Browsing by Author "Mgocheki, N."
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- ItemEffect of contact pesticides on vine mealybug parasitoids, Anagyrus sp. near pseudococci (Girault) and Coccidoxenoides perminutus (Timberlake) (Hymenoptera: Encyrtidae)(SASEV, 2009-08) Mgocheki, N.; Addison, PiaAnagyrus species near pseudococci (Girault) and Coccidoxenoides perminutus (Timberlake) (Hymenoptera: Encyrtidae) are well-known mealybug parasitoids. Both are proven biological control agents of Planococcus ficus (Signoret) (Hemiptera: Pseudococcidae) in vineyards. These parasitoids are affected by some pesticides used for the control of ants (Hymenoptera: Formicidae) and P. ficus in vineyards. To establish which of the vineyard pesticides is more toxic to parasitoids, pesticide bioassays were carried in the laboratory using adult and pupal parasitoids. Fipronil and α-cypermethrin caused significant acute toxicity of both parasitoids. Low mortality was recorded for all these pesticides for parasitoids emerging from mummies indicating that the mummy case was an effective barrier to pesticides for parasitoids. Buprofezin, mancozeb and an insecticidal soap were not toxic to parasitoids in both bioassays. Some pesticides have far-reaching negative impacts on parasitoids of orchard and vineyard arthropod pests. A refinement on pest management strategies regarding method and timing of application of pesticides where parasitoids constitute part of the pest management program is essential.
- ItemThe sublethal effects of a systemic insecticide on the vine mealybug parasitoids anagyrus sp. near pseudococci (girault) and coccidoxenoides perminutus (timberlake) (hymenoptera : encyrtidae)(South African Society for Enology and Viticulture, 2015-12) Mgocheki, N.; Addison, PiaImidacloprid is a systemic insecticide used for the control of the vine mealybug Planococcus ficus. However, biological control of P. ficus is the primary alternate management method recommended for the integrated control of this pest. We therefore aimed to establish the detrimental effects on the development of Anagyrus. sp. near pseudococci and Coccidoxenoides perminutus feeding on imidacloprid-contaminated vine mealybugs as indicated by the subsequent emergence and survival of the F generation. The results imply that A. sp. near pseudococci and C. perminutus were equally susceptible to imidacloprid, based on probit analysis. However, survival was significantly different between the control and insecticide treatment for C. perminutus (χ2 = 23.80; d.f. = 3; p < 0.001), but not for A. sp. near pseudococci (χ2 = 5.07; d.f. = 3; p = 0.17). As this study was laboratory based, the effect of imidacloprid on populations of parasitoids in the field should be assessed further. Treatment recommendations to minimise the impact on parasitoids are discussed briefly.