Predatory Enemies Research Articles

Identification and odor exposure regulation of odorant-binding proteins in Picromerus lewisi.

The highly developed sensitive olfactory system is essential for Picromerus lewisi Scott (Hemiptera: Pentatomidae) adults, an widely distributed natural predatory enemy, to locate host plants. During this process, odorant-binding proteins (OBPs) are thought to have significant involvement in the olfactory recognition. However, the roles of OBPs in the olfactory perception of P. lewisi are not frequently reported. Here, we conducted odor exposure and transcriptome sequencing experiments using healthy and Spodoptera litura-infested tobacco plants as odor sources. The transcriptomic data revealed that the alteration in the expression of mRNA levels upon exposure to odor was sex-dependent. As the expression profiles differed significantly between male and female adults of P. lewisi. A total of 15 P. lewisi OBPs (PlewOBPs) were identified from the P. lewisi transcriptome. Sequence and phylogenetic analysis indicated that PlewOBPs can be classified into two subfamilies (classic OBP and plus-C OBP). The qRT-PCR results showed that the transcript abundance of 8 PlewOBPs substantially altered following exposure to S. litura-infested tobacco plants, compared to the blank control or healthy plants. This implies that these PlewOBPs may have an olfactory function in detecting S. litura-infested tobacco plants. This study establishes the foundation for further understanding of the olfactory recognition mechanism of P. lewisi and helps discover novel targets for functional characterization in future research.

Non-Consumptive Effects of Harmonia axyridis on the Reproduction and Metabolism of Spodoptera frugiperda.

An increasing body of research has underscored the significant impact of non-consumptive effects on the dynamics of prey pests, encompassing growth, development, reproduction, and metabolism across various vertebrate and invertebrate taxa, rivaling the influence of consumption effects. In our investigation, we delved into the non-consumptive effects exerted by the natural predatory enemy Harmonia axyridis on the reproductive capacity and metabolism of Spodoptera frugiperda adults. Our findings revealed a substantial decrease in the reproductive ability of S. frugiperda adults when exposed to the non-consumptive effects of H. axyridis. Concurrently, we observed an elevation in hydrogen peroxide (H2O2) content and the activities of antioxidant enzymes such as superoxide dismutases (SODs), catalases (CATs), and peroxidases (PODs). Furthermore, notable alterations were detected in energy metabolism, characterized by heightened triglyceride levels and diminished glycogen and trehalose concentrations. These outcomes underscored the adaptive response of the pest aimed at mitigating non-consumptive adverse effects by augmenting antioxidant enzyme activity to counteract oxidative stress and minimize cellular damage. Nonetheless, this defensive mechanism entails a significant expenditure of energy resources, resulting in shifts in energy utilization. Elevated triglyceride levels and reduced glycogen and trehalose concentrations diminish available resources for reproductive processes, such as egg laying, ultimately culminating in decreased fecundity. This study contributes novel insights into the non-consumptive effects observed in insects, while also furnishing valuable insights into the mechanisms underlying insect stress responses.

Chromosome-level genome assembly of the predatory stink bug Arma custos

The stink bug Arma custos (Hemiptera: Pentatomidae) is a predatory enemy successfully used for biocontrol of lepidopteran and coleopteran pests in notorious invasive species. In this study, a high-quality chromosome-scale genome assembly of A. custos was achieved through a combination of Illumina sequencing, PacBio HiFi sequencing, and Hi-C scaffolding techniques. The final assembled genome was 969.02 Mb in size, with 935.94 Mb anchored to seven chromosomes, and a scaffold N50 length of 135.75 Mb. This genome comprised 52.78% repetitive elements. The detected complete BUSCO score was 99.34%, indicating its completeness. A total of 13,708 protein-coding genes were predicted in the genome, and 13219 of them were annotated. This genome provides an invaluable resource for further research on various aspects of predatory bugs, such as biology, genetics, and functional genomics.

