Characterization of carboxylesterase PxαE8 and its role in multi-insecticide resistance in Plutella xylostella (L.)

Carboxylesterase (CarE) was considered as important phase-I detoxifying enzymes which participated in detoxification of different types of insecticides. Up-regulation of CarE genes has been proved playing a major role in insecticide resistance in many pest insects, but its involvement in resistance to insecticides in Plutella xylostella has been rarely reported. In this study, a CarE cDNA named PxαE8 was identified in P. xylostella, which has an open reading frame of 1 599 nucleotides and putatively encodes 532 amino acids. The investigation of spatial expression profiles of PxαE8 revealed that it was expressed in all developmental stages, especially in larvae and adults. The body part/tissue-specific expression profiles showed that the PxαE8 mainly expressed in fat body, malpighian tubule and hemolymph of larvae. Further, the relative expression of PxαE8 in two multi-resistant field populations, Hainan (HN) and Guangdong (GD) populations, was found 24.4- and 15.5-fold higher than that in susceptible population, respectively. Knockdown of PxαE8 by RNA interference dramatically increased the mortalities of larvae of HN population treated with LC₅₀ of beta-cypermethrin and phoxim by 25.3 and 18.3%, respectively. These results suggested that up-regulation of PxαE8 was involved in resistance to both beta-cypermethrin and phoxim in P. xylostella, which shed light on further understanding of molecular mechanisms of multi-insecticide-resistance in P. xylostella and other pest insects.     

Ultrastructure of the sensilla on antennae and mouthparts of larval and adult Plutella xylostella (Lepidoptera: Plutellidae)

Plutella xylostella (L.) (Plutellidae) is an important agricultural pest throughout the world. In this study, the morphology of antennal and mouthpart sensilla in the larvae and adults of P. xylostella (L.) was observed by using a scanning electron microscope. The larval antennae possess six sensilla basiconica, two sensilla chaetica and one sensillum styloconicum. Larval mouthparts possess six types of sensilla: sensilla chaetica, sensilla digitiformia, sensilla epipharyngeal, sensilla basiconica, sensilla styloconica and sensilla placodea. In the adult, seven types of sensilla are found on the antennae in males and six types of sensilla (sensilla basiconica absent) occur in females. Sexual dimorphism is also found in the number and size of these sensilla on the antennae of adults. We describe for the first time the five types of sensilla on the mouthparts of the adult of P. xylostella. This study provides useful information for further research into the function of these sensilla, and better understanding the behavioral mechanisms involved in pest control.     

Tradeoff between triglyceride consumption and ovariole development in Plutella xylostella (L.) released in mixed-host environments

After exposure to mixed environments with multiple hosts, the frequency of flight take-offs for Plutella xylostella (L.) is known to increase with a concomitant decrease in female fecundity. The objective of the present study was to elucidate the physiological mechanism underlying the increased flight activity and decreased fecundity of P. xylostella in mixed-host environments. We measured ovariole length, and triglyceride and vitellogenin (Vg) content in P. xylostella females after they were released into different host environments consisting of either a single host (Brassica campestris, Brassica oleracea or Brassica juncea) or a mixture of all three hosts. Our results indicated that ovariole length varied significantly between female adults from different host environments. Females from the B. campestris environment had the longest ovarioles, whereas those from the mixed environment had the shortest ones. A negative correlation was found between ovariole length and the flight take-off frequency of P. xylostella adults. Additionally, there were significant differences in the triglyceride content of P. xylostella females from different host environments. Our data revealed that more triglyceride was consumed by P. xylostella female adults from B. oleracea and the mixed environments than those from environments containing only B. campestris or B. juncea. In contrast, the relative Vg content in P. xylostella females from the mixed environment was lower than that in females from the B. campestris-, B. juncea- or B. oleracea-only environments. In conclusion, the mixed environment caused increased consumption of available energy resources (triglyceride) at the cost of retarding ovarian development and decreasing the amount of Vg produced.     

