Evaluation of lignins and particle films as solar protectants for the granulovirus of the codling moth, Cydia pomonella

Author： Arthurs S. P. Lacey L. A. Behle R. W.

ISSN： 1360-0478

Source： Biocontrol Science and Technology, Vol.18, Iss.8, 2008-01, pp. : 829-839

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Abstract

The identification of effective solar protectants for field application of the codling moth, Cydia pomonella (L.), granulovirus (CpGV) is of interest to improve its efficacy and commercial viability as a biological pesticide. We evaluated several materials as potential adjuvants to protect CpGV from ultraviolet degradation. In laboratory tests with a solar simulator (9.36×106 J/m2), the addition of kaolin clay (Surround® WP at 3 and 6%, w/v), a paraffin wax-based emulsion (SPLAT™ at 5%, v/v), and a bark extract trans-cinnamaldehyde combined with a film agent (both at 1%, v/v) did not significantly reduce larval entries or increase larval mortality in irradiated apples that were treated with a commercial CpGV product (Cyd-X). In semi-field tests in an apple orchard, a spray-dried lignin formulation containing CpGV (6.57×1012 OBs/ha) and a lignin-based adjuvant used with Cyd-X (both applied at 4.7-5.6 kg lignin/ha) significantly improved residual activity of CpGV compared with Cyd-X alone applied at the same rate. However, the benefits were short lived and could not be detected after 7 days. In orchard tests, we evaluated two additional refined lignin-products (Lignosulfonate and Vanisperse™ CB at 5.61 kg/ha) and two particle film materials (kaolin clay, 'Cocoon™', and calcium with boron 'Eclipse™') as adjuvants for UV protection of Cyd-X (6.57×1012 OBs/ha) in tests against a dense codling moth infestation. Although all virus treatments were highly effective (causing ≥90% larval mortality), no significant effects of the adjuvant treatments could be detected. In these latter tests, the use of a silicone based wetting agent at 0.025% (v/v) may have been beneficial at increasing mortality among older larvae inside the fruit.