中稻田三种飞虱的捕食性天敌优势种及农药对天敌的影响

对两优0923非防治的中稻田白背飞虱、灰飞虱和褐飞虱与其天敌间的关系,采用灰色关联度法、生态位分析方法,对盆拍法调查的3种飞虱与其捕食性天敌在数量、时间和空间三方面关系进行分析,对每一种天敌对应的关联度、生态位重叠指数和相似性比例等参数标准化后的密切指数相加,按照密切指数值之和大小排序,评判3种飞虱捕食性天敌优势种.并用同样方法分析常规防治田农药对飞虱捕食性天敌的影响,以期为合理施药,科学保护和利用天敌优势种提供科学依据,其结果是,非防治田白背飞虱前三位天敌是条纹蝇虎、草间小黑蛛和锥腹肖蛸;灰飞虱的是八斑球腹蛛、茶色新园蛛和锥腹肖蛸;褐飞虱的是纵条蝇狮、四点亮腹蛛和黑肩绿盲蝽.防治田白背飞虱前三位天敌是条纹蝇虎、草间小黑蛛和锥腹肖蛸;灰飞虱的是拟水狼蛛、四点亮腹蛛和草间小黑蛛;褐飞虱的是黑肩绿盲蝽、拟水狼蛛和四点亮腹蛛.盆拍法的防治田和非防治田之间3种飞虱前三位的相同天敌,白背飞虱完全相同,灰飞虱没有相同天敌,褐飞虱的是黑肩绿盲蝽和四点亮腹蛛.飞虱与天敌在时间和数量关系上,扫网法的防治田和非防治田之间3种飞虱前三位的相同天敌,白背飞虱的是锥腹肖蛸和四点亮腹蛛,灰飞虱完全相同,褐飞虱的是纵条蝇狮和条纹影虎.两种稻田的差异主要是农药杀伤了飞虱,使飞虱数量减少,并对天敌有一定杀伤力,进而影响到天敌的发生规律.非防治田的盆拍法和扫网法之间,3种飞虱前三位相同的天敌,白背飞虱的是锥腹肖蛸,灰飞虱的也是锥腹肖蛸,褐飞虱的是纵条蝇狮.防治田两调查方法结果之间,白背飞虱的是锥腹肖蛸,灰飞虱和褐飞虱前3位天敌中没有相同天敌,其差异主要是两法调查稻株的部位不同所致.     

Genome‐wide characterization and developmental expression profiling of long non‐coding RNAs in Sogatella furcifera

The genome‐wide characterization of long non‐coding RNA (lncRNA) in insects demonstrates their importance in fundamental biological processes. Essentially, an in‐depth understanding of the functional repertoire of lncRNA in insects is pivotal to insect resources utilization and sustainable pest control. Using a custom bioinformatics pipeline, we identified 1861 lncRNAs encoded by 1852 loci in the Sogatella furcifera genome. We profiled lncRNA expression in different developmental stages and observed that the expression of lncRNAs is more highly temporally restricted compared to protein‐coding genes. More up‐regulated Sogatella furcifera lncRNA expressed in the embryo, 4th and 5th instars, suggesting that increased lncRNA levels may play a role in these developmental stages. We compared the relationship between the expression of Sogatella furcifera lncRNA and its nearest protein gene and found that lncRNAs were more correlated to their downstream coding neighbors on the opposite strand. Our genome‐wide profiling of lncRNAs in Sogatella furcifera identifies exciting candidates for characterization of lncRNAs, and also provides information on lncRNA regulation during insect development.     

