Automated Counting of Rice Planthoppers in Paddy Fields Based on Image Processing

A quantitative survey of rice planthoppers in paddy fields is important to assess the population density and make forecasting decisions. Manual rice planthopper survey methods in paddy fields are time-consuming, fatiguing and tedious. This paper describes a handheld device for easily capturing planthopper images on rice stems and an automatic method for counting rice planthoppers based on image processing. The handheld device consists of a digital camera with WiFi, a smartphone and an extrendable pole. The surveyor can use the smartphone to control the camera, which is fixed on the front of the pole by WiFi, and to photograph planthoppers on rice stems. For the counting of planthoppers on rice stems, we adopt three layers of detection that involve the following：（a） the first layer of detection is an AdaBoost classifier based on Haar features;（b） the second layer of detection is a support vector machine（SVM） classifier based on histogram of oriented gradient（HOG） features;（c） the third layer of detection is the threshold judgment of the three features. We use this method to detect and count whiteback planthoppers（Sogatella furcifera） on rice plant images and achieve an 85.2% detection rate and a 9.6% false detection rate. The method is easy, rapid and accurate for the assessment of the population density of rice planthoppers in paddy fields.

Survey on Spawning Characteristics of Rice Planthoppers in Different Rice Varieties

The fecundity and spawning locations of rice planthoppers in several rice varieties were surveyed in the test. The results showed that spawning behavior of rice planthoppers obeyed obvious niche distribution; rice planthopper preferred to lay eggs in the leaf sheath with spawning mark distance more than 20 cm, while they liked to lay eggs in the leaves with spawning mark distance of 10 - 20 cm. The average fecundity in leaf sheaths was obviously higher than that in leaves, indicating that leaf sheaths were more suitable for spawning of rice planthoppers than leaves.

Relationship of egg parasitoids of rice planthoppers between rice and non-rice habitats

Egg parasitoids,Anagrus spp.and Oligositaspp.have been found to be important biologi-cal agents in suppressing rice planthoppers inAsian countries.However,most of these stud-ies have been confined to conditions within ricefields.In this study,field surveys were madeto study the floral and faunal diversity in vari-ous habitats surrounding rice fields.The riceand grass(Echinochloa spp.)plants were in-

Long range migration of rice planthoppers and associated meteorological conditions in Yulin,Ganzhou,and Huangyan

In recent years,it has been demonstrated that thelow-level jet streams(LLJs)developed in thesouth of the Meiyu(Baiu)front play a critical role inthe overseas migrations of the planthoppers intoJapan and Korea. However, the involement of theLLJs during the process of sequential displacements

Various infection status and molecular evidence for horizontal transmission and recombination of Wolbachia and Cardinium among rice planthoppers and related species

Wolbachia and Cardinium are widely distributed and are considered important for their ability to disturb reproduction and affect other fitness-related traits of their hosts. By using multilocus sequence typing （MLST）, RFLP （restriction fragment length poly- morphism） and 16S ribosomal DNA gene sequencing methods, we extensively surveyed Wolbachia and Cardinium infection status of four predominant rice planthoppers and one kind of leafhopper in different rice fields. The results demonstrated that Sogatellafurcifera （Horv^ith） and Laodelphax striatellus （Fallrn） were infected with the same Wolbachia strain （wStri）, while Nilaparvata lugens （St^l） and its closely related species Nilaparvata muiri China were infected with two phylogeneticlly distant strains, wLug and wMui, respectively. Three new Wolbachia strains （provisionally named wMfasl, wMfas2 and wMfas3） were detected in the leafhopper Macrostelesfascifrons （Stal）. Only S. furcifera was co-infected with Cardinium, which indicated that the distribution of Cardinium in these rice planthop- pers was narrower than that of Wolbachia. Unambiguous intragenic recombination events among these Wolbachia strains and incongruent phylogenetic relationships show that the connections between different Wolbachia strains and hosts were more complex than we expected. These results suggest that horizontal transmission and host associated special- ization are two factors affecting Wolbachia and Cardinium infections among planthoppers and their related species.

