不同水稻品种对三化螟抗性差异的机理

研究了不同水稻品种对三化螟Scirpophaga incertulas抗性差异的机理。结果表明, 在汕优63、镇稻2号和92-109稻株中, 虫体的游离必需氨基酸含量极低（0.422～0.875 nmol/mg）, 幼虫生长发育缓慢;而在9-92、武育粳3号等稻株中, 虫体的游离必需氨基酸含量高（2.788～5.421 nmol/mg）, 幼虫生长快。虫体的游离必需氨基酸含量和生长发育的差异, 与不同水稻品种的游离必需氨基酸含量、总必需氨基酸含量、还原糖含量和叶鞘硅化细胞密度均无明显相关。叶鞘维管束间距、鞘脊宽度及小于蚁螟头宽的叶鞘维管束间距百分率的差异, 是不同水稻品种抗螟性差异的主要作用因子。     

Soil application of silicon reduces yellow stem borer,Scirpophaga incertulas (Walker) damage in rice

The effect of soil application of rice husk ash (RHA), a cheap renewable source of silicon, and imidazole (a silicon solubilizer and carrier) on yellow stem borer (YSB), Scirpophaga incertulas (Walker), and its damage to rice plants were investigated. Treatments included soil application of RHA (T1), imidazole (T2), RHA + imidazole (applied once at vegetative stage, T3) and RHA + imidazole (applied twice at both vegetative and booting stages of crop growth, T4) with an untreated control (T5). The effect was tested in five varieties, viz., BPT 5204, KRH2, Pusa Basmati 1, MTU1010 and Vandana. All the soil treatments reduced damage by YSB at vegetative and reproductive phases across five varieties as compared to untreated control. Scanning electron micrograph and electron‐dispersive X‐ray spectrum analysis of stem tissue of rice variety BPT 5204 treated with silicon revealed the enhanced deposition of silicon in cell walls and 2.1‐ to 5.3‐fold increase in silicon content across treatments. Larvae collected from the silicon‐treated plants had worn mandibles, and the histological studies showed rupture of the peritrophic membrane, increased vacuolation, disintegration of columnar cells and discharge of cellular contents into the gut lumen due to abrasion of midgut epithelium, as compared to untreated control where the columnar cells and midgut lining were intact. Although all the treatments were effective, T4‐imidazole applied twice along with RHA was more effective in reducing YSB damage followed by T3‐imidazole applied once with RHA at tillering stage, T2‐imidazole alone and T1‐RHA in the descending order of efficacy.     

Egg parasitism of the yellow rice borer,Scirpophaga incertulas [Lep.: Pyralidae] in Bangladesh deepwater rice

Studies on deepwater rice in Bangladesh from 1977 to 1980 showed that 61–89% of the egg masses of the yellow rice borer,Scirpophaga incertulas (Walker), were attacked by hymenopterous parasites. Egg parasitism increased from 43–48% in broods 2–4 (May–August) to 64–88% in broods 5–6 (September–November). Parasitism was reduced in broods 4 and 5 in 1979 (because of lower host densities) and in 1980 (possibly due to extreme late flooding). Telenomus rowani (Gahan), active throughout the year, parasitized 64% of the eggs in the masses it attacked, 32 larvae/mass surviving.Tetrastichus schoenobii Ferrière first appearing at medium host densities, increased rapidly to attack half of the brood 5 and 6 masses. More than 98% of the eggs in the attacked masses were parasitized, leaving only 1.6 surviving larvae/mass. In 1979 its appearance was delayed by 10 weeks and fewer masses were parasitized due to lower host densities.Trichogramma japonicum Ashmead andTelenomus sp. (a new record) were less important. Multiple parasitism of masses rose from 7% in brood 2 to 28% in brood 5. Egg parasites clearly reduce the numbers ofS. incertulas, a major pest, and thus probably improve the yields of deepwater rice.     

