Combined use of eco-friendly insecticides with natural enemies is increasingly being used in pest management. In this study, the combination of eco-friendly insecticides and Orius nagaii (Yasunaga) (Hemiptera: Anthocoridae), an important predator of the thrips, in controlling Dendrothrips minowai (Priesner) (Thysanoptera: Thripidae), a major tea pest, was evaluated in both laboratories and tea plantations. Five commercial insecticides were first screened the toxicity to D. minowai, and their safety to O. nagaii. The results showed mineral oil and Metarhizium anisopliae CQMa421 were toxic against D. minowai, while diafenthiuron, mineral oil and M. anisopliae CQMa421 were relatively safe for O. nagaii. Sublethal bioassay on eggs, nymphs, and adults of O. nagaii showed that mineral oil exposure minimized hatching rate among the 5 insecticides. The adverse effects of diafenthiuron and M. anisopliae CQMa421 on the development and reproduction of O. nagaii were inferior to those of spinetoram and indoxacarb. Both spinetoram and indoxacarb displayed significant acute and sublethal effects on O. nagaii. Field trials unveiled that the combined use of O. nagaii and diafenthiuron was an effective and lasting pest control strategy against D. minowai. The results contribute to an improved D. minowai management coordinated eco-friendly insecticide with natural enemy insects.

ABSTRACT Begomoviruses are significant constraints to the production of many crops worldwide. Efficient passage of the circulatively transmitted begomoviruses through the midgut and primary salivary gland (PSG) of their whitefly vector is an essential step in productive virus transmission. While how begomoviruses transport across the whitefly midgut wall has been characterized, the mechanisms underlying the trafficking of begomoviruses through whitefly PSG remain poorly understood. In this study, we combined direct injection of purified virions into the whitefly hemolymph with inhibitor and dsRNA treatment and investigated the roles of endocytosis and endosomes in the entry and intracellular trafficking of begomoviruses in whitefly PSG. We found that clathrin-mediated endocytosis and early endosomes mediated the entry of tomato yellow leaf curl virus (TYLCV) into whitefly PSG. Additionally, late and recycling endosomes were not involved in TYLCV trafficking in PSG. Notably, the regulating proteins of vesicle trafficking such as Arp2/3 complex; CORVET complex subunits Vps8, Vps11, and Vps33a; and sorting nexin Snx12 did not seem to play a role in TYLCV entry into PSG. Furthermore, clathrin-mediated endocytosis and early endosomes were found to mediate the entry of another begomovirus into PSG, indicating it might be a conserved pathway exploited by begomoviruses to enter PSG. Our results uncovered the key whitefly components that mediate the trafficking of begomoviruses in PSGs of their insect vectors. IMPORTANCE Many plant viruses are transmitted by insect vectors in a circulative manner. For efficient transmission, the entry of the virus from vector hemolymph into the primary salivary gland (PSG) is a step of paramount importance. Yet, vector components mediating virus entry into PSG remain barely characterized. Here, we demonstrate the role of clathrin-mediated endocytosis and early endosomes in begomovirus entry into whitefly PSG. Our findings unravel the key components involved in begomovirus transport within the whitefly body and transmission by their whitefly vectors and provide novel clues for blocking begomovirus transmission.

c-Jun N-terminal protein kinase (JNK) plays a crucial role in eukaryotic cell adaptation to various stress stimuli. Nevertheless, the role of the JNK pathway in the interplay between plant viruses and their insect vectors remains poorly understood. Working with tomato yellow leaf curl virus (TYLCV), a plant DNA virus of the genus Begomovirus, transmitted by the whitefly Bemisia tabaci, we found that activation of whitefly JNK pathway can facilitate TYLCV accumulation and transmission. In vivo study revealed that JNK and c-Jun transcription factor are phosphorylated in response to TYLCV infection. Suppressing the JNK signaling pathway by chemicals or double strand RNAs remarkably reduced viral accumulation and gene transcription. Moreover, the c-Jun transcription factor directly bound to the intergenic region of viral genome and promoted viral gene transcription. Our results suggest that TYLCV might trigger the JNK signaling pathway within their insect vectors, therefore enhance viral accumulation in whitefly.

