False codling moth (FCM), Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae) is considered the most important indigenous pest of citrus in southern Africa. Major concerns such as progressive insecticidal resistance, the negative impact of insecticides on the environment, as well as the influence of consumers opposed to chemical residues on fruit, created opportunities for biological control methods such as Sterile Insect Technology (SIT). This technology is now established in the Western and Eastern Cape provinces of South Africa as an effective, sustainable alternative to conventional FCM control methods. Due to the prevalence of the pest in all citrus producing areas of South Africa, potential for SIT to expand is enormous. Success of an SIT programme is highly dependent on efficient application of the technology to achieve its objectives in a timeous manner. The aim of this study was to advance the application of SIT for control of FCM on citrus in South Africa, by investigating the effect of certain critical stages in the process. The effect of long-distance transportation on fitness of irradiated FCM was determined, showing reduced performance with cold-immobilized transport. A significant decrease in flight ability and longevity of irradiated FCM was found, although critically, realized fecundity was not affected. The effect of two different insecticides in the pyrethroid and organophosphate chemical groups were investigated for their residual effect on mortality of released irradiated FCM, to determine if these pest control programmes could be integrated. Both chlorpyrifos and tau-fluvalinate were effective in killing irradiated FCM for a number of days after application, after which degradation of the active ingredient rendered it harmless. This effect was found to be similar for irradiated and non-irradiated males, consequently ratios of sterile : wild male FCM should be retained regardless of whether sprays are applied or not. The modes for release of sterile FCM in an SIT programme were investigated. Efficacy of ground and aerial release platforms were tested by evaluating the recovery of released irradiated male FCM in these orchards. More irradiated FCM were recovered in orchards released from the ground compared to air. However, an economic analysis of both methods shows application of irradiated insects over a large geographical area is more cost-effective by air. Depending on the terrain and size of the target area, a combination of both methods is ideal for application of SIT for control of FCM in citrus. Development of application technology for advance of the programme is discussed and recommendations for future research and development are offered.

The false codling moth (FCM), Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae), is an important pest of citrus in South Africa and challenging to manage due to its inconspicuous nature. An effective method currently being employed for the area-wide suppression of the FCM is the Sterile Insect Technique (SIT) and the effective dispersal of sterile moths is very important for success with SIT. This study was conducted in the Addo area of the Sundays River Valley (Eastern Cape) where the programme is commercially used. In this study, sterile male moths were released in different orchards on a citrus farm, and in nearby veld at different times of the year, and their dispersal was monitored through the use of pheromone traps. Various climatic factors were monitored. This provided insight into the local dispersal of sterile male FCM adults in response to abiotic cues (particularly climatic factors). The movement of the FCM in four citrus cultivars, namely lemons, navel and Valencia oranges and mandarins and in the nearby veld (open field), was determined at six different stages of the year. Results clearly indicated that sterile FCM movement is concentrated within citrus orchards, as very few moths were trapped beyond 30 m from the release point, particularly in navel and Valencia orchards. Of the climatic factors measured, minimum and maximum temperatures had the most significant influence on FCM dispersal, and based on the results, various recommendations are made for the releases of sterile FCM in an area-wide SIT management programmes on citrus. A better understanding of the dispersal capabilities of the FCM in an agricultural system, under different conditions and at different times of the year, is invaluable not only in improving release strategies in an SIT programme but in planning future control strategies against the FCM.

