Effect of Rapid Cold Hardening on the Cold Tolerance of the Larvae of the Rice Stem Borer,Chilo suppressalis(Walker)

The effects of rapid cold hardening （RCH） on the cold tolerance of the last instar larvae of Chilo suppressalis （Walker） were evaluated for the first time. The discriminating temperature, induction, detection, duration and extent of RCH of the larvae in the laboratory were tested, and the supercooling points （SCPs） and the contents of water and lipid of the larvae after RCH treatment were determined, respectively. The results showed that the discriminating temperature of the larvae was about -21℃. Mean survival rates of the larvae which exposed to either 0 or 5℃ for 2 and 4 h before exposure to the discriminating temperature for 2 h were significantly higher than those of the control groups （P 〈 0.05）. Moreover, the highest survival rate appeared in the larvae after 0℃ for 4 h treatment. The protection against low temperature gained by RCH at 0℃ for 4 h was rapidly lost on return to 28℃. Mean survival rates of RCH larvae were significantly higher than those of non-acclimated （NACC） larvae and acclimation （ACC） larvae when they were exposed to the discriminating temperature for 2 or 4 h （P〈 0.05）. Moreover, the rates of NACC, ACC, RCH and ACC ＋ RCH larvae from 2 to 6 h to the discriminating temperature resulted in a significant decline. The values of SCPs and the contents of lipid of the larvae which exposed to either 0 or 5℃ for 2 and 4 h showed no significant difference at 0.05 level compared to those of the control groups. But the contents of water in the larvae were obviously decreased. Therefore, it could be concluded that RCH could enhance cold tolerance and affect partly physiological and biochemical components of the larvae of C. suppressalis, but the underlying mechanisms needs to be further explored.

Application of vetiver grass Vetiveria zizanioides: Poaceae(L.) as a trap plant for rice stem borer Chilo suppressalis: Crambidae(Walker) in the paddy fields

Rice is an important staple food in China and it is at risk of attack by rice striped stem borer Chilo suppressalis, which occurs in most rice growing areas. In recent years, severe C. suppressalis outbreaks have been observed in China mainly due to changes in the rice cultivation systems, wide adoption of hybrid varieties and resistance to the dominant insecticides. Management relies primarily on chemical insecticides and resistance is an important contributing factor in these outbreaks. As a result, food safety of agricultural produce is reduced and the ecological and environmental integrities are threatened as well. Recently, environmentally friendly pest management measures, such as trap plants have been introduced for C. suppressalis management and this method can greatly reduce insecticide use. Our previous results indicated that the vetiver grass(Vetiveria zizanioides) is a dead-end trap plant that can effectively attract the adult females of C. suppressalis to lay eggs on it but where larvae are unable to complete their life cycle. This paper further explored the application of vetiver grass as a trap plant to manage C. suppressalis in the paddy fields. This environment-friendly tool can not only reduce C. suppressalis populations, it can also increase the diversity and abundance of natural enemies that can provide better environmental conditions for rice production.

Electrophysiological responses of the rice striped stem borer Chilo suppressalis to volatiles of the trap plant vetiver grass (Vetiveria zizanioides L.)

Vetiver grass （Vetiveria zizanioides L.） was previously found to effectively attract female adults of Chilo suppressalis （Walker）, an important pest of rice. To determine the volatile compounds involved in this attraction, electroantennography （EAG） responses to seven synthetic volatiles released from vetiver plants were examined. Our results indicated that the responses of C. suppressalis adult antennae to the different compounds varied widely. The compounds elicited strong EAG responses in female antennae were subsequently selected for further EAG response tests, namely, caryophyllene, β-ocimene, linalool and a-pinene. EAG responses to a combination of these four compounds did not differ significantly from the individual compounds. However, pair combination tests indicated that 0.01μg μL-1linalool and 50 μg μL-1 α-pinene, 50 μgμL-1 caryophyllene and 0.01μg μL-1 linalool, 0.01 μg μL-1 13-ocimene and 0.01 μg μL-1 linalool, and 0.01μg μL-1 β-ocimene and 50 μg μL-1 caryophyllene elicited significantly greater EAG responses in 3-day female moths compared to the 1-day female. These compound combinations and the corresponding ratios are probably playing an important role in attracting female adults of C. suppressalis to the vetiver grass.

