No description available.

Thesis (MSc)--University of Stellenbosch, 2008. / Bibliography. Also available via the Internet.

Of the estimated 1100 species of mealybugs, approximately 6% are described as possessing degenerative legs and antennae in the adult female developmental stage or having lost these structures altogether. Fifteen genera composing 63 species are often separated into their own taxonomic group based on these vestigial features (e.g., Sphaerococcinae), and are collectively known as the "legless" mealybugs. A comparative morphological analysis of adult females was undertaken to clarify the taxonomic placement of these species and to determine their relationships. Methods were included on collecting, preserving, slide-mounting, and measuring specimens, and on preparing illustrations. Keys to genera and species of "legless" mealybugs were developed. Reduction or loss of legs and antennae apparently occurred convergently in response to similar environmental conditions and was not found supportive of homogeneity in the "legless" group as a whole. However, the genera Chaetococcus Maskell, Idiococcus Takahashi & Kanda, Kermicus Newstead, Serrolecanium Shinji, Tangicoccus Kozar & Walter, and a newly established genus share many characteristics and were treated as the tribe Serrolecaniini Shinji. The adult females of 13 species contained in these genera were redescribed, with illustrations produced for 12. A phylogenetic analysis of the tribe showed that converse to simplification in appendages, adaptations in other features (e.g., latero-projecting lobes and a caudally-directed vulva) probably developed to increase reproductive success and survivorship. The genera Acinococcus Williams, Antonina Signoret, Antoninoides Ferris, Cypericoccus Williams, Nesticoccus Tang, Paludicoccus Ferris, Parapaludicoccus Mamet, Peridiococcus Williams, Pseudantonina Green, and Sphaerococcus Maskell are not closely related to one another or to members of the tribe Serrolecaniini based on adult female morphology. These 10 genera and their type species were redescribed, and illustrations produced for all but Nesticoccus sinensis Tang. Comments or redescriptions are provided for the 21 additional species that comprise these genera; however, the taxonomic placement of 18 additional species erroneously assigned to Pseudantonina and Sphaerococcus is uncertain. Lectotypes were designated for Antonina crawi Cockerell, A. graminis Parrott, A. phragmitis Marchal, A. purpurea Signoret, A. waterstoni Newstead, Jdiococcus bambusae Takahashi & Kanda, Pseudantonina bambusae Green, Pseudolecanium disticlium Kuwana, and Sphaerococcus ethelae Fuller. A replacement name was proposed for the junior homonym Antoninella Sulc. The species names Antonina anceps Green, Antonina maritima Green, and Jdiococcus maanshanensis Tang & Wu are considered junior synonyms. Two species of Serrolecanium were described, and a new genus was established for the placement of Serrolecanium jiuhuaensis Wu and Serrolecanium sasae (Siraiwa). Six new name combinations are also made. / Ph. D.

1. The developing time of the mealybug from catalpa exceeded that of the mealybug from apple. 2. In no experiment did cross-breeding of the mealybug from apple and from catalpa take place. 3. Each mealybug was able to live successfully on both hosts. 4. The parasites, Clausenua purpurea Ishii, from the mealybugs from catalpa parasitized the mealybugs from apply failed to parasitize mealybugs from catalpa. 5. Some female mealybugs may overwinter in the adult form if fully protected from the weather and if the temperature does not drop below 45 °F. 6. Under optimum conditions, several mealybugs lived exceptionally long lives, passing a maximum of 145 days. 7. A color differentiation of the females of the two mealybugs was noticeable. / Master of Science

Thesis (MScAgric)--Stellenbosch University, 2004. / ENGLISH ABSTRACT: Colonies of Planococcus ficus (Signoret) were reared from three different areas, Hex River Valley, Robertson and Stellenbosch. An insectary colony and a table grape colony from Nietvoorbij experimental farm were also included in the study. A range of concentrations of chlorpyrifos was applied topically to individuals from the different colonies. The Stellenbosch population had the lowest LDso, although it was not significantly different from that of the insectary and Robertson colonies. The Hex River Valley and table grape colonies had a significantly higher LDso than the Robertson, Stellenbosch and insectary colonies, although the relative tolerance was 1.5, which would probably not result in significant control failure in the field. However, this does indicate that there is potential for the development of resistance to chlorpyrifos in the vine mealybug in South Africa. / AFRIKAANSE OPSOMMING: Kolonies van Planococcus ficus (Signoret), is versamel en geteel uit drie verskillende areas, Hex.riviervallei, Robertson en Stellenbosch. 'n Bestaande insektarium kolonie van die Lanbou Navorsings Raad en 'n tafeldruif kolonie vanaf Nietvoorbij proefplaas is ook ingesluit in die studie. 'n Reeks konsentrasies van chlorpyrifos is topikaal aangewend aan individue van die verskillende kolonies. Die Stellenbosch populasie het die laagste LDso getoon alhoewel dit nie betekenisvol verskil het van die LDso van die insektarium - en Robertson kolonies nie. Die Hexriviervallei en tafeldruif kolonies se LDso was betekenisvol hoër as die Robertson, Stellenbosch and insektarium kolonies. Alhoewel die relatiewe weerstand 1.5 was, sal dit waarskynlik nie tot 'n aansienlike beheermislukking in die veld lei nie. Nogtans dui dit op die potensiaal vir moontlike ontwikkeling van weerstand teen chlorpyrifos in die wingerdwitluis.

