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Thesis (MScAgric)--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: Codling moth, Cydia pomonella (L.), infested fluit were collected in a sprayed, unsprayed and an organic orchard. The time of emergence was monitored to see if there was selection for a delayed emergence caused by different treatments. Moths from fruit collected in the sprayed and unsprayed orchards in Desember 2001, had a peak emergence during January 2002 and a smaller peak during February 2002. Moths from fruit collected during February 2002 from an organic orchard, had a peak emergence during February 2002 and an extended emergence from diapause until January 2003. Moths from fluit collected during March 2002 had a peak emergence during November 2002 with an extended emergence in the sprayed orchards until January 2003. Delayed emergence from diapause was observed. Not all the moths from diapause emerged during the first flight, but overlapped with the second flight in December and January. / AFRIKAANSE OPSOMMING: Kodlingmot, Cydia pomonella (L.), geïnfesteerde vrugte is in 'n onbespuite, chemies behandelde en 'n organiese boord versamel. Die tyd van motuitkoms is gemonitor om te bepaal of verskillende behandelings dalk seleksie in die motpopulasie kan veroorsaak ten op sigte van 'n vertraagde motuitkoms. Motte uit vrugte wat in die gespuite boorde in Desember 2001 versamel is, het 'n piek uitkoms in Januarie en 'n kleiner een in Februarie 2002 gehad. Motte uit die ongespuite boord se vrugte, het ook 'n piek uitkoms in Januarie 2002 getoon. Motte uit vrugte wat in Februarie 2002 in 'n organiese boord versamel is, het 'n piek uitkoms in Februarie 2002 gehad, met 'n verlengde uitkoms vanuit diapause vanaf Oktober 2002 tot Januarie 2003. Motte uit vrugte wat in Maart 2002 versamel is, het 'n piek uitkoms in November 2002 gehad. Daar was ook 'n verlengde motuitkoms vanaf diapause by die chemies behandelde boorde tot Januarie 2003. 'n Vertraagde motuitkoms vanaf diapause is waargeneem. Die motte vanuit diapause maak nie almal deel uit van die eerste vlug nie, maar oorvleuelook met motte van die tweede vlug wat gedurende Desember en Januarie in die veld voorkom.

The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Title from PDF of title page (University of Missouri--Columbia, viewed on September 22, 2009). Thesis advisor: Dr. Bruce Barrett. Includes bibliographical references.

Repetitive DNA comprises substantial part of the eukaryotic genome. ?Junk DNA?, as it was originally understood at the beginning of its discovery has attracted a lot of attention lately due to many studies proving its functional perspectives. Analysis of its dynamics, characteristics and distribution has been widely studied in organisms with monocentric chromosomes. Holokinetic system, however, was left behind in these efforts and whole image of repetitive DNA distribution and dynamics in this system remains to be elucidated. In this thesis various approaches were used to isolate and characterise repetitive DNA in the genome of the codling moth, Cydia pomonella. Satellite DNA CPSAT-1 was successfully isolated, characterised with Dot blot and Southern blot and mapped with FISH in the genome of C. pomonella. 17 microsatellite probes were used to localize microsatellite arrays in the genome of C. pomonella. Method of microsatellite FISH revealed distribution of all tested microsatellites in C. pomonella complement.

Thesis (MScAgric (Conservation Ecology and Entomology)--University of Stellenbosch, 2009. / The false codling moth (FCM), Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae), is an indigenous pest of citrus fruit in southern Africa, and is a pest of high phytosanitary concern, impacting negatively on the export of fresh citrus fruit from South Africa to some international markets. FCM is a particularly serious pest in the Citrusdal area in the Western Cape Province of South Africa. FCM is known to infest most types of citrus, with navel oranges being particularly prone to attack, whereas lemons are not considered to be a favoured host. Conventional control strategies that rely on the use of insecticides are of limited use due to high levels of insecticide resistance in FCM populations. Mating disruption, the Sterile Insect Technique (SIT) and the integration of different control techniques are options that are currently being adopted. Little is known about FCM host preferences in this geographical area, or about its dispersal capacity. The ability of FCM to migrate between various host patches, including citrus orchards and indigenous fynbos vegetation, and its ability to maintain a viable population in alternative host plants when there is no fruit available for infestation in citrus orchards has not been well studied. Knowledge of these largely behavioural facets is important in planning an effective control strategy for FCM. Towards addressing this dearth of knowledge, FCM pheromone traps were set out in transects in the Citrusdal area. These transects included citrus orchards, and extended beyond citrus orchards, to include a range of habitat types and elevational gradients. This provided a grid to assess the spatial and temporal distribution of male FCM in the area. In addition, intensive sampling and inspection of potential host plant material was undertaken in the area in an attempt to identify any alternative host plants.