Volatile chemical cues emitted by an agricultural companion plant (Cnidium monnieri) attract predatory lacewings (Chrysoperla sinica)

Plant volatiles play an important role in the recruitment of arthropod natural enemies and are widely used in foraging by many species. Therefore, identification of plants that release useful volatile organic compounds (VOCs) for influencing natural enemies and for the control of pests can be helpful in conservation biological control. Cnidium monnieri (L.) can convene many predatory enemies (lady beetles, hoverflies, lacewings) as a functional plant. The Chrysoperla sinica (Tjeder) is a dominant generalist predator, and can control the population of various pests in agricultural fields. However, how C. monnier recruits C. sinica and the chemical association between them is unknown. In this study, we tested the attractiveness of odor released by flowers and leaves of C. monnieri to C. sinica in Y-tube olfactometer. Next, we conducted solid phase microextraction (SPME), gas chromatography-mass spectrometry (GC–MS), and electrophysiological studies (EAG) to analyze the compounds and identified the volatile components which have effects on C. sinica. We also used a Y-tube olfactometer to verify the effectiveness of the volatile components on C. sinica under laboratory conditions. In olfactometer trials, C. sinica adults preferred flowers compared with leaves and fresh air. In GC–MS and electroantennography trials, seventy-six volatiles extracted from C. monnieri, twelve antenna-active components in three different concentrations (0.1 μg/mL, 1 μg/mL, 10 μg/mL) were detected for electroantennography. In the last behavioral identification assays, four synthetic compounds (10 μg/mL) had significant attractiveness of adult C. sinica antenna (i.e., γ-terpinene, trans-β-Ocimene, nerolidol, (Z)-3-Hexen-1-ol). These studies suggest that there is a chemical association between natural enemies C. sinica and the functional plant C. monnieri. This study provides a basis that can facilitate the production and application of attracting natural enemy and development and application of enhancing attractants.

MicroRNA response to temperature stress in the wolf spider Pardosa pseudoannulata (Araneae: Lycosidae)

AbstractMicroRNAs (miRNAs) are conserved noncoding small RNAs that play essential regulatory roles in gene function by regulating target genes. Pardosa pseudoannulata is an important natural predatory enemy of insect pests and plays a significant role in controlling pests in rice fields, with temperature having a significant impact on their growth and development. To understand the response of miRNAs to temperature stress in P. pseudoannulata, we performed miRNA identification analyses of adult spiders exposed to 10°C and 40°C for 12 h, as low‐temperature and high‐temperature treatment groups, respectively. We obtained 54.74 M clean reads from 69.84 M raw reads after filtering out low‐quality reads, and 78 miRNAs including 13 novel miRNAs were identified from three small RNA libraries (10°C, 25°C and 40°C). At the low temperature and the high temperature, eight (one upregulated and seven downregulated) and ten (nine upregulated and one downregulated) differentially expressed miRNAs were identified, respectively. These differentially expressed miRNAs negatively regulated 43 and 12 target mRNA (the unigenes in our previous transcriptome sequence data) in response to low‐ and high‐temperature stress, respectively. These target genes are mainly involved in translation, ribosome structure and biotransformation, as well as the generation and conversion of energy. This study represents the first report of miRNA identification related to the Araneae spider species in response to temperature stress. These results will greatly facilitate our understanding of the physiological and biochemical mechanisms of spiders in response to temperature stress, which might be beneficial for the conservation and utilization of this species as an important natural insect enemy of pests in rice ecosystems.

Buprofezin delayed the molting of Pardosa pseudoannulata, a predatory enemy for insect pests, by suppressing chitin synthase 1 expression

Spiders, the major predatory enemies of insect pests in fields, are vulnerable to insecticides. In this study, we observed that the recommended dose of buprofezin delayed the molting of the pond wolf spider Pardosa pseudoannulata, although it had no lethal effect on the spiders. Since buprofezin is an insect chitin biosynthesis inhibitor, we identified two chitin synthase genes (PpCHS1 and PpCHS2) in P. pseudoannulata. Tissue-specific expression profiling showed that PpCHS1 was most highly expressed in cuticle. In contrast, PpCHS2 showed highest mRNA levels in the midgut and fat body. RNAi knockdown of PpCHS1 significantly delayed the molting of 12-days old spiderlings, whereas no significant effect on the molting was observed in the PpCHS2-silencing spiderlings. The expression of PpCHS1 was significantly suppressed in the spiderlings treated with buprofezin, but rescued by exogenous ecdysteroid ponasterone A (PA). Consistent with this result, the molting delay caused by buprofezin was also rescued by PA. The results revealed that buprofezin delayed the molting of spiders by suppressing PpCHS1 expression, which will benefit the protection of P. pseudoannulate and related spider species.

