Pseudococcus Longispinus Research Articles

Mealybug species from Chilean agricultural landscapes and main factors influencing the genetic structure of Pseudococcus viburni.

The present study aimed to characterize the distribution of mealybug species along Chilean agro-ecosystems and to determine the relative impact of host plant, management strategy, geography and micro-environment on shaping the distribution and genetic structure of the obscure mealybug Pseudococcus viburni. An extensive survey was completed using DNA barcoding methods to identify Chilean mealybugs to the species level. Moreover, a fine-scale study of Ps. viburni genetic diversity and population structure was carried out, genotyping 529 Ps. viburni individuals with 21 microsatellite markers. Samples from 16 localities were analyzed using Bayesian and spatially-explicit methods and the genetic dataset was confronted to host-plant, management and environmental data. Chilean crops were found to be infested by Ps. viburni, Pseudococcus meridionalis, Pseudococcus longispinus and Planococcus citri, with Ps. viburni and Ps. meridionalis showing contrasting distribution and host-plant preference patterns. Ps. viburni samples presented low genetic diversity levels but high genetic differentiation. While no significant genetic variance could be assigned to host-plant or management strategy, climate and geography were found to correlate significantly with genetic differentiation levels. The genetic characterization of Ps. viburni within Chile will contribute to future studies tracing back the origin and improving the management of this worldwide invader.

Enantiospecific Synthesis of Both Enantiomers of the Longtailed Mealybug Pheromone and Their Evaluation in a New Zealand Vineyard.

The irregular monoterpenoid sex pheromone of Pseudococcus longispinus and its enantiomer were prepared from the corresponding bornyl acetates. The use of readily accessible chiral starting materials and lactone-lactone rearrangement are the highlights of the present synthesis. The biological activities of the two enantiomers and racemic mixture were tested in a New Zealand vineyard. The (S)-(+)-enantiomer was significantly more attractive to P. longispinus males than the racemic mixture or the (R)-(-)-enantiomer.

The link between independent acquisition of intracellular gamma-endosymbionts and concerted evolution in Tremblaya princeps.

Many insect species establish mutualistic symbiosis with intracellular bacteria that complement their unbalanced diets. The betaproteobacterium “Candidatus Tremblaya” maintains an ancient symbiosis with mealybugs (Hemiptera: Pseudococcidae), which are classified in subfamilies Phenacoccinae and Pseudococcinae. Most Phenacoccinae mealybugs have “Candidatus Tremblaya phenacola” as their unique endosymbiont, while most Pseudococcinae mealybugs show a nested symbiosis (a bacterial symbiont placed inside another one) where every “Candidatus Tremblaya princeps” cell harbors several cells of a gammaproteobacterium. Genomic characterization of the endosymbiotic consortium from Planococcus citri, composed by “Ca. Tremblaya princeps” and “Candidatus Moranella endobia,” unveiled several atypical features of the former's genome, including the concerted evolution of paralogous loci. Its comparison with the genome of “Ca. Tremblaya phenacola” PAVE, single endosymbiont of Phenacoccus avenae, suggests that the atypical reductive evolution of “Ca. Tremblaya princeps” could be linked to the acquisition of “Ca. Moranella endobia,” which possess an almost complete set of genes encoding proteins involved in homologous recombination. In order to test this hypothesis, we performed comparative genomics between “Ca. Tremblaya phenacola” and “Ca. Tremblaya princeps” and searched for the co-occurrence of concerted evolution and homologous recombination genes in endosymbiotic consortia from four unexplored mealybug species, Dysmicoccus boninsis, Planococcus ficus, Pseudococcus longispinus, and Pseudococcus viburni. Our results support a link between concerted evolution and nested endosymbiosis.

Problemas fitosanitarios que amenazan la conservación de las orquídeas de Costa Rica

Orchids from private collections, nurseries and wild areas, located in different ecological regions of Costa Rica, were studied in order to know the pests and diseases affecting them. 16 insect and two mite genera were identified as pests on different orchids and 28 pathogens were found as causal agents of infec- tious diseases. The most frequent pests were: Tenthecoris orchidearum, Stethobaris sp., Xylosandrus com- pactus, Pseudococcus longispinus, Diaspis boisduvalii and Tenuipalpus pacificus. The main diseases found were caused by: Phytophthora spp., Pythium spp., Fusariun oxysporum, Fusarium spp., Sclerotium rolfsii, Colletotrichum gloeosporioides, Sphenospora spp., Uredo spp., Cymbidium Mosaic virus and Odontoglossum Ring Spot Virus. This results demonstrate the diversity of organisms producing sanitary problems on orchids in Costa Rica, and suggests the inclusion of pest and diseases management in strate- gies for orchid conservation.