3种绿色防控技术对小菜蛾的防治效果

小菜蛾（Plutella xylostella）是危害十字花科植物的重要害虫之一,防治方法主要是应用化学农药防治,使得农药残留、抗药性及再猖獗问题日益严重。为明确不同绿色防治技术对小菜蛾的防治效果,采用田间试验方法,在甘蓝田进行不同类型的诱捕器和诱芯比较、7种生物农药筛选及释放螟黄赤眼蜂防治小菜蛾的3种绿色防控技术试验。结果表明：不同诱捕器和诱芯诱蛾效果差异显著,天然橡胶塞诱芯诱蛾效果明显优于毛细管型诱芯,船型诱捕器配绿色天然橡胶塞型诱芯或红色塑料毛细管型诱芯为最佳组合。生物药剂中乙基多杀菌素防治小菜蛾的速效性最好,药后1 d防效达到78.93%;小菜蛾颗粒体病毒在药后7 d防效达到最高,达到86.68%,但持效性较短。田间释放螟黄赤眼蜂对小菜蛾卵寄生率均达到65%以上,对小菜蛾卵的寄生效果良好。这3种技术对小菜蛾的绿色防控具有一定的指导和参考价值,可在田间示范和推广。     

光叶铁仔提取物对小菜蛾幼虫生长发育的影响

【目的】研究光叶铁仔Myrsine stolonifera提取物对小菜蛾Plutella xylostella生长发育的影响。【方法】采用叶片载毒法,测定了光叶铁仔根、茎、叶甲醇提取物和大孔吸附树脂乙醇馏分对小菜蛾的生物活性;测定了大孔吸附树脂乙醇馏分对小菜蛾生长发育的影响。【结果】光叶铁仔根、茎、叶甲醇提取物和大孔吸附树脂乙醇馏分对小菜蛾具有胃毒作用,以叶部50%(φ)乙醇馏分的效果较佳,72 h后校正死亡率达到75.56%。根茎部95%(φ)乙醇馏分与叶部50%(φ)乙醇馏分,对小菜蛾的幼虫具有一定的拒食作用与体质量抑制效果,其拒食率与体质量抑制率整体高于90%,且对化蛹及羽化有一定的影响。【结论】光叶铁仔提取物对小菜蛾幼虫具有较强的杀虫活性,其活性成分及作用机理值得深入研究。     

Effects of Temperature on Functional Response of Anagrus nilaparvatae Pang et Wang (Hymenoptera: Mymaridae) on the Eggs of Whitebacked Planthopper,Sogatella furcifera Horváth and Brown Planthopper,Nilaparvata lugens Stål

Understanding the temperature affecting parasitic efficiency is critical to succeed in utilizing parasitoid as natural enemy in pest management. Laboratory studies were carried out to determine the effects of temperature on parasitoid preference of female Anagrus nilaparvatae Pang et Wang (Hymenoptera: Mymaridae) to the eggs of whitebacked planthopper (WBPH), Sogatella furcifera Horváth and brown planthopper (BPH), Nilaparvata lugens Stål to build a composite model describing changes in parasitic response along a temperature gradient (18, 22, 26, 30, 34C). The results showed that attack responses of A. nilaparvatae on WBPH and BPH were the best described by a Type II functional response. The two parameters, attack rates (a) and handling times (T_h), of A. nilaparvatae to both eggs were influenced by the temperature. The maximum attack rates to WBPH (1.235) and BPH (1.049) were at 26 and 34C, respectively, and the shortest handling times to WBPH (0.063) and BPH (0.057) were at 30 and 26C, respectively. However, the optimal temperature for parasitic efficiency of A. nilaparvatae to WBPH and BPH eggs was both at 26C, which showed that the present microclimate temperature of the habitat in the paddyfield was beneficial to A. nilaparvatae and indicated that parasitic efficiency of A. nilaparvatae would be impaired by global warming.     

Selection of reference genes for RT-qPCR analysis of Phenacoccus solenopsis (Hemiptera: Pseudococcidae) sex-dimorphic development

Mealybugs, such as Phenacoccus solenopsis, are highly sexually dimorphic. Winged adult males present such remarkable morphological differences from females that, to the untrained eye, conspecific adults of both sexes of P. solenopsis may be considered as two different insect species. A method to investigate sex-dimorphic mechanisms is by evaluating gene expression using RT-qPCR. However, the accuracy and consistency of this technique depend on the reference gene(s) selected. In this study, we analyzed the expression of 10 candidate reference genes in male and female P. solenopsis at different development stages, using common algorithms including the ?Ct method, NormFinder, geNorm, BestKeeper, and a web-based analysis tool, RefFinder. The results showed that EF1-β, RP-L32 and RP-18 S were selected as the most stable genes by both the ?Ct method and NormFinder; TUB-α was the most stable gene identified by BestKeeper; and RP-L40 and RP-L32 were the most stable genes ranked by geNorm. RefFinder, a comprehensive analysis software, ranked the ten genes and determined EF1-β and RP-L32 as the most suitable reference genes for the various developmental stages in male and female P. solenopsis. Furthermore, the two most suitable reference genes were validated by examining expression of the juvenile hormone acid O-methytransferase(JHAMT) gene. Results of the validation portion of the study showed that JHAMT expression was sex-biased towards males and exhibited a dynamic and classic expression pattern among the P. solenopsis developmental stages. The results can help further our knowledge on the molecular mechanisms underlying sexual dimorphic development in P. solenopsis.     

