Automated detection and identification of white-backed planthoppers in paddy fields using image processing

A survey of the population densities of rice planthoppers is important for forecasting decisions and efficient control. Tra- ditional manual surveying of rice planthoppers is time-consuming, fatiguing, and subjective. A new three-layer detection method was proposed to detect and identify white-backed planthoppers （WBPHs, Sogatella furcifera （Horvath）） and their developmental stages using image processing. In the first two detection layers, we used an AdaBoost classifier that was trained on a histogram of oriented gradient （HOG） features and a support vector machine （SVM） classifier that was trained on Gabor and Local Binary Pattern （LBP） features to detect WBPHs and remove impurities. We achieved a detection rate of 85.6% and a false detection rate of 10.2%. In the third detection layer, a SVM classifier that was trained on the HOG features was used to identify the different developmental stages of the WBPHs, and we achieved an identification rate of 73.1%, a false identification rate of 23.3%, and a 5.6% false detection rate for the images without WBPHs. The proposed three-layer detection method is feasible and effective for the identification of different developmental stages of planthoppers on rice plants in paddy fields.

Mapping of Wbph6(t)-a new gene resistant to white-backed planthopper

Whitebacked planthopper (WBPH,Sogatella furcifera Horvath) is one ofthe most destructive insects for rice.The utilization of WBPH resistancegenes is always an efficient solution tothis problem. Besides five WBPHresistance genes registered, Wbph1,Wbph 2 , Wbph 3 , wbph 4 , andWbphS, classical segregation analysis

Efficient nanoparticle-based CRISPR-Cas13d induced mRNA disruption of an eye pigmentation gene in the white-backed planthopper,Sogatella furcifera

The discovery of the clustered regularly interspaced short palindromic repeat(CRISPR)system has driven gene manipulation technology to a new era with applications reported in organisms that span the tree of life.The utility of CRISPR-mediated editing was further expanded to mRNA following identification of the RNA-targeting Cas13 family of smaller endonuclease proteins.Application of this family to insect research,however,has been more limited.In this study,the smallest Cas13 family member,Cas13d,and guide RNAs(gRNAs)were complexed with a versatile nanomaterial(star polycation,SPc)to generate a proof-of-concept RNA-editing platform capable of disrupting mRNA expression of the eye pigmentation gene tryptophan 2,3-dioxygenase(SfTO)in white-backed planthoppers(WBPHs).The resulting red-eye phenotype was present in 19.76%(with SPc)and 22.99%(without SPc)of the treatment groups and was comparable to the red-eye phenotype generated following conventional RNA interference knockdown(22.22%).Furthermore,the Cas13/gRNA phenotype manifested more quickly than RNA interference.Consistent with the expected Cas13d mechanism,SfTO transcript levels were significantly reduced.Taken together,the results indicate that the SPc-CRISPR-Cas13d/gRNA complex negatively impacted expression of the target gene.These findings confirm the utility of this novel mRNA disruption system in insects and lay the foundation for further development of these tools in the implementation of green agricultural pest management tactics.

Ecological Fitness of Non-vector Planthopper Sogatella furcifera on Rice Plants Infected with Rice Black Streaked Dwarf Virus

We evaluated the effects of rice black streak dwarf virus （RBSDV）-infested rice plants on the ecological parameters and its relevant defensive and detoxification enzymes of white-backed planthopper （WBPH） in laboratory for exploring the relationship between RBSDV and the non-vector planthopper. The results showed that nymph survival rate, female adult weight and fecundity, and egg hatchability of WBPH fed on RBSDV-infested rice plants did not markedly differ from those on healthy plants, whereas the female adult longevity and egg duration significantly shortened on diseased plants. Furthermore, significantly higher activities of defensive enzymes （dismutase, catalase and peroxidase） and detoxification enzymes （acetylcholinesterase, carboxylesterase and glutathione S-transferase） were found in WBPH adults fed on infected plants. Results implied that infestation by RBSDV increased the ecological fitness of non-vector planthopper population.

Resistance of Major Rice Cultivars in Hangzhou Area of China against Southern Rice Black-streaked Dwarf Virus

Resistance of 17 major rice cultivars in Hangzhou region of China against southern rice black-streaked dwarf virus was tested in the paper. The results showed that the incidence rate of southern rice black-streWed dwarf virus had certain positive correlation with quantity of white-backed planthopper （Sogatellafurci-fera） and resistance among various cultivars was significant. Two varieties, Yueyou 9113 and Tianyouhuazhan, were most susceptible ; Yongyou 8, Jiayou 2 and Xi-ushui 134 had best resistance and could be used as disease-resistant varieties to prevent the disease.

Southern Rice Black Streaked Dwarf Virus Directly Manipulate the Feeding Behavior of Its Vector Sogatella furcifera(Horváth) and the Key to Inoculation

Southern rice black streaked dwarf virus(SRBSDV) is vectored by white-backed planthopper(WBPH),Sogatella furcifera,in a circulative,propagative,and persistent manner.To better understand the relationship of virus- vector- host plant and the transmission mechanism of WBPH,this study evaluated the direct effects of SRBSDV on the feeding behavior of WBPH and determined the feeding behavior of viruliferous WBPH in relation to SRBSDV inoculation.The third to fifth- instar nymphs of WBPH were allowed to feed for 48 hours on SRBSDV- infected rice plants,and then reared on the healthy seedlings for 8- 15 days.Electronic penetration graph(EPG) was used to monitor the feeding behavior of both the non-viruliferous and viruliferous WBPH for 12 hours.Fifteen- 22 days after the recording,total RNA was isolated from rice plant and used to determine whether or not the rice plant had been infected by RT- PCR.EPG showed that the duration of the 1st phloem contact(N4) was 15 times longer in viruliferous WBPH than in non- viruliferous WBPH.The mean duration of watery salivation(N4- a) of viruliferous WBPH was significantly longer than that of nonviruliferous WBPH.Meanwhile,the stepwise- backward logistic regression model showed that the total duration of N4 was the most significant variable(P= 0.019) positively correlated with SRBSDV inoculation,which was followed by the number of N4- a(> 10min) preceding N4- b(P =0.034).The study revealed that SRBSDV modified the feeding behavior of WBPH in a direct way and enhanced the inoculation efficiency.Salivation into phloem region might be the most important stylet activity for the inoculation of SRBSDV.