The effect of precipitation on the break of diapause in the white rice borer Rupela albinella (Cr.) in surinam (South America)

Diapause was studied in the white rice borer to find a sound basis for an effective rice stubble destruction programme. Diapausing larvae of this borer remain in the stubble after harvesting and carry the species over a period during which the hostplant may be scarce or absent. The influence of rainfall on the duration of diapause was experimentally analysed. As a rule the higher the amount of precipitation, the sooner the moths make their appearance. This break of diapause is accelerated the longer the diapausing larvae stayed in the dry stubble. It is suggested that under the prevailing weather conditions stubble destruction within one month after harvest will prevent the appearance of the moths.

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Résumé L'auteur a étudié la diapause chez le borer du riz Rupela albinella afin de trouver une base solide pour un programme de destruction des chaumes du riz. Les chenilles en diapause restent abritées dans le chaume après la récolte. L'influence des précipitations sur la durée de la diapause a été analysée expérimentalement. L' auteur observa une corrélation directe entre la quantité des précipitations et l'apparition des papillons. Ce réveil des chenilles en diapause est acceléré en fonction de la durée de leur séjour dans le chaume sec.L'auteur suggère que la destruction des chaumes dans le mois suivant la récolte peut empêcher l'apparition des papillons.

     

Seasonal parasitism by egg parasites of the yellow rice borer,Scirpophaga incertulas [Lepidoptera: Pyralidae]

Scirpophaga incertulas (Walker) [Lep.: Pyralidae] is a common pest of rice in West Bengal, India. A three year study (1978–1981) revealed that egg parasites were important in reducing the borer population in an uninterrupted rice cultivation practice. The parasite activity showed periodical fluctuation coinciding with the moth emergence. It was evident thatTelenomus spp. were most common and most dominating in the early summer crop and became highly adaptive under diverse crop growing situations. Among three species ofTelenomus, T. rowani Gahan was the most abundant durint the summer and winter seasons.Tetrastichus schoenobii Ferriere was second in importance in regulating the borer population and its attack was heaviest on the later broods in rice crops cultivated during winter.Trichogramma japonicum Ashmead was very sporadic and had a particular preference for the dry period. It usually occurred in association with other two parasites in the later part of the year. Parasitism of egg masses by two or more species of the parasites was also common during the peak period of parasite activity.      

再生稻与三化螟越冬幼虫的关系的研究

在华南,秋季水稻收获后,留在田间的一些稻桩,既含有再生稻株,亦藏蛰伏的三化螟幼虫,当再生稻桩率为14％～19％时,其中藏有的三化螟幼虫占该虫总数的47％～65％。由于三化螟得到再生稻株的保护,在整个越冬期间藏于再生株内的蝗虫死亡率偏低,至多为非再生株同时的50％,再生株百株活虫数为26～42头,而非再生株内仅为1～7头。     

福建省水稻螟虫种群发生变化及原因初探

根据资料及系统调查分析了福建水稻螟虫发生的新特点,揭示了不同稻区不同年份间二化螟种群变动情况及其原因,旨在为稻螟的预测预报和可持续综合治理提供理论依据。     

Evaluation of three aqueous plant extracts and Lamdacot in controlling eggplant fruit borer (Daraba laisalis Wlk.) (Lepidoptera: Pyralidae) in north-eastern Nigeria

Field experiments carried out in Dadinkowa, Gombe State, Nigeria, during 2007 and 2008 cropping seasons evaluated the efficacy of three aqueous plant extracts namely neem (Azadirachta indica A.H.L. Juss.), bitter melon (Momordica balsamina Linn.) and siam weed (Chromolaena odorota (L.) King and Robinson) compared to a conventional insecticide, Lamdacot 500EC, in managing fruit borer (Daraba laisalis Wlk.) attack of eggplants in north-eastern Nigeria. The experiments were laid out in a randomised complete block design replicated four times including controls. The results showed that the application of aqueous extracts (5% w/v concentration) of A. indica and M. balsamina at one-week interval during the fruiting stage was effective and at par with the conventional insecticide, Lamdacot, in reducing eggplant fruit borer infestation and fruit damage, as well as the resulting increase in fruit yield. Farmers can therefore adopt the practice of applying 5% w/v concentration of the above aqueous plant extracts at weekly intervals to control fruit borer attack of eggplants in the north-eastern region of Nigeria.     