Effect of organic rice farming on planthoppers 4. Reproduction of the white backed planthopper,Sogatella furcifera Horváth (Homoptera: Delphacidae)

The reproduction ofSogatella furcifera was investigated in a chemically fertilized rice field and an organically farmed field. In the latter, the density of immigrants was significantly higher, while the settling rate of female adults and the survival rate of immature stages of ensuing generations were lower. The number of eggs laid by a female of the invading and following generations was smaller, and the percentage of brachypterous females in the next generation was also lower. Consequently, the density of nymphs and adults in the ensuing generations decreased in the organically farmed field. For an experimental comparison, potted rice plants were cultivated using seedlings and soil from the chemically fertilized or the organically farmed fields. WhenSogatella furcifera was reared on these plants, both the reproductive rate and the appearance rate of brachypterous female adults were lower in the organic treatment. Egg hatchability was also lower in the organic treatment. This experiment suggested that a specific nutritional condition in rice plants suppressed the population ofS. furcifera in the organically farmed field.     

Sublethal effects of buprofezin on development,reproduction, and chitin synthase 1 gene (SfCHS1) expression in the white-backed planthopper,Sogatella furcifera (Hemiptera: Delphacidae)

The white-backed planthopper, Sogatella furcifera (Horváth) (Hemiptera: Delphacidae), is a major rice pest in some Asia-Pacific countries. Buprofezin is an insect growth regulator with relatively low mammalian toxicity but high efficacy to many rice pests. In this study, we estimated the toxicity of buprofezin against 3rd-instar nymphs of S. furcifera using the rice-stem dipping method. The results showed that the LC₅₀ of buprofezin to 3rd-instar nymphs were 0.89?mg/L. When 3rd-instar nymphs were exposed to the LC₁₀ and LC₂₅ (0.10 and 0.28?mg/L) of buprofezin, the duration of juvenile development was significantly prolonged in the F₀ and F₁ generations. The fecundity (eggs per female) of the F₁ females was reduced by 5.29% and 12.34%, respectively, in addition to the survival rate, emergence rate, copulation rate, and hatchability were decreased by treatment with buprofezin at LC₁₀ and LC₂₅, compared with the control group. The relative fitness of S. furcifera in LC₁₀ and LC₂₅ treatments was reduced by 47% and 63%, respectively. Furthermore, real-time quantitative PCR analyses revealed increased the expressions of SfCHS1 and its two variants following the exposure of nymphs to buprofezin. Increased these genes mRNA levels associated with reduced chitin biosynthesis may result from the inhibition of chitin synthase activity, and thereby leading to a higher mortality of S. furcifera. Overall, sublethal concentrations of buprofezin suppressed the population growth of S. furcifera.     

A new genus and species of the subtribe Aolina (Hemiptera: Cicadidae: Dundubiini) from Vietnam,with discussion on the taxonomic positions of Meimuna-like genera and species groups

A new cicada genus, Cantata Lee & Pham gen. nov., is erected in the subtribe Aolina Boulard, 2012, with the designations of Cantata phiaoacensis Lee & Pham sp. nov. as its type species. This new genus is morphologically similar to Meimuna Distant, 1905 but distinguished from Meimuna mainly by the absence of the extended base of uncus, the presence of the basal lobe of male pygofer, the shape of the uncal lobes, and the presence of the fore wing infuscations. Cantata phiaoacensis Lee & Pham sp. nov. is described from Phia Oac – Phia Den National Park, Cao Bang province in northern Vietnam. A distribution map and biological data for Cantata phiaoacensis are provided. A key to the genera and the species groups of Aolina is provided.     

Effects of the susceptibility of rice varieties to Sogatella furcifera on nymphal development and reproduction of Microvelia horvathi through a food chain

The effects of four rice varieties highly susceptible （ Xiang-Zao-Xian31 and Jia-Yu 164 ）, moderately susceptible （ Wei-You402 ）, and resistant （ Zhu-Liang-You02 ） to the whitebacked planthopper Sogatellafurcifera on the nymphal development, reproduc- tion and survival of Microvelia horoathi were investigated through a food chain using SogateUafurcifera as herbivore prey. Significant longer nymphal developmental time were observed in the 1 st, 4th, 5th instar and whole nymphal stage of M. horvathi raised on S. furcifera fed ZLY02 and WY402 than those of the other two varieties. M. horvathi raised on S. furcifera fed resistant ZLY02 showed a significant lower survival of whole nymphal stage than those fed other three susceptible varieties. Moreover, M. horvathi raised on S. furcifera fed resistant ZLY02 had shorter female longevity and lower lifetime fecundity than those of on susceptible XZX3l. Our results suggest that the S. furcifera- resistant rice variety ZLY02 had a negative effect on the growth and development of the predator M. horvathi through a food chain.     