FUMIGATION OF MEALYBUGS IN AUSTRALIAN TABLE GRAPES AND GRAPEFRUIT

Mealybug species such as long-tailed mealybug Pseudococcus longispinus (Targioni-Tozzetti) and citrus mealybug Planococcus citri (Risso) are sometimes present in Australian table grapes and grapefruits at harvest. Quarantine restrictions in some markets require fruit to be fumigated with methyl bromide at or above 21°C before shipment. Problems of phytotoxicity and reduced shelf life make this treatment unattractive. Alternative treatments, fumigation with ethyl formate and carbon dioxide for 2.5 h in export cartons in simulated cool down from 15 to 10°C were found to control mealybugs without damaging the produce. These treatments satisfy “generally regarded as safe” criteria and are suitable for use in grapes and grapefruits produced under organic certification.

The effect of mealybug Pseudococcus longispinus (Targioni Tozzetti) infestation of different density on physiological responses of Phalaenopsis × hybridum 'Innocence'.

Cultivated orchids are the most abundantly attacked by polyphagous mealybugs. This study documented how different density of mealybug Pseudococcus longispinus (Targioni Tozzetti) infestation is associated with a response of antioxidative systems of Phalaenopsis × hybridum 'Innocence'. The degree of cell damage, estimated by electrolyte leakage measurement and the level of thiobarbituric acid reactive substances (TBARS), the content of pigments as well as the activity of antioxidative enzymes and proline level, as measurements of stress and stress compensation in moth orchid were examined. The highest electrolyte leakage (E L) value among samples from colonized plants was found in the orchids from series III (50 individuals/plant), whereas the lowest in the plants from series II (20 individuals/plant). The TBARS content reached the highest level at the lowest number of feeding insects (series I). Peroxidase activity toward guaiacol was significantly increased in series I (5 individuals/plant). The highest catalase activity was recorded in plants colonized by the highest number of scale insects (series III). Whereas, the highest value of proline was in series II. The content of individual photosynthetic pigments (chlorophyll a, chlorophyll b and carotenoids) in plant tissues did not vary significantly between control and colonized orchids. The results have not confirmed hypothesis that the increasing number of mealybugs occurring on plant enhanced plant physiological response. The degree of longtailed mealybug infestation on plants was positively correlated only with electrolyte leakage and catalase activity in leaf tissues.

Preliminary study on the biology, natural enemies and chemical control of the invasive Macrohomotoma gladiata (Kuwayama) on urban Ficus microcarpa L. trees in Valencia (SE Spain)

The phenology and natural enemies of Macrohomotoma gladiata (Kuwayama) (Hemiptera, Homotomidae) on Ficus microcarpa L. in Valencia (Spain) were studied in 2013. During the study, all immature instars of the pest were found on infested shoots indicating overlapping generations. However, two consistent increases in the proportion of the first two nymphal instars were detected in early March and June, possibly suggesting the beginning of spring and summer generations. Eggs of M. gladiata were usually found below the stipules of new healthy shoots, arranged in groups of 15–30 units. First two nymphal instars usually preferred the innermost part of the shoot, whereas the older developmental stages were localised more externally. The abundance of pest population increased in February–April and lowered from May onward. A number of other pest species were collected on the sampled trees. These included: Gynaikothrips ficorum (Marchal) (Thysanoptera, Phlaeothripidae), Pseudococcus longispinus (TargioniTozzetti) (Hemiptera, Pseudococcidae) and Greenidea ficicola Takahashi (Hemiptera: Aphididae). Unlike M. gladiata, the populations of these insects on shoots remained high from May onward. Among natural enemies of the invasive pest, Prionomitus mitratus (Dalman) (Hymenoptera, Encyrtidae) and Anthocoris nemoralis (Fabricius) (Hemiptera, Anthocoridae) were the most abundant. The encyrtid is here reported for the first time as a parasitoid of M. gladiata. Its presence was constant all along the study period, with a peak in May and June and an apparent preference for the older instars (third to fifth nymph stages) was recorded. In an attempt to indicate a possible remedy to the heavy infestations of M. gladiata, and considering the urban location of the sampled trees, two pesticides, a paraffin and a botanical oil, were tested. Treatments significantly reduced the population of the psyllid. The botanical oil resulted more effective than paraffin oil in reducing the number of the first two nymphal instars, regardless their innermost position on infested shoots.