Thesis (PhD (Agric) (Conservation Ecology and Entomology))--University of Stellenbosch, 2006. / A study was performed to develop a generic pest monitoring system for sampling the main table grape pests in vineyards in the Hex River Valley, Western Cape Province of South Africa. The presence of phytophagous and predatory mites on cover crop plants was also investigated as this may contribute to biological control of the phytophagous mites in vines. Life table studies for Epichoristodes acerbella (Walker), an important phytosanitary pest, were conducted to determine whether or not this pest was sensitive to high temperatures. Information gained from the latter can also be used for breeding purposes in the possible future development of a sterile insect technique (SIT) programme to control this pest. The sampling system consisted of inspecting 20 plots of five vines per plot per one to two hectares. The top fork of each of the five vines per plot was examined for Planococcus ficus (Signoret) to a distance of within 30 cm of the stem, as well as the distal 15 cm of one cane per vine for the presence of P. ficus and damage caused by Phlyctinus callosus Boh. One bunch per vine was examined for insect damage or presence, and one leaf per vine for the presence of leaf infesting arthropods, such as Tetranychus urticae Koch, P. ficus and Frankliniella occidentalis (Pergande). Corrugated cardboard bands, tied around the stem of one vine per plot, were used to monitor activity of P. callosus. Blue sticky traps, at a density of four to five traps per one to two hectares, were used to monitor activity of F. occidentalis. Pheromone traps, at a density of one trap per one to two hectares, were used to monitor activity of P. ficus, E. acerbella and Helicoverpa armigera (Hübner). All the above-mentioned inspections were done at two-weekly intervals, except traps for E. acerbella and H. armigera, which were inspected weekly. In each of the rows in which the sample plots were situated, one leaf of each of the cover crop plant species was examined for the presence of phytophagous mites and their predators. The abundance and distribution of cover crop plants were determined using a co-ordinate sampling system. Cover crop sampling was done at monthly intervals. The current threshold for P. ficus is 2% stem infestation, which is reached when more than 65 males per pheromone trap are recorded. Counting mealybugs on the sticky pads in the pheromone traps is time consuming. However, the number of grid blocks on the sticky pad with males present can be counted. When P. ficus males are found in 27 blocks on the sticky pad, stem inspections should commence. Due to the spatial association between P. ficus bunch and stem infestation, stem infestation could give an indication of where bunch infestation could be expected. The use of blue sticky traps for predicting halo spot damage, caused by F. occidentalis, is not recommended. The presence of thrips on the vine leaves could not give an indication of where to expect bunch damage, since thrips on the leaves and halo spot damage were not spatially associated. A suitable sampling method for F. occidentalis still needs to be developed. The monitoring system described here can only provide information on the infestation status of the vineyard. For E. acerbella, H. armigera and P. callosus, the traps and cardboard bands could be used to identify vineyards where these pests are present and therefore, where phytosanitary problems may arise. The presence of P. callosus under the bands was spatially associated with P. callosus damage and could be used as an indicator of the latter. The presence of drosophilid flies in the bunches could not be used as an indicator of the presence of E. acerbella in the bunches. If 5% bunch damage is used as an economic threshold for E. acerbella and P. callosus, there will be a good chance of not under spraying if control measures are applied at 1% bunch damage. Epichoristodes acerbella favoured more moderate constant temperatures, with constant temperatures of 28°C and above being unfavourable for development. The economic threshold for Tetranychus urticae Koch is six mites per leaf, or if presence-absence sampling is used, 11 to 29% leaf infestation. Three important predatory mites, that kept T. urticae under control, were found in the Hex River Valley, namely Euseius addoensis (Van der Merwe & Ryke), Neoseiulus californicus (McGregor) and an undescribed phytoseiid in the genus Typhlodromus. Various cover crop plants served as hosts for T. urticae and predatory mites. The presence of these plants created suitable conditions for the survival of these mites and may have influenced their presence on the vine leaves. In the case of phytosanitary pests, both field and pack shed inspections can be used to conclude with a 99% degree of certainty that infestation levels in the pack shed will be 10% or less, since similar results for both methods were obtained. However, more than 20 plots will have to be inspected.