江淮稻区三化螟发生、防治的几个问题及防治对策的重新思考

20 0 0年江淮稻区 3代三化螟Ｔｒｙｐｏｒｙｚａｉｎ ｃｅｒｔｕｌａｓ(Ｗａｌｋｅｒ)发生危害严重 ,部分县、乡 (镇 )特大发生 ,发生危害实属历史罕见。相当一部分田块危害 (白穗 )程度可称为触目惊心。以邗江新坝为例 ,3代三化螟白穗率最高达 6 5 7% ;白穗率 3 0 %以上的田块占 1 0 %左右 ;白穗率5%～ 1 0 %的田块占 40 %～ 50 % ;5%左右的田块占 3 0 %～ 40 %。相当一部分严重危害的田块看上去象秋天的芦苇滩 ,健穗反而难以见到。本文就 2 0 0 0年三化螟的发生、防治的调查结果 ,结合过去对三化螟的一些研究阐述三化螟的几个问题 ,并提出…     

Cyanobacteria in the Australian northern savannah detect the difference between intermittent dry season and wet season rain

This research was conducted in the northern Australian savannah at Boodjamulla National Park where cyanobacterial crusts dominate the soil and rock surfaces in between tussock grasses. It is widely accepted that terrestrial cyanobacteria are drought tolerant and rapidly recommence photosynthesis once moisture is available. Initial tests at the research site indicated that cyanobacteria did not respond to rehydration during the dry season, even after several days. We hypothesised that resurrection had not taken place and new growth from survival cells had to take place during the follow-up wet season. To further understand the desiccation–resurrection processes we tested photosystem II (PSII) responses both during the dry and wet seasons. In the 2009 dry season after 125 days without rain, crust samples were regularly rehydrated. Over the 10 day trial cyanobacteria did not recover PSII activity or CO₂-uptake. Although new colonies of Nostoc grew other cyanobacteria remained inactive, even though liverworts and lichens in the same crusts had responded within 24 h. Dry season cyanobacterial crusts were collected in 2010 then reintroduced into their natural environment and exposed to rainfall during the 2011 wet season. Within 24 h PSII in cyanobacteria from a range of crust types had resurrected and CO₂-uptake was verified, although different crust types responded at significantly different rates. These are the first studies that have demonstrated that PSII does not respond to rainfall during the dry season and cyanobacterial function appears controlled by other environmental conditions. It is likely that mass extracellular polysaccharide (EPS) production during the wet season, once dry, protects cyanobacteria from premature resurrection in the dry season. We propose that EPS regulates moisture penetration, thus the resurrection of PSII at the onset of the wet season, at which time moisture and humidity alters the rheological properties of EPS permitting rehydration.     

Effects of temperature on the development and reproduction of sugarcane top borer Scirpophaga excerptalis (Lepidoptera: Pyralidae)

To determine the effects of temperature on the development and reproduction of top borer Scirpophaga excerptalis Walker (Lepidoptera: Pyralidae), the durations of different developmental stages and reproductive capacity of S. excerptalis were measured at 20, 23, 26, 29 and 32℃. The results showed that the average durations of various developmental stages of S. excerptalis shortened with increasing temperatures from 20 to 32℃. The durations to complete one life cycle were 113.17 days at 20℃, and 39.50 days at 32℃. The developmental rate of each stage and generation was positively correlated with the temperature, which was consistent with the Logistic regression model. The temperature thresholds for egg, larval, pupal and preoviposition stages and the total cycle were 13.73, 14.73, 13.91, 13.66 and 14.10℃, respectively. The effective accumulative temperature was 112.62, 370.01, 188.17, 23.82 and 718.07 degree-days (DD), respectively. The adult longevity shortened with increasing temperatures, and the highest number of eggs laid per female was 204.74 eggs at 29℃. The survival rates of eggs, larvae and the whole generation were the highest at 26℃, which were 87.25%, 56.67% and 37.21%, respectively while the highest survival rate of the pupa was 76.69% at 29℃. There was no significant difference for the total cycle at 23-29℃. The results indicated that temperature was the key factor affecting the development and reproduction of S. excerptalis, and the optimum temperature for development and reproduction ranged from 23 to 29℃.     