Preliminary Study on Resistance of the Rice Stem Borer (Chilo Suppressalis) to Fipronil

By means of topical application, fipronil resistance was surveyed in the rice stem borer, Chilo suppressalis, from 12 diferent areas in east China from 2001 to 2004. The rice stem borers in most regions of Jiangsu and Anhui were still susceptible to fipronil. But in Wuxi, Jiangsu Province and Cixi, Zhejiang Province, their sensitivity became decreased （resistance ratios were 3.1 and 3.6, respectively）, and the medium level of resistance （resistance ratio was 21.2） was found in Cangnan, Zhejiang Province. So, it was still at the early stage for fipronil resistance development in this pest. Synergism experiments showed that piperonyl butoxide（PBO） had a little effect on both susceptible and resistant borers （synergism ratios were 1.1-1.2）. Though triphenyl phosphate （TPP） and diethyl meleate （DEM） had no effect on the susceptible borers, they had significant synergism on fipronil in the resistant population to fipronil （synergism ratios were 1.8 and 1.6, respectively）, indicating esterase and glutathion S-transferase may be involved in the resistance mechanism. Bioassay with currently used insecticides indicated that triazophos （because of high resistance）, trichlorphon and acephate had very low toxicity to resistant borers. But diazinon, pyridaphenthion, decamethrin and avermeatin showed high toxicity and had no cross resistance to fipronil, which could be considered as substitute insecticides in the resistance managment.

Effects of High-Quality Aromatic Rice Varieties on the Fitness of the Striped Stem Borer, Chilo suppressalis (Walker) in Central China

The striped stem borer （SSB）, Chilo suppressalis （Walker） （Lepidoptera： Pyralidae）, is a major pest of rice in China. Variation in host-plant quality may affect the body size of herbivorous insects, which in turn, can determine their life-history parameters such as survival, fecundity and fitness. In this study, we tested the effects of high-quality aromatic rice varieties on the fitness of SSB in China. Results showed that 1st instar larvae had higher penetrating rates and survival rates on the high-quality aromatic rice varieties （EX-1 and WX-988） than that on the non-aromatic rice varieties （EZ-5 and LYP-9）. In addition, shorter developmental periods, greater female pupal weights and higher of other life-history parameters （hatching rate, pupation rate, eclosion rate and increase index） were found on the high-quality aromatic rice varieties, although only female pupal weight showed a significant difference between the two varieties. The highest dead heart rate was found on the aromatic rice variety of EX-1. These results indicate that SSB sustains a lower fitness cost when consuming the high-quality aromatic rice varieties （EX-1 and WX-988） than on the non-aromatic rice varieties （EZ-5 and LYP-9） in Central China.

Suppression of Rice Stem Borer, Chilo suppressalis by Mass Trapping Using Synthetic Sex Pheromone in Paddy Field

Suppressing effects of mass trapping using synthetic sex pheromone with main active ingredients of Z-11-hexadecenal, Z-13-octadecenal and Z-9-hexadecenal on the rice stem borer, Chilo suppressalis were investigated during the flight periods of the overwintering and 1st generation in the paddy area of 60 ha in 1999. Population density of C. suppressalis in the pheromone-treated fields was lower than that in control. The egg masses decreased by 74.39% and population size of adult males of the 1st generation decreased by 61.64% in the treated fields as compared to control. Meanwhile, the damage by C. suppressalis larvae was significantly lower in the treated fields than control (t-test, P=0.05). Percentages of brownish leaf sheath, dead heart, and white head in the treated fields were decreased by 70.90%, 57.01% and 44.30%, respectively in contrast to control. The present study demonstrated that mass trapping to C. suppressalis using synthetic sex pheromone shows great potential as an alternative measure in an environment-friendly pest management and at the same challenging the insecticide use that has some environment impacts.