Inocellia (Amurinocellia) calida (Raphidioptera, Inocelliidae) was first observed as a predator of Monochamussaltuarius (Coleoptera, Cerambycidae) in China, the vector of Bursaphelenchusxylophilus (Aphelenchida, Aphelenchoididae).

Monochamussaltuarius Gebler (Coleoptera, Cerambycidae) serves as the primary carrier of Bursaphelenchusxylophilus (Steiner & Buhrer) (Aphelenchida, Aphelenchoididae) in the middle-temperate zone of China. Pine wilt disease caused by B.xylophilus leads to serious losses to pine forestry around the world. It is necessary to study the biological control of M.saltuarius to effectively prevent the further spread of B.xylophilus. To explore the insect resources that act as natural enemies of M.saltuarius, investigations were conducted on natural enemy insects by splitting Pinuskoraiensis Siebold & Zucc (Pinales, Pinaceae) damaged by M.saltuarius and dissecting their trunks in Yingpan Village, Fushun County, Fushun City, Liaoning Province, China, in 2023. A larva of Inocellia (Amurinocellia) calida (H. Aspöck & U. Aspöck) (Raphidioptera, Inocelliidae) was discovered in the trunk of an infested P.koraiensis. Additionally, the feeding habits of I.calida were preliminarily examined under indoor conditions and a description of its morphological characteristics was provided. When placed in an indoor environment, the I.calida larva began pupating after a period of 21 days, during which time it consumed and attacked a total of 23 M.saltuarius larvae. Ultimately, after a pupal period of ten days, the I.calida larva emerged successfully as an adult. This discovery marks the first recorded presence of I.calida in Liaoning Province and the first documentation of I.calida in China, serving as a natural predatory enemy of M.saltuarius.

The impact of field margins on biological pest control: a meta-analysis

Floral field margins are known to benefit invertebrate species diversity and abundance within agricultural landscapes, but variation in success limits widespread uptake. Understanding how variation within floral field margins can affect certain entomological groupings is lacking but would allow for a more individualised design of margins to enhance biological control. This meta-analysis aims to answer the question; do floral field margins benefit biological pest control over grassy field margins? We found that floral margins significantly benefit the natural enemy community and biological control services, relative to non-floral grass margins. We confirm that field margin type is linked to higher abundance and diversity of natural enemies, lower numbers of herbivorous invertebrate pests, and reduced crop damage. We consider whether specific characterisations of natural enemies and pest communities vary between these margin types, finding key differences in the abundances of aerial and epigeal enemies, the diversity of parasitoid and predatory enemies and pest abundances found in naturally regenerating and sown floral field margins. The finding here cements the implementation of floral field margins as a legitimate control method for crop pests in the face of losses due to pesticides and highlights design and management considerations for the success of floral margins.

Three Heat Shock Protein Genes and Antioxidant Enzymes Protect Pardosa pseudoannulata (Araneae: Lycosidae) from High Temperature Stress.

Pardosa pseudoannulata (P. pseudoannulata) is an essential natural predatory enemy in rice ecosystems. The fluctuating climate may cause them to experience heat stress, whereas heat shock proteins (HSPs) and antioxidant enzymes help resist heat damage. Herein, we cloned and characterized the full-length genes PpHSP27, PpHSP60, and PpHSC70 from P. pseudoannulata. Changes in gene expression levels and superoxide dismutase (SOD), catalase (CAT), and glutathione transferase (GST) activities in adult male and female P. pseudoannulata were measured at different stress exposure times and temperatures. We found that the abovementioned HSP genes belong to the sHSP, HSP60, and HSP70 families. The expression of the three HSP genes and the activities of SOD, CAT, and GST were significantly upregulated with the increasing stress temperature and time. The knockdown of the three HSP genes via RNA interference significantly decreased the survival rate of male and female P. pseudoannulata during high temperature stress. Thus, PpHSP27, PpHSP60, and PpHSC70 play an important role in the heat tolerance of P. pseudoannulata, and SOD, CAT, and GST enable recovery heat stress-induced oxidative damage. Their changes and regulation during high temperature stress can improve spiders' adaptability in the field and enhance the biological control of environmental pests.