Field study demonstrates that exotic parasitoids (Hymenoptera: Encyrtidae) of mealybugs (Hemiptera: Pseudococcidae) are absent from a native forest habitat in New Zealand

Laboratory-based, physiological host-range tests of classical biocontrol agents may be complemented by examining the ecological (realised) host-range of similar, previously established species. Sentinel long-tailed mealybugs (Pseudococcus longispinus (Targioni-Tozzetti)) on potted citrus plants, and two species of native mealybugs on potted native trees, were placed in pairs in an orchard and a native forest block 500 m away. Sentinel P. longispinus on citrus plants were also placed along transects anchored in each habitat and extending towards the other by 100–150 m. Parasitoids were reared from the retrieved mealybugs. P. longispinus in the orchard was regularly parasitized by four species of exotic Encyrtidae, but was never parasitized by them in the native forest even though the parasitoids were present in the surrounding environment. Sentinel native mealybugs were not parasitized by any species in either habitat, although native parasitoids (especially Errolium sp. (Hym: Platygastridae) and unidentified Hym: Aphelinidae) were collected from native mealybugs within the native forest.

Effects of Reduced-Risk Insecticides on Three Orchid Pests and Two Predacious Natural Enemies

The toxicity of 2 reduced-risk pesticides, 2% horticultural oil with 0.05% Silwet L-77 and Grandevo (Chromobacterium subtsugae Strain PRAA4-1T), to 2 predators: Metaseiulus occidentalis (Nesbitt) (Acari: Phytoseiidae) and Hemicheyletia wellsina DeLeon (Acari: Cheyletidae), and 3 orchid pests: the two-spotted spider mite Tetranychus urticae Koch (Prostigmata: Tetranychidae), the phalaenopsis mite, Tenuipalpus pacificus Baker (Acari: Tenuipalpidae), and the longtailed mealybug Pseudococcus longispinus (Targioni-Tozzetti) (Hemiptera: Pseudococcidae) were tested. Grandevo did not kill either predator, and it failed to suppress populations of T. urticae and P. longispinus, but it reduced T. pacificus by 84%. The Silwet and horticultural oil mixture caused mortality of at least 82% in all 5 species tested.

Cascading effects of introduced scale insects on Nesospiza finches at the Tristan da Cunha archipelago

Abstract Three cosmopolitan scale insect pests have been introduced to the Tristan da Cunha archipelago, where their main host species is the island tree Phylica arborea , the only tree native to the islands. This can affect the populations of large-billed forms of Nesospiza finches because they rely on Phylica fruits. We report the distribution of scale insects at Inaccessible and Nightingale Islands, and assess their impact on Phylica fruit production. Hemiberlesia rapax has been recorded from all three islands in the archipelago, Coccus hesperidum from Inaccessible Island and the main island of Tristan, and Pseudococcus longispinus only from Tristan. Hemiberlesia is widespread on Phylica trees at Nightingale Island, but there are no recent records from Inaccessible. It appears to have little impact on Phylica fruit loads. Infestations of Coccus are associated with a sooty mould Seiridium phylicae , and together they significantly reduce Phylica fruit production. Coccus probably is a recent arrival at Inaccessible Island; it is restricted to two areas and infestation rates are quite low. Should it spread and infest a large proportion of trees, consideration should be given to the potential use of biological control agents to limit its impact. Strict quarantine measures should be enforced to prevent the introduction of Coccus and Seiridium to Nightingale Island, where they might threaten the Endangered Wilkins’ finch Nesospiza wilkinsi .