Thesis (MSc)--Stellenbosch University, 2000. / Full text to be digitised and attached to bibliographic record. / ENGLISH ABSTRACT: The cultivation of citrus in the Vaalharts region is a fairly recent development. With the introduction of this crop, an insect pest complex has also developed in this region. The presence of these pests was studied in eleven orchards, planted with three citrus cultivars and of varying ages, distributed in the 300 square kilometer cultivation area. Each orchard was inspected for the presence of pests by making use of two weekly sampling techniques. Ten of the most important insect pests of citrus in the Vaalharts region are briefly described by refering to their general appearance, life cycles, feeding and pest status and economic threshold. For every pest various control options, including operational systems, crop cultivation, biological and chemical control, are discussed and, where applicable, illustrated by means of graphic presentations. The seasonal presence of the cirtrus pests in the Vaalharts region is tabulated and discussed individually. With these details as background, an insect pest management programme for citrus in the Vaalharts region is compiled. / AFRIKAANSE OPSOMMING: Die verbouing van sitrus in die Vaalhartsgebied is 'n redelik onlangse ontwikkeling. Gepaard met die nuwe gewas het daar ook 'n insekplaagkompleks in die gebied ontstaan. Die voorkoms van die plae is in elt .boorde, beplant met drie sitruskultivars en van verskillende ouderdomme, verspreid in die 300 vierkante kilometer verbouingsareaal, bestudeer. Elk van die boorde is weekliks ondersoek vir die aanwesigheid van plae deur van twee moniteringstegnieke gebruik te maak. Die tien belangrikste insekplae van sitrus in die Vaalhartsgebied word kortliks beskryf deur na hulle algemene voorkoms, lewenssiklus, voeding en plaagstatus en ekonomiese drempelwaardes asook die moniteringsmetodes wat gebruik is, te verwys. Vir elke plaag word beheeropsies, wat operasionele stelsels, gewasverbouing, bloloqlese en chemiese beheer insluit, bespreek wat, waar toepaslik, aan die hand van grafiese voorstellings gemustreer word. Die seisoenale aanwesigheid van die sitrusplae word in 'n tabel aangedui en individueel bespreek. Met die gegewens as agtergrond is 'n insekplaagbestuurprogram vir sitrus in die Vaalhartsgebied opgestel.

Thesis (MTech. degree in Agriculture.)--Tshwane University of Technology, 2011. / Using the Participatory Extension Approach adopted by the Limpopo Department of Agriculture, this study documented the development, implementation and impact of a community-based rodent control strategy at Regae in Limpopo Province. The results of a homestead survey and the trapping of rodents in dwellings, home gardens and fields confirmed the severity of the rodent problem in the village, which was caused by Rattus rattus, Mus musculus, Mus minutoides, Mastomys coucha and Rhabdomys pumilio.

Please read the abstract (preface) in the section 00front of this document / Dissertation (MSc)--University of Pretoria, 2002. / Microbiology and Plant Pathology / Unrestricted

Four trap crops were tested for their ability to intercept stinkbugs (Heteroptera pentatomidae) in a cucurbit field crop at Waterpoort, Limpopo Province. The experimental trap crops were: Sunnhemp (Crotolaria juncea), okra (Abelmoschus esculentum), mustard mixture (Brassica hirta and Brassica juncea) and cowpea (Vigna unguiculata). The surveys were based on visual counts of stinkbugs from all the trap crops. Stinkbugs were collected from trap crops in a field crop trial of cantaloupe (Cucumis melo). The correlation between Brassica hirta and Brassica juncea with other trap crops had a great variance. The repeated B. hirta and B. juncea inner row experiment in 2012 interestingly lured the green stinkbug (Nezara viridula) into the cantaloupe field. Amongst the entire trap crops, stinkbugs recovered from Brassica hirta and Bassica juncea, exceeded the average of the other three trap crops. The number of adult N. viridula captured had significantly increased in March 2012 and started to drop on the B. hirta and B. juncea mixture in the first week of April. During this increase, the crops were at the seeding stage. The perimeter trap-cropping system practiced for all four trap crops varied in the attraction of stinkbugs along the perimeter of the field and inner row. B. hirta and B. juncea attracted a high number of N. viridula along the perimeter but fewer in the inner row. The B. hirta and B. juncea recorded the highest number of N. viridula in the inner rows and outer rows, compared to the other four trap crops, followed by V. ungiuculata. This study has demonstrated a significant potential of using trap crops as biological alternative for managing stinkbug pests in cucurbit crops. / Agriculture and  Animal Health / M. Sc. (Agriculture)