Highly Sensitive and Specific Monoclonal Antibody-Based Serological Methods for Rice Ragged Stunt Virus Detection in Rice Plants and Rice Brown Planthopper Vectors

Rice ragged stunt virus（RRSV） is a serious rice disease in Asia, causing serious yield losses on rice. The capsid protein（CP） gene of the major outer capsid protein of RRSV was expressed in Escherichia coli BL21（DE3） using the pMAL-C2 X expression vector. The recombinant protein was used as the immunogen to immunize BALB/c mice. A hybridoma cell line 8A12 secreting monoclonal antibody（MAb） against RRSV was obtained by fusing mouse myeloma cells（Sp 2/0） with spleen cells from the immunized BALB/c mice. Western blot analysis showed that the MAb 8A12 can specifically react with RRSV CP. Using the MAb, an antigen-coated-plate enzyme-linked immunosorbent assay（ACP-ELISA）, a dot enzyme-linked immunosorbent assay（dot-ELISA）, and immunocapture-RT-PCR（IC-RT-PCR） assay were developed to detect RRSV. The established ACP-ELISA, dot-blot ELISA and IC-RT-PCR methods could detect RRSV in infected rice tissue crude extracts with dilutions of 1：40 960, 1：1 280 and 1：655 360（w/v, g mL-1）, respectively. The ACP-ELISA and dot-blot ELISA methods could detect RRSV in infected insect vector crude extracts with dilutions of 1：12 800 and 1：1 600（an individual planthopper μL-1）, respectively. The field survey revealed that Rice ragged stunt disease occurs on rice in Hainan, Yunnan, Guangxi, Sichuan, Guizhou, Fujian, Hunan, Jiangxi and Zhejiang in China.

Rice planthopper resistance of interspecific protop last fusin line"pf9279" between O.sative and O.officinalis

An interspecific hybrid line pf9279 was obtained by proto-plast fusion between 02428(japonica, with a wide com-patibility gene) and CNW240 (O. officinalis, fromMalaysia) at CNRRI in 1992. Possible introgression of

Tolerance evaluation of rice varieties to the brown planthopper,Nilaparvata lugens feeding

The brown planthopper,Nilaparata lugens(Stl)(BPH)is one of the most important insect pests of rice in China and other east-southern Asian countries.Untilization of rice resistance varieties is one of the most econnomic and effective ways for

Relationship between “Two Insects and One Spider” and Their Occurrence and Damage Regularity during Different Sowing Periods in Single Cropping Hybrid Rice

[Objective]The paper was to study the relationship between rice leaf roller,rice planthopper and spider and their ecological regulation ability in the field.[Method]The population dynamics of rice leaf roller,rice planthopper and spider at three different sowing and transplanting periods of single cropping hybrid rice in the treatment area with combination of 3 drug formulations and untreated area were monitored.[Result]There were significant or extremely significant positive correlations among rice leaf roller,rice planthopper and spider in single cropping hybrid rice.However,with the delay of planting and transplanting period,the population fluctuation crest of rice leaf roller and rice planthopper decreased,but the intensity increased with the advance of time,and the natural ecological regulation ability was relatively improved.[Conclusion]The sowing period of single cropping hybrid rice is delayed 5-10 d compared with conventional rice,that is,sowing in late May and early June.The seedling age of 20-30 d is beneficial not only to reduce the initial population quantity of rice leaf roller and rice planthopper in the field,but also to increase the population quantity of spiders.

QTLs for ovicidal response to whitebacked planthopper in rice

Japanese japonica rice commonlyprovides with an ovicidal resistanceagainst the whitebacked planthopper(WBPH). Similarly, ovicidal activi-ty was also found to play a significantrole in a stable field resistance toWBPH in some Chinese japonicarice. Rice varieties with ovicidal re-

The ENSO event and rice planthopper occurrence in China

The rice planthopper,including brown planthopper(Nilaparvata hugens Stal)and white—backed planthopper(Sogata furcifera Hor-vath),is one kind of tropical pests.They im-migrate with the southeast monsoon from low—latitude area into China at March of April.The global climatic anomaly especially the ElNi (?)o event and the Southern Oscillation(theENSO event)directly influence the rice plan-

基于主成分回归法的稻飞虱百穴虫量冠层光谱检测(英文)