Thesis (MSc)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: Thaumatotibia leucotreta, the false codling moth (FCM), is a phytosanitary pest in South Africa posing a substantial threat to many of the country’s international export markets. Its pest status is of high importance because it has a wide ecological range and has been reported in all areas where citrus is produced in South Africa. Many methods of control have been implemented, such as chemical and cultural control, mating disruption and sterile insect releases. There was a need to obtain a more accurate understanding of FCM biology on deciduous fruit in South Africa and this then us to pose the questions described in the chapters to follow. The first aim was focused on the possibility of FCM diapause during winter. If FCM were to undergo diapause this could pose further problems for control methods, but knowledge thereof could also assist in more accurate and timely control methods. Considering past research on other Lepidoptera species, four physiological traits were chosen as indicative of a diapause state. Water loss rate, metabolic rate and the supercooling points should be lower if the individuals were in a diapause state, with a higher fat content expected for these individuals. Diapause induction was attempted through a gradual lowering of the environmental temperature in combination with longer nights to simulate overwintering conditions. Diapause was not observed in these experimental individuals. The second aim was to better understand the field biology of FCM. This was studied through in-field flight ability studies and damage assessments on four fruit kinds. Six release dates were used to measure the flight ability. The highest recapture rates were at minimum temperatures above 16°C and maximum temperatures averaging above 30°C, although the recapture rates were not significant in relation to the amount released. The recapture rates in the different fruit kinds were not significantly different, with the amount recaptured at the closest distance of 30 m being significantly more than that of the other distances. This was also only for the last release at the warmest temperatures. Fruit damage assessments were conducted and we were able to rear wild FCM from Granny smith apples, Forelle pears, Larry Ann plums and Satsuma and Clementine citrus cultivars. Citrus infestations had the highest count and a prolonged occurrence compared to the other varieties, due to its later harvest period. The third aim was to study the developmental parameters of FCM in different fruit kinds and an artificial medium. Firstly, FCM did not infest apples, Royal Gala and Pink lady’s, under laboratory conditions. Results were obtained using Forelle pears, Clementines and Thompson seedless grapes. On average the grapes had the shortest FCM developmental time from egg to adult stage, followed by oranges and then pears. Pears had the lowest developmental success rate, with that of oranges and grapes being much higher. Infestations took place at the stalk end of the fruit for the grapes and oranges, with the pears being infested at the calyx end. Future research should include an in-field life cycle, to determine the life cycle of FCM on different economically important fruit kinds under field conditions. The focus could also be shifted to where FCM overwinter, leading to better preventative control leading to lower infestation pressure during harvest periods. This is of utmost importance in an environment where maximum residue levels for pesticides dictate market access. / AFRIKAANSE OPSOMMING: Thaumatotibia leucotreta, die vals kodling mot (VKM) is ‘n fitosanitere pes in Suid Afrika, wat kan