Antifeedant Activity and Active Ingredients Against Plutella xylostella from Momordica charantia Leaves

With the bioguided fractionation of the ethanol extracts from the leaves of Momordica charantia, we obtained two most active compounds against the feeding of the diamondback moth, Plutella xylostella larvae. The antifeedant activity of momordicine Ⅰ and momordicine Ⅱ against the second and the third instar larvae of Plutella xylostella were tested using leaf discs of cabbage in the laboratory. The results showed that momordicin Ⅰ and momordicin Ⅱ had significant antifeedant activity on the larvae of P. xylostella, and momordicin Ⅱ was more active than momordicin Ⅰ. The concentrations for 50% antifeedant effects （AFC50） of momordicin Ⅱ against the second and the third instar larvae of P. xylostella were 76.69 and 116.24μg mL^-1, whereas that of momordicin I was 144.08 and 168.42μg mL^-1, respectively. In addition, momordicin Ⅰ and momordicin Ⅱ had significant inhibitive effect on the rate of weight gain and survival of P. xylostella larvae.     

Automatic X-ray quarantine scanner and pest infestation detector for agricultural products

This paper presents a new automatic and effective quarantine system for detecting pest infestation sites in agricultural products, e.g. fruits. This work integrated mechanical design, mechatronics instrumentation, X-ray and charge-coupled device (CCD) image acquisition devices, LabVIEW-based analysis and control software, and image diagnosis algorithms into the automatic X-ray quarantine scanner system. Based on the LabVIEW development platform, a friendly graphical user interface (GUI) was designed for assisting the operations of quarantine scanner system. To enhance the accuracy and efficiency of pest quarantine process, a control scheme for performing start-up procedure of the system, parameter setting and calibration of the X-ray source and line-scan sensor, and automatic inspection for pest were developed. A novel pest infestation detector consisted of image processing algorithms were also proposed to aid the operator in identifying possibly infested fruits. The image processing procedures include contrast enhancement, median filtering, mathematical morphology operators, and adaptive thresholding by statistical z-test for identifying the infested sites of fruit on an X-ray image. Experimental results show that the X-ray quarantine scanner and pest infestation detector are able to locate the infested sites with highly successful rate up to 94% on the 4th day after eggs implanted. Furthermore, both intact and egg-implanted fruits were used to evaluate the sensitivity, specificity, accuracy, and precision of the proposed system. The evaluation results are respectively 96.8%, 98.6%, 97.7%, and 98.7%, which are significantly better than traditional visual inspection.     

略阳乌鸡蛋品质分析

为研究略阳乌鸡蛋品质特性和蛋的营养价值,选取相同的玉米-豆粕型饲料饲喂的同一笼养鸡舍饲养条件下320~325日龄的略阳乌鸡、东乡乌鸡、尼克粉蛋鸡所产的鸡蛋各200枚,分别测定蛋品质指标、营养成分和蛋黄中的胆固醇、卵磷脂质量分数和脂肪酸构成比例。研究表明,(1)蛋品物理性状:略阳乌鸡蛋质量最小,且个体差异较大;蛋壳颜色一致性最差,蛋形指数最大,鸡蛋偏圆形;蛋壳厚度和蛋壳强度大于东乡乌鸡(P0.05),但小于尼克粉蛋鸡(P0.05);蛋黄色泽品种间差异不显著(P0.05);蛋白高度、哈氏单位、蛋黄与蛋白比率小于东乡乌鸡(P0.05),但大于尼克粉蛋鸡(P0.05);(2)蛋品营养物质:粗蛋白质、粗脂肪质量分数与其他品种差异不显著(P0.05);蛋黄中胆固醇质量分数显著高于其他品种(P0.05),卵磷脂质量分数品种间差异不显著(P0.05);饱和脂肪酸(SFA)的比例较高(P0.05);不饱和脂肪酸(UFA)比例较低(P0.05);单不饱和脂肪酸(MUFA)总体比例最低(P0.05);多不饱和脂肪酸(PUFA)总体的比例位于3个品种之间,与其他品种差异不显著(P0.05);距羧基最远端的双键在倒数第6个碳原子上的多不饱和脂肪酸(n-6PUFA)与距羧基最远端的双键在倒数第3个碳原子上的多不饱和脂肪酸(n-3PUFA)比值最高(P0.05)。由此说明,略阳乌鸡蛋的内部蛋品质较优,但在蛋质量、蛋壳质量和脂肪酸构成上还存在较大的改良空间。     

