Submitted to: Journal of Invertebrate Pathology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 11/27/2001
Publication Date: 1/31/2002
Citation: TAMEZ-GUERRA, P., MCGUIRE, M.R., BEHLE, R.W., SHASHA, B.S., PINGEL, R.L. STORAGE STABILITY OF ANAGRAPHA FALCIFERA NUCLEOPOLYHEDROVIRUSES (AFMNPV)AS SPRAY-DRIED FORMULATIONS. JOURNAL OF INVERTEBRATE PATHOLOGY. 2002. v.79. p. 7-16. Interpretive Summary: A microorganism known as AfMNPV is one that has the potential to become a successful biological insecticide for control of many caterpillar pests of crops in lieu of chemical insecticides. One drawback to commercialization is the lack of development of an effective formulation with storage stability. We previously developed new dry formulations of AfMNPV that uses lignin to form microcapsules that protect the virus from degradation when applied in the field. In this experiment, we tested variations of this lignin-based formulation for storage stability. We found that adding sugar helped to improve storage stability of the virus and confirmed that dry formulations lose activity faster at higher storage temperatures. Unlike the dry formulations, the unformulated virus (in water) did not lose insecticidal activity during storage at room temperature for 12 months. This information will help to guide the development of stable formulations and improve the potential for commercialization of this and other biological insecticides. Successful development of biological insecticides will benefit growers and consumers by reducing the chemical pesticide load for production.
Technical Abstract: A multinuclear polyhedrovirus isolated from Anagrapha falcifera (AfMNPV) loses insecticidal activity when stored dry. We tested spray dried AfMNPV formulations for insecticidal activity against neonate Trichoplusia ni (Hubner) after storage for 12 months at room and refrigerated temperatures. Twelve experimental formulations made using combinations of corn flours, lignin, and sucrose compared the effect of (1) the ratio of formulation ingredients (lignin and corn flour) to virus concentration, (2) different sources of lignin, or (3) different corn flours and sugar. Overall, spray drying AfMNPV to make these formulations did not significantly reduce insecticidal activity. After 12 months' storage, refrigerated samples maintained insecticidal activity better than corresponding samples stored at room temperatures. Unformulated virus stock did not lose activity when stored at refrigerated or room temperatures. Changing the ratio of virus to formulation ingredients was less important for shelf-life of virus activity compared with formulations made with different ingredients. Formulations that contained sugar tended to maintain activity during storage better than formulations without sugar. We believe that stability of AfMNPV insecticidal activity during storage as dry formulations is related to the general composition of the formulation and that sugar may play help to maintain insecticidal activity.