Phosphorus supply and the growth of frequently defoliated white clover (Trifolium repens L.) in dry soil

A previous study found that increased phosphorus (P) supply to frequently defoliated white clover plants, growing in a low-P, dry soil, alleviated water stress symptoms and increased plant recovery on rewatering. In this study we determined how these stresses influence white clover growth. Measurements were made of the leaf canopy, stolon infrastructure and root system of the white clover plants growing in a low-P soil. Treatments included the factorial combination of four levels of P supply, two defoliation frequencies and two soil water treatments. White clover growth declined markedly when P-deficient plants were exposed to frequent defoliation and dry soil conditions. Leaf area was more affected than other parameters, in that the combination of stresses reduced leaf area to 2% of maximum observed for infrequently defoliated plants growing in high-P soil, with adequate water. Increased P supply generally increased the growth of all plant parts. Frequently defoliated plants growing in dry soil produced similar or greater leaf mass and leaf area as plants from similar treatments growing in wet soil, when the P supply increased to 50 mg P kg-1 soil. Higher P rates were able to negate the effect of dry soil on these frequently defoliated plants, as a result of larger water and P uptake. Also, the frequently defoliated plants with restricted root growth did not respond to a small increase in P supply (17 mg P kg-1 soil) for the leaf growth, irrespective of whether they were growing in wet or dry soil. Infrequently defoliated plants with greater root growth, compared to frequently defoliated plants, more than doubled their leaf mass with this P treatment.     

扬州地区水稻二化螟寄生蜂种类及主要寄生蜂发生动态

本文报道了江苏扬州地区水稻二化螟Chilo suppressalis(Walker)寄生蜂主要有10种,即中华钝唇姬蜂Eriborus sinicus(Holmgren)、二化螟盘绒茧蜂Cotesia chilonis(Munakata)、稻螟小腹茧蜂Microgaster russata Haliday、螟甲腹茧蜂Chelonus munakatae Munakata、中华茧蜂Amyosoma chinensis(Szepligeti)、螟黄足盘绒茧蜂Cotesia flavipes(Cameron)、夹色姬蜂Auberteterus alternecoloratus(Cushman)、桑蟥聚瘤姬蜂Iseropus(Gregopimpla)kuwanae(Viereck)、螟蛉瘤姬蜂Itoplectis naranyae(Ashmead)以及二化螟盘绒茧蜂的重寄生蜂绒茧灿金小蜂Trichomalopsis apanteloctena(Crawford)。田间系统调查表明:扬州地区7-9月水稻二化螟寄生蜂的主要种类为二化螟盘绒茧蜂、中华钝唇姬蜂、螟甲腹茧蜂、稻螟小腹茧蜂、螟蛉瘤姬蜂、桑蟥聚瘤姬蜂,但这些寄生蜂对一代水稻二化螟幼虫的寄生率较低,对二代水稻二化螟幼虫的寄生率高。水稻二化螟越冬期的系统调查表明:扬州地区二化螟越冬幼虫的寄生蜂主要有3种,即二化螟盘绒茧蜂、中华钝唇姬蜂和稻螟小腹茧蜂,其中二化螟盘绒茧蜂和中华钝唇姬蜂是寄生水稻二化螟越冬幼虫的优势种。水稻二化螟越冬幼虫的寄生率调查表明,扬州地区水稻二化螟越冬幼虫的寄生率在不同年份间有一定的波动,但一般都在15%以上,有的甚至高达89.88%,因此寄生蜂对二化螟越冬幼虫具有很好的控制作用,能有效压低来年水稻二化螟的田间越冬基数。此外,3种寄生蜂出茧时间在1月和2月之间达到最长,分别达到19.79 d、17.26 d和27.00 d,该结果表明,在扬州地区这3种寄生蜂可能都存在滞育现象。     

两种稻螟灯下蛾峰日与月相的关系

经常规及圆形统计分析我国 2 0世纪 5 0年代灯光诱蛾资料 ,发现三化螟和二化螟的蛾峰日受到月相的显著影响。三化螟蛾峰数的平均角 (集中趋势 )对应于农历 2 6日 0时 5 3分 (P<0 0 0 1) ,二化螟对应于 2 4日 2 3时 5 3分 (P <0 0 0 1) ,二者差异不显著 (P >0 2 5 ) ,合并对应于 2 5日 11时 36分。     