Identification and expression of the CEP gene family in apple (Malus×domestica)

Plant peptide hormones play important roles in plant growth and development. Among these hormones, the C-TERMINALLYENCODED PEPTIDE(CEP) belongs to a newly found peptide family that regulates root development in Arabidopsis as well as in other species. However, nothing is known about the CEP genes in apple(Malus×domestica, MdCEP). In this study, a total of 27 apple CEP genes were identified through a genome-wide analysis and were phylogenetically divided into three classes(Ⅰ, Ⅱ and Ⅲ). The predicted MdCEP genes were distributed across 10 of 17 chromosomes with different densities. Next, the gene structures and motif compositions of the MdCEP genes were analyzed. Subsequently, the expression analysis suggested that the MdCEP genes were highly activated in roots and that MdCEP23 may play an important role in regulating the growth and development of roots. Moreover, all of the MdCEP genes were responsive to multiple abiotic stresses, indicating that MdCEP genes may be involved with various aspects of physiological processes in apple. Nearly one-third of MdCEP genes had a significant response to low nitrogen treatment. Most of the MdCEP genes were up-regulated under stress, including mannitol, polyethylene glycol(PEG) and abscisic acid(ABA), suggesting that MdCEP genes may be involved in the drought stress response. This study provides insight into the putative functions of the MdCEP genes using a genome-wide analysis of the CEP gene family.     

Biochemical Mechanism of Chlorantraniliprole Resistance in the Diamondback Moth,Plutella xylostella Linnaeus

The insecticide chlorantraniliprole exhibits good efficacy and plays an important role in controlling the diamondback moth, Plutella xylostella Linnaeus. However, resistance to chlorantraniliprole has been observed recently in some field populations. At present study, diamondback moths with resistance to chlorantraniliprole (resistant ratio (RR) was 82.18) for biochemical assays were selected. The assays were performed to determine potential resistance mechanisms. The results showed that the selected resistant moths (GDLZ-R) and susceptible moth could be synergized by known metabolic inhibitors such as piperonyl butoxide (PBO), triphenyl phosphate (TPP) and diethyl-maleate (DEM) at different levels (1.68–5.50-fold and 2.20–2.89-fold, respectively), and DEM showed the maximum synergism in both strains. In enzymes assays, a high level of glutathione-S-transferase (GST) was observed in the resistant moth, in contrast, moths that are susceptible to the insecticide had only 1/3 the GST activity of the resistant moths. The analysis of short-term exposure of chlorantraniliprole on biochemical response in the resistant strain also showed that GST activity was significantly elevated after exposure to a sub-lethal concentration of chlorantraniliprole (about 1/3 LC₅₀, 12 mg L⁻¹) 12 and 24 h, respectively. The results show that there is a strong correlation between the enzyme activity and resistance, and GST is likely the main detoxification mechanism responsible for resistance to chlorantraniliprole in P. xylostella L., cytochrome P450 monooxygenase (P450) and carboxy-lesterase (CarE) are involved in to some extent.     

Progress in understanding hormonal regulation during the postembryonic development of Helicoverpa armigera

Lepidoptera, with 0.16 million species, is the second largest order of insecta. This order includes silk worms, butterflies, and many agricultural pests. The cotton bollworm, Helicoverpa armigera(Hübner) is one of the pests in Lepidoptera that seriously harms cotton plant and other crops in China and other countries. This pest develops resistance to chemical insecticides rapidly. Bacillus thuringiensis(Bt) transgenic cotton plants are developed to control H. armigera population in the field. However, during the past years, the rapid evolution of Bt toxin resistance is observed in H. armigera in transgenic cotton fields. New approaches for the development of new environmentally friendly insecticides to control H. armigera have become necessary, and the molecular mechanisms underlying the development and physiological processes of this species need to be further understood. Considerable progress in the study of H. armigera development and physiology has been achieved in the last decade. This mini-review summarizes the main findings on the molecular mechanisms of hormonal regulation of the development of H. armigera to present new target genes for developing new approaches to control the pest.     