lei tot groot finansiele verliese. Die VKM se wye gasheerreeks en die feit dat dit al in al die sitrus verbouings-areas in Suid Afrika opgelet is, maak dit ‘n ernstige pes. Daar word van verskeie beheer metodes gebruik gemaak, insluitend chemiese en kulturele metodes. In sommige areas word daar ook van paaringsontwrigting en steriele insek vrylatings gebruik gemaak en hierdie metodes word gewoonlik met ander gekombineer. Daar is ‘n groot behoefte vir meer inligting omtrent die status van VKM in sagtevrugte in Suid Afrika en het gelei tot die vrae wat in hierdie studie aangespreuk word. Die eerste doelwit was om te bepaal of die VKM wel diapouse ondergaan. Dit sal verskeie beheermetodes belemmer, maar kennis hiervan kan meer gefokusde en gevolglik meer effektiewe beheermaatreels tot gevolg hê. Daar is gekyk na vier fisiologiese eienskappe wat beduidend tot diapouse van ander Lepidoptera spesies is. Daar word verwag dat VKM wat diapouse ondervind ‘n hoër vetinhoud sal he, terwyl die metabolise tempo, “supercooling’ punte en tempo van waterverlies laer sal wees. Hierdie eienskappe kon egter nie by die individue geidentifiseer word nie. Ons het diapouse probeer induseer deur gebruik te maak van ‘n gesimuleerde oorgang na winterstoestande in die laboratorium. Die toestande het toegelaat vir korter dae en laer gemiddelde temperature gedurende beide die dag en nag. Die tweede doelwit waarna gekyk is, is die bepaling van VKM se beweging in die boorde en die vrugskade op verskillende vrugsoorte. Daar kon ‘n duidelike tendens geidentifiseer word in die toename van VKM hervangs by temperature bo ‘n minimum van 16°C en gemiddelde maksimum bo 30°C. Daar was 6 vrylatings periodes, met geen betekenisvolle getalle van hervangs nie. Daar was geen betekenisvolle verskille tussen die hervangsgetalle in die verskillende vrugsoorte nie, alhoewel die 30m lokval ‘n betekenisvol hoër gemiddelde hervangs gehad het, in vergelyking met lokvalle by 60m en 90m. Die hoeveelheid vrugskade is ook gemonitor op Granny smith appels, Forelle pere, Larry Ann pruime en Satsuma en Clementine sitrus kultivars. Die vrugte is na die laboratorium geneem waar die VKM tyd gegee is om uit te broei. Al die vrugsoorte het VKM volwassenes opgelewer, maar die eksperiment kon nie op appels in die laboratorium herhaal word tydens die toets van verkillende onwikkeling stadiums nie. Ons glo dus die VKM wat hier vanaf appels uitgebroei het, is weens sekondere infeksies in die boorde. Die hoogste skadetelling is in die sitrusboord gevind. Die derde doelwit was om die duur van onderskeie ontwikkeling stadiums te bepaal op vier vrugsoorte, sowel as op ‘n kunsmatige medium. Ons het ondervind dat die VKM nie Royal Gala of Pink lady kultivars kan infesteer onder laboratorium toestande nie. Die vrugsoorte wat dus ontwikkeling kon onderhou was Forelle pere, Clementines en Thompson pitlose druiwe. Die ontwikkeling vanaf eier na volwasse stadium was die kortste op druiwe, gevolg deur lemoene en pere. Die pere het die minste VKM onderhou in vergelyking met die lemoene en druiwe. Al die vrugte is binnegedring naby die aansluiting van die stingel aan die vrugte, behalwe die pere wat nader aan die kelk binnegedring is. Toekomstige navorsing sal gefokus moet word op die lewenssiklus in die veld, vir die verskillende vrugsoorte. Daar sal ook gekyk moet word na die spesifieke alternatiewe gashere of plekke waar die VKM kan oorwinter sodat beheer meer voorkomend plaas kan vind. Dit sal infestasie vlakke onderdruk, om veral laer druk tydens oesperiodes te verseker. Dit is uiters belangrik om beheer stategieë te kombineer met die hoeveelheid druk vanaf uitvoermarkte oor maksimum residu vlakke van chemiese middels.

