Effect of Temperature on Long-Term Storage of Codling Moth Granulovirus Formulations

Lawrence A. Lacey, Heather L. Headrick, Steven P. Arthurs
2008 Journal of Economic Entomology  
Codling moth, Cydia pomonella (L.), is the major pest of apple (Malus spp.) in the western United States and many other regions of the world. The codling moth granulovirus (CpGV) provides a selective and safe means of its control. We assessed the long-term stability and storage potential of two commercial formulations of CpGV, Cyd-X, and Virosoft. All assays were performed with individual C. pomonella neonate larvae in 2-ml vials on 1 ml of artiÞcial larval diet that was surface inoculated with
more » ... ace inoculated with 10 l of the test virus suspension. Baseline quantitative assays for the two formulations revealed that the LC 50 and LC 95 values (occlusion bodies per vial) did not differ signiÞcantly between the formulations. For year-long studies on Cyd-X stability, the product was stored at Ϫ20, 2, 25, and 35ЊC, and quantitative bioassays were conducted after 0, 3, 6, and 12 mo of storage. Cyd-X retained good larvicidal activity from Ϫ20 to 25ЊC, and it was the least negatively affected at the lowest temperature. Storage of Cyd-X at 35ЊC was detrimental to its larvicidal activity within 3 mo of storage. For longer term storage studies, Cyd-X and Virosoft formulations were stored at 2, 25, and 35ЊC, and assayed for larvicidal activity over a 3-yr period. For recently produced product, a 10-l sample of a 10 Ϫ5 dilution of both formulations resulted in 95Ð100% mortality in neonate larvae. Larvicidal activity for the Cyd-X formulation remained essentially unaffected for 156 wk when stored at 2 and 25ЊC, but it began to decline signiÞcantly after 20 wk of storage at 35ЊC. The Virosoft formulation stored at 2ЊC also remained active throughout the 3-yr study, but it began to decline in larvicidal activity after 144 wk at 25ЊC and 40 wk at 35ЊC. The information reported in this study should be useful to growers and commercial suppliers for avoiding decreases in CpGV potency due to improper storage conditions.
doi:10.1603/0022-0493(2008)101[288:eotols]2.0.co;2 pmid:18459390 fatcat:zzk2l474njf37kbingj6bitmy4