Specificity of <Emphasis Type="Italic">Anagyrus</Emphasis> sp. nov. nr. <Emphasis Type="Italic">sinope</Emphasis> and <Emphasis Type="Italic">Leptomastix dactylopii</Emphasis> for six mealybug species

In order to understand better non-target effect and potential uses, the host specificity of two parasitoid species (Anagyrus sp. nov. nr. sinope Noyes & Menezes and Leptomastix dactylopii Howard) (both Hymenoptera: Encyrtidae) for six mealybug species [Ferrisia virgata (Cockerell), Phenacoccus madeirensis Green, Phenacoccus solani Ferris, Planococcus citri (Risso),Pseudococcus longispinus (Targioni-Tozzetti) and Pseudococcus viburni (Signoret)] (all Hemiptera: Pseudococcidae) was studied through behavioral observations and laboratory rearing. The selected mealybug species represent major subfamilies and tribes of Pseudococcidae. Except for F. virgata, all mealybug species induced examinations by Anagyrus sp. nov. nr. sinope and L. dactylopii. Anagyrus sp. nov. nr. sinope was specific to P. madeirensis, which was the only mealybug species selected for oviposition and suitable for complete development of the parasitoid. No encapsulation of Anagyrus sp. nov. nr. sinope in P. madeirensis was observed. Leptomastix dactylopii accepted multiple species for oviposition, with the ranking of species preference as P. citri > P. viburni > P. longispinus > P. solani > P. madeirensis. Only P. citri, P. longispinus and P. viburni supported the development of L. dactylopii. Parasitoids developing in P. longispinus and P. viburni suffered from high encapsulation rates, while no encapsulation was observed when developing in P. citri. The results of this study suggest that Anagyrus sp. nov. nr. sinope is highly host specific. Leptomastix dactylopii, on the other hand, has a wider host range. The use of Anagyrus sp. nov. nr. sinope in a mealybug biological control program is limited to P. madeirensis and L. dactylopii to P. citri. The results presented in this study also lead us to question the accuracy of the reported host range of L. dactylopii, which include all six mealybug species tested.     

Inventory and abundance of mealybug species in immature and mature cocoa farms in Côte d'Ivoire

From 2013 to 2018, surveys were conducted in counties not previously surveyed in order to determine species of mealybugs present in the cocoa orchard in Côte d'Ivoire as well as their abundance according to the age of cocoa trees. Immature and mature cocoa trees were inspected to hand‐height in 5 and 29 counties infected with Cacao swollen shoot virus (CSSV). In each cocoa farm, mealybugs were searched for on fruits, leaves, flowers, twigs and trunks. Mealybug species were identified, and colonies were counted. Five mealybug species were identified on immature cocoa trees: Ferrisia virgata, Formicococcus njalensis, Planococcus citri, Planococcus kenyae and Pseudococcus longispinus. In addition to these species, four species, Dysmicoccus brevipes, Maconellicoccus hirsutus, Phenacoccus hargreavesi and Pseudococcus jackbeardsleyi were identified on mature cocoa trees. On immature cocoa trees, Fo. Njalensis, Pl. citri and Ps. longispinus comprised were, respectively, 35%, 33% and 19% of colonies, respectively. On mature cocoa trees, Fo. Njalensis and Pl. citri comprised 63.2% and 21.0%, and others species 15.8%. Nevertheless, the abundance of mealybug species varied according to the age of cocoa trees. The preferred organs of mealybugs were pods (74.1%) followed by twigs (13.4%) and flowers (7.4%). Previously, the mealybug Paracoccus burnerae (Brain) was found on Theobroma cacao, which is the first record for this species in Côte d'Ivoire and on this host‐plant.     