Revision of the Agrilus beatissimus species–group (Coleoptera,Buprestidae) with description of five new species from Southeast Asia

The newly defined Agrilus beatissimus species–group comprising seven species from Southeast Asia is revised. The key to species is provided and complemented with illustrations of habitus, genitalia and type specimens. The following five new species are described: Agrilus bilyanus sp. nov. (Thailand); A. campana sp. nov. (Laos); A. galazopos sp. nov. (Laos); A. plurifrons sp. nov. (Laos, Myanmar) and A. undatus sp. nov. (Laos). Comprehensive commented references, data on type specimens and new faunal records are cited. The distribution is updated for A. beatissimusDescarpentries and Villiers 1963 and A. dunoyeriBaudon 1968.     

Four new species of the Didymopanax group of <Emphasis Type="Italic">Schefflera</Emphasis> (Araliaceae) from the Brazilian Amazon

Four new species of the Didymopanax group of Neotropical Schefflera (Araliaceae) from the Brazilian Amazon are here described and illustrated. Two of these are mainly known from the surroundings of Manaus, Amazonas state (Schefflera ciliatifolia and Schefflera umbrosa). The first is distinguished by its ciliate leaflets, while the second is characterized by leaflets varying in shape from trilobed to entire. Schefflera plurifolia is known only from southern Amazonian forests, and is remarkable in its pinnately-compound leaflets. Schefflera dichotoma, only known from the type collected on “campinarana” forests from Upper Rio Negro, at the municipality of São Gabriel da Cachoeira (Amazonas), is characterized by dichotomously branching inflorescences. Comments on the geographic distribution and ecology of the new species are provided, as well as an identification key to the species of the Didymopanax group found in Brazilian Amazonian rainforests and savannas.     

Description of new species of two genera Dayus Mahmood and Znana Dworakowska from Thailand (Hemiptera: Cicadellidae: Typhlocybinae)

Two genera, Dayus Mahmood, 1967 and Znana Dworakowska, 1994 of the leafhopper tribe Empoascini (Hemiptera: Cicadellidae: Typhlocybinae) are reviewed. One new species of each genus, Dayus furcatus sp. nov. and Znana furca sp. nov., are described from Thailand. A checklist and distribution summary of Dayus Mahmood species is given. Male habitus photos and illustrations of male genitalia of the two new species and notes on allied species are also provided.     

Elicitor(s) in Sogatella furcifera (Horváth) Causing the Japanese Rice Plant (Oryza sativa L.) to Induce the Ovicidal Substance,Benzyl Benzoate

We elucidate the mechanism for inducing the production of ovicidal benzyl benzoate by Japonica rice varieties to kill eggs of the whitebacked planthopper, Sogatella furcifera (Horváth), lying in the rice plant. Even when subjected to physical damage by a needle or damage with water, the rice plant produced no benzyl benzoate. However, significant benzyl benzoate was produced when the plant was damaged with a methanol extract or homogenate of S. furcifera. The extract of the male did not induce the production of benzyl benzoate, but that of the female did. We concluded from these results that benzyl benzoate was induced by some elicitor(s) in the female of S. furcifera.     