SURVEY OF SCALE INSECTS AND MEALYBUGS INFESTING SOME AVOCADO CULTIVARS AND THEIR ASSOCIATED NATURAL ENEMIES IN EGYPT

The present work was conducted for one year (January - December, 2013) on six avocado cultivars cultivated in new reclaimed lands at Borg El Arab (Alexandria Governorate), El Bostan (Beheira Governorate), El Sadat (Menofiya Governorate) and Sarapium (Ismailiya Governorate). The study was conducted to survey the scale insect and mealybug species and their associated natural enemies as well as the degree of infestation on avocado trees. The obtained results revealed eight species of scale insects and Mealybugs. Two coccid species [Coccus hesperidum L. and Pulvinaria psidii (Mask.)], Four diaspidid species [Hemiberlesia lataniae (Sign.), Aulacaspis tubercularis (Newst)., Aonidiella aurantii (Mask.) and Aspidiotus nerii Bouche] and Two Pseudococcid species [Pseudococcus longispinus (Targ.-Tozz.) and Ferrisia virgata (Ckll.)]. Associated parasitoids were Coccophagus scutellaris on C. hesperidum, Aphytis lepidosaphes, Habrolepis aspidioti and Marietta leopardina on H. lataniae, Encarsia citrina and Habrolepis diaspidi on A. tubercularis and Anagyrus spp. on P. longispinus. Also, associated predators were Rodalia cardinalis on C. hesperidum and two coccinellid predators (Cryptolaemus montrouzieri and Scymnus syriacus) on P. longispinus. H. lataniae was the most abundant (56.8%) followed by F. virgata (42.5%) , A. tubercularis (39.8%) , P. longispinus (31.7 % ), C. hesperidum (26.6%), P. psidii (15%), A. aurantii (15%) and A. nerii (14.3%). Hass cultivar proved the highest infestation rate in the four localities followed by Boothy and Waldim cultivars. Fuerte, Gwen and Lula cultivars had the lowest infestation rate.

The effect of a mealybug infestation on the activity of amino acid decarboxylases in orchid leaves

Changes in the activity of lysine decarboxylase (LDC), tyrosine decarboxylase (TyDC), and ornithine decarboxylase (ODC) within orchid (Phalaenopsis × hybridum ‘Innocence’) leaves, infested by two mealybug species: Pseudococcus longispinus (Targ. Tozz.) and Pseudococcus maritimus (Ehrh.) were quantified. The pattern of changes was dependent on the insect species and duration of infestation. P. longispinus feeding increased LDC and TyDC activity after one week during the total period of observations. This species inhibited ODC activity after one week but increased later. P. maritimus decreased LDC activity in orchid leaves at all studied terms. TyDC action also went up during the first week of the infestation and was reduced after two weeks, while ODC was decreased after one day and induced later. The mechanism for the participation of analysed amino acid decarboxylases in local and/or systemic steps of orchid responses to mealybug infestation is discussed.

Synthesis of a Sex Pheromone of the Longtailed Mealybug, Pseudococcus longispinus

The synthesis of a recently identified and highly active sex pheromone of the longtailed mealybug, Pseudococcus longispinus is reported. A concise synthetic route, use of the under explored Meyer–Schuster rearrangement, Claisen rearrangement, and ring-closing metathesis are the highlights of this work.

Pheromone-Based Monitoring of <I>Pseudococcus maritimus</I> (Hemiptera: Pseudococcidae) Populations in Concord Grape Vineyards

The grape mealybug, Pseudococcus maritimus (Ehrhorn), is the dominant mealybug in Washington's Concord grape vineyards (Vitis labrusca L.). It is a direct pest of fruit clusters and a vector of grapevine leafroll-associated viruses. Using traps baited with the sex pheromone of Ps. maritimus, we determined the optimal trap density for monitoring Ps. maritimus, with the goal of providing a more rapid monitoring method for Ps. maritimus than visual surveys. Varying densities of pheromone-baited traps (one, four, and eight traps per 12.14 ha) were deployed in Concord vineyards to monitor Ps. maritimus seasonal phenology in 2010 and 2011. In both years, flights of adult males were detected in early May and captures peaked twice per season in mid-June and mid-August, indicating two generations each year. Trap data were analyzed using Taylor's Power Law, Iwao's patchiness regression, and the K parameter of the negative binomial model to determine optimal sample size. The formula using the K parameter provided the lowest required sample size, showing that four to eight traps per 12.14 ha were needed to provide 30% sampling precision efficiency throughout the entire season. Fewer traps were needed during flight peaks when trap capture numbers were great. Only one pheromone-baited trap per 12.14 ha was sufficient to provide Ps. maritimus flight phenology data to make informed management decisions. Species-specific pheromone-baited traps deployed for Planococcus ficus (Signoret), Pseudococcus longispinus (Targioni Tozzetti), and Pseudococcus viburni (Signoret) did not detect any of these species in the vineyards sampled.