Suitability of five mealybug species (Hemiptera,Pseudococcidae) as hosts for the solitary parasitoid Anagyrus sp. nr. pseudococci (Girault) (Hymenoptera: Encyrtidae)

Anagyrus sp. nr. pseudococci is an endoparasitoid which has been used as a biological control agent of mealybug pests. In this study, we compared the suitability of five mealybugs species with different phylogenetic relationships and geographical origins as hosts of this parasitoid. The selected mealybugs were: (1) a Mediterranean-native species, Planococcus ficus, sharing a long co-evolutionary history with the parasitoid; (2) three exotic species, the Afrotropical Planococcus citri, the Australasian Pseudococcus calceolariae and the Neotropical Pseudococcus viburni, with a recent history; and (3) the Neotropical Phenacoccus peruvianus, with no previous common history with the parasitoid. Host suitability was assessed based on different fitness parameters, such as body size, developmental time, emergence rate and sex ratio. The parasitoid was able to complete development in all mealybug species. Nevertheless, its emergence rate significantly varied among mealybug species, with the highest values observed in Pl. ficus and Pl. citri, intermediate values in Ps. calceolariae and the lowest ones in Ps. viburni and Ph. peruvianus. The body size of adult wasp females varied with host suitability and was positively correlated with other measures of parasitoid fitness, including the emergence rate and the sex ratio. The parasitoid developmental time differed among mealybug species but did not correlate with any other measure of fitness. A female biased sex ratio was found in the parasitoid progeny emerged from all mealybug species, except in Ps. viburni and Ph. peruvianus. There was a direct relationship between the proportion of females in the parasitoid progeny and the emergence rate.     

Defense Response of Native and Alien Mealybugs (Hemiptera: Pseudococcidae) Against the Solitary Parasitoid Anagyrus sp. nr. pseudococci (Girault) (Hymenoptera: Encyrtidae)

The host behavioral and immune (encapsulation) defenses against the parasitoid Anagyrus sp. nr. pseudococci were compared for five mealybug species with different phylogenetic relationships and geographical origins: i) a Mediterranean native mealybug species, Planococcus ficus, with a long co-evolutionary history with the parasitoid; ii) three alien mealybugs species, Planococcus citri, Pseudococcus calceolariae and Pseudococcus viburni, with a more recent co-evolutionary history; and iii) a fourth alien mealybug species, Phenacoccus peruvianus, with no previous common history with the parasitoid. Three host defense behaviors were registered: abdominal flipping, reflex bleeding and walking away. The native host Pl. ficus and its congener Pl. citri exhibited the lowest probability of defense behavior (0.11?±?0.01 and 0.09?±?0.01 respectively), whereas the highest value was observed in P. viburni (0.31?±?0.02). Intermediate levels of defense behavior were registered for Ps. calceolariae, and Ph. peruvianus. The probability of parasitoid encapsulation was lowest and highest for two alien host species, Ph. peruvianus (0.20?±?0.07) and Ps. viburni (0.86?±?0.05), respectively. The native host Pl. ficus, its congener Pl. citri and Ps. calceolariae showed intermediate values (0.43?±?0.07, 0.52?±?0.06, and 0.45?±?0.09, respectively). The results are relevant with respect to biological control and to understand possible evolutionary processes involved in host range of A. sp. nr. pseudococci.     

中国进境水果携带粉蚧疫情分析(2013—2016)

【目的】中国是水果生产大国和进口大国。水果是最容易携带虫害的产品之一,粉蚧是口岸水果检疫过程中常发现的害虫类群,中国口岸每年从进境水果截获大量粉蚧。通过分析中国进境水果携带粉蚧疫情,可为一线口岸检疫查验提供指导,为相关部门开展产地检疫和口岸监测提供依据,以防止危险性粉蚧的传入,保障中国水果生产安全,促进国际水果贸易健康发展。【方法】通过FAO网站、动植物检验检疫信息资源共享服务平台、中国知网等收集中国进境水果贸易数据及其携带粉蚧疫情,统计分析了中国水果进口贸易情况、粉蚧截获情况以及截获粉蚧的种类、来源地、截获口岸和寄主。【结果】2013—2016年,中国口岸从进境水果上截获的昆虫中粉蚧科昆虫截获量最大,占47.31%;其中截获量前十的粉蚧种类为杰克贝尔氏粉蚧、木槿曼粉蚧、双条拂粉蚧、大洋臀纹粉蚧、南洋臀纹粉蚧、柑橘棘粉蚧、甘蔗簇粉蚧、康氏粉蚧、菠萝灰粉蚧和李比利氏灰粉蚧;而这些有害生物的主要来源地为越南和泰国;粉蚧的主要截获口岸为广西、深圳和云南;而火龙果、榴莲、龙眼和山竹是截获粉蚧最多的进境水果。【结论】中国进境水果粉蚧疫情与水果的贸易量和贸易方式、输出国有害生物发生和检疫除害处理措施、口岸关注度和能力建设等情况相关。     