Molecular characterization of six heat shock protein 70 genes from Arma chinensis and their expression patterns in response to temperature stress.

Arma chinensis is an important predatory enemy of many agricultural and forest pests. Heat shock protein 70 (Hsp70) plays an essential role in insect adaptation to various stress factors. To explore the functions of Hsp70s in relation to thermal tolerance of A. chinensis, full-length cDNAs of six Hsp70 genes (AcHsp70Ba, AcHsp70-4, AcHsp68a, AcHsp68b, AcHsp70-2, and AcHsc70-4) were cloned. Their open reading frames (ORFs) were 1902, 2454, 1884, 1905, 1872, and 1947bp, respectively. Developmental expression profiles showed that AcHsp70Ba, AcHsp70-4, and AcHsc70-4 were extremely highly expressed in adult stages. AcHsp68a and AcHsp70-2 showed the highest level of expression in nymph stages, and AcHsp68b was mainly expressed in male adults. Tissue distribution analysis demonstrated that the AcHsp70s were ubiquitously expressed but showing gene-specific and sex-driven patterns of expression. High temperature induced the expression of the six AcHsp70s. Among them, AcHsp70Ba, AcHsp70-4, AcHsp68a, and AcHsc70-4 were significantly induced at 38°C for 6h, while all six AcHsp70s were significantly induced at 38°C for 24h. There were differences in responses of the six AcHsp70s to low-temperature stress. The expressions of AcHsp70-4, AcHsp68a, and AcHsp68b in male adults were significantly repressed at 4°C for 6h, whereas AcHsp70Ba and AcHsp70-2 were significantly induced. The levels of AcHsp70Ba, AcHsp68b, and AcHsp70-2 in female adults were significantly repressed at 4°C for 24h, whereas AcHsc70-4 was significantly induced. These results suggested that AcHsp70s play important roles in various developmental stages and tissue function, and contribute to the tolerance of A. chinensis to extreme temperatures.

The complete mitochondrial genome of Pheropsophus occipitalis MacLeay, 1825 (Coleoptera: Carabidae)

Pheropsophus occipitalis MacLeay is a predatory enemy prey heavily on agricultural pests. The length of the complete mitochondrial genome of P. occipitalis was 16,800 bp with 20.4% GC content, including 41.2% A, 11.9% C, 8.4% G, 38.5% T. The genome encoded 13 protein-coding genes (PCGs), 22 transfer RNA genes (tRNA), two ribosomal RNA genes (rRNA). Phylogenetic analysis showed that P. occipitalis was clustered with Pheropsophus bimaculatus and Pheropsophus sobrinus. This study provided a scientific basis for the population genetics, phylogeny, and molecular taxonomy of P. occipitalis.