Genetic variation of two apterous wasps Haplogonatopus apicalis and H. oratorius (Hymenoptera: Dryinidae) in East Asia

The females of Haplogonatopus (Hymenoptera: Dryinidae) are wingless. Thus, the migration ability of adult wasps should be highly restricted. However, passive dispersal of larvae parasitizing their hosts may be possible. In this study we discuss the genetic variation of H. apicalis Perkins and H. oratorius (Westwood) in East Asia, from the perspective of the geographical distribution and the long-distance migration ability of their hosts, using 807 bp of mitochondrial COI gene sequences. Genetic variation of H. apicalis parasitizing Sogatella furcifera (Horváth) was examined on the basis of individuals from western Japan, southern China, and northern Vietnam. High genetic diversity was observed but geographical populations were not recognized. For H. oratorius parasitizing Laodelphax striatellus (Fallén), individuals from the northern and southern coasts of eastern Japan, western Japan, eastern China, and Taiwan were examined. The southern coast of eastern Japan population was discriminated from the other populations, and three core haplotype groups moderately associated with geographical distribution were apparent. However, the population sampled at Hokuriku, located on the northern coast of eastern Japan, was composed of a mixture of haplotypes dominant in other locations, even geographically far separated from China. This may imply the occurrence of the migration pathway of L. striatellus from continental China toward eastern Japan. The results for two parasitoid species can be explained on the basis of the migration ability of the host species.     

Host-recognition kairomone from Sogatella furcifera for the parasitoid Anagrus nilaparvatae

A kairomone produced by the rice white-backed planthopper Sogatella furcifera (Horvath) for the mymarid egg parasitoid Anagrus nilaparvatae Pang et Wang was investigated. Eggs, female and male adults, nymphs, exuvia, honeydew, nymph-damaged plants and plants with S. furcifera eggs all elicited searching behavior in the parasitoid. Eggs, female adults and plants with eggs were the most attractive, while exuvia and honeydew evoked the weakest responses. The active compound(s) from S. furcifera female adults, nymphs and plants with eggs could be effectively extracted with methanol, acetone, n-hexane, ethyl ether and dichloromethane. Isolation of the active chemical(s) in three solvent extracts, the acetone and n-hexane extracts of S. furcifera female adults, and the acetone extract of S. furcifera nymphs, was accomplished by thin-layer chromatography. Only one fraction was active and had the same chemical properties in the three solvent extracts. Infra-red analysis of this fraction revealed a kind of ester with saturated and unsaturated fatty acids, which was previously found to be active in the same compound as the extracts from the nymphs and female adults of the rice brown planthopper, Nilaparvata lugens (Stål), and identified as palm oil. The results are discussed in relation to host location by A. nilaparvatae.     

Accumulation of salicylic acid,jasmonic acid and phytoalexins in rice, <Emphasis Type="Italic">Oryza sativa</Emphasis>, infested by the white-backed planthopper, <Emphasis Type="Italic">Sogatella furcifera</Emphasis> (Hemiptera: Delphacidae)

In order to clarify the mechanism of induced resistance to blast disease in rice, Oryza sativa, that had been previously infested by the white-backed planthopper, Sogatella furcifera Horváth, we first investigated the accumulation of salicylic acid (SA) and jasmonic acid (JA) in rice plants infested by the planthopper. The results confirmed that infestation of S. furcifera strongly stimulates the production of SA and JA in rice. These results indicate that both salicylate- and jasmonate-mediated pathways (SA and JA pathways), which are involved in the general defense system in plants, were activated in rice infested by S. furcifera. Further results confirmed that S. furcifera infestation induces accumulation of a major rice diterpenoid phytoalexin, momilactone A, and a flavonoid phytoalexin, sakuranetin, which are well known as antimicrobial chemicals, particularly in blast disease caused by the blast fungus, Magnaporthe oryzae B. Couch. All these results strongly suggest the following hypothetical mechanism of induced-resistance to M. oryzae in rice infested by S. furcifera. First, S. furcifera releases some elicitor-active compounds, which might be produced in the salivary glands, into the rice plant during feeding. Next, the defense signal systems, SA- and JA-mediated pathways, are activated by the elicitor. Finally, phytoalexins are induced in rice as antimicrobial compounds mainly through activation of the JA-mediated pathway.