Thesis (MScAgric (Conservation Ecology and Entomology))--Stellenbosch University, 2008. / Codling moth (CM), Cydia pomonella (Linnaeus) (Lepidoptera: Tortricidae), is the major pest of apples and pears in the South Western Cape, South Africa. Apart from conventional insecticide sprays, area-wide biologically intensive control methods, such as Sterile Insect Technique (SIT) and pheromone mediated mating disruption (MD) are currently in use on two farms in the Elgin valley. The indigenous parasitoid Trichogrammatoidea lutea Girault (Hymentoptera: Trichogrammatidae) attacks eggs of false codling moth (FCM), Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae), as well as CM and has been found to have considerable parasitism potential on both. Elevated host egg numbers, as achieved by SIT are thought to support establishment of populations of these natural enemies in the orchards. For rapid and secure Trichogrammatoidea species identification, the ITS2 sequences of Trichogrammatoidea lutea and T. cryptophlebiae Nagaraja (an indigenous FCM parasitoid on citrus) were determined and species specific primers were developed. Lifetable studies of T. lutea indicated an optimal temperature for reproduction at around 20 °C. Food was provided by the application of honey-solution soaked cotton wool, behind fine netting. The effect of food provision by this method was found to be dependent on temperature. The acceptance of CM eggs from sterilized vs. fertile parents and of radiation-sterilized eggs vs. fertile ones was assessed in choice trials. While no difference was observed between radiated and fertile eggs, sterile eggs from irradiated parents were significantly less attractive than eggs from fertile parents. In several field studies the dispersal capacity and population sustainability of released T. lutea were investigated. Trials took place in apple and pear orchards in the Elgin valley that formed part of an area-wide sterile CM SIT program. Most of the wasp releases were carried out within blocks of up to 1 ha. A square grid of up to 36 monitoring trees per block allowed spatial distribution analysis. Following single central point releases, parasitism of sentinel eggs was recorded until the end of all experiments, the longest of which lasted 37 weeks. T. lutea females were found to disperse up to 73 m, within one week. Studies concerning toxicity of four commonly used insecticides and one fungicide to immature and adult T. lutea indicated no to low susceptibility of wasps at egg- to first-instar-stage within host eggs. Contact toxicity of the tested materials to adults differed significantly, depending on the compound. All five pesticides caused significantly higher mortality among adults relative to the control. The overall aim of above studies was to determine the potential of T. lutea for broad-scale releases against CM, within a broader integrated pest management program in apple and pear orchards in the Western Cape.

Thesis (MScAgric (Conservation Ecology and Entomology))--Stellenbosch University, 2008. / The codling moth, Cydia pomonella (L.), is a key pest in pome fruit orchards in South Africa. In the past, broad spectrum insecticides were predominantly used for the local control of this moth in orchards. Concerns over human safety, environmental impact, widespread dispersal of resistant populations of codling moth and sustainability of synthetic pesticide use have necessitated the development and use of alternative pest management technologies, products and programmes, such as the use of entomopathogenic nematodes (EPNs) for the control of codling moth. Entomopathogenic nematodes belonging to either Steinernematidae or Heterorhabditidae are ideal candidates for incorporation into the integrated pest management programme currently being developed for pome fruit orchards throughout South Africa with the ultimate aim of producing residuefree fruit. However, these lethal pathogens of insects are not exempted from governmental registration requirements and have therefore not yet been commercialized in South Africa. A nontarget survey was conducted to find suitable isolates of EPNs from local soils and to test their effectiveness as control agents against the codling moth. Soil samples were collected from several habitats and regions throughout South Africa and nematodes were recovered using the insect baiting technique. All EPN isolates obtained were identified to species level using a molecular taxonomic approach. Entomopathogenic nematodes were recovered from 20 of the 200 soil samples (10 %). Of these, eight (40 %) yielded Steinernema spp., identified as three isolates of S. khoisanae and five undescribed Steinernema spp. The other 12 (60 %) of the samples were positive for Heterorhabditis spp. and included six isolates of H. bacteriophora, five H. zealandica and one H. safricana. These isolates were then evaluated in laboratory bioassays for their potential as microbial agents of codling moth under varying conditions. A morphometric study indicated that all natural openings (mouth, anus and spiracles) of final instar codling moth were large enough for the infective juveniles (IJs) of all tested EPN species to gain entry into the larvae.