茶园重要捕食性天敌白斑猎蛛在中国的潜在适生区预测

PDF HTML阅读 XML下载 导出引用 引用提醒 茶园重要捕食性天敌白斑猎蛛在中国的潜在适生区预测 DOI: 10.5846/stxb202107021766 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 福建省创新战略研究计划项目（2020R0036）；国家自然科学基金项目（31501650）；福建农林大学科技创新专项基金（CXZX2019009G）；福建农林大学茶产业链科技创新与服务体系建设项目（K1520005A03） Prediction of potential geographical distribution of predatory enemy Evarcha albaria in tea plantations in China Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:白斑猎蛛是茶园重要的捕食性天敌，对茶园害虫生物防治起着重要作用。研究白斑猎蛛的潜在分布范围以及气候变暖对其分布潜在的影响，对保护和利用白斑猎蛛，充分发挥其对茶园害虫的生态调控作用具有重要意义。基于白斑猎蛛当前在中国的163个分布点和6个环境变量，利用MaxEnt模型预测当前及未来（2050年）2种气候情景（SSP2_4.5、SSP5_8.5）下白斑猎蛛在中国的潜在适生区。结果显示，MaxEnt模型对白斑猎蛛潜在适生区分布预测具有较好的准确度，平均受试者工作特征曲线下面积（AUC）值为0.852；测试样本遗漏率与预测遗漏率基本吻合，模型构建效果很好。白斑猎蛛在中国大部分省份均有分布，当前适宜分布区总面积约为429.93万km2，占国土总面积的44.78%；高适生区主要分布在山东、河南、江苏、安徽、湖北、重庆、浙江、江西、湖南、贵州、福建。未来气候情景下，白斑猎蛛潜在适生区面积呈扩大趋势，主要体现在新疆、吉林、辽宁、内蒙古、陕西、广东、广西、海南的适生区范围扩张。在SSP5_8.5气候情景下，总适生区面积变化最大，由当前的429.93万km2增加到562.22万km2，增幅达30.77%。未来两种气候情景下，白斑猎蛛的潜在适生区范围相对当前均有不同程度的扩大和北移。利用Jackknife刀切法计算得到影响白斑猎蛛潜在分布的主要环境变量为最冷月份最低温（bio6）、最湿月份降水量（bio13）、最干月份降水量（bio14）和最暖季平均温度（bio10）。白斑猎蛛广泛分布于中国大部分地区，未来气候条件有利于其生存和繁殖。应加强白斑猎蛛的保护和利用，充分挖掘并发挥其对茶园害虫的控害作用，减少茶园化学农药使用，保障茶叶安全优质生产和茶产业的可持续发展。 Abstract:Evarcha albaria (L. Koch) is an important predatory enemy in tea plantations, which plays an important role in biological control of pests in tea plantations. To study the potential distribution range of the E. albaria and the potential impact of climate warming on its distribution is of great significance for protecting and utilizing the E. albaria and giving full play to its ecological regulation on pests in tea plantations. In this study, based on the current 163 distribution sites and 6 environmental variables in China, the maximum entropy model (MaxEnt) was used to predict the potential distribution regions of the E. albaria in current and future (2050) under two climate scenarios (SSP2_4.5 and SSP5_8.5) in China. The results showed that the MaxEnt model had a good accuracy in predicting the distribution of potential suitable regions of the E. albaria, and the average area under the receiver operating characteristic curve (AUC) value was 0.852; The missing rate of test samples was basically consistent with the predicted missing rate, and the model construction effect was very good. The suitable distribution regions of the E. albaria were about 4.2993 million km2, accounting for 44.78% of the total area of China. The high suitable regions were mainly distributed in Shandong, Henan, Jiangsu, Anhui, Hubei, Chongqing, Zhejiang, Jiangxi, Hunan, Guizhou, and Fujian in current. Under the future climate scenarios, the potential suitable regions of the E. albaria were expanding, mainly in Xinjiang, Jilin, Liaoning, Inner Mongolia, Shaanxi, Guangdong, Guangxi, and Hainan. Under the SSP5_8.5 climate scenario, the total suitable regions changed the most, from the current 4.2993 million km2 to 5.6222 million km2, an increase of 30.77%. Under the two future climate scenarios, the potential suitable distribution regions of the E. albaria will expand and move northward in varying degrees compared with the current. The main environmental variables affecting the potential distribution of the E. albaria were the lowest temperature in the coldest month (bio6), the precipitation in the wettest month (bio13), the precipitation in the driest month (bio14), and the average temperature in the warmest season (bio10), which calculated by Jackknife method. The E. albaria is widely distributed in most regions of China, and the future climate conditions are conducive to its survival and reproduction. In order to ensure the safe and high-quality production of tea and the sustainable development of tea industry, it is necessary to strengthen the protection and utilization of the E. albaria, fully exploit and play its biological control, and reduce the use of chemical pesticides in tea plantations. 参考文献 相似文献 引证文献

RNA interference in Pardosa pseudoannulata, an important predatory enemy against several insect pests, through ingestion of dsRNA-expressing Escherichia coli.