Development of a multiplex PCR for identification of vineyard mealybugs

A simple molecular tool was developed and tested to identify seven mealybug species found in North American vineyards: Pseudococcus maritimus Ehrhorn, Pseudococcus viburni (Signoret), Pseudococcus longispinus (Targioni-Tozzeti), Pseudococcus calceolariae (Maskell), Planococcus ficus (Signoret), Planococcus citri (Risso), and Ferrisia gilli Gullan. The developed multiplex PCR is based on the mitochondrial cytochrome c oxidase subunit one gene. In tests, this single-step multiplex PCR correctly identified 95 of 95 mealybug samples, representing all seven species and collected from diverse geographic regions. To test the sensitivity, single specimen samples with different Pl. ficus developmental stages (egg to adult female and adult male) were processed PCR and the resulting output provided consistent positive identification. To test the utility of this protocol for adult males caught in sex baited pheromone traps, Pl. ficus adult males were placed in pheromone traps, aged at a constant temperature of 26±2°C, and processed with the multiplex each day thereafter for 8 d. Results showed consistent positive identification for up to 6 d (range, 6-8 d). Results are discussed with respect to the usefulness of this molecular tool for the identification of mealybugs in pest management programs and biosecurity of invasive mealybugs.     

New records of some potential pest mealybugs (Hemiptera: Coccoidea: Pseudococcidae) in Japan

Four species of mealybugs, Dysmicoccus neobrevipes, Phenacoccus defectus, Ph. parvus, and Ph. solenopsis (Hemiptera: Coccoidea: Pseudococcidae) are recorded for the first time from Japan in the Ry?ky? (Ryukyu) Archipelago, with brief biological notes. We discuss some features of these species compared with those of related species, D. brevipes and Ph. solani, and we consider their potential risks to Japanese agriculture and/or horticulture.     

EPG waveform characteristics of solenopsis mealybug stylet penetration on cotton

The solenopsis mealybug, Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae), is a polyphagous insect known to cause severe damage to cotton (especially transgenic varieties) in South Asia, and currently poses a serious threat in Asia and potentially elsewhere. Stylet penetration behavior of P. solenopsis on cotton was monitored using the electrical penetration graph (EPG) technique (DC system) and the EPG characteristics were compared with those previously published from Phenacoccus manihoti Matile‐Ferrero and Planococcus citri (Risso). We identified and further characterized typical waveforms of A, B, C, and pd (together pathway), E1 and E2 (phloem), F (derailed stylet mechanics), and G (xylem). Five novel EPG aspects were distinguished in the EPG waveforms from P. solenopsis: (1) obvious B waveforms occurred following waveform A, (2) during waveform C, some aphid‐like E1e waveforms were observed, (3) prolonged potential drops (pd) up to >1 h occurred with two continuously alternating sub‐phases pd1 and pd2, (4) the pd1 waveform always occurred as the first waveform related to phloem sieve elements, preceding the other phloem waveforms (E), the labeling of which we changed to achieve a better comparison to the aphid E waveforms, and (5) waveform F, related to derailed stylet mechanics occurred but was not reported from other mealybugs so far. This is mainly a waveform morphology study to extend existing knowledge on mealybug EPGs to investigate mealybug‐host plant interactions. Further experimental verification of waveform correlations with plant tissue positions of stylet tips and insect activities is still needed.     

