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L V C Santacecilia - One of the best experts on this subject based on the ideXlab platform.
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host preference and biology of two cryptic species Planococcus citri risso and Planococcus minor maskell hemiptera pseudococcidae
Scientia agraria, 2018Co-Authors: Ana Luiza Viana De Sousa, Brigida Souza, L V C Santacecilia, Marlice Botelho Costa, Renato Ribeiro De LimaAbstract:The mealybugs Planococcus minor (Maskell) and Planococcus citri (Risso) (Hemiptera: Pseudococcidae) are cryptic species to be morphologically similar and share common hosts. However some host preference has been observed. In addition to preference, evidence showed that host plants could affect the reproductive traits of mealybugs. Although there are few studies about the influence of these plants on development of Planococcus spp. In this work, we conducted laboratory studies to: (a) determinate the effect of original host cocoa, coffee and orange (leaves and fruits) on the preference of P. minor and P. citri using free choice assays; and, (b) investigate the nymph’s development and female’s oviposition of both P. minor and P. citri in cocoa, coffee and orange (fruits). P. minor before the preference and development assays was reared in cocoa fruits and P. citri was reared in coffee seedlings and orange fruits. In free choice assays, P. minor showed a great preference for cocoa fruits than P. citri . Rearing substrates did not affect the choice and development of P. citri . The preference of P. minor for cocoa fruits shows a possible food conditioning. All three tested hosts (original hosts: cocoa, coffee and orange) were accepted for this mealybug’s species but the oviposition was strongly increased only on cocoa fruits, in both species P. citri and P. minor .
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Planococcus citri risso hemiptera pseudococcidae male female relationships and influences in the reproductive biology
Coffee Science, 2017Co-Authors: L V C Santacecilia, Brigida Souza, Ernesto Prado, Andressa Barbosa Pereira, Lara SalesAbstract:The reproduction of the citrus mealybug, Planococcus citri (Hemiptera: Pseudococcidae) has been reported as biparental with facultative parthenogenesis or exclusively biparental. Parthenogenesis may be an attribute of local populations, thus geographic variations could be determinant for the type of reproduction. Therefore, this work aimed to increase our knowledge on the reproduction of P. citri by evaluating the type of reproduction of a Brazilian population of the citrus mealybug collected in coffee trees (Coffea arabica) in south of Minas Gerais state, Brazil. We explored the kind of reproduction, the effect of the temperature on the sexual ratio, the mating capacity of males of 1 or 2 days after emergency and female´s age from 1 to 40 days old, and the number of successful mating of a male. The citrus mealybug from that population presented sexual reproduction exclusively. There was a bias to a higher female proportion at 20°C and 30°C, rearing temperatures considered no optimal for the mealybug development, while at 25°C conduced to a similar proportion of males and females. No mealybug developed at 15°C. The male sexual maturity seems to occur already inside the cocoon where it remains for about 2 days and was able to mate during the first 24 h after emergence. Although short lived, around 2 days after emergence, the male were able to mate up to 21 females. Females between 1 and 40 days were able to mate and reproduce at the same proportion.
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fertility life table of the Planococcus citri risso and Planococcus minor maskell hemiptera pseudococcidae in coffee tree
Coffee Science, 2016Co-Authors: Marlice Botelho Costa, Brigida Souza, Ernesto Prado, L V C SantaceciliaAbstract:The mealybugs Planococcus citri and Planococcus minor (Hemiptera: Pseudococcidae) have increased their importance in brazilian coffee and cause similar damage to plants. Our objective was to determine the characteristics related to the development of these species, testing the hypothesis that, despite of considered cryptic, they have different biological characteristics. Mealybugs crawlers were individually isolated inside Petri dishes containing coffee leaf discs on an agar layer. Its development was monitored until adult emergence when females were enclosed with a male. We evaluated fertility parameters and by means of a life table, we estimated the mean generation time (T), the reproduction net rate (Ro), the increasing net rate (Rm), the finite increasing rate (λ) and the time needed to double the number of individuals (TD). Generally, the reproductive and fertility parameters did not differ between both species. These results show that females of both species produce similar number of descendents rejecting the tested hypothesis.