Four trap crops were tested for their ability to intercept stinkbugs (Heteroptera pentatomidae) in a cucurbit field crop at Waterpoort, Limpopo Province. The experimental trap crops were: Sunnhemp (Crotolaria juncea), okra (Abelmoschus esculentum), mustard mixture (Brassica hirta and Brassica juncea) and cowpea (Vigna unguiculata). The surveys were based on visual counts of stinkbugs from all the trap crops. Stinkbugs were collected from trap crops in a field crop trial of cantaloupe (Cucumis melo). The correlation between Brassica hirta and Brassica juncea with other trap crops had a great variance. The repeated B. hirta and B. juncea inner row experiment in 2012 interestingly lured the green stinkbug (Nezara viridula) into the cantaloupe field. Amongst the entire trap crops, stinkbugs recovered from Brassica hirta and Bassica juncea, exceeded the average of the other three trap crops. The number of adult N. viridula captured had significantly increased in March 2012 and started to drop on the B. hirta and B. juncea mixture in the first week of April. During this increase, the crops were at the seeding stage. The perimeter trap-cropping system practiced for all four trap crops varied in the attraction of stinkbugs along the perimeter of the field and inner row. B. hirta and B. juncea attracted a high number of N. viridula along the perimeter but fewer in the inner row. The B. hirta and B. juncea recorded the highest number of N. viridula in the inner rows and outer rows, compared to the other four trap crops, followed by V. ungiuculata. This study has demonstrated a significant potential of using trap crops as biological alternative for managing stinkbug pests in cucurbit crops. / Agriculture and  Animal Health / M. Sc. (Agriculture)

Thesis (PhD (Agric) (Conservation Ecology and Entomology))--University of Stellenbosch, 2005. / Six tortricid species are of major economic importance to the South African fruit industry. They are the codling moth Cydia pomonella, the oriental fruit moth Grapholita molesta, the false codling moth Thaumatotibia leucotreta, the macadamia nut borer T. batrachopa, the litchi moth Cryptophlebia peltastica and the carnation worm Epichoristodes acerbella. For phytosanitary purposes and to aid the management of population levels of the aforementioned species, their identities at species and population level were investigated using morphological and molecular genetic techniques. Morphological characteristics were used to distinguish and differentiate between the final instar larvae and pupae of the six species. For this purpose the morphology of the final instar larvae and pupae of the Afrotropical species T. leucotreta, T. batrachopa, Cr. peltastica and E. acerbella was described and illustrated using line drawings and scanning electron micrographs. Taxonomic characters found to be useful for the identification of the larvae were the presence and structure of the anal comb and the number and arrangement of crochets on the prolegs. The pupae could be distinguished based on the presence or absence of a distinct cremaster, the shape of the spiracle, the position of the setae on the anal rise, the structure of the mouthparts and the length of the procoxa in relation to that of the protarsus. These characters were used to develop keys to distinguish between the tortricid species occurring on tropical and subtropical fruit (T. leucotreta, T. batrachopa and Cr. peltastica) and deciduous fruit (E. acerbella, C. pomonella, G. molesta and T. leucotreta). At population level, molecular techniques were employed to compare geographic populations of each of the six species. Amplified fragment length polymorphism (AFLP) analysis with five selective primer pairs was used to investigate genetic diversity. In addition, host populations of species were compared where relevant. No evidence was found to suggest that populations from different hosts were genetically differentiated. However, geographic populations were found to be genetically distinct in each of the six species, with extensive genetic divergence apparent over local geographic scales and significantly high estimates of population differentiation ranging between Gst = 0.2625 and 0.3778. Factors influencing the genetic population structure of the six species were investigated by comparing the amount and distribution of genetic variation between oligophagous and polyphagous species as well as introduced and native species. Results indicated that host range and population history did not have a major effect on population genetic structure. It was therefore suggested that other factors such as limited dispersal were responsible for the extensive genetic divergence observed between geographic populations of each of the six tortricid species. These results should be incorporated into existing pest management programs and taken into consideration when designing new control strategies. This is the first report of its kind to identify, with a high level of accuracy, the aforementioned tortricids and the first to determine the population genetic structure of these species.