利用种特异性COI引物（SS-COI）鉴别扶桑绵粉蚧

扶桑绵粉蚧Phenacoccus solenopsis Tinsley是我国近年新发现的一种严重威胁农林业生产的重要外来入侵害虫。针对扶桑绵粉蚧与其他粉蚧类昆虫难以准确快速识别且适生区广泛的问题, 以扶桑绵粉蚧为靶标, 以我国常见的其他7种粉蚧为参照, 采用基于线粒体DNA细胞色素C氧化酶亚基Ⅰ (mtDNA COI) 基因序列的种特异性(species-specific COI, SS-COI) PCR方法, 研究其快速分子检测技术。通过已知粉蚧的COI基因序列设计通用型引物1对, 获得扶桑绵粉蚧及其他7种粉蚧包括康氏粉蚧Pseudococcus comstocki Kuwana、 南洋臀纹粉蚧Planococcus lilacius Cockerell、 木槿曼粉蚧Maconellicoccus hirsutus (Green)、 甘蔗红粉蚧Saccharicoccus sacchari (Cockerell)、 新菠萝灰粉蚧Dysmicoccus neobrevipes Beardsley、 番石榴粉蚧Planococcus minor Maskel和石蒜绵粉蚧Phenacoccus solani Ferris的COI基因序列, 根据测序结果及数据库中已知粉蚧的COI基因序列设计SS COI引物1对(PSZTF1/PSZTR1), 其扩增片段大小为546 bp。种特异性检验结果表明, 该引物只对扶桑绵粉蚧的COI基因具有扩增能力, 对其他7种粉蚧不具有扩增效果; 该引物不仅对成虫具有良好的扩增能力, 对不同虫态的扶桑绵粉蚧以及来自我国不同省市的14个地理种群和口岸截获的来自巴基斯坦的扶桑绵粉蚧亦具有同样的扩增效能。这些结果表明, 该技术体系完全可用于扶桑绵粉蚧的准确识别及其检测监测, 对有效阻截其进一步扩张蔓延意义重大。     

Probable Site of Sex Pheromone Emission in Female Vine and Obscure Mealybugs (Hemiptera: Pseudococcidae)

In laboratory bioassays, male Pseudococcus viburni (Signoret) and Planococcus ficus Signoret were attracted to body sections of females that included the metathoracic legs. Extracts of the metathoracic legs of female P. ficus were much more attractive to males than extracts of the other legs, and males exhibited copulatory behavior towards these extracts. Scanning electron microscopy showed the presence of translucent pores on the coxae of mature but not immature females. Collectively, the data suggest that the female-produced sex pheromones of these species are released from the metathoracic legs, probably from the translucent pores.     

Vector transmission of Banana streak virus in the screenhouse in Uganda

Although mealybug transmission of Banana streak virus.(BSV) by Planococcus citri and Saccharicoccus sacchar has been demonstrated elsewhere, these mealybugs have not been identified on bananas in Uganda and their role and that of other agents in BSV transmission is not well documented. Insect samples were collected from banana farms in sites with low, moderate and high BSV infections in Uganda. Subsequently, live mealybugs and aphids were again collected and used in acquisition, retention and transmission tests, and BSV diagnosed using TAS‐ELISA. Dysmicoccus brevipes (pineapple mealybug), S. sacchari (sugarcane mealybug) and Pentalonia nigronervosa (banana aphid) were the most abundant insect species from banana fields sampled. Abundance of D. brevipes was positively and significantly correlated with BSV incidence unlike that of. P. nigronervosa. Transmission studies in the screenhouse showed that mealybugs acquired BSV one day after feeding on virus sources and approached optimum acquisition after the third day. Pineapple and sugarcane mealybugs retained BSV up to 5 days from the day of transfer from the virus source. BSV was first detected in the recipient banana plants 4 wk after transmission using pineapple mealybug and 6 wk after inoculation using sugarcane mealybug. Under screenhouse conditions, both mealybugs therefore appear to transmit BSV semipersistently.     

Responses of Second-Instar Male Nymphs of Four Mealybug Species (Hemiptera: Pseudococcidae) to Conspecific and Heterospecific Female Sex Pheromones