Movement of Mexican rice borer (Lepidoptera: Crambidae) through the Texas rice belt

Pheromone-baited traps were used to monitor the movement of the Mexican rice borer, Eoreuma loftini (Dyar) (Lepidoptera: Crambidae), through the Texas rice belt from 2000 to 2005. Based on location of discovery in each county and year, the average rate of spread from 1980 to 2005 was 23 km/yr. From 2000 to 2005, the leading edge of the infestation has moved 16.5 km/yr toward Louisiana. The 1.8-fold increase (99% confidence interval) of the area occupied from 2000 to 2005 in the Texas rice belt indicates an expansion of the distribution of E. loftini. If movement continues to occur at similar rates, E. loftini will reach Louisiana by 2008.     

转 Bt 基因水稻对三化螟自然种群的影响

为了了解水稻重要害虫三化螟 Scirpophaga incertulas（Walker）对转 Bt 基因水稻产生抗性的潜在风险,本文利用自然种群生命表,研究了第 3 代三化螟在转Bt基因杂交稻汕优 63 及非转 Bt 基因杂交稻汕优 63 上的种群参数。结果表明：在 Bt 稻上1～2 龄幼虫的存活率为 4.03%,极显著低于非转基因 SY63（55.76%）;Bt 稻上幼虫为害率为1.75%,极显著低 于非转基因 SY63（5.98%）;Bt 稻上存活的幼虫发育历期明显长于非转 Bt SY63。     

Correlation between large-scale atmospheric fields and the olive pollen season in Central Italy

Olives are one of the largest crops in the Mediterranean and in central and southern Italy. This work investigates the correlation of the Olea europaea L. pollen season in Perugia, the capital city of the region of Umbria in central Italy, with atmospheric parameters. The aim of the study is twofold. First, we study the correlation between the pollen season and the surface air temperature of the spring and late spring in Perugia. Second, the correlation between the pollen season and large-scale atmospheric patterns is investigated. The average surface temperature in the spring and late spring has a clear impact on the pollen season in Perugia. Years with higher average temperatures have an earlier onset of the pollen season. In particular, a 1°C higher (lower) average surface temperature corresponds to an earlier (later) start of the pollen season of about 1 week. The correlation between the pollen season and large-scale atmospheric patterns of sea level pressure and 500-hPa geopotential height shows that the cyclonic activity in the Mediterranean is unequivocally tied to the pollen season in Perugia. A larger than average cyclonic activity in the Mediterranean Basin corresponds to a later than average pollen season. Larger than average cyclonic activity in Northern Europe and Siberia corresponds to an earlier than average pollen season. A possible explanation of this correlation, that needs further investigation to be proven, is given. These results can have a practical application by using the seasonal forecast of atmospheric general circulation models.     

Difference in the time of mating activity between host-associated populations of the rice stem borer, Chilo suppressalis (Walker)

Mating activities of the rice stem borer, Chilo suppressalis, were compared between rice‐ and wateroat‐feeding populations, and two potential temporal factors that may act as reproductive barriers were examined. Seasonal data of the number of moths attracted to pheromone traps showed that the peak of emergence at the rice field was approximately 10 days earlier than that at the wateroat vegetation in the first flight season, although there was a broad overlap of emergence at the two locations. Both field observations and a laboratory experiment showed that moths from the rice field started mating earlier than those from the wateroat vegetation. However, whereas the difference was distinctive in the laboratory experiment, mating activity at the wateroat vegetation shifted significantly to an earlier time phase than that observed in the laboratory. Body size data showed that the male moths attracted to the pheromone traps at the wateroat vegetation were significantly larger than those at the rice field, suggesting that the traps at the two locations mainly attracted moths originating from different host plants. However, pheromone‐trapped males at the rice field were significantly larger than those reared from overwintering samples. These results support the idea that males from the wateroat vegetation migrate to the rice field. The differences in seasonal and temporal mating activity and their effects on development of reproductive isolation between host‐associated populations are discussed.