Dissertation (PhD)--University of Stellenbosch, 2003. / ENGLISH ABSTRACT: A survey was conducted in the Western Cape Province during the 1999/2000 and 2000/2001 seasons on mealybugs occurring in vineyards. P/anococcus ficus (Signoret) was the dominant mealybug in vineyards during this time. During this study P. ficus was recorded for the first time on roots of grapevines, which has far reaching implications for the control of this important vine leafroll virus vector as control actions were focused on above ground control. Other mealybugs presently recorded in local vineyards included Pseudococcus /ongispinus (Targioni) and Ferrisia ma/vastra (McDaniel). Pseudococcus viburni (Maskell) and Ps. so/ani Ferris were found on weeds in vineyards. Natural enemies of P. ficus recorded most frequently were species of Nephus predatory beetles, and the parasitaids Coccidoxenoides peregrinus (Timberlake), Anagyrus sp. and Leptomastix dacty/opii (Howard). Developmental studies on P. ficus and C. peregrinus indicated that the intrinsic rate of increase (rm) was similar, peaking at 25°C (rm = 0.169 for P. ficus; rm = 0.149 for C. peregrinus). The net replacement rate (Ra) was higher for P. ficus than for C. peregrinus at all five temperatures tested. The Ra for P. ficus reached a maximum at 21°C (308.87) and C. peregrinus at 25°C for C. peregrinus (69.94). The lower and upper thresholds for development of P. ficus were estimated at 16.59 and 35.61°C respectively. The lower threshold for development of C. peregrinus was 8.85°C. These parameters indicated that both insects were well adapted to temperatures in the Western Cape Province. The lower minimum threshold temperature of C. peregrinus in relation to that of P. ficus suggests that C. peregrinus should be more active during winter and early spring than P. ficus. A central systematic presence-absence sampling system was developed for P. ficus. Monitoring three different plant parts on the vine indicated that new growth areas on vines adjacent to the main stem could serve as an early warning system for pending P. ficus bunch infestations. Intervention should be planned when 2 % of the stems are infested with P. ficus when using this system. Seasonal population studies of P. ficus and its natural enemies showed that stem infestation by P. ficus reached peak levels during January in Robertson and Stellenbosch and during February in the Hex River Valley. Vine mealybugs colonised new growth early in the season, followed by the leaves and eventually the bunches towards the end of the season. High stem infestations early in the season resulted in high bunch infestation levels at harvest. A density dependent relationship was evident between P. ficus populations and parasitoid populations, suggesting that the parasitoids played a mayor role in the biological control of P. ficus populations. Biological control was however only achieved towards the end of the season when damage to the crop had already occurred. Mass releases of C. peregrinus on P. ficus populations were done in order to augment biological control as an alternative to chemical control. Between five and six releases of 20 000 C. peregrinus per release were done at monthly intervals in three grapegrowing areas. Mass released C. peregrinus controlled P. ficus adequately in the Hex River Valley. Control of P. ficus using this approach was no worse than using chemical control in Robertson and Stellenbosch. C. peregrinus is commercially available and can therefore be used as an alternative to chemical control by producers. Degree day estimation was used to predict development of P. ficus populations. This information was used as an input in a P. ficus pest management model. Data acquired from P. ficus and ant monitoring were used as components to construct a decision chart. This chart can be used by producers to optimise the control of P. ficus populations using either chemical control or mass releases of C. peregrinus. / AFRIKAANSE OPSOMMING: "n Studie is gedurende die 1999/2000 en 2000/2001 