The response of the late second-instar male nymphs of the mealybug species (Hemiptera, Pseudococcidae), Planococcus citri (Risso), Planococcus ficus (Signoret), Pseudococcus cryptus Hempel Nipaecoccus viridis (Newstead), to their conspecific and heterospecific female pheromone was studied. Males that exhibited the typical appearance of late-second-instar nymphs were tested. The male behavior was monitored soon after their exposure to the tested female sex pheromone in glass Petri dish arenas. Male nymph behavior toward the pheromone source was characterized based on their aggregation on the disks in the arena. Males of all four tested mealybug species were attracted to their conspecific female pheromone. By contrast, almost no interceptions of male nymphs with disks impregnated with a heterospecific female pheromone were observed. The mode of attraction of each of male nymphs of P. ficus, among most of the tested individuals (>80%), to the conspecific female sex pheromone, (S)-lavandulyl senecioate and or (S)-lavandulyl isovalerate, was the same as the mode of attraction latter on as adult. We suggest that by being attracted to the conspecific pheromone these males may direct themselves to a suitable pupation site near conspecific non-sibling mature females, thus preventing inbreeding. The repellency of heterospecific sex pheromone to males that are looking for a pupation site suggests that the latter try to avoid close contact with heterospecific females.     

Host selection behaviour and specificity of the solitary parasitoid of mealybugs Anagyrus sp. nr. pseudococci (Girault) (Hymenoptera,Encyrtidae)

The host selection behaviour of Anagyrus sp. nr. pseudococci was compared in no-choice tests among five mealybug species of different geographical and phylogenetic origin, including the Mediterranean native host, Planococcus ficus and four exotic mealybug species, one of the same genus, Pl. citri, two Pseudococcus species, Ps. calceolariae and Ps. viburni and a more distant one, Phenacoccus peruvianus. All five studied mealybug species were recognised by the parasitoid as potential hosts and parasitised, but the behavioural pattern of host recognition, host handling and the level of host acceptance of Anagyrus sp. nr. pseudococci significantly varied among the five studied species, indicating a clear preference for the two Planococcus species, Pl. ficus in particular. The results suggest that A. sp. nr. pseudococci has a broader host range and a more generalist behaviour in comparison with other Anagyrus species. Practical implications of the findings are discussed.     

Pre‐release host range determination of the parasitoid Allotropa burrelli for the biocontrol of Pseudococcus comstocki in France

We performed “no‐choice” tests to study the host range of the parasitoid Allotropa burrelli (Muesebeck) (Hymenoptera: Platygastridae) for use against the Comstock mealybug, Pseudococcus comstocki (Kuwana) (Hemiptera: Pseudococcidae), in Southern France. We tested three Pseudococcidae species as potential non‐target hosts: two species from the same genus (Pseudococcus longispinus and Pseudococcus viburni) and Planococcus citri. Allotropa burrelli did not parasitize any of the non‐target mealybug species tested. No attempt of oviposition was recorded for the three species tested during the first 20 min of parasitoid release and no parasitism occurred in 6–8 hr of exposure of the mealybugs to the parasitoid.     

Using parasitoids to infer a native range for the obscure mealybug, <Emphasis Type="Italic">Pseudococcus viburni</Emphasis>, in South America

The co-evolutionary relationships between mealybug hosts (Hemiptera: Coccoidea) and Encyrtidae (Hymenoptera) appear to be particularly strong, and many successful classical biological control programmes against mealybugs have been carried out using these parasitoids. It is a puzzle, then, that the obscure mealybug, Pseudococcus viburni (Signoret) (Hemiptera: Pseudococcidae), is considered to be an American species but is not attacked by native parasitoids in the USA, whereas it is controlled in Europe by Acerophagus maculipennis (Mercet) (Encyrtidae) which was described from the Canary Islands (as Pseudophycus maculipennis). An examination of the biogeographical origins of both the Pseudococcus maritimus complex (to which P. viburni clearly belongs) and the genus Acerophagus Smith, coupled with historical trade records, supports the hypothesis that P. viburni and A. maculipennis are co-evolved Neotropical species, and that both were transported from S. America (probably Chile) to Europe via the Canary Islands on host plants such as potato, possibly as early as the sixteenth century. Invasion of P. viburni into the USA (and elsewhere around the world) occurred later, but without A. maculipennis (or other natural enemies). This explains why P. viburni in the USA is not attacked by native North American parasitoids and why A. maculipennis is not known to attack any mealybugs of Palaearctic origin. The hypothesis adds confidence that well conducted classical biocontrol programmes involving these taxa pose a low environmental risk to native, non-target fauna.     

