species. The most common parasitoids in cultivated habitats were Cotesia flavipes Cameron, Cotesia sesamiae (Cameron), Pediobius furvus Gahan and the tachinid Siphona sp., whereas in natural habitats, Siphona sp. was the most common. The majority of parasitoids were stenophagous species; only five species –Cotesia sp., Enicospilus ruscus Gauld and Mitchell, Pristomerus nr. bullis, Sturmiopsis parasitica (Curran) and Syzeuctus ruberrimus Benoit – were monophagous. In both cultivated and natural habitats, parasitoid species diversity was highest on the most dominant stem borers Busseola spp. and Chilo spp. On cereal crops, parasitoid diversity was highest on maize and among wild host plants, it was highest on Setaria spp. The ingress‐and‐sting attack method was the most common strategy used by parasitoids in both habitats. In all agroecological zones, parasitoid species diversity was significantly higher in natural than in cultivated habitats. Furthermore, the majority of parasitoid species were common to both cultivated and natural habitats. It was concluded that natural habitats surrounding cereal crops serve as refugia for sustaining the diversity of stem borer parasitoids from adjacent cereal fields.     

Stem borer infestation of cereal crops in Jere,the Sudan-Sahelian savanna region of Nigeria

Field data collected during the rainy season of two years, 2010 and 2011, were used to determine the per cent plant infestation and stem borer abundance on cultivated cereal crops grown by farmers' in Jere or the Sudan-Sahelian savanna ecological region of Nigeria. Stem borers were recovered using destructive sampling. Mean total per cent plant infestation and stem borer abundance per farmers' field were significantly higher on millet (40% and 25 individuals, respectively) and sorghum (30% and 21 individuals, respectively) than on maize (19% and 13 individuals, respectively). Of the five stem borer species found in this study, Coniesta ignefusalis (Lepidoptera: Pyralidae) (3.5)/Chilo sp. nr. aleniellus (Lepidoptera: Crambidae) (2), Busseola fusca (Lepidoptera: Noctuidae) (3.1)/Sesamia calamistis (Lepidoptera: Noctuidae) (2.4) and S. calamistis (2.9), with significantly higher number of individuals per plant, tended to be more important pests on millet, sorghum and maize crops, respectively. Although, mean total per cent plant infestation and abundance of stem borers in this study were generally moderate, further studies on the effects of different types of cereals intercropping (locally practiced) on stem borer infestation and abundance should ascertain the true importance of these pest species in the Sudan-Sahelian savanna ecological region of Nigeria.     

越桔两种蛀干害虫的发生与防治

咖啡豹蠹蛾Zeuzera coffeae Nietner和樟泥色天牛Uraecha angusta(Pascoe)是江苏地区的美国兔眼越桔上2种主要蛀干害虫。前者在枝干中向顶端方向蛀食,排出圆粒状虫粪;后者向植株基部方向蛀食,排出粉末状虫粪,均造成枝干枯死。咖啡豹蠹蛾发生量较大,是主要虫种。防治这2种蛀干害虫,应采用保护利用天敌、改善果园生态环境、促使树体健壮生长等综合管理措施。     

Field boundaries of Panicum maximum as a reservoir for predators and a sink for Chilo partellus

Abstract:  The biological-control function of field boundaries of Guinea grass, Panicum maximum Jacq. on the spotted stem borer, Chilo partellus Swinhoe was examined as a reservoir for arthropod predators and as a trap plant for the pest. Field border vegetation and predator density were manipulated to determine the effect of the grass border on the abundance of stem borers and their predators in maize fields, and the effect of predators on the stem borer population. The strip of Guinea grass supported an abundance of earwigs and spiders, the potential predators of stem borer eggs and larvae. Density of C. partellus larvae in the Guinea grass strips was low throughout the season and only young larvae were collected, suggesting the inferiority of the grass stand as a habitat for stem borer larvae. These results indicate that Guinea grass is a good agent of habitat management to selectively enhance arthropod predators of stem borers and act as a sink for the pest. Predator removal resulted in a higher density of C. partellus than control in maize-bordered plots. On the other hand, no difference was found in the stem borer density between predator treatments in grass-bordered plots, probably because of insufficient predator reduction in removal plots. These results suggest that the predator assemblage found in the study site has, if sufficiently abundant, potential to limit the C. partellus population in maize fields. Even though the Guinea grass stand harboured an abundant number of predators, the grass boundaries around maize fields did not enhance predator populations within the crop field. Furthermore, field boundaries of Guinea grass had no measurable effect on the within-field density of C. partellus as a trap crop. Creating a polyculture within the crop and early planting of the grass could further enhance the biological-control function of Guinea grass boundaries.     

Rice (<i>Oryza sativa</i> L.) Breeding among Hassawi Landrace and Egyptian Genotypes for Stem Borer (<i>Chilo agamemnon</i> Bles.) Resistance and Related Quantitative Traits

Rice stem borer (Chilo agamemnon Bles.) is a primary insect pest of rice and is a major limiting factor to rice production. Breeding for insect-resistant crop varieties has been an economic way of integrated pest management (IPM) as it offers a viable and ecologically acceptable approach. This study was aimed to evaluate rice genotypes for their resistance against rice stem borer. Seven parental genotypes with twenty one F1 crosses were evaluated for genotypic variation in field experiments. Analysis of variance revealed significant differences for the studied traits in almost all crosses and parents. In addition, the mean squares of parents versus their crosses were signifi- cant for stem borer resistance and other associated traits. Moreover, both general combining ability (GCA) and specific combining ability (SCA) variances were highly significant for all characters studied in the F1 generation. Based on GCA, 4 genotypes (Sakha101, Gz6903-3-4-2-1, Gz9577-4-1-1 and Hassawi) exhibited highly significant negative values for stem borer resistance (–0.53, –1.06, –0.18 and –0.49, respectively) indicating they are the best combiners for stem borer resistance. Based on SCA analysis, nine cross combinations showed highly significant negative effects for stem borer resistance. Similarly, the cross Giza178 Hassawi was the best combination with significantly highest value for early maturity. In addition, seven crosses showed highly significant negative SCA for plant height trait. On the other hand, for panicle length, number of primary branches/panicle, panicle weight and 1000-grain weight, seven, four, eight and six crosses showed highly significant positive SCA, respectively. The result further revealed that the non-additive dominance genetic variance was higher than the additive variance for all evaluated traits indicating that non-additive genetic variances have a role in their inheritance. The broad-sense heritability estimates were high for all the studied traits. The stem borer resistance was significantly correlated with panicle weight and 1000-grain weight, which also showed a highly significant correlation with grain yield/plant. Thus these traits can be effectively employed in a breeding program to confer resistance against stem borer infestation in rice. It was further supported by biplot analysis, which clustered these potentially important traits into two quadrants showing their importance in any future breeding program to control stem borer infestation. This study has contributed valuable information for evaluation of genetic diversity in the local rice germplasm and its utilization in futuristic rice genetic improvement programs.