Thesis (Ph. D.)--University of Hawaii at Manoa, 1995. / Includes bibliographical references (leaves 120-122). / Also available in microform / xvii, 128 leaves, bound ill. 29 cm

Thesis (MSc (Genetics))--Stellenbosch University, 2008. / The vine mealybug, Planococcus ficus (Signoret), is a severe pest of grapevine in many grape and wine producing countries around the world. It is renowned not only for the considerable damage it infers to grapevine of its own accord, but in particular for its role in transmitting deleterious viral diseases such as grapevine leafroll disease, Kober stem grooving, Shiraz disease and corky bark. Incidentally, it is an exceptionally tenacious antagonist of grapevine, being resistant to both chemical and biological control mechanisms. As a result, finding an effective strategy for P. ficus control has become a main priority of viticultural industries worldwide. Possible implementation of biotechnological approaches to pest management has resulted in a need for P. ficus genetic data - of which there are currently very little available. The transcribed genes of an organism can be captured in a cDNA library, and the sequences of the various transcripts can then be characterized. In this study altogether five cDNA libraries were constructed from the transcribed sequences of Planococcus ficus (Signoret). Instrumental to their construction was the identification of an RNA extraction protocol that provided large quantities of high quality RNA from mealybugs. The five cDNA libraries were the result of a set of modifications to the Creator™ SMART™ cDNA Library Construction Kit (used for Primary Library construction), and differed mainly with regards to range of insert sizes they contain. Whereas an abundance of short fragments were found in the Primary Library (42% of screened inserts 60.5 kb, and 20% >1 kb), the Fractionated Libraries contained inserts of specific size ranges that were more-or-less equally represented. The broadest size range was found in Fractionated Library 4, for which a uniform distribution over the range 0.25 kb - 4 kb was observed. Average insert sizes of Fractionated Libraries 1 to 4 were estimated at 0.25 kb, 0.5 kb, 1 kb and 2 kb respectively. These results demonstrated the importance of using a protocol designed to circumvent the bias towards incorporation of shorter transcripts in cDNA libraries. Although the libraries were not exhaustively analyzed, the outcome of a pilot investigation indicated that 41% of the submitted sequences had matches in the non-redundant database of the National Center for Biotechnology Information (NCBI, E-value 6 10-5), and that approximately 82% of these were of insect origin. Moreover, two potential targets for an RNAi-mediated approach to P. ficus pest control were identified. With one exception, these sequences seemed to be unique to arthropods. Future research needs to investigate the efficiency by which these sequences are able to constrain P. ficus proliferation, and their suitability for grapevine transformation.

Typescript. / Thesis (Ph. D.)--University of Hawaii at Manoa, 1979. / Bibliography: leaves [86]-89. / Microfiche. / xiii, 89 leaves ill. 29 cm

Mealybugs (Hemiptera: Pseudococcidae) cause severe damage to many commercial crops, including grapevine. This is largely because of their ability to transmit various grapevine viral diseases, in particular grapevine leafroll-associated viruses (GLRaVs). Grapevine leafroll is one of the most wide-spread grapevine diseases worldwide. Managing the field-spread of grapevine leafroll disease requires, amongst others, stringent mealybug control. Mealybug monitoring and control methods rely on timely and accurate identification of the species present. However, proper identification of mealybug species is problematic, time-consuming and requires an expert taxonomist. In most cases, only adult females can be reliably identified morphologically. Immature insects, males and damaged specimens cannot be assigned to species. In this study, a molecular method was developed to rapidly and accurately distinguish three mealybug species associated with grapevine, namely the vine mealybug Planococcus ficus (Signoret), the citrus mealybug Planococcus citri (Risso) and the longtailed mealybug Pseudococcus longispinus (Targioni-Tozzetti). During the development of this identification method, a number of tasks were undertaken. Firstly, rapid and reliable DNA extraction methods were tested for mealybug DNA. Two rapid extraction methods were adapted and tested, namely the direct buffer method and the spot-PCR method. These methods reliably extracted DNA even from very small or damaged individuals, and could be performed in 15-20 minutes and three hours, respectively. Secondly, mealybug mitochondrial DNA from the cytochrome c oxidase subunit 1 (CO I) gene was amplified and sequenced. It was found that DNA from the 3’-end of CO I showed minimal intraspecific variation (<1%), but sufficient interspecific variation (7-12%) to clearly delineate species. This region was then used to develop three species-specific forward primers, which were used in conjunction with a common universal reverse primer. These primers were all used in a multiplex PCR to differentially amplify DNA from each of the three species. The primers were designed such that each yielded a DNA product of different length which could be separated by electrophoresis on an agarose gel. In this manner the identity of the species could be determined. The entire identification protocol (including extraction, PCR and electrophoresis) could be completed in approximately four hours. All amplified specimens in a blind trial were correctly identified, regardless of size or condition of the specimen. The protocol is simple enough to be implemented in any molecular laboratory. This represents a considerable improvement over currently available techniques for mealybug identification, and is certain to be of great use in diagnostic identification of mealybugs in vineyards and export consignments. / Dissertation (Magister Scientiae)--University of Pretoria, 2007. / Zoology and Entomology / unrestricted