Predation potential of <Emphasis Type="Italic">Rhynocoris marginatus</Emphasis> (Hemiptera: Reduviidae) against three mealybug species of agricultural importance

The predation potential of a generalist predator Rhynocoris marginatus (Fab.) (Hemiptera: Reduviidae) against three important mealybug pests of cotton, Phenacoccus solenopsis Tinsley, Maconellicoccus hirsutus Green, and Coccidohystrix insolita Green (Hemiptera: Pseudococcidae) was evaluated under laboratory conditions. The specific objective of the study was to determine the prey capturing time, prey handling time, and prey preference among the three mealybug species for different developmental stages of R. marginatus. The number of prey consumed/predator/24 h by R. marginatus was dependent on the mealybug species and the predator developmental stage. Rhynocoris marginatus showed a decrease in prey capturing time and handling time as the predator grew older. After evaluating the prey stage preference, results indicated that the developmental stages of R. marginatus preferred adult mealybugs over the younger stages. In a choice-test bioassay including the three mealybug species, no significant difference in prey species selection was observed for the various R. marginatus developmental stages. However, the mortality of P. solenopsis was observed to be highest among the mealybugs, followed by M. hirsutus and C. insolita. This supports the idea that R. marginatus can be effectively utilized for the management of one of the most destructive mealybug pests of cotton, P. solenopsis. Results from this study are important for the development of a knowledge-based management program for cotton agroecosystems affected by various mealybug pests.     

广西及越南农业外来有害生物入侵现状

【背景】广西地理环境独特,与越南水陆相连,气候、作物等条件相似,边境贸易往来频繁,致使其成为我国遭受外来有害生物入侵最严重的地区之一。【方法】通过本底调查,分析总结了广西农业外来有害生物入侵的现状。【结果】广西主要入侵动物26种,入侵微生物18种,入侵植物21种,高风险入侵物种包括辣椒实蝇、木薯绵粉蚧、扶桑绵粉蚧、稻水象甲、黄瓜绿斑驳花叶病毒等;来自越南的潜在危险性有害生物共38种。【结论与意义】广西受外来有害生物入侵的风险加剧,并有进一步扩散蔓延的趋势。提出应对入侵生物的综合防控对策,为广西外来入侵有害生物的防控提供参考。     

Comparative development and reproduction of Planococcus ficus and Planococcus citri (Hemiptera: Pseudococcidae) on grapevine under field conditions

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Comparison of Phenacoccus solenopsis specimens from different regions of Pakistan using COI molecular barcoding (Hemiptera: Pseudococcidae)

Because correct identification of insects is crucial for pest management involving chemical or biological control agents, we have used a molecular approach to identify and characterize specimens of the cotton pest Phenacoccus solenopsis Tinsley (Sternorrhyncha: Pseudococcidae) present in different regions of Pakistan. The specimens were analyzed through DNA sequence analysis of their mitochondrial COI (mtCOI) gene using an improved procedure that could distinguish between the pest and its associated parasitoid. Our analysis showed no variation among the mealybug specimens from different geographical locations of Pakistan and confirmed that this is the same species and haplotype that is infesting cotton plants in other parts of Asia. This information will assist in the development of biological control programs against P. solenopsis in Pakistan and other Asian countries.     

Fortuitous biological control of the invasive mealybug Phenacoccus peruvianus in Southern Europe

Phenacoccus peruvianus Granara de Willink (Hemiptera: Pseudococcidae) is a Neotropical invasive mealybug that has rapidly spread throughout Mediterranean Basin. It has established itself as the principal pest of several ornamental plants, causing considerable problems in nurseries and urban landscapes. The aim of this study was to determine the natural enemy complex of this pest and report the feasibility of its biological control. Six urban green spaces were surveyed in eastern Spain from 2008 to 2010. The most abundant natural enemies of P. peruvianus were found to be the primary parasitoids Acerophagus n. sp. near coccois and Leptomastix epona Walker (Hymenoptera: Encyrtidae). Phenacoccus peruvianus populations were lower during the second and third year of the survey, coinciding with an increase of the parasitoid Acerophagus sp., which displaced the native L. epona. Differential female offspring and resource preemption are discussed as the main reasons for this displacement.