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evaluation of silicon on the probing behavior of the citrus mealybug Planococcus citri risso pseudococcidae in coffee
Coffee Science, 2014Co-Authors: L V C Santacecilia, Ernesto Prado, Jair Campos De MoraisAbstract:Pesquisas visando a utilizacao de silicio contra insetos-praga tem demonstrado o aumento do grau de resistencia das plantas ao ataque desses organismos. Assim, foi estudado o efeito desse mineral no comportamento alimentar da cochonilhabranca [Planococcus citri (Pseudococcidae)] em cafeeiro, utilizando a tecnica de monitoramento eletronico (EPG). A fonte de silicio foi o silicato de calcio (CaSiO3) incorporado ao solo na dosagem de 1 g/250 g de solo/vaso, contendo plantas de Coffea arabica cvs. Catuai e Catucai e a testemunha (sem aplicacao). O estudo do comportamento alimentar mostrou que, nas plantas crescidas em solo tratado com silicato de calcio, as cochonilhas atingiram o floema, seu local de alimentacao, em tempo similar ao verificado nas plantas nao tratadas, demonstrando ausencia de barreira mecânica por efeito da aplicacao do silicio. Nenhum parâmetro associado as fases floematicas e xilematicas apresentou diferencas, seja nas cultivares ou nos tratamentos com e sem silicato de calcio. Dessa forma, o emprego do silicato, na dosagem avaliada, nao afetou os parâmetros do comportamento alimentar estudado na cochonilha P. citri, em cafeeiro.
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sobre o condicionamento alimentar na cochonilha branca Planococcus citri risso hemiptera pseudococcidae
Revista Brasileira De Fruticultura, 2013Co-Authors: L V C Santacecilia, Ernesto Prado, Mayara Silva OliveiraAbstract:Estudos do comportamento alimentar mediante a tecnica de "Electrical Penetration Graphs" (EPG) das cochonilhas-farinhentas (Pseudococcidae) provenientes de um hospedeiro de criacao alternativo tem mostrado que esses insetos nao atingem ou demoram cerca de 9 horas para alcancar a fase floematica. Por outro lado, aqueles provenientes do hospedeiro-fonte atingem a fase floematica mais rapidamente e apresentam maior frequencia de alimentacao nos vasos crivados. Esses resultados indicam a presenca do fenomeno de condicionamento alimentar, ainda nao demonstrado em cochonilhas. Assim, o presente trabalho teve como objetivo determinar a existencia desse fenomeno em Planococcus citri (Risso) (Hemiptera: Pseudococcidae). Foram realizados testes de livre escolha, monitoramento eletronico (EPG) e estudos de alguns parâmetros biologicos. Em todos os experimentos, o cafeeiro (Coffea arabica L.), os citros (Citrus sinensis L.) e abobora (Cucurbita maxima L.) foram utilizados como substratos de criacao (fonte) da cochonilha, sendo os tratamentos constituidos pela combinacao entre os hospedeiros-fonte e os hospedeiros receptores (cafe e citros). O teste de escolha entre cafeeiro e citros nas primeiras 72 horas mostrou que as cochonilhas criadas em cafeeiro apresentaram preferencia pelo cafeeiro; aquelas originadas dos citros mostraram uma tendencia, embora nao significativa, em selecionar os citros em relacao ao cafeeiro e aquelas criadas em abobora nao mostraram preferencia por nenhum dos hospedeiros. Os estudos do comportamento alimentar mediante o monitoramento eletronico (EPG) mostraram que a fase floematica, considerada como a fase de aceitacao do hospedeiro, foi mais frequente em cafeeiro, seja com cochonilhas oriundas deste substrato, seja de citros. Aqueles insetos mantidos em abobora e transferidos para o cafeeiro ou citros apresentaram excepcionalmente ou nao apresentaram nenhuma fase floematica, respectivamente. A transferencia de cochonilhas de qualquer hospedeiro-fonte para cafeeiro ou citros nao afetou o tempo de desenvolvimento, fecundidade e mortalidade, porem aquelas criadas e mantidas em abobora mostraram maior fecundidade quando comparadas com qualquer outro substrato receptor. Conclui-se que a transferencia do substrato, seja cafeeiro, seja citros, nao influencia significativamente o comportamento alimentar e o desenvolvimento de P. citri, embora possa existir preferencia inicial pelo hospedeiro-fonte.