Thesis (MSc (Botany and Zoology))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT:Chapter 1 - Mealybugs are tiny, soft-bodied insects which constitute the second largest scale insect family Pseudococcidae (Downie & Gullan 2004). The family comprises approximately 2000 species in 300 genera (Ben-Dov 1994), of which 20 species are pests of cultivated plants in South Africa (Annecke & Moran 1982). In South Africa, approximately 109 species of mealybugs have been recorded from 50 genera (Millar 2002). Chapter 2 - The effect of constant temperatures on the development, survival and fecundity of the oleander mealybug, Paracoccus burnerae on citrus was determined. Developmental time, rate of development, fecundity and survival were investigated at five constant temperatures and a 16L: 8D light: darkness regime. The rate of development increased linearly with an increase in temperature for the egg, 1st nymphal and pupal stages as well as the entire biological cycle (egg – adult), but was nonlinear for the 2nd and 3rd nymphal stages. Survival decreased with an increase in temperature. P. burnerae required 666.7 degree-days above a lower threshold of 8.7°C to complete one generation. The highest mean number of 68 eggs per female was reached at 22°C. A sex ratio of 0.52:0.48 (male:female) was obtained from the life table. The net reproductive rate (Ro) was >1 at all five temperatures, an indication that it is capable of increasing its population numbers despite the high mortality experienced in the 1st and 2nd nymphal stages. Chapter 3 - The oleander mealybug, Paracoccus burnerae (Brain) is a pest of citrus in South Africa. This study was carried out to determine the effect of temperature on development rate of P. burnerae and to investigate whether development rate is the reason why P. burnerae is out competing the citrus mealybug, Planococcus citri (Risso), in the Eastern and Western Cape Provinces of South Africa. The influence of temperature on life history traits of P. burnerae was determined at 20, 22, 25 and 27°C and compared with corresponding data for P. citri. The rate of development increased linearly with an increase in rearing temperature in the embryonic, first nymphal and pupal stages but reached a climax at 26.13 and 28.6°C in the second nymphal stage of both species, respectively. P. citri exhibited lower developmental thresholds except in first instar, shorter degree-days and higher developmental rates than P. burnerae. Results of the current study indicated that the dominance of oleander mealybug over the citrus mealybug is neither linked to developmental rates nor sum of effective temperatures. Chapter 4 - The importance of Paracoccus burnerae has risen over the years to an extent where it is now regarded as a quarantine pest for citrus fruit 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 to 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 the parasitoid Coccophagus sp. The most popular species of parasitoids used in the biolological control of mealybugs, Anagyrus sp. and Coccixenoides sp. were insignificant in the case of P. burnerae. Chapetr 5 - Biological control programs of mealybug species have relied on sprouting potatoes, pumpkins and butternut for rearing of both mealybugs and their natural enemies. In this study, the suitability of sprouting potatoes, butternuts and citrus as mass rearing substrates for the oleander mealybug, Paracoccus burnerae was investigated. Developmental times, rate and fecundity on each substrate were determined and compared at three different temperatures. The developmental time on sprouting potatoes was shorter than on citrus. P. burnerae was unable to complete its life cycle on butternut. The rate of development increased linearly with an increase in temperature on both sprouting potatoes and citrus. P. burnerae required 666.7 degree-days on citrus and 434.8 degree-days on sprouting potatoes above lower developmental thresholds of 7.6°C and 10.4°C respectively to complete one generation. The mean number of eggs per female was higher on sprouting potatoes (121.3) than on citrus (68), but declined with an increase in temperature from 22 to 27°C. Despite the shorter shelf life, sprouting potatoes are the preferred host for mass rearing of the oleander mealybug. Chapter 6 - general conclusions Chapter 7 - Researchers often present impressive results of their studies on the biology of the Coccoidea without mentioning the problems they came across and had to solve. In this paper the practical problems encountered during a study of the biology of the oleander mealybug, Paracoccus burnerae (Brain), an endemic pest of citrus in South Africa, are discussed. / AFRIKAANSE OPSOMMING: Geen opsomming beskikbaar.