Use of novel film forming starch complexes to directly and indirectly reduce insect damage to plants

Authors: Hay, William; Behle, Robert; RUIZ-VERA, URSULA - University Of Illinois; Fanta, George; Selling, Gordon

Submitted to: Crop Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/8/2019
Publication Date: 4/8/2020
Citation: Hay, W.T., Behle, R.W., Ruiz-Vera, U.M., Fanta, G.F., Selling, G.W. 2020. Use of novel film forming starch complexes to directly and indirectly reduce insect damage to plants. Crop Protection. 130:105048. https://doi.org/10.1016/j.cropro.2019.105048.
DOI: https://doi.org/10.1016/j.cropro.2019.105048

Interpretive Summary: We have developed a modified starch formulation which protects plants from insect damage and resists rain wash-off allowing for long lasting protection. This treatment not only improves the performance of commercially available crop protectants but does not harm the plant nor reduce yields. The modified starch is made from corn starch and a vegetable oil (ex. corn or soybean) derivative which are processed using steam. The modified starch can be combined with natural biocontrol agents (such as a virus) and when applied to leaves it remains attached to the surface and resists being washed off by rain. These viruses target a specific insect pest and by being resistant to rain wash-off, the formulation provides extended crop protection without hurting the plant or other beneficial insects. The modified starch treatment also toughens the surface of the leaf making it difficult for insect pests, which may not be the target of the virus, to consume the otherwise vulnerable leaves. The starch complexes are produced from low cost biobased materials, and the technology can be rapidly adopted for industrial scale production. The technology will be useful to all producers and consumers in the corn and soybean value chain.

Technical Abstract: Formulations of amylose complexes produced from fatty acid and fatty ammonium salts blended with polyvinyl alcohol (PVOH) provide significant rainfastness for the biocontrol baculovirus, AfMNPV. Blends of the amylose complexes and PVOH were significantly more water resistant then either of their constitutive components, and adhered strongly to treated leaves. The amylose complex/PVOH treatments had no impact on soybean photosynthesis or yield in replicated field trials. The AfMNPV baculovirus was incorporated into the amylose complex formulations to determine efficacy against Trichoplusia ni (Hübner) (cabbage looper) on spray treated soybean exposed to a simulated 5 cm rain event. After the simulated rain event, soybean treated with the amylose sodium palmitate (Na-Palm)/PVOH (1:1) treatment displayed a significantly greater, 94.5%, of the original virus activity remaining as compared with the virus only control treatment, 52.4%. The film coatings of amylose-hexadecylammonium chloride complex (Hex-Am) alone inhibited the growth and development of T. ni, but only the formulation of the Hex-Am/PVOH was observed to cause insect mortality. Increasing film thickness results in increased T. ni mortality and developmental delay. Neither the PVOH nor Na-Palm/PVOH (1:1) film treatments alone were observed to have any negative effect on T. ni growth and development. These investigations demonstrate the potential of a new novel modified starch complex formulation to improve the rainfastness of biocontrol agents on soybean foliar tissue.