[ Objective] Aiming at problems of early warning for occurrence of rice pests and dynamic monitoring of rice planthopper in field, a detection model for rice planthopper populations was established based on PCR with spectrum detection technology, r Method] Canopy reflectance data were collected using FieldSpeo 3 spectrometer in paddy field, and rice planthoppers populations in hundred hills were detected simultaneously. The sample size was 71, and there were 51 samples in the calibration set and 20 samples in the prediction set. Modeling band was 350 -1 139 nm, and the original spectra were pretreated by first order differential. [ Result] The correlation coefficient of measured values and predictive values was 0. 78, and the RMSEP was 161. [ Conlmion] Spectrum detection was able to be used in investigation and forecasting of rice planthoppere.

稻飞虱迁飞气象条件等级预报研究(英文)

By comparative analysis on the meteorological conditions and occurrences of rice planthoppers in Guilin of Guangxi during recent 5 years,the temperature,precipitation,wind direction,wind velocity,humidity were chosen as the factors that affected the migration of rice planthopper in Guilin.Thinking of meteorological conditions and injurious number in early period,regression analysis method was used to establish the work system for grade forecast of meteorological conditions that affected the migration of rice planthopper.The forecast factors and targets were divided as 5 grades in the work system.Using one-week's weather forecast conclusion that local observatory had published,whether the meteorological conditions and injurious number were favorable or not was analyzed synthetically.The meteorological conditions grades that affected the migration of rice planthopper for each day in future 1-7 days were predicted.This is a practical forecast work system and the forecast accuracy for each day is larger than 70%.The work system has positive function in the manufacture practice.

超级稻甬优6号褐飞虱种群繁殖速率的密度制约效应(英文)

[ Objective ] The paper was to study the density restriction effects of reproductive rate of rice brown planthopper （BPH） population in super indiea and japonica hybrid rice Yongyou 6. [Method] Different amounts of rice brown planthoppor were released to super indiea and japonica hybrid flee Yongyou 6 during fillering, booting and gain filling stage, respectively. The reproductive rate and variation dynamics of rice brown planthoppor in super rice was also investigated and analyzed. [Result] Tillering stage： the population quantity of rice brown planthoppor during booting and gain filling stage gradually increased with the increasing basal amount of its population during tillering stage; when the population density of rice brown planthopper during grain filling stage reached a certain limit （ 〉 250 head/cluster）, the population density during milking stage showed decrease trend with the increasing of such density; the development of rice brown planthoppor population in super rice Yongyou 6 showed the characteristics of fast in middle and slow in two ends. Booting stage： the development of rice brown planthopper pop- ulation from booting to gain filling stage increased with the increasing basal amount of density, and their correlation during milking stage was not significant; flee brown planthopper population still had high reproduction capacity in the middle and late stage of super rice, which had latent risk on rice yield. Gain filling stage ： when population density of rice brown planthopper 〈 70 head/cluster, the development of it population increased with the increase of basal amount of density, which had great threat to yield. [ Conclusion] The result provided theoretical basis for establishment and improvement of monitoring early warning system, cost-ef- fective control of occurrence and damage of rice brown planthopper, and improvement of the sustained control ability against rice brown planthopper.

Differentially methylated genomic fragments related with sexual dimorphism of rice pests, Sogatella furcifera

Sogatella furcifera （Hovarth） is a major rice pest with sexual dimorphism. The objective of the current research was to monitor differentially cytosine methylation at CCGG sequences in male and female adults of S. furcifera to determine the association between gene methylation and sexual phenotypes using methylation-sensitive representa- tional difference analysis. After the second subtractive hybridization, four differentially methylated DNA bands were obtained and sequenced. Ten different fragments were found. One fragment from the positive hybridization was 120 bp, and highly similar to the tram- track genes from Nasonia vitripennis. Another fragment from the reverse hybridization was 414 bp, and homologous to the 28S rRNA gene of S. furcifera with a similarity rate as high as 99%. We also discussed how DNA methylation of tramtrack and 28S rRNA genes produced effects on sexual differentiation and development. These results provide potential evidence that DNA methylation of some genes may be related to sexual phenotype variations in S.furcifera and will facilitate future studies on the epigenetic mechanisms of insect sexual dimorphism.