Ken L. Pringle

Germination, radial growth, and sporulation of Beauveria bassiana and Metarhizium anisopliae isolates and their virulence to Chilo partellus (Lepidoptera : Pyralidae) at different temperatures

The effect of temperature regimes on conidia germination, radial growth and virulence of Beauveriabassiana and Metarhizium anisopliae against the spotted stalk borer Chilo partellus was investigated with Ethiopian isolates. Conidia germination, radial growth and sporulation of all isolates were retarded at 15 and 35°C. A suitable temperature range for the isolates was between 20 to 30°C. Conidia germination was less tolerant of low temperature (15°C) than radial growth. Radial growth and sporulation reacted differently to temperature. At both 25 and 30°C, all isolates induced 100% mortality to C. partellus larvae in six days. The LT50 decreased for the isolates with increasing temperature.

Seasonal occurrence of vine pests in commercially treated vineyards in the Hex River Valley in the Western Cape Province, South Africa

The population fluctuations of arthropods attacking table grapes were studied in 12 commercially treated vineyards in the Hex River Valley in South Africa for three years. Sampling was conducted by inspecting different plant parts and using a variety of traps. Planococcus ficus (Signoret) males in the pheromone traps started increasing during December, to reach a peak at the end of February. Cordon infestation preceded bunch infestation by three to five months, the latter occurring from about January or February. Thrips, mainly Frankliniella occidentalis (Pergande), caught on blue sticky traps were active during spring and early summer. Damage to the berries occurred about four weeks after thrips were recorded on the sticky traps. Phlyctinus callosus Boh. was recorded under fluted cardboard bands tied around the stems of vines from early October, with the first bunch damage recorded towards the end of October. More Epichoristodes acerbella (Walker) moths were caught in pheromone traps during the cool winter months than during the hotter summer months. Damage to the bunches started during November and declined during January and February, only to increase again towards the end of February and March. Although Helicoverpa armigera (Hübner) moths were caught in pheromone traps, no damage ascribed to this insect was recorded. The only phytophagous mite was Tetranychus urticae Koch, which was active throughout the fruiting season. The most common predatory mite was Euseius addoensis (Van der Merwe & Reyke).

Evaluation of Beauveria bassiana and Metarhizium anisopliae for Controlling Chilo partellus (Lepidoptera: Crambidae) in Maize

Maize (variety Katumani) was planted in a greenhouse and plants were infested with 20 Chilo partellus second instar larvae 3 and 4 weeks after plant emergence. One isolate of Beauveria bassiana (BB-01) and four isolates of Metarhizium anisopliae (PPRC-4, PPRC-19, PPRC-61 and EE-01) were sprayed onto the leaf whorl at 2×108 conidia/mL 24 h after infestation. Leaf damage by the larvae was greatly reduced by the treatments. The mean daily temperature and relative humidity in the greenhouse ranged from 10 to 35°C and 30 to 90%, respectively. The growth of infested unsprayed plants was less than that of fungi treated plants. Stem tunneling (1-5%), deadheart (0-33%), number of attacked nodes (0.3-2.5) and holes (0.2-3.3) were also reduced in plants sprayed with conidial suspensions. Isolates PPRC-4, PPRC-19 and PPRC-61 seemed to be the best candidates for further development.

Efficacy of soil-applied and seed dressing insecticides for the control of false wireworms, Somaticus species (Coleoptera: Tenebrionidae), in maize

Abstract Larvae of Somaticus g. geniculatus were placed in pots with maize seedlings (Zea mays) where the soil was treated at planting with aldicarb, carbofuran, cloethocarb or terbufos granules, and where the seed was treated with thiodicarb or furathiocarb. Seeds treated with furathiocarb were planted at different depths. There was a positive linear relationship between damaged plants and planting depth, shallow-planted seeds giving the best results. No other treatment reduced the number of pots with damaged plants as significantly as shallow-planted seeds treated with furathiocarb. There was also an indication that furathiocarb may have a repellent action.

The presence of Tetranychus urticae (Acari: Tetranychidae) and its predators on plants in the ground cover in commercially treated vineyards

The presence of Tetranychus urticae and its predators on plants in the ground cover in commercially treated vineyards in the Hex River Valley, Western Cape Province, South Africa was investigated. Six Barlinka and six Dauphine vineyards were surveyed. Leaf samples from the plants on the vineyard floor were taken at monthly intervals and microscopically examined for spider mites and their predators. The coverage of the plants was determined using a co-ordinate sampling system. A wide variety of plant species was found on the vineyard floor. Most of the spider mites found on these plants were T. urticae. The phytoseiid mites on the plants were Euseius rubicolus, Neoseiulus californicus and an undescribed Typhlodromus species. The presence of these plants made it possible for T. urticae and phytoseiid mites to occur throughout the year, with a similar pattern in their seasonal activity on the vineyard floor and the vine leaves.

