Submitted to: Biocontrol Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/16/2008
Publication Date: 9/26/2008
Citation: Arthurs, S., Lacey, L.A., Behle, R.W. 2008. Evaluation of Lignins and Particle Films as Solar Protectants for the Granulovirus of the Codling Moth, Cydia pomonella. Biocontrol Science and Technology. 18:829-839. Interpretive Summary: Codling moth is the most serious insect pest of apple in the Pacific Northwest. The granulovirus of the codling moth (CpGV) has recently been registered as a microbial (environmentally safe) pesticide and is used by orchardists in this region to selectively control codling moth larvae. However, current commercial formulations have a short residual activity because the activity of the virus is reduced through sunlight (ultraviolet) exposure. This limitation means the virus often requires frequent reapplication during the growing season, thus increasing costs. In 2006 and 2007, researchers at the USDA-ARS Laboratories in Wapato, WA and Peoria, IL evaluated several additives (lignin and particle films) for improved ultraviolet protection of CpGV. Results showed that the new formulation provided significant protection and extended the residual activity of the virus exposed to ultraviolet radiation when applied at relatively high dosages. These results will improve the effectiveness of the virus for orchardists in the Pacific Northwest and elsewhere.
Technical Abstract: The identification of effective adjuvants for field application of the codling moth, Cydia pomonella L., granulovirus (CpGV) is of interest to improve the commercial viability and utility of this biological pesticide. We evaluated several materials as potential adjuvants to protect CpGV from ultra-violet degradation. In laboratory tests with a solar simulator (9.36 × 106 joules/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.