Brigida Souza - One of the best experts on this subject based on the ideXlab platform.
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host preference and biology of two cryptic species Planococcus citri risso and Planococcus minor maskell hemiptera pseudococcidae
Scientia agraria, 2018Co-Authors: Ana Luiza Viana De Sousa, Brigida Souza, L V C Santacecilia, Marlice Botelho Costa, Renato Ribeiro De LimaAbstract:The mealybugs Planococcus minor (Maskell) and Planococcus citri (Risso) (Hemiptera: Pseudococcidae) are cryptic species to be morphologically similar and share common hosts. However some host preference has been observed. In addition to preference, evidence showed that host plants could affect the reproductive traits of mealybugs. Although there are few studies about the influence of these plants on development of Planococcus spp. In this work, we conducted laboratory studies to: (a) determinate the effect of original host cocoa, coffee and orange (leaves and fruits) on the preference of P. minor and P. citri using free choice assays; and, (b) investigate the nymph’s development and female’s oviposition of both P. minor and P. citri in cocoa, coffee and orange (fruits). P. minor before the preference and development assays was reared in cocoa fruits and P. citri was reared in coffee seedlings and orange fruits. In free choice assays, P. minor showed a great preference for cocoa fruits than P. citri . Rearing substrates did not affect the choice and development of P. citri . The preference of P. minor for cocoa fruits shows a possible food conditioning. All three tested hosts (original hosts: cocoa, coffee and orange) were accepted for this mealybug’s species but the oviposition was strongly increased only on cocoa fruits, in both species P. citri and P. minor .
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Planococcus citri risso hemiptera pseudococcidae male female relationships and influences in the reproductive biology
Coffee Science, 2017Co-Authors: L V C Santacecilia, Brigida Souza, Ernesto Prado, Andressa Barbosa Pereira, Lara SalesAbstract:The reproduction of the citrus mealybug, Planococcus citri (Hemiptera: Pseudococcidae) has been reported as biparental with facultative parthenogenesis or exclusively biparental. Parthenogenesis may be an attribute of local populations, thus geographic variations could be determinant for the type of reproduction. Therefore, this work aimed to increase our knowledge on the reproduction of P. citri by evaluating the type of reproduction of a Brazilian population of the citrus mealybug collected in coffee trees (Coffea arabica) in south of Minas Gerais state, Brazil. We explored the kind of reproduction, the effect of the temperature on the sexual ratio, the mating capacity of males of 1 or 2 days after emergency and female´s age from 1 to 40 days old, and the number of successful mating of a male. The citrus mealybug from that population presented sexual reproduction exclusively. There was a bias to a higher female proportion at 20°C and 30°C, rearing temperatures considered no optimal for the mealybug development, while at 25°C conduced to a similar proportion of males and females. No mealybug developed at 15°C. The male sexual maturity seems to occur already inside the cocoon where it remains for about 2 days and was able to mate during the first 24 h after emergence. Although short lived, around 2 days after emergence, the male were able to mate up to 21 females. Females between 1 and 40 days were able to mate and reproduce at the same proportion.