Phytosanitary host status of apples as a host for false codling moth, Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae) : short communication

Recent publications suggest that apples, Malus domestica Borkh., and pears Pyrus communis L., are hosts for false codling moth (FCM), Thaumatotibia leucotreta (Meyrick) (Timm 2005; Timm et al. 2007; Timm et al. 2010). In these publications Blomefield (1989) and Newton (1998) are cited. However, these last two authors did not actually mention apples or pears as hosts for T. leucotreta. This error has also been alluded to in a recent T. leucotreta pest risk analysis (EPPO 2013). In addition, a personal communication with A.E. Timm(a.timm@ru.ac.za) confirmed that she had only caught T. leucotreta in pheromone traps in apple and pear orchards, and had not obtained material directly from infested fruit.

Developing a generic sampling system for monitoring the key arthropod pests of table grapes, Vitis vinifera L.

We describe a system developed for monitoring arthropod pests of table grapes in the Hex River Valley, South Africa. The system has wide applicability for monitoring pests at grape-producing localities in the country. Six Vitis vinifera cv. Barlinka and six V. vinifera cv. Dauphine vineyards were used as sampling sites. In each vineyard, 100 vines were inspected bi-weekly, to record damage or the presence of arthropod pests on the cordon, one bunch and one leaf per vine. Sampling precision and operating characteristic (OC) curves were estimated for each of the pests. Using previously determined economic thresholds together with the OC curves, action thresholds were determined for Tetranychus urticae Koch (Prostigmata: Tetranychidae) (11–29% leaf infestation), Planococcus ficus (Signoret) (Hemiptera: Pseudococcidae) (2% cordon infestation), Epichoristodes acerbella (Walker) (Lepidoptera: Tortricidae) and Phlyctinus callosus Boh. (Coleoptera: Curculionidae) (1% bunch damage). This novel system can be used for monitoring arthropod pest population levels in all types of South African vineyards, providing a basis for the development of integrated pest management (IPM) systems in these vineyards.We describe a system developed for monitoring arthropod pests of table grapes in the Hex River Valley, South Africa. The system has wide applicability for monitoring pests at grape-producing localities in the country. Six Vitis vinifera cv. Barlinka and six V. vinifera cv. Dauphine vineyards were used as sampling sites. In each vineyard, 100 vines were inspected bi-weekly, to record damage or the presence of arthropod pests on the cordon, one bunch and one leaf per vine. Sampling precision and operating characteristic (OC) curves were estimated for each of the pests. Using previously determined economic thresholds together with the OC curves, action thresholds were determined for Tetranychus urticae Koch (Prostigmata: Tetranychidae) (11–29% leaf infestation), Planococcus ficus (Signoret) (Hemiptera: Pseudococcidae) (2% cordon infestation), Epichoristodes acerbella (Walker) (Lepidoptera: Tortricidae) and Phlyctinus callosus Boh. (Coleoptera: Curculionidae) (1% bunch damage). This novel system can be used f...

Effect of Genetically Modified Bt Maize in an Artificial Diet on the Survival of Cydia pomonella (Lepidoptera: Tortricidae)

Abstract Genetically modified maize contains an insecticidal gene from the soil bacterium Bacillus thuringiensis (Bt), which is an important component in integrated pest management strategies against lepidopteran pests of maize. A project is being implemented in the Western Cape of South Africa against the codling moth, Cydia pomonella (L.) (Lepidoptera: Tortricidae), a pome fruit pest, using an area-wide integrated pest management approach with a sterile insect technique component. The project requires rearing of large numbers of the target pest for which an artificial diet that contains maize meal as the main ingredient is used. Most of the maize produced in South Africa is Bt maize, which is known to be toxic to codling moth. The aim of this study was to assess the impact of Bt maize in the diet of codling moth on its production parameters. Codling moths were reared for a period of 44 d on artificial diets that contained 5 different concentrations of Bt maize meal and a control using non-Bt maize. The use of Bt maize in the larval diet resulted in larval mortality, delayed larval development and larvae leaving the diet prematurely. Delayed larval development seemed to be the response with most negative consequences. Since optimal rearing of codling moth is not feasible using meal from genetically modified maize with insecticidal properties, another nutritious meal lacking an insecticidal component must be substituted in the artificial diet.