[目的 ]探明辣椒根际土壤中对尖孢镰刀菌(Fusarium oxysporum)有拮抗作用的微生物,筛选可抑制辣椒枯萎病的生防菌,为绿色防控辣椒连作导致的枯萎病提供有效的生防微生物资源.[方法]采用平板稀释法分离辣椒不同生长阶段根际土壤中的微生物,再通过平板对峙法筛选拮抗菌株并鉴定拮抗菌发酵液抑菌活性,结合形态学和分子生物学方法鉴定拮抗菌株种类.[结果]从辣椒根际土壤中共分离出真菌50株,其中5株木霉菌株对尖孢镰刀菌有拮抗作用,对峙培养抑菌率为60.47％～78.04％,LJ06020803菌株的抑菌率最高,为78.04％,其不含菌体的发酵液抑菌率为40.92％;根据LJ06020803菌株形态学特征和系统发育树鉴定其为哈茨木霉菌(Trichoderma harzianum).[结论]菌株LJ06020803为哈茨木霉菌(Tri-choderma harzianum),对辣椒枯萎病病原菌有很好的拮抗效果,可作为一种生防资源用于防治辣椒枯萎病.

Nutritional mutualism between insects and symbiotic bacteria is widespread. The various sap-feeding whitefly species within the Bemisia tabaci complex associate with the same obligate symbiont (Portiera) and multiple secondary symbionts. It is often assumed that some of the symbionts residing in the whiteflies play crucial roles in the nutritional physiology of their insect hosts. Although effort has been made to understand the functions of the whitefly symbionts, the metabolic complementarity offered by these symbionts to the hosts is not yet well understood. We examined two secondary symbionts, Arsenophonus and Wolbachia, in two species of the B. tabaci whitefly complex, provisionally named as Asia II 3 and China 1. Genomic sequence analyses revealed that Arsenophonus and Wolbachia retained genes responsible for the biosynthesis of B vitamins. We then conducted transcriptomic surveys of the bacteriomes in these two species of whiteflies together with that in another species named MED of this whitefly complex previously reported. The analyses indicated that several key genes in B vitamin syntheses from the three whitefly species were identical. Our findings suggest that, similar to another secondary symbiont Hamiltonella, Arsenophonus and Wolbachia function in the nutrient provision of host whiteflies. Although phylogenetically distant species of symbionts are associated with their respective hosts, they have evolved and retained similar functions in biosynthesis of some B vitamins. Such metabolic complementarity between whiteflies and symbionts represents an important feature of their coevolution.

探明贵阳地区温室草莓[Fragaria ananassa(Duchesne)]在生态草莓(不施用杀虫剂)和常规管理(正常施用杀虫剂)模式下二斑叶螨[Tetranychus urticae(Koch)]的种群动态及发生规律,为其科学防治提供参考,于2021年3—4月对温室草莓二斑叶螨的种群动态进行了调查.结果表明:3月上旬到4月中旬,生态草莓上二斑叶螨的虫口数量持续增加,到4月15日达到顶峰,平均虫口数约为6965头/10株;常规管理草莓上二斑叶螨的虫口数量一直维持在较高水平,平均2000～3000头/10株,未出现峰值.根据温室草莓二斑叶螨的种群动态及发生规律,建议在3月初释放捕食螨防治,以减少化学农药的使用.

In nature, a plant can be infected by multiple viruses simultaneously. However, the effects of coinfection on plant-vector interactions are less well studied.Two begomoviruses of the family Geminiviridae,Tomato yellow leaf curl virus (TYLCV) and Tomato yellow leaf curl China virus (TYLCCNV), occur sympatrically in China. Each of them is reported to increase the performance of whitefly vector via manipulation of plant traits. In this study, we examined the effects of coinfection by the two viruses TYLCV and TYLCCNV on plant-whitefly interactions, compared to that infected by a single virus. We found that plants infected by two viruses showed aggravated symptoms but the performance and preference of whiteflies were not altered significantly compared to singly-infected plants. Coinfection suppressed the transcription of genes involved in jasmonic acid (JA) signaling pathway in plants, but showed no significant difference to single-virus infected plants. These findings suggest that although TYLCV and TYLCCNV may synergistically induce plant symptoms, they did not manipulate synergistically plant-mediated responses to the insect vector.