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fertility life table of the Planococcus citri risso and Planococcus minor maskell hemiptera pseudococcidae in coffee tree
Coffee Science, 2016Co-Authors: Marlice Botelho Costa, Brigida Souza, Ernesto Prado, L V C SantaceciliaAbstract:The mealybugs Planococcus citri and Planococcus minor (Hemiptera: Pseudococcidae) have increased their importance in brazilian coffee and cause similar damage to plants. Our objective was to determine the characteristics related to the development of these species, testing the hypothesis that, despite of considered cryptic, they have different biological characteristics. Mealybugs crawlers were individually isolated inside Petri dishes containing coffee leaf discs on an agar layer. Its development was monitored until adult emergence when females were enclosed with a male. We evaluated fertility parameters and by means of a life table, we estimated the mean generation time (T), the reproduction net rate (Ro), the increasing net rate (Rm), the finite increasing rate (λ) and the time needed to double the number of individuals (TD). Generally, the reproductive and fertility parameters did not differ between both species. These results show that females of both species produce similar number of descendents rejecting the tested hypothesis.
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desenvolvimento de Planococcus citri risso 1813 hemiptera pseudococcidae em cafeeiros
Acta Scientiarum-agronomy, 2009Co-Authors: L V C Santacecilia, Lilian Roberta Batista Correa, Brigida Souza, Ernesto Prado, Eliana AlcantraAbstract:The citrus mealybug Planococcus citri (Risso, 1813) feeds mainly on flowers and fruits of coffee plants from blooming until harvest. Little is known about its development in coffee although its occurrence is already known for several years. This work aims to study the nymph development of this mealybug in coffee plants. Eggs were isolated from a stock culture kept in laboratory and placed inside Petri dishes containing leaf sections in agar. The tested cultivars were Acaia Cerrado, Mundo Novo, Catuai Vermelho ( Coffea arabica ) and Apoata ( C. canephora ). Insects were kept in a climatized chamber at 25oC, 70 ± 10% humidity and 12-hour photophase. The longest development period in females was obtained in cultivar Catuai Vermelho. No differences in mortality were found among cultivars. Mealybugs developed in all cultivars and the results did not show clear differences in susceptibility.
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aspectos biologicos de chrysoperla externa hagen 1861 neuroptera chrysopidae alimentada com Planococcus citri risso 1813 hemiptera pseudococcidae e toxoptera citricida kirkaldy 1907 hemiptera aphididae
Ciencia E Agrotecnologia, 2009Co-Authors: Jean Patrick Bonani, L V C Santacecilia, Brigida Souza, Lilian Roberta Batista CorreaAbstract:O ecossistema citricola abriga muitas especies de inimigos naturais, entre eles Chrysoperla externa (Hagen, 1861) que apresenta um grande potencial como agente de controle biologico de pragas. Neste trabalho, objetivou-se avapar o efeito das presas Planococcus citri (Risso, 1813) e Toxoptera citricida (Kirkaldy, 1907) sobre o desenvolvimento das fases de larva e pupa de C. externa. O ensaio foi conduzido em sala cpmatizada a uma temperatura de 25±1oC, 70±10% UR e fotofase de 12 horas, sendo os tratamentos constituidos pelo fornecimento continuo e alternado dessas duas presas em cada instar do predador, alem de ovos de Anagasta kuehniella (Zeller, 1879), utilizados para fins de comparacao. Foram avaliados o tempo de vida e a viabilidade das fases de larva, pupa e do periodo larva-adulto de C. externa. Constatou-se que T. citricida fornecido isoladamente ao longo do desenvolvimento larval ou em dois instares consecutivos do predador, nao foi uma presa adequada, constatando-se 100% de mortalidade no periodo larva-adulto. Quando as larvas alimentaram-se de P. citri fornecida em dois instares do predador, a viabilidade no periodo larva-adulto foi semelhante a dieta constituida por apenas ovos de A. kuehniella, exceto quando se alimentaram de T. citricida no primeiro instar.
M Ferraro - One of the best experts on this subject based on the ideXlab platform.