Expression Comparisons of Pathogenesis-Related (PR) Genes in Wheat in Response to Infection/Infestation by Fusarium,Yellow dwarf virus (YDV) Aphid-Transmitted and Hessian Fly

Expression profiles of ten pathogenesis-related (PR) genes during plant defense against Fusarium, Yellow dwarf virus (YDV) aphid-transmitted and Hessian fly (Hf) were compared temporally in both resistant and susceptible genotypes following pathogen infection or insect infestation. Quantitative real-time PCR (qRT-PCR) revealed that PR1, PR2, PR3, PR5, PR6, PR8, PR9, and PR15 appeared to be induced or suppressed independently in response to Fusarium, YDV aphid-transmitted or Hf during the interactions. The PR gene(s) essential to defense against one organism may play little or no role in defense against another pathogen or pest, suggesting the alternative mechanisms may be involved in different interactions of wheat-Fusarium, wheat-YDV aphid-transmitted and wheat-Hf. However, strong up- or down-regulation of PR12 and PR14 encoding low molecular membrane acting protein, defensin and lipid transfer protein (LTP), respectively, had been detected after either pathogen infection or insect infestation, therefore showed broad responses to pathogens and insects. It was postulated that low molecular proteins such as defensins and LTPs might play a role in the early stages of pathogenesis in the signaling process that informs plants about the attack from biotic stresses. In addition, a synergistic action between different PR genes might exist in plants to defense certain pathogens and insects on the basis of comprehensive expression profiling of various pathogenesis-related genes revealed by qRT-PCR in this study.     

Effects of Various Degrees of Antennal Ablation on Mating and Oviposition Preferences of the Diamondback Moth,Plutella xylostella L.

Using scanning electron microscopy, we investigated the distribution of the trichoid, basiconic, and coeloconic sensilla on the antennae of the diamondback moth (DBM; Plutella xylostella). The trichoid sensilla were the most abundant sensory organ, and the male moth antennae host significantly more trichoid sensilla than female moth antennae. Conversely, basiconic and coeloconic sensilla were found more frequently on female than on male antennae. We performed experiments with various degrees of antennal ablation and demonstrated that DBM antennae played a key role in the control of mating and oviposition. We found that neither oviposition preference nor mating behaviors changed significantly when less than 1/4 of both antennae were removed. However, there was a significant behavioral change when the antennae were ablated by more than half. As the length of the antenna was shortened, the successful mating rate decreased and mating peak was delayed. An otherwise consistent host preference for oviposition was eliminated when both antennae were completely removed. Furthermore, we found that the number of trichoid sensilla was positively correlated with mating rate and oviposition preference. However, the numbers of basiconic and coeloconic sensilla were not correlated with mating rate and mating peak, but highly correlated with oviposition preference. Taken together, our results indicate that antennal sensory information plays a critical role in the mating and oviposition behaviors of this economically important pest.     

Development of EST-PCR Markers for the Chromosome 4V of Haynaldia villosa and Their Application in Identification of 4V Chromosome Structural Aberrants

EST-PCR based molecular markers specific for alien chromosomes are not only useful for the detection of the introgressed alien chromatin in the wheat background, but also provide evidence of the syntenic relationship between homoeologous chromosomes. In the present study, in order to develop high density and evenly distributed molecular markers on chromosome 4V of Haynaldia villosa, a total of 607 primer pairs were designed according to the EST sequences, which were previously located in 23 different bins of wheat chromosomes 4A, 4B and 4D. By using the Triticum durum-H, villosa amphiploid and T. aestivum-H, villosa alien chromosome lines involving chromosome 4V, it was found that 9.23% of the tested primers could amplify specific bands for chromosome 4V. Thirty and twenty-six specific markers could be assigned to chromosome arms 4VS and 4VL, respectively. These 4V specific markers provided efficient tools for the characterization of structural variation involving the chromosome 4V as well as for the selection of useful genes located on chromosome 4V in breeding programs.     

Range expansion of the invasive cotton mealybug,Phenacoccus solenopsis Tinsley: An increasing threat to agricultural and horticultural crops in China

The globally invasive cotton mealybug Phenacoccus solenopsis Tinsley, has recently invaded several Chinese regions, and continues to expand its range. This mealybug is a polyphagous insect pest, with at least 200 host plants from 63 families, including cotton, food crops, fruits, ornamental plants, tobacco, and vegetables. Here, we describe the first finding of P. solenopsis in Shandong Province, and investigate the abundances of its natural enemies (predator Coccinella septempunctata L. and parasitoid Aenasius bambawalei Hayat). All three species were detected from ornamental and weed species in Linyi, Shandong, in September 2018, and were positively identified using DNA barcoding. BLAST analysis revealed significant identity (99.38–100%) between sequences of P. solenopsis obtained in this study and those published in the past. This invasive pest represents a major potential threat to agri-horticulture in Shandong, which is a key province of China for production and export of many vegetables, flowers, fruits, and other crops. This mealybug species has a wide range of potential distribution in Shandong and is easily dispersed with agricultural and horticultural transport products. Further monitoring and management strategies are required to limit the spread of this pest species.