载体植物系统作为一种新型的生物防治手段,具有良好的防治效果和应用价值.蚕豆蚜Aphis fabae偏好豆科植物,对茶树安全,且作为猎物可满足南方小花蝽Orius strigicollis生长和繁殖的需要.因此本研究以蚕豆蚜作为替代猎物、蚕豆Vicia faba作为载体植物及南方小花蝽作为天敌昆虫构建"南方小花蝽-蚕豆-蚕豆蚜"载体植物系统来防治茶叶害虫.为探究该载体系统是否可有效控制茶叶害虫,本研究事先在室内比较了该载体植物系统与直接释放南方小花蝽对茶蚜Toxoptera aurnantii的防治效果;之后在田间调查中发现茶树上主要有茶蚜、茶棍蓟马Dendrothrips minowai及小贯小绿叶蝉Empoasca onukii共3种害虫混合发生,且它们均可被南方小花蝽捕食,因此在田间试验中本研究同时评价了载体植物系统及直接释放南方小花蝽对这3种害虫的防治效果.结果显示:在室内试验中,载体植物系统与直接释放南方小花蝽相比,在前3次调查中茶蚜种群数量显著降低,且虫口减退率及防治效果均显著高于直接释放南方小花蝽,其中载体植物系统对茶蚜的控制效果最高可达92.16％,而直接释放南方小花蝽对茶蚜的防治效果仅为72.25％,表明该载体植物系统有应用于田间防治茶叶害虫的潜力.在田间试验中,载体植物的布局(条状、块状及点状)对载体植物系统的防治效果无显著影响;载体植物系统与直接释放南方小花蝽均对小贯小绿叶蝉有显著的防治效果,且最高防效均在90％左右,但对茶蚜及茶棍蓟马则无明显的控制作用,表明载体植物系统与直接释放南方小花蝽均可用于茶叶害虫的防治,但在应用时需考虑到多种害虫同时发生对防治效果的影响.

The stick tea thrip Dendrothrips minowai (Priesner) (Thysanoptera: Thripidae) is a destructive pest in tea plantations in south and southwest China. To control this pest, a non-crop banker plant system was developed using a polyphagous predator Orius strigicollis (Poppius) (Heteroptera: Anthocoridae) with the black bean aphid Aphis fabae (Scopoli) (Hemiptera: Aphididae) as an alternative prey and the faba bean Vicia faba as the banker plant to support the predator in targeting the pest. The fitness of A. fabae on tea plants and faba bean was evaluated to determine its host specificity. Moreover, the control efficacy of the banker plant system on D. minowai on tea plants was tested in the laboratory and compared with that of direct release of O. strigicollis. The experiments showed that faba bean was an excellent non-crop host for A. fabae because, while the aphid population increased quickly on faba bean, it could only survive for up to 9 days on tea plants. Compared with direct release of O. strigicollis, lower densities of pest were observed when introducing the banker plant system. Our results indicate that this banker plant system has the potential to be implemented in the field to improve the control of the pest thrips.

小花蝽是农业生产上一类极具利用和开发前景的捕食天敌昆虫,人工饲养扩繁是小花蝽广泛应用的前提,然而在大规模饲养中产卵基质、饲料和饲养条件等制约了人工饲养扩繁.为小花蝽大规模生产及田间大面积推广应用提供参考,从小花蝽人工饲养(产卵基质、饲料、饲养条件、饲养工具及储藏条件)、捕食能力和应用技术等方面综述小花蝽的研究进展,.

南方小花蝽Orius strigicollis作为一种广食性捕食性天敌昆虫,可高效控制蓟马、蚜虫及螨类等多种害虫,极具生防潜能.但目前国内南方小花蝽商业化进程相对滞后,其中未找到适合的饲料来源是主要的限制因素之一.本研究以新鲜麦蛾Sitotroga cerealella卵和紫外线处理的麦蛾卵作为饲养南方小花蝽的替代猎物,以南方小花蝽的天然猎物西花蓟马Frankliniella occidentalis为对照,通过比较其发育历期、存活率及寿命等生物学指标,组建生命表来评价麦蛾卵对南方小花蝽的饲喂效果.结果发现:以新鲜麦蛾卵、紫外处理麦蛾卵和西花蓟马饲喂的南方小花蝽若虫发育历期均无显著性差异,但取食新鲜麦蛾卵的南方小花蝽若虫存活率(60.5％)高于其他两种猎物;同时,饲喂新鲜麦蛾卵的南方小花蝽雌虫寿命(37.3 d)和雄成虫寿命(23.0 d)以及产卵量(74.0粒)均最高,其次是紫外处理麦蛾卵,而西花蓟马最低;饲喂新鲜麦蛾卵的南方小花蝽存活率、净增殖率(47.91)、内禀增长率(0.10)、周限增长率(1.11)和世代平均周期(36.5 d)均大于饲喂紫外处理麦蛾卵和饲喂西花蓟马,且种群加倍时间也以饲喂新鲜麦蛾卵的南方小花蝽最短(6.57 d).本研究结果表明麦蛾卵可作为南方小花蝽饲养的替代猎物,且以新鲜麦蛾卵为最佳.

