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Control of the Clearwing Moth, Monopetalotaxis candescens (Lepidoptera: Sesiidae), on Cultivated ‘Rooibos’, Aspalathus linearis (Fabaceae), in South Africa

Author:
Hatting, J.L., Brand, J., Thiebaut, N.M.
Source:
African entomology 2013 v.21 no.2 pp. 294-303
ISSN:
1021-3589
Subject:
Aspalathus linearis, Nomuraea rileyi, Sesiidae, active ingredients, beneficial insects, branches, chemical concentration, entomopathogenic fungi, esfenvalerate, harvest date, hatching, leaves, moths, neonates, pests, plantations, pollution, stomach, South Africa
Abstract:
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.
Agid:
1242490