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germline cyst development and imprinting in male mealybug Planococcus citri
Chromosoma, 2004Co-Authors: Giovanni Luigi Buglia, M FerraroAbstract:In the epigenetic modifications involved in the phenomenon of imprinting, which is thought to take place during gametogenesis, one of the primary roles is exerted by histone tail modifications acting on chromatin structure. What is more, in insects like mealybugs, with a lecanoid chromosome system, imprinting is strictly related to sex determination. In many diverse species gametes originate in specific, highly evolutionarily conserved structures called germline cysts. The use of staining techniques specific for fusomal components like F-actin has allowed us to describe for the first time the morphogenesis of male germline cysts in the mealybug Planococcus citri. Antibodies to anti-methylated lysine 9 of histone H3 (MeLy9-H3) and anti-heterochromatin protein 1 (HP1) were used during cyst formation to investigate the involvement of these epigenetic modifications in the phenomenon of imprinting and their possible concerted action in sex determination in P. citri. These observations indicate: (i) a specific role for F-actin in the segregation, typical of the lecanoid chromosome system, of genomes of paternal origin; (ii) that the two vital gametes originating from a given meiosis, although carrying the same genome, differ in the levels of both MeLy9-H3 and HP1, one of them being more heavily labelled by both antibodies.
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Planococcus citri homoptera coccoidea a paradigmatic case of chromosome structure as an epigenetic way to control gene expression
2002Co-Authors: M FerraroAbstract:It is becoming increasingly clear that chromatin structure might play an essential role in regulating gene expression. The elucidation of the different ways through which this type of epigenetic control can be accomplished is therefore of apparent importance. In this context the mealybug Planococcus citri represents an excellent experimental model system. Males and females, in fact, start development as diploid from fertilized eggs in which both maternally and paternally derived genomes are euchromatic. However, early in the development in embryos which will develop as males, the haploid set of paternal origin undergoes heterochromatization and remains so and mostly inactive, in most of the tissues. Amongst the factors possibly involved in this event we investigated methylation at CpGs and histone H4 acetylation. Our results suggest that in P. citri, most probably underacetylation of histone H4 plays a role in the heterochromatization/silencing of the paternal genome rather than methylation at CpGs.
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involvement of histone h4 acetylation in the epigenetic inheritance of different activity states of maternally and paternally derived genomes in the mealybug Planococcus citri
Chromosoma, 2001Co-Authors: M Ferraro, Giovanni Luigi Buglia, Francesca RomanoAbstract:Modification of histones by acetylation is a well-known mechanism for the establishment and maintenance of specific chromatin structures with different activity states. In Planococcus citri males the paternal genome, early in development, becomes mostly inactive and heterochromatic. As we had not found methylation in the genome of P. citri, we analyzed the acetylation state of histone H4. We report here that, in males, differences in the level of histone H4 acetylation are indeed present in the two genomes of different parental origin; these differences were confirmed by treatment with the histone deacetylase inhibitor Trichostatin A. There is also evidence of acetylation of histone H4 on metaphase chromosomes. Our data therefore suggest a role of histone H4 acetylation in the imprinting of the paternal genome in P. citri males, thus supporting a role of modification of chromatin-related structural proteins in the epigenetic transmission of imprinting.
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cytogenetic characterization of the genome of mealybug Planococcus citri homoptera coccoidea
Caryologia, 1998Co-Authors: M Ferraro, Chiara Epifani, Silvia Bongiorni, Anna Maria Nardone, Saviana Parodidelfino, Giorgio PranteraAbstract:Summary Mealybugs although being agriculturally harmful insects have been very poorly studied by modern cytogenetics techniques, and no cytotaxonomic criteria to distinguish between closely related species is available yet. In the mealybug Planococcus citri (2n=10) male and female individuals are both diploid, however in males, at the stage of blastula, the haploid chromosome set of paternal origin becomes heterochromatic, even though its complete inertia has been considered questionable. Here we present data on the cytogenetic characterization of the chromosomes of Planococcus citri. We report on (i) the fluorescence karyotype (D287/170), which to our knowledge is the first banded karyotype of a mealybug to be described; (ii) the chromosome localization of constitutive heterochromatin; (iii) the chromosome localization of rDNA sites; (iv) NORs activity. Our data also show, for the first time, that in the heterochromatic chromosome set ribosomal genes are still active.
Lilian Roberta Batista Correa - One of the best experts on this subject based on the ideXlab platform.