储蓄植物系统作为一种开放式的天敌饲养系统,越来越多地应用到温室及田间的害虫防治.南方小花蝽 Orius similis Zheng可捕食蓟马、蚜虫等多种害虫,是农业上一类极具应用价值的捕食性天敌.为提高南方小花蝽的控害效果,建立南方小花蝽储蓄植物系统是一种极为有效的方法.为了筛选适用于南方小花蝽保育和增殖的储蓄植物,进而构建南方小花蝽储蓄植物系统,本研究选择了月季Rosa chinensis、长寿花Narcissus jonquilla、辣椒Capsicum annuum、黄瓜Cucumis sativus和蚕豆Vicia faba作为候选的储蓄植物,通过六臂嗅觉仪分析了南方小花蝽对5种植物花朵的气味选择性,同时分析了南方小花蝽在5种植物上的繁殖系数、发育历期、存活率等生物学参数.结果表明43.33％的南方小花蝽雌虫偏好辣椒花朵气味,其次为蚕豆(26.67％);南方小花蝽卵的孵化率在辣椒上最高达到95.59％,其次为蚕豆为80.74％;同时,南方小花蝽卵在蚕豆上的发育历期显著低于另外4种植物,仅有4.92 d.综上所述,本研究初步认为辣椒和蚕豆比较适合用来构建南方小花蝽储蓄植物系统.

为温室白粉虱的可持续防治提供高效且环境友好的农药选择,采用微生物农药100亿孢子/mL金龟子绿僵菌油悬浮剂(400倍液、480倍液、600倍液)对番茄温室白粉虱[Trialeurodes vaporariorum(Westwood)]进行防治,并与10％溴氰虫酰胺可分散油悬浮剂1800倍液进行比较分析,以评价该微生物农药对温室白粉虱的防治效果并筛选最佳使用浓度.结果表明:100亿孢子/mL金龟子绿僵菌400倍液防治温室白粉虱的速效性与持续性均最佳,其药后1 d、3 d、7 d的防效分别为80.49％、90.61％、82.88％,而对照药剂10％溴氰虫酰胺可分散油悬浮剂的防效分别为29.57％、12.9％、88.5％.100亿孢子/mL金龟子绿僵菌油悬浮剂400倍液对番茄温室白粉虱具有较好的防治效果,可在生产上推广应用.

Begomoviruses (genus Begomovirus, family Geminiviridae) are transmitted by whiteflies of the Bemisia tabaci complex in a persistent, circulative manner. Considering the extensive damage caused by begomoviruses to crop production worldwide, it is imperative to understand the interaction between begomoviruses and their whitefly vector. To do so, localization and quantification of the virus in the vector tissues is crucial. Here, using tomato yellow leaf curl virus (TYLCV) as an example, we describe a detailed protocol to localize begomoviruses in whitefly midguts, primary salivary glands, and ovaries by immunofluorescence. The method is based on the use of specific antibodies against a virus coat protein, dye-labeled secondary antibodies, and a confocal microscope. The protocol can also be used to colocalize begomoviral and whitefly proteins. We further describe a protocol for the quantification of TYLCV in whitefly midguts, primary salivary glands, hemolymph, and ovaries by quantitative PCR (qPCR). Using primers specifically designed for TYLCV, the protocols for quantification allow the comparison of the amount of TYLCV in different tissues of the whitefly. The described protocol is potentially useful for the quantification of begomoviruses in the body of a whitefly and a virus-infected plant. These protocols can be used to analyze the circulation pathway of begomoviruses in the whitefly or as a complement to other methods to study whitefly-begomovirus interactions.

Apoptosis is generally considered the first line of defense against viral infection. However, the role of apoptosis in the interactions between plant viruses and their insect vectors has rarely been investigated. By studying plant DNA viruses of the genus Begomovirus within the family Geminiviridae, which are transmitted by whiteflies of the Bemisia tabaci species complex in a persistent manner, we revealed that virus-induced apoptosis in insect vectors can facilitate viral accumulation and transmission. We found that infection with tomato yellow leaf curl virus activated the apoptosis pathway in B. tabaci Suppressing apoptosis by inhibitors or silencing caspase-3 significantly reduced viral accumulation, while the activation of apoptosis increased viral accumulation in vivo Moreover, the positive effect of whitefly apoptosis on virus accumulation and transmission was not due to its cross talk with the autophagy pathway that suppresses begomovirus infection in whiteflies. We further showed that viral replication, rather than the viral coat protein, is likely the critical factor in the activation of apoptosis by the virus. These novel findings indicate that similarly to many animal and a few plant RNA viruses, plant DNA viruses may activate apoptosis in their insect vectors leading to enhanced viral accumulation and transmission.IMPORTANCE Of the approximately 1,100 known plant viruses, about one-third are DNA viruses that are vectored by insects. Plant virus infections often induce cellular and molecular responses in their insect vectors, which can, in many cases, affect the spread of viruses. However, the mechanisms underlying vector responses that affect virus accumulation and transmission are poorly understood. Here, we examined the role of virus-induced apoptosis in the transmission of begomoviruses, a group of single-stranded plant DNA viruses that are transmitted by whiteflies and cause extensive damage to many crops worldwide. We demonstrated that virus infection can induce apoptosis in the insect vector conferring protection to the virions from degradation, leading to enhanced viral accumulation and transmission to host plants. Our findings provide valuable clues for designing new strategies to block the transmission of insect-vectored plant viruses, particularly plant DNA viruses.