RNA interference is an important technology for gene functional research in many organisms. The pond wolf spider (Pardosa pseudoannulata) is an important natural enemy of rice field pests. To facilitate large-scale gene functional research in this spider species and others, we developed an RNA interference (RNAi) method via ingestion of bacteria expressing dsRNA. The dsRNA targeting a cytochrome P450 monooxygenase (cyp41g2) was expressed in Escherichia coli HT115 (DE3). And then the bacterial suspension was fed to 14-20 days old spiderlings. The mRNA abundance of the target gene was significantly reduced after 3-day's ingestion of bacteria expressing dsRNA, and between day 5 and 7, RNAi efficiency remained stable. Thus, we selected 5 days as the optimum interference time. Furthermore, the bacteria resuspension containing 20 ng/μl dsRNA was selected as the optimum concentration. To evaluate the applicability of this method, three other genes with different tissue expression pattern were also selected as targets. And the mRNA abundance of all the four target genes was significantly reduced with RNAi efficiency between 66.0% and up to 86.9%. The results demonstrated that the oral delivery of bacteria expressing dsRNA would be an effective RNAi method for the gene functional study in P. pseudoannulata.

Tea saponin reduces the damage of Ectropis obliqua to tea crops, and exerts reduced effects on the spiders Ebrechtella tricuspidata and Evarcha albaria compared to chemical insecticides.

BackgroundTea is one of the most economically important crops in China. However, the tea geometrid (Ectropis obliqua), a serious leaf-feeding pest, causes significant damage to tea crops and reduces tea yield and quality. Spiders are the most dominant predatory enemies in the tea plantation ecosystem, which makes them potentially useful biological control agents of E. obliqua. These highlight the need for alternative pest control measures. Our previous studies have shown that tea saponin (TS) exerts insecticidal activity against lepidopteran pests. Here, we investigate whether TS represents a potentially new alternative insecticide with no harm to spiders.MethodsWe investigated laboratory bioactivities and the field control properties of TS solution against E. obliqua. (i) A leaf-dip bioassay was used to evaluate the toxicity of TS to 3rd-instar E. obliqua larvae and effects of TS on the activities of enzymes glutathione-S-transferase (GST), acetylcholinesterase (AChE), carboxylesterase (CES) and peroxidase (POD) of 3rd-instar E. obliqua larvae in the laboratory. (ii) Topical application was used to measure the toxicity of 30% TS (w/v) and two chemical insecticides (10% bifenthrin EC and 50% diafenthiuron SC) to two species of spider, Ebrechtella tricuspidata and Evarcha albaria. (iii) Field trials were used to investigate the controlling efficacy of 30% TS against E. obliqua larvae and to classify the effect of TS to spiders in the tea plantation.ResultsThe toxicity of TS to 3rd-instar E. obliqua larvae occurred in a dose-dependent manner and the LC50 was 164.32 mg/mL. Activities of the detoxifying-related enzymes, GST and POD, increased in 3rd-instar E. obliqua larvae, whereas AChE and CES were inhibited with time by treatment with TS. Mortalities of E. tricuspidata and E. albaria after 48 h with 30% TS treatment (16.67% and 20%, respectively) were significantly lower than those with 10% bifenthrin EC (80% and 73.33%, respectively) and 50% diafenthiuron EC (43.33% and 36.67%, respectively). The highest controlling efficacy of 30% TS was 77.02% at 5 d after treatment, which showed no difference to 10% bifenthrin EC or 50% diafenthiuron SC. 30% TS was placed in the class N (harmless or slightly harmful) of IOBC (International Organization of Biological Control) categories for natural enemies, namely spiders.ConclusionsOur results indicate that TS is a botanical insecticide that has a good controlling efficacy in E. obliqua larvae, which suggests it has promise as application in the integrated pest management (IPM) envisaged for tea crops.

