Browsing by Author "Grove, T."

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    Field evaluation of insecticides for the control of citrus thrips Scirtothrips aurantii (Thysanoptera: Thripidae), on mango
    (2000) Grove, T.; Giliomee, J. H.; Pringle, K. L.
    The South African citrus thrips, Scirtothrips aurantli, also infests mango (Mangifera indica), causing lesions and rendering the fruit unsuitable lor export. Several insecticides were evaluated in the field for the control of S. aurantiion mango fruit in the Mpumalanga Province of South Africa. The inseC1icides tested were formetanate, lormetanate + sugar, tartar emetic + sugar, methamidophos, sulphur, phenthoate, cypermethrin, fipronil, lenthion, isofenphos, prothiolos and an extract 01 syringa (Melia azedarach), A non-toxic, garlic-based insect repellent and feeding depressant was also evaluated. Best control was obtained with formetanate and lipronil. The garlic-based substance showed potential, but not the syringa extract.
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    A sampling system for estimating population levels of the citrus thrips, Scirtothrips aurantii Faure (Thysanoptera: Thripidae) in mango orchards
    (2000) Grove, T.; Pringle, K. L.
    Data were collected over a two-year period at four localities in Mpumalanga Province, South Africa, to formulate a sampling technique for monitoring population levels of the citrus thrips, Scirtothrips aurantii Faure, in mango orchards. Using a two-stage sampling system for determining population levels, the optimum combination of the number of trees per orchard (primary units) and fruit per tree (secondary units), was estimated. Taylor's power law regression of log(S2) on 10g(X. . ) provided a good fit for both the within-tree (r-2 = 0.887) and between-tree (r-2 0.746) data. The value for the aggregation coefficient, b, in both cases was>1, indicating a dumped distribution. Sampling precision, D, improved with increasing average numbers of S. aurantii pedruit. ln addition, keeping the total number of fruit examined constant, sampling precision at low population levels improved by increasing the number of trees sampled and decreasing the number of fruit examined per tree. Examining 50 fruit per orchard should be sufficient for obtaining suitably accurate population estimates for pest management purposes.
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    Treatment levels for citrus thrips, Scirtothrips aurantii (Thysanoptera: Thripidae), in mango orchards
    (2000) Grove, T.; Giliomee, J. H.; Pringle, K. L.
    ENGLISH ABSTRACT: Field work was carried out at three different sites in the Mpumalanga Province of South Africa to determine the correlation between the numbers of citrus thrips, Scirtothrlps aurantii, and the damage caused on mango. Adults of S. aurantiiwere monitored weekly by means of yellow sticky traps, while fruit was inspected visually and the number of adults and larvae recorded. Percentage fruit unacceptable lor export was determined at harvesting. Cumulative insect-days computed for S. aurantii on the traps and fruit were correlated with the percentage fruit showing lesions exceeding the level acceptable for export. The relationship between the number of S. aurantiion traps (cumulative insect-days) and the percentage fruit culled was described by Y 0 + 0.OO2X, while the number on fruit was described by Y = 0 + 0.21 Ox. To maintain the percentage culled fruit at a 5 % or lower level, producers should implement chemical intervention when the number of S. aurantii exceeds 2326 cumulative insect-days on traps, or 24 days on fruit.