Background Bacterial symbiosis is widespread in arthropods, especially in insects. Some of the symbionts undergo a long-term co-evolution with the host, resulting in massive genome decay. One particular consequence of genome decay is thought to be the elimination of transcriptional elements within both the coding region and intergenic sequences. In the whitefly Bemisia tabaci species complex, the obligate symbiont Candidatus Portiera aleyrodidarum is of vital importance in nutrient provision, and yet little is known about the regulatory capacities of it. Methods Portiera genomes of two whitefly species in China were sequenced and assembled. Gene content of these two Portiera genomes was predicted, and then subjected to Kyoto Encyclopedia of Genes and Genomes pathway analysis. Together with two other Portiera genomes from whitefly species available previously, four Portiera genomes were utilized to investigate regulatory capacities of Portiera, focusing on transcriptional elements, including genes related with transcription and functional elements within the intergenic spacers. Results Comparative analyses of the four Portiera genomes of whitefly B. tabaci indicate that the obligate symbionts Portiera is similar in different species of whiteflies, in terms of general genome features and possible functions in the biosynthesis of essential amino acids. The screening of transcriptional factors suggests compromised ability of Portiera to regulate the essential amino acid biosynthesis pathways. Meanwhile, thermal tolerance ability of Portiera is indicated with the detection of a σ32 factor, as well as two predicted σ32 binding sites. Within intergenic spacers, functional elements are predicted, including 37 Shine-Dalgarno sequences and 34 putative small RNAs.

Heat shock proteins (HSP) are essential molecular chaperones that play important roles in the stress stimulation of insects. Bemisia tabaci, a phloem feeder and invasive species, can cause extensive crop damage through direct feeding and transmission of plant viruses. Here we employed comprehensive genomics approaches to identity HSP superfamily members in the Middle East Asia Minor 1 whitefly genome. In total, we identified 26 Hsp genes, including three Hsp90, 17 Hsp70, one Hsp60 and five sHSP (small heat shock protein) genes. The HSP gene superfamily of whitefly is expanded compared with the other five insects surveyed here. The gene structures among the same families are relatively conserved. Meanwhile, the motif compositions and secondary structures of BtHsp proteins were predicted. In addition, quantitative polymerase chain reaction analysis showed that the expression patterns of BtHsp gene superfamily were diverse across different tissues of whiteflies. Most Hsp genes were induced or repressed by thermal stress (40°C) and cold treatment (4°C) in whitefly. Silencing the expression of BtHsp70-6 significantly decreased the survival rate of whitefly under 45°C. All the results showed the Hsps conferred thermo-tolerance or cold-tolerance to whiteflies that protect them from being affected by detrimental temperature conditions. Our observations highlighted the molecular evolutionary properties and the response mechanism to temperature assaults of Hsp genes in whitefly.

Bacterial symbionts form an intimate relationship with their hosts and confer advantages to the hosts in most cases. Genomic information is critical to study the functions and evolution of bacterial symbionts in their host. As most symbionts cannot be cultured in vitro, methods to isolate an adequate quantity of bacteria for genome sequencing are very important. In the whitefly Bemisia tabaci, a number of endosymbionts have been identified and are predicted to be of importance in the development and reproduction of the pests through multiple approaches. However, the mechanism underpinning the associations remains largely unknown. The obstacle partially comes from the fact that the endosymbionts in whitefly, mostly restrained in bacteriocytes, are hard to separate from the host cells. Here we report a step-by-step protocol for the identification, extraction and purification of endosymbionts from the whitefly B. tabaci mainly by dissection and filtration. Endosymbiont samples prepared by this method, although still a mixture of different endosymbiont species, are suitable for subsequent genome sequencing and analysis of the possible roles of endosymbionts in B. tabaci. This method may also be used to isolate endosymbionts from other insects.