Population Genetic Analysis of the Rice Stem Borer, Chilo suppressalis, in the South China

Genetic variation and patterns of genetic differentiation of the rice stem borer, Chilo suppressalis （Lepidoptera： Pyralidae）, from the South China were analyzed using 6 microsatellite markers and two partial mtDNA （cox1 and cox2） regions. All of the 6 microsatellite loci were polymorphic in the studied seven populations. The allelic richness per population ranged between 5.67 and 14.00, and average H E and H O values were 0.6246-0.8329 and 0.2634-0.6061, respectively. As the mitochondrial genome is a single genetic locus, we only present results for the concatenated data set （cox1 plus cox2 gene sequences, 513 bp）. The concatenated data showed high level of genetic diversity and there are 23 variable polymorphic sites among the 513 sites in concatenated data. Nearly all of （20 of 21） pairwise F ST comparisons among populations showed genetic differentiation with moderate to high pairwise F ST values based on microsatellite markers. However, for the mtDNA data, most of the seven populations did not show significant differentiation with other populations. The differences of population differentiation obtained with the two different genetic markers could be mainly attributed to the different mutation rates of microsatellite and mtDNA. There was not genetic structure existed in these studied populations based on microsatellite loci and mtDNA data. The analysis based on network, mismatch distribution, Tajima＇s D and F S indicated that the studied populations were from the recent same ancestor or the same refuge and followed by a sudden demographic expansion condition.

Cloning,Tissue Distribution,and Transmembrane Orientation of the Olfactory Co-Receptor Orco from Two Important Lepidopteran Rice Pests,the Leaffolder(Cnaphalocrocis medinalis) and the Striped Stem Borer(Chilo suppressalis)

In insects,the sense of smell is mainly mediated by olfactory receptors（Ors）.Olfactory co-receptor（Orco）,which is coexpressed with the Ors in almost all olfactory receptor neurons（ORNs）,is demonstrated to be an essential component in the insect olfactory system.It can be potential target for developing novel olfactory-disruption strategy to control insect pests.In this study,two full-length cDNA sequences encoding Orcos（CmedOrco and ChsupOrco） were cloned from two Lepidopteran rice pests,the rice leaffolder,Cnaphalocrocis medinalis and the rice striped stem borer,Chilo suppressalis.The amino acid sequences of CmedOrco and ChsupOrco showed high similarity to the previously identified Orcos from other insect species. Bioinformatic prediction and cellular immunofluorescence indicated that CmedOrco and ChsupOrco were both seven-transmembrane proteins with intracellular N-termini and extracellular C-termini.mRNA expression levels of the two Orcos were much higher in male and female antennae than those in non-olfactory tissues,and the ChsupOrco transcripts reached a peak level in adults compared to other life stages.Our results provide a foundation from which it will be possible to elucidate the roles of Orco in moth olfaction and for the development of environment-friendly management strategies of these two rice insect pests.

The insecticide resistance in stripped stem borer,Chilo suppressalis(Walker)

The stripped stem borer (SSB),Chilo suppressalis (Walker) is one ofthe major insect pests of rice in Chi-na. Chemical control has been acommon practice in SSB managementsince 1950s. Insecticides used in-cluded BHC before 1983; organophos-

Rice(Oryza sativa L.)Breeding among Hassawi Landrace and Egyptian Genotypes for Stem Borer(Chilo agamemnon 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.

Identification of Bt-transgenic Rice Plants for Resistance to Stripe Stem Borer (Chilo suppressalis) and Genetic Analysis of the Transgenes

Resistance to herbicide Basta was used to identify Bt-transgenic rice plants and the progenies of crosses between the Bt-transgenic rice and the rice varieties cultivated in the Huang Huai area of China. The results demonstrated that the Basta-positive rice plants were highly resistant to stripe stem borer (Chilo sup-pressalis) both in the laboratory and field tests. Both cryIA (b) and bar genes were expressed and co-inherited in both self ing and crossing progenies. Mendelian segregation of the marker gene bar was observed in F2 and BC1 progenies. The results implicates that it is possible to transfer cryIA (b) gene into other cultivated varieties through crosses and back crosses.

