The clearwing moth, Monopetalotaxis candescens, is a major root-boring pest of cultivated ‘rooibos’, Aspalathus linearis, in South Africa. Neonates penetrate the tap root at the base of the stem within a few hours of hatching, presenting a brief window for control of an otherwise highly cryptic pest. Several systemic and contact/stomach insecticides as well as the entomopathogenic fungus, Nomuraea rileyi, were evaluated from 2005–2012 on 6–8-month-old plantations of A. linearis. A strategy based on prophylactic applications of a contact/stomach insecticide (active ingredient: Esfenvalerate) during early to midNovember resulted in > 97 % control. This level of control was realized following delivery of 10 ml aliquots of a 0.4 % concentration of the chemical to the stem-base of individual plants. Attempts at biological suppression of M. candescens with N. rileyi proved unsuccessful. Commercial-scale application of the chemical was possible through the development of an automated measured-dose applicator (vehicle-mounted) consisting of multiple nozzle-lines carried/directed individually by operators. The stem-directed application strategy developed here implies reduced chances of the chemical coming into contact with leaves (and twigs) to be harvested early in the following year, minimum environmental pollution and/or little to no impact on beneficial insects residing on the plant.
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1 September 2013
Control of the Clearwing Moth, Monopetalotaxis candescens (Lepidoptera: Sesiidae), on Cultivated ‘Rooibos’, Aspalathus linearis (Fabaceae), in South Africa
J.L. Hatting,
J. Brand,
N.M. Thiebaut
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African Entomology
Vol. 21 • No. 2
September 2013
Vol. 21 • No. 2
September 2013
agricultural insect pests
clearwing borer
control
red bush tea