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desenvolvimento de Planococcus citri risso 1813 hemiptera pseudococcidae em cafeeiros
Acta Scientiarum-agronomy, 2009Co-Authors: L V C Santacecilia, Lilian Roberta Batista Correa, Brigida Souza, Ernesto Prado, Eliana AlcantraAbstract:The citrus mealybug Planococcus citri (Risso, 1813) feeds mainly on flowers and fruits of coffee plants from blooming until harvest. Little is known about its development in coffee although its occurrence is already known for several years. This work aims to study the nymph development of this mealybug in coffee plants. Eggs were isolated from a stock culture kept in laboratory and placed inside Petri dishes containing leaf sections in agar. The tested cultivars were Acaia Cerrado, Mundo Novo, Catuai Vermelho ( Coffea arabica ) and Apoata ( C. canephora ). Insects were kept in a climatized chamber at 25oC, 70 ± 10% humidity and 12-hour photophase. The longest development period in females was obtained in cultivar Catuai Vermelho. No differences in mortality were found among cultivars. Mealybugs developed in all cultivars and the results did not show clear differences in susceptibility.
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aspectos biologicos de chrysoperla externa hagen 1861 neuroptera chrysopidae alimentada com Planococcus citri risso 1813 hemiptera pseudococcidae e toxoptera citricida kirkaldy 1907 hemiptera aphididae
Ciencia E Agrotecnologia, 2009Co-Authors: Jean Patrick Bonani, L V C Santacecilia, Brigida Souza, Lilian Roberta Batista CorreaAbstract:O ecossistema citricola abriga muitas especies de inimigos naturais, entre eles Chrysoperla externa (Hagen, 1861) que apresenta um grande potencial como agente de controle biologico de pragas. Neste trabalho, objetivou-se avapar o efeito das presas Planococcus citri (Risso, 1813) e Toxoptera citricida (Kirkaldy, 1907) sobre o desenvolvimento das fases de larva e pupa de C. externa. O ensaio foi conduzido em sala cpmatizada a uma temperatura de 25±1oC, 70±10% UR e fotofase de 12 horas, sendo os tratamentos constituidos pelo fornecimento continuo e alternado dessas duas presas em cada instar do predador, alem de ovos de Anagasta kuehniella (Zeller, 1879), utilizados para fins de comparacao. Foram avaliados o tempo de vida e a viabilidade das fases de larva, pupa e do periodo larva-adulto de C. externa. Constatou-se que T. citricida fornecido isoladamente ao longo do desenvolvimento larval ou em dois instares consecutivos do predador, nao foi uma presa adequada, constatando-se 100% de mortalidade no periodo larva-adulto. Quando as larvas alimentaram-se de P. citri fornecida em dois instares do predador, a viabilidade no periodo larva-adulto foi semelhante a dieta constituida por apenas ovos de A. kuehniella, exceto quando se alimentaram de T. citricida no primeiro instar.
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desenvolvimento da cochonilha branca Planococcus citri risso 1813 hemiptera pseudococcidae em frutiferas
Arquivos do Instituto Biológico, 2008Co-Authors: Lilian Roberta Batista Correa, Brigida Souza, L V C SantaceciliaAbstract:DEVELOPMENT OF THE CITRUS MEALYBUG Planococcus citri (RISSO, 1813) (HEMIPTERA: PSEUDOCOCCIDAE) ON DIFFERENT FRUIT-BEARING PLANTS. The citrus mealybug, Planococcus citri is an important pest attacking several crops. Biotic and abiotic factors, as well as the substrate they feed on influence its population. The present study was aimed to study the effect of some feeding substrates on mealybug development in laboratory conditions. Leaf disks of guava, fig and cherimoya were placed individually on an agar film inside a Petri dish. One egg of the insect was confined inside each container, replicated 60 times for each treatment. Containers were kept in a climatized chamber at 25o C, 70 ± 10% RH and 12 hours photophase. Insects reared on guava leaves showed a longer nymphal development, while the female longevity was longer on fig leaves. However, no statistical differences were found in the survival index, which showed values higher than 83%, suggesting that all substrates studied here were adequate for the development of P. citri.