A New and Simple Method for Collecting Eggs of the Striped Stemborer,Chilo suppressalis

The method for collecting eggs of the striped stem borer, Chilo suppressalis using plastic bags was studied in comparison with using caged rice plants. There was no significant difference in fecundity of C. suppressalis at 279 eggs/moth and in percentage of hatched eggs at 95% between in plastic bags and on rice plants. More egg masses were collected on plastic bags than on rice plants, whereas more smaller egg masses (less than 100 eggs per mass) in plastic bags than on rice plants. The advantages in collecting eggs of C. suppressalis and other insects by using plastic bags were also discussed.

Analysis of sex pheromone production and field trapping of the Asian corn borer(Ostrinia furnacalis Guenée)in Xinjiang,China

Identifying the sex pheromone systems of local pest populations facilitates their management,especially for moth species that show significant geographic variation in sex pheromone communication.We investigated the pheromone production and behavioral responses of the Asian corn borer(Ostrinia furnacalis Guenée;ACB)in Xinjiang,China.The ACB produces three compounds:(Z)-12-tetradecenyl acetate(Z12-14:Ac)and(E)-12-tetradecenyl acetate(E12-14:Ac)which are two sex pheromone compounds,and n-tetradecyl acetate(14:Ac)which has variable roles in mediating behavioral responses.The ratios of these three compounds produced in female gland are geographically distinct among different populations.Quantitative analysis of pheromone production showed that the proportions of Z12-14:Ac in the E/Z isomers(i.e.,Z and E12-14:Ac)and the proportions of 14:Ac in the ternary blend respectively averaged 60.46%(SD=5.26)and 25.00%(SD=7.37),with their probabilities normally or near-normally distributed.Trapping experiments in a cornfield indicated that deploying the E/Z isomers and the three compounds in rubber septa close to their gland ratios yielded the most captured males,while other ratios that deviated from the gland ratios showed reduced field captures.The ternary blend was significantly more attractive to males than the E/Z isomers in the field,indicating a functional role of 14:Ac as the third pheromone component used by the local population.Additionally,the dose-response test demonstrated that the application of the three compounds at dosages between 200 and 350μg attracted significantly more males compared to other dosages.Therefore,the characterization of this local ACB pheromone system provides additional information about its geographic variation and serves as a basis for optimizing the pheromone-mediated control of this pest in Xinjiang.

Biological Investigation of Nano-Organometallic Agents against Bacteria and Chilo polychrysus

Nanotechnology is the new hope, and is hailed as having the potential to increase the efficiency of energy consumption, help clean the environment, and solve major health problems. This research aims to increase the biological activities of natural syringaldehyde. The synthesis of syringaldehyde derivatives and controls the size of the material particles in the nanometer ranges. Nano-organic compounds (L1 - L2) and nano-organometallic compounds (C1 - C4) are used for the study of physicochemical characterization and biological activities. Antioxidant capacities were the DPPH and FRAP techniques, and bacterial abilities against Escherichia coli, Salmonella spp. and Staphylococcus aureus. The syringaldehyde salicylic hydrazone (L2) showed a high scavenging ability to DPPH. Free radical exhibited with IC50 values as low as 51.109 ppm. The ability of antioxidants by FRAP showed that substances are capable of reducing Fe3+ and most of C3, the ability to inhibit the growth of bacteria with the lowest MIC and MBC values and the ability to Chilo polychrysus (Meyrick) found that C1 and C2 showed LT50 at 24 h and 48 h (19.00 and 19.33). These particles should develop as biological agents to reduce the use of chemicals that are harmful to humans and the environment.