<strong>Effects of host plant species on the development and reproduction of <em>Neoseiulus bicaudus</em> (Phytoseiidae) feeding on <em>Tetranychus turkestani</em> (Tetranychidae)</strong>

Abstract The leaf structure of the host plant can affect the development and reproduction of the predatory enemies of spider mites. The objective of this study was to compare the effects of five host plant species [cucumber (Cucumis sativus L.), cotton (Gossypium hirsutum L.), eggplant (Solanum melongena L.), tomato (Lycopersicon esculentum Mill.) and green bean (Phaseolus vulgaris L.)] on the development and reproduction of Neoseiulus bicaudus feeding on Tetranychus turkestani. There were significant differences in the characteristics of trichomes on the surfaces of the host plant species. Tomato leaves had the greatest trichome density (782 trichomes/cm2) whereas green bean leaves had the least density (58 trichomes/cm2). Cucumber had the longest trichomes (1.58 mm) and green bean had the shortest (0.14 mm). N. bicaudus developed into adulthood and completed its development on all five plant species. The total immature period of N. bicaudus feeding on T. turkestani was shortest (5.07 d) on tomato. N. bi...

Natural Predatory Enemies of Mango Red Mite Oligonychus mangiferus (Tetranychidae) in Eastern Egyptian Mango Orchards

Survey for natural predatory enemies of the mango red spider mite, Oligonychus mangiferus (Rhaman and Sapra), on mango trees were carried out in Ismailia governorate, Egypt to determine prospective species for the biological control of this pest. One peak of O. mangiferus during the year, from April to June was noticed. Total averages of 218.84 specimens of natural predatory enemies were found in 240 collected samples. Of these, 176.57 were predatory mites and 42.27 were predatory insects. Twelve species of predaceous arthropods, including mites and insects, have been reported in association with O. mangiferus, of which Typhlodromus pyri Schueten was the most abundant representing 14.06% of the total collected predaceous mites. Most of collected predatory mites and insects were generalist predators. Orius albidipennis (Reuter) was the most abundant representing 46.49 % of the total collected predatory insects. The distribution patterns of natural enemies always correlated with abundance of the mango red spider mite.

Validating the importance of two acetylcholinesterases in insecticide sensitivities by RNAi in Pardosa pseudoannulata, an important predatory enemy against several insect pests

The pond wolf spider (Pardosa pseudoannulata) is an important predatory enemy against several insect pests and showed relative different sensitivities to organophosphate and carbamate insecticides compared to insect pests. In our previous studies, two acetylcholinesterases were identified in P. pseudoannulata and played important roles in insecticide sensitivities. In order to understand the contributions of the two acetylcholinesterases to insecticide sensitivities, we firstly employed the RNAi technology in the spider. For a suitable microinjection RNAi method, the injection site, injection volume and interference time were optimized, which then demonstrated that the injection RNAi method was applicable in this spider. With the new RNAi method, it was revealed that both Pp-AChE1 and Pp-AChE2, encoded by genes Ppace1 and Ppace2, were the targets of organophosphate insecticides, but Pp-AChE1 would be more important. In contrast, the carbamate acted selectively on Pp-AChE1. The results showed that Pp-AChE1 was the major catalytic enzyme in P. pseudoannulata and the major target of organophosphate and carbamate insecticides. In a word, an RNAi method was established in the pond wolf spider, which further validated the importance of two acetylcholinesterases in insecticide sensitivities in this spider.

Sequence Analysis of Insecticide Action and Detoxification-Related Genes in the Insect Pest Natural Enemy Pardosa pseudoannulata.