seisoene gedoen met die doelom die witluisspesies wat in wingerde voorkom, te identifiseer. Planococcus ficus (Signoret) is tans die dominante witluisspesie in wingerde in die Wes Kaap Provinsie. P. ficus kolonies is op wingerdwortels gevind. Dié bevinding kan verreikende gevolge hê vir die beheer van dié plaag as "n belangrike rolbladvirus vektor aangesien beheer tot dusver gefokus het op bogrondse gedeeltes. Ander witluisspesies wat in wingerde gevind is, sluit in Pseudococcus /ongispinus (Targioni) en Ferrisia malvastra (McDaniel). Pseudococcus vibumi (Maskell) en Ps. so/ani Ferris is op onkruide in wingerde gevind. Dominante natuurlike vyande van P. ficus sluit predatoriese kewertjies van verskeie Nephus spp. en die parasitoïede Coccidoxenoides peregrinus (Timberlake), Anagyrus sp. en Leptomastix dacty/opii (Howard) in. Ontwikkelingstudies op P. ficus en C. peregrinus het aangetoon dat die inhirente voortplantingstempo (rm) soortgelyk was vir beide insekte met "n maksimum by 25°C (0.169 vir P. ficus, 0.149 vir C. peregrinus). Die netto vervangingstempo (Ra) was in vergelyking met C. peregrinus hoër vir P. ficus by al vyf temperature getoets. Die Ra van P. ficus het "n maksimum bereik teen 21°C (308.87) en die van e. peregrinus by 25°C (69.94). Die teoretiese hoër en laer drempels vir ontwikkeling van P. ficus was onderskeidelik 16.59 en 35.61 oe. Die teoretiese laer drempelwaarde van ontwikkeling vir e. peregrinus was 8.85°e. Hierdie parameters dui aan dat beide insekte goed aangepas is by temperature in die Wes Kaap Provinsie. Die laer minimum drempel vir ontwikkeling van C. peregrinus in verhouding tot P. ficus impliseer dat C. peregrinus in die winter en vroeë lente meer aktief sal wees as P. ficus. 'n Sentrale sistematiese aan-afwesig moniteringsisteem met bekende vlakke van steekproefnemingsfout is ontwikkel in kommersiële wingerde vir P. ficus. Monitering van drie verskillende dele op die wingerdstok het aangedui dat die nuwe groei areas kan dien as 'n vroeë waarskuwing vir latere P. ficus trosinfestasies. Dié sisteem sal produsente in staat stelom te bepaal wanneer optrede noodsaaklik is. Daar word voorgestel dat optrede noodsaaklik is by 'n P. ficus besmettingsvlak van 2 % op die nuwe groei areas op stokke. Stambesmetting deur P. ficus het in Januarie piekvlakke bereik in Stellenbosch en Robertson, en in Februarie in die Hex Rivier Vallei. P. ficus koloniseer nuwe groei vroeg in die seisoen waarna blare en trosse aan die einde van die seisoen gekoloniseer word. Dié data dui aan dat P. ficus besmetting op nuwe groei vroeg in die seisoen 'n aanduiding kan gee van hoë trosbesmetting aan die einde van die seisoen. 'n Digtheidsafhanklike verwantskap was waarneembaar tussen P. ficus plaagpopulasies en parasitoïed populasies. Dié verwantskap dui aan dat parasitoïede die belangrikste rol speel in biologiese beheer van P. ficus populasies. Biologiese beheer van witluis is egter eers aan die einde van die seisoen bereik toe die oes reeds beskadig was. Massavrylatings van C. peregrinus is in P. ficus besmette blokke gedoen om biologiese beheer aan te help en sodoende as alternatief tot chemiese beheer te dien. Tussen vyf en ses vrylatings met 20 000 C. peregrinus is een keer per maand gedurende die seisoen gedoen. Die vrygelate C. peregrinus het P. ficus populasies voldoende beheer in die Hex Rivier Vallei. Beheer van P. ficus deur massavrylatings van C. peregrinus was soortgelyk as chemiese beheer in Robertson en Stellenbosch. C. peregrinus is kommersieel beskikbaar en kan om hierdie rede as alternatief tot chemiese beheer gebruik word. Graaddag bepaling is gebruik om die ontwikkeling van P. ficus populasies te voorspel. Hierdie inligting is gebruik as 'n verdere hulpmiddel in die P. ficus plaagbeheermodel. Inligting verkry vanuit P. ficus en mier monitering is gebruik as komponente in die opstel van 'n besluitnemingstabel. Hierdie tabel kan gebruik word deur produsente om beheer van P. ficus plaagpopulasies te optimaliseer deur chemiese beheer of massavrylatings van C. peregrinus.