Thesis (MSc (Agric) (Conservation Ecology and Entomology))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: Ambient temperature plays a key role in insect-physiology, -population dynamics and ultimately -geographic distribution. Here, I investigate the survival of codling moth, Cydia pomonella (Linnaues) (Lepidoptera: Tortricidae), which is a pest of economic importance in pome fruit production, to a wide range of temperature treatments. In this thesis, I first explore how temperature affects the survival and limits to activity of codling moth and secondly investigate if thermal acclimation can improve field performance of moths used in sterile insect technique control programmes under ecologically relevant conditions. First, I found that absolute temperature as well as the duration of temperature exposure significantly affects adult C. pomonella survival. Lethal temperatures, explored between -20 °C to -5 °C and 32 °C to 47 °C over a range of durations, showed that 50% of the adult C. pomonella population killed at -12 °C and at 44 °C after 2 hrs for each treatment. At high temperatures a pretreatment at 37 °C for 1 hr dramatically improved survival at 43 °C for 2 hrs from 20% to 90% (p<0.0001). Furthermore, high temperature pre-treatments (37 °C for 1 hr) significantly improved low temperature survival at -9 °C for 2 hrs. In sum, my results suggest pronounced plasticity of acute high temperature tolerance in adult C. pomonella, but limited acute low temperature responses. Secondly, low-temperature acclimated laboratory-reared moths were recaptured in significantly higher numbers (d.f. = 2, χ2 = 53.13 p<0.001), by sex pheromone traps, under cooler conditions in the wild relative to warm-acclimated or non-acclimated moths. However, these improvements in low temperature performance in cold-acclimated moths came at a cost to performance under warmer conditions in the wild. This novel study demonstrates the importance of thermal history on C. pomonella survival and clear costs and benefits of thermal acclimation on field and laboratory performance, and thus, the potential utility of thermal pre-treatments for improved efficacy in the sterile insect technique programme for C. pomonella control under cooler, springtime conditions. Finally, on a global scale, this study highlights that low and high temperatures could play a role in CM adult survival through direct mortality and thus, may influence, or have influenced in the pest, population dynamics. / AFRIKAANSE OPSOMMING: Temperatuur speel ‘n belangrike rol in die fisiologie, populasiedinamika en geografiese verspreiding van insekte. In hierdie tesis ondersoek ek die rol van ‘n wye reeks temperature op die oorlewing van kodlingmot Cydia pomonella (Linnaues) (Lepidoptera: Tortricidae), ‘n sagtevrug pes-spesie van ekonomiese belang. Ek ondersoek hoofsaaklik die effek van temperatuur op die fisiologie en fiksheid van kodlingmot, asook die mate waartoe termiese akklimasie (‘n mate van aanpassing) die veldgedrag van die steriele insek beheer-metode (SIT), d.m.v. kodlingot, in relevante omgewingstemperature kan verbeter. Ek het (i) gevind dat die temperatuur en duur van die temperatuur toediening ‘n betekenisvolle toename in volwasse C. pomonella oorlewing tot gevolg het. In die deel van die studie is temperature tussen -20 °C en -5 °C and tussen 32 °C en 47 °C ondersoek oor ‘n reeks van 0.5, 1, 2, 3 en 4 ure van duur. In kort lei -12 °C en 44 °C vir 2 uur onderskeidelik tot die uitsterf van 50% van die volwasse C. pomonella populasie. Indien die motte vooraf gehou is by 37 °C vir ongeveer 1 uur, is oorlewing by 43 °C vir 2 ure betekenisvol verbeter van 20% tot 90% (p<0.0001). Hoër temperatuur vooraf-blootstellings (akklimasie), by 37 °C vir 1 uur, het daartoe gelei dat lae temperatuur lae-temperatuur-oorlewings by -9 °C vir 2 ure betekenisvol verbeter het. Oor die algemeen het die resultate gedui dat hoër akute temperatuurstoleransie in C. pomonella bestaan, maar beperkte akute lae-temperatuur reaksies bestaan. Verder het lae-temperatuur akklimasie (laboratorium geteelde) motte ‘n betekenisvolle hoër getal hervangste deur geslagsferomone in koeler omgewings opgelewer (v.i. = 2, χ2 = 53.13, p<0.001) in vergelyking met warmer-temperatuur geakklimatiseerder motte. Hierdie verbeteringe in laetemperatuur reaksies vanaf lea-temperatuur akklimasie groepe is teen ‘n koste teen warmer reaksie-toestande in die natuur geïs. Hierdie eersdaagse studie demonstreer die belang van historiese temperatuur op die oorlewing van C. pomonella. Die kostes- en voordele van termiese akklimasie op veld- en laboratoriumpopulasie reaksies en die potensiële gebruik daarvan in die verbetering van steriele insek tegniek programme, onder koeler omstandighede, is uitgelig. Laastens, beklemtoon hierdie studie die belangrikheid van temperatuur as bepalende faktor van kodlingmot-oorlewing en die invloed daarvan op die vrugte-pes populasiedinamika.