The pond wolf spider Pardosa pseudoannulata, an important natural predatory enemy of rice planthoppers, is found widely distributed in paddy fields. However, data on the genes involved in insecticide action, detoxification, and response are very limited for P. pseudoannulata, which inhibits the development and appropriate use of selective insecticides to control insect pests on rice. We used transcriptome construction from adult spider cephalothoraxes to analyze and manually identify genes enconding metabolic enzymes and target receptors related to insecticide action and detoxification, including 90 cytochrome P450s, 14 glutathione S-transferases (GSTs), 17 acetylcholinesterases (AChEs), 17 nicotinic acetylcholine receptors (nAChRs), and 17 gamma-aminobutyric acid (GABA) receptors, as well as 12 glutamate-gated chloride channel (GluCl) unigenes. Sequence alignment and phylogenetic analysis revealed the different subclassifications of P450s and GSTs, some important sequence diversities in nAChRs and GABA receptors, polymorphism in AChEs, and high similarities in GluCls. For P450s in P. pseudoannulata, the number of unigenes belonging to the CYP2 clade was much higher than that in CYP3 and CYP4 clades. The results differed from insects in which most P450 genes were in CYP3 and CYP4 clades. For GSTs, most unigenes belonged to the delta and sigma classes, and no epsilon GST class gene was found, which differed from the findings for insects and acarina. Our results will be useful for studies on insecticide action, selectivity, and detoxification in the spider and other related animals, and the sequence differences in target genes between the spider and insects will provide important information for the design of selective insecticides.

Identification of key amino acid differences between Cyrtorhinus lividipennis and Nilaparvata lugens nAChR α8 subunits contributing to neonicotinoid sensitivity

High sensitivity to neonicotinoid insecticides have been reported in the miridbug Cyrtorhinus lividipennis, an important predatory enemy of rice planthoppers, such as Nilaparvata lugens (brown planthopper). In the present study, the sensitivity of neonicotinoid insecticides between C. lividipennis and N. lugens were detected and compared. The results showed that neonicotinoid insecticides were much more toxic to the miridbug than to the brown planthopper. A nicotinic acetylcholine receptor subunit was cloned from the miridbug and denoted as α8 subunit (Clα8) according to sequence similarities and important functional motifs. Key amino acid differences were found in specific loops from α8 subunits between C. lividipennis (Clα8) and N. lugens (Nlα8). In order to understand the roles of key amino acid differences in insecticide sensitivities, the different amino acid residues in specific loops of Nlα8 were introduced into the corresponding sites in Clα8 to construct several subunit mutants. Clα8 or subunit mutants were co-expressed with rat β2 to obtain the functional receptors in Xenopus oocytes. The single mutation N191F in loop B reduced imidacloprid sensitivity, with EC50 value in Clα8N191F/β2 of 15.21μM and 5.74μM in Clα8/β2. Interestingly, although the single mutation E240T in loop C did not cause the significant change in imidacloprid sensitivity, it could enhance the effects of N191F and cause more decrease in imidacloprid sensitivity. The results indicated that E240T might contribute to neonicotinoid sensitivity in an indirect way.

Identification of polymorphisms in Cyrtorhinus lividipennis RDL subunit contributing to fipronil sensitivity

As one of the most important predatory enemies, the miridbug, Cyrtorhinus lividipennis, plays an important role in rice planthoppers control, such as Nilaparvata lugens (brown planthopper). In order to compare insecticide selectivity between C. lividipennis and N. lugens, the contact acute toxicities of six insecticides (diazoxon, paraoxon, carbaryl, fenobucarb, fipronil and ethofenprox) were monitored. The results showed that all tested insecticides were more toxic to C. lividipennis than to N. lugens and fipronil had the biggest difference. The RDL subunit (Cl-RDL) was cloned from C. lividipennis and a RDL isoform (Cl-RDL-In) was also found with 31 amino acids insertion in RDL intracellular region. In order to understand the role of the insertion on insecticide sensitivities, three subunits (Nl-RDL, Cl-RDL and Cl-RDL-In) were constructed to obtain the functional receptors in Xenopus oocytes and the fipronil sensitivities were detected by the voltage-clamp technique. Nl-RDL (IC50 = 32.36 ± 4.07 µM) was more insensitive to fipronil than Cl-RDL (IC50 = 6.47 ± 1.12 µM). The insertion in Cl-RDL significantly reduced fipronil sensitivity with IC50 value in Cl-RDL-In of 16.83 ± 2.30 µM. Interestingly, after the elution of fipronil, the current response of Cl-RDL-In appeared obvious recovery, which were not observed in Cl-RDL and Nl-RDL. It might imply that the insertion played a special role in fipronil sensitivity.