Stylet penetration behaviour of Pseudococcus longispinus in relation to acquisition of grapevine leafroll virus 3

Grapevine leafroll–associated virus-3 (GLRaV-3) is transmitted from infected grapevines to healthy vines by mealybugs. The stylet penetration behaviour of Pseudococcus longispinus (Hemiptera: Pseudococcidae) was electronically monitored on leaves of grape plants to quantify the time taken to access the phloem and the duration of phloem ingestion. More of the first instar nymphs than of the adults showed sustained (>10 min) phloem ingestion; however, nymphs were affected adversely by longer monitoring periods. The probing and phloem ingestion periods of adults on GLRaV-3-infected Red Globe and uninfected Pinot noir were not significantly different from each other. Most adults showed the first phloem ingestion and the first sustained phloem ingestion after 12 h and after 24 h of their first probe, respectively. Free (unwired) and electrical penetration graph (EPG)-monitored (wired) P. longispinus adults were tested for acquisition of virus after different acquisition access periods (AAP). Acquired GLRaV-3 RNA in extracts of whole insects was detected by reverse transcription and polymerase chain reaction amplification. For the unwired adult mealybugs, 30 % that had an AAP of 48 h and 90 % that had an AAP of 72 or 96 h were positive for GLRaV-3. Five out of 24 (21 %) of the wired mealybugs allowed at least 24 h APP (1.8–44.4 h of phloem ingestion) were positive for GLRaV-3. None of the adult mealybugs acquired virus during the first 24 h of AAP. We conclude that GLRaV-3 acquisition by P. longispinus generally occurs within 24–72 h AAP with as little as 1.8 h of phloem ingestion.

Optimizing Metabolic Stress Disinfection and Disinfestation Components to Control <I>Pseudococcus longispinus</I>

Metabolic stress disinfection and disinfestation (MSDD) has been demonstrated to effectively control longtailed mealybug, Pseudococcus longispinus (Targioni Tozzetti). Standard components previously used for testing MSDD system included a 30-min physical phase of short cycles pressure changes followed by a 60-min chemical phase using ethanol vapor at 10 kPa. This study investigated the effect of varying the following MSDD components on mealybug mortality: duration of the physical and chemical phases, ethanol concentration, and extent of vacuum during the chemical phase. Mealybug mortality responses were analyzed, and the components were optimized using binary logistical regression to achieve 99% mortality of three life stages of the longtailed mealybug (adults, second- and third-instar nymphs and crawlers). Data indicated that the optimal components to achieve 99% mortality of all life stages were a 30-min physical phase and a 45-min chemical phase with 275 mg/liter ethanol at 30 kPa. Optimized components were obtained using binary logistical regression models. These optimized components yielded a 15-min reduction in total treatment time and a 20-kPa decrease in pressure during the chemical phase. Achievement of optimal insecticidal efficacy required all four MSDD components. Nevertheless, optimization and validation achieved 17 and 22% reductions in duration of treatment time and extent of vacuum, respectively.

Seasonal Phenology and Natural Enemies of the Oleander Mealybug,Paracoccus burnerae(Brain) (Hemiptera: Pseudococcidae), in South Africa