广西越冬稻螟种类及其空间分布型研究

【目的】水稻螟虫在广西广泛分布,严重威胁水稻生产,明确广西稻螟的越冬情况及其空间分布型,了解水稻螟虫的种类及分布情况,为其预测预报及科学防治提供依据。【方法】分别在桂东北、桂西北、桂东南、桂西南和沿海地区,共27个市(县)进行越冬螟虫调查,并采用棋盘式取样法,将稻桩带回室内仔细剥查鉴定螟虫种类及数量,分析螟虫种群的空间分布型。【结果】本次越冬调查结果表明,广西越冬螟虫种类有大螟(Sesamia inferens)、二化螟(Chilo suppressalis)、三化螟(Scirpophaga incertulas)和台湾稻螟(Chilotraea auricilia),其中大螟和二化螟为优势种。三化螟主要分布在纬度23°-25°,其他螟虫在广西越冬未呈现明显规律。空间分布参数表明,除13、20和22号田块大螟呈均匀分布外,其他田块螟虫均呈聚集分布,且聚集度随密度的增加而升高。大部分田块螟虫聚集原因是由环境因素引起的。【结论】在广西,越冬螟虫呈聚集分布,大螟和二化螟为田间越冬优势种群,台湾稻螟次之,三化螟零星发生。

辽河流域栽培稻对二化螟(Chilo suppressalis)的抗性

采用活体成株鉴定法测定了辽河流域主栽水稻品种对二化螟发育和为害的影响,同时测定了不同品种的主要形态特性、硅细胞数量和主要生化特性,评价这些品种对二化螟的抗性、分析其发生的可能机制。盐丰47对二化螟幼虫表现出较好的抗性,在沈农265上二化螟幼虫体重最小。在所测定的特性中,螟害株率与不同品种倒二叶叶角的自然对数之间具有显著的正相关关系,与稻茎Si含量之间具有显著的负线性相关关系;二化螟幼虫体重只与不同品种稻茎直径之间具有显著的正线性相关关系。研究结果对水稻品种抗性利用和未来水稻抗性育种的意义。

纳米农药防治水稻二化螟效果初探

近年来,二化螟在宁波市水稻上逐年加重发生。为明确纳米水性制剂(以下简称“纳米农药”)对二化螟的防治效果,在二化螟防治适期,选择甲氨基阿维菌素苯甲酸盐传统制剂和纳米制剂、乙多·甲氧虫、乙基多杀菌素、四唑虫酰胺共5种杀虫剂开展田间药效试验。结果表明,5%甲氨基阿维菌素苯甲酸盐纳米制剂施药14 d后的枯心防效和杀虫防效分别在80%和85%以上,且保产效果更佳,挽回损失率达44%~45%,防效及挽回损失率均极显著高于5%甲氨基阿维菌素苯甲酸盐传统制剂。

芦禾草螟研究进展

芦苇是我国重要的湿地资源,因受芦禾草螟钻蛀危害,生态和经济损失严重。本文对芦禾草螟的生物生态学、防治技术方面的研究进行综述,以期为加强吉林省芦苇分布区芦禾草螟防治工作提供参考。

林州山楂园桃小食心虫发生规律及性诱剂防控技术

桃小食心虫是危害山楂果实的重要害虫之一。研究分析了该虫在河南林州山楂树上的发生规律,同时明确了诱芯种类、高度和性诱芯悬挂数量对桃小食心虫成虫的诱集效果。结果表明,桃小食心虫在每年发生1~2代,山楂树上主要有1个发生高峰,在8月10日前后为防治关键期。3种诱芯诱虫效果没有显著性差异,2 m悬挂诱芯效果最好,诱芯数量对桃小食心虫的诱集数量没有明显影响。

34%乙多·甲氧虫SC防治盘锦稻区二化螟效果初报

研究了34%乙多·甲氧虫SC对盘锦地区水稻田二化螟的防治效果及对水稻的安全性。田间试验结果表明:34%乙多·甲氧虫SC田间用量24 g/667 m^(2)、20 g/667 m^(2),于二化螟卵孵化盛期,即每代次二化螟幼虫为害显状初期开始第一次施药,连施2次,间隔7~10 d,对一代二化螟防效分别为94.6%、88.2%,对二代二化螟防效分别为86.4%、84.7%。对照药剂25%乙基多杀菌素WG田间用量15 g/667 m^(2),240 g/L甲氧虫酰肼SC田间用量28 g/667 m^(2)对一代二化螟的防效分别为97.8%、78.5%;对二代二化螟防效分别为89.8%、69.5%。参试药剂处理区水稻生长正常。综上,34%乙多·甲氧虫SC对二化螟防效较理想,且对水稻安全。