Giorgio Prantera - One of the best experts on this subject based on the ideXlab platform.
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epigenetic regulation of facultative heterochromatinisation in Planococcus citri via the me 3 k9h3 hp1 me 3 k20h4 pathway
Journal of Cell Science, 2007Co-Authors: Silvia Bongiorni, Prim B Singh, Barbara Pasqualini, Monia Taranta, Giorgio PranteraAbstract:Using RNA interference (RNAi) we have conducted a functional analysis of the HP1-like chromobox gene pchet2 during embryogenesis of the mealybug Planococcus citri. Knocking down pchet2 expression results in decondensation of the male-specific chromocenter that normally arises from the developmentally-regulated facultative heterochromatinisation of the paternal chromosome complement. Together with the disappearance of the chromocenter the staining levels of two associated histone modifications, tri-methylated lysine 9 of histone H3 [Me(3)K9H3] and tri-methylated lysine 20 of histone H4 [Me(3)K20H4], are reduced to undetectable levels. Embryos treated with double-stranded RNA (dsRNA) targeting pchet2 also exhibit chromosome abnormalities, such as aberrant chromosome condensation, and also the presence of metaphases that contain `lagging9 chromosomes. We conclude that PCHET2 regulates chromosome behavior during metaphase and is a crucial component of a Me(3)K9H3-HP1-Me(3)K20H4 pathway involved in the facultative heterochromatinisation of the (imprinted) paternal chromosome set.
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the relationship between dna methylation and chromosome imprinting in the coccid Planococcus citri
Genetics, 1999Co-Authors: Silvia Bongiorni, Orietta Cintio, Giorgio PranteraAbstract:The phenomenon of chromosome, or genomic, imprinting indicates the relevance of parental origin in determining functional differences between alleles, homologous chromosomes, or haploid sets. In mealybug males (Homoptera, Coccoidea), the haploid set of paternal origin undergoes heterochromatization at midcleavage and remains so in most of the tissues. This different behavior of the two haploid sets, which depends on their parental origin, represents one of the most striking examples of chromosome imprinting. In mammals, DNA methylation has been postulated as a possible molecular mechanism to differentially imprint DNA sequences during spermatogenesis or oogenesis. In the present article we addressed the role of DNA methylation in the imprinting of whole haploid sets as it occurs in Coccids. We investigated the DNA methylation patterns at both the molecular and chromosomal level in the mealybug Planococcus citri. We found that in both males and females the paternally derived haploid set is hypomethylated with respect to the maternally derived one. Therefore, in males, it is the paternally derived hypomethylated haploid set that is heterochromatized. Our data suggest that the two haploid sets are imprinted by parent-of-origin-specific DNA methylation with no correlation with the known gene-silencing properties of this base modification.
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cytogenetic characterization of the genome of mealybug Planococcus citri homoptera coccoidea
Caryologia, 1998Co-Authors: M Ferraro, Chiara Epifani, Silvia Bongiorni, Anna Maria Nardone, Saviana Parodidelfino, Giorgio PranteraAbstract:Summary Mealybugs although being agriculturally harmful insects have been very poorly studied by modern cytogenetics techniques, and no cytotaxonomic criteria to distinguish between closely related species is available yet. In the mealybug Planococcus citri (2n=10) male and female individuals are both diploid, however in males, at the stage of blastula, the haploid chromosome set of paternal origin becomes heterochromatic, even though its complete inertia has been considered questionable. Here we present data on the cytogenetic characterization of the chromosomes of Planococcus citri. We report on (i) the fluorescence karyotype (D287/170), which to our knowledge is the first banded karyotype of a mealybug to be described; (ii) the chromosome localization of constitutive heterochromatin; (iii) the chromosome localization of rDNA sites; (iv) NORs activity. Our data also show, for the first time, that in the heterochromatic chromosome set ribosomal genes are still active.