The importance of Paracoccus burnerae has risen over the years to an extent where it is now not only a serious pest of citrus, but is also a quarantine pest for citrus fruit imported from South Africa. The field biology of P. burnerae on citrus in the Western Cape Province of South Africa was studied through periodic sampling of leaves from twigs enclosed in sleeve cages. The species composition and abundance of natural enemies was investigated. Both adult and immature stages attained maximum population peaks in March and P. burnerae had four generations. The highest level of mortality was experienced in the immature stages. Climate and an unidentified fungus were the key mortality factors. The level of abundance of the two observed predators, the harlequin beetle, Harmonia axyridis, and the green lacewing, Chrysoperla sp., was relatively low. Although parasitism occurred in some cages, the level was low, ranging between 1.62 and 9.43 %. If biocontrol is the preferred method of controlling P. burnerae, suitable candidate parasitoids for inoculative biocontrol are Acerophagus sp., Leptomastix sp. and Microterys nietneri. The oleander mealybug does not share the same parasitoids with Planococcus citri, Pseudococcus calceolariae and Pseudococcus longispinus except for the parasitoid Coccophagus sp. The most popular species of parasitoids used in the biolological control of mealybugs, Anagyrus sp. and Coccidoxenoides sp., were insignificant in the case of P. burnerae.

Identification of mealybug pest species (Hemiptera: Pseudococcidae) in Egypt and France, using a DNA barcoding approach

Pseudococcidae (mealybugs) is a large taxonomic group, including a number of agronomic pests. Taxonomic identification of mealybug species is a recurrent problem and represents a major barrier to the establishment of adequate pest management strategies. We combined molecular analysis of three DNA markers (28S-D2, cytochrome oxidase I and internal transcribed spacer 2) with morphological examination, for the identification of 176 specimens collected from 40 mealybug populations infesting various crops and ornamental plants in Egypt and France. This combination of DNA and morphological analyses led to the identification of 17 species: seven in Egypt (Planococcus citri (Risso), Planococcus ficus (Signoret), Maconellicoccus hirsutus (Green), Ferrisia virgata (Cockerell), Phenacoccus solenopsis Tinsley, Phenacoccus parvus Morrison and Saccharicoccus sacchari (Cockerell)) and 11 in France (Planococcus citri, Pseudococcus viburni Signoret, Pseudococcus longispinus (Targioni-Tozzetti), Pseudococcus comstocki (Kuwana), Rhizoecus amorphophalli Betrem, Trionymus bambusae (Green), Balanococcus diminutus (Leonardi), Phenacoccus madeirensis Green, Planococcus vovae (Nasonov), Dysmicoccus brevipes (Cockerell) and Phenacoccus aceris Signoret), Pl. citri being found in both countries. We also found genetic variation between populations considered to belong to the same species, justifying further investigation of the possible occurrence of complexes of cryptic taxa.

Effect of Plant Characteristics and Within-Plant Distribution of Prey on Colonization Efficiency ofCryptolaemus montrouzieri(Coleoptera: Coccinellidae) Adults

Cryptolaemus montrouzieri(Coleoptera: Coccinellidae) has been widely used in classical and inundative biological control of mealybugs, including the long-tailed mealybug,Pseudococcus longispinus(Hemiptera: Pseudococcidae). This study was conducted to investigate colonization and establishment efficiency ofC. montrouzierito manageP. longispinuson three different ornamental plant species (Ficus elastica, Lilium longiflorum, andDieffenbachia seguine). Within-plant distribution pattern ofP. longispinusand the colonization ecology of adultC. montrouzieriwere investigated. Significantly moreP. longispinuswere found on the upper parts of the plants regardless of plant species, andC. montrouzieriadults discoveredP. longispinussignificantly faster when they were released on the top of the plants than on the bottom. Choice tests revealed thatC. montrouzieriadults preferred smallerP. longispinusnymphs. The implications for utilization ofC. montrouzierifor biological control of mealybugs on various ornamental plants are discussed.

Effect of Different Temperatures and Host Plants on the Biology of the Long-Tailed Mealy Bug Pseudococcus longispinus (Targioni and Tozzetti) (Homoptera: Pseudococcidae)

Experiments were done to determine the effects of different temperature levels and three host plants namely, Cucurbita moschata (butternut squashes), Solanum tuberosum var. Desiree (red potato), and Solanum tuberosum var. Cara (white potato) on the biology of mealy bug Pseudococcus longispinus (Targioni and Tozzetti). It was found that the temperature had a significant effect on the development period of both male and female mealy bugs. For males the period decreased with increasing temperatures up to 28 °C, but increased thereafter and host plant had no effect, except at 24 °C. All the aspects of females including total pre-adult, prelarviposition, larviposition period, life span, fecundity and sex ratio were affected by the fluctuating temperatures, but host plant produced no effect on fecundity and sex ratio.