Bioactive paints with volatile organic alcohols for the control of Sitophilus zeamais

Abstract

Cereals represent a large percentage of food inputs in food production, with annual losses estimated to vary between 7 and 50% due to the actions of pests. Argentina is one of the main producers and exporters of corn globally. Post-harvest pests, such as the insect Sitophilus zeamais, can cause losses of more than 10%, representing a very important negative economic impact on the industry. For pest control many synthetic insecticides are used. Nevertheless, these insecticides show toxicity to mammals and environmental contamination and cause resistance. For this, there is a constant need to introduce new substances used in the protection of crops and the plant extracts and their volatile products are an interesting alternative. In this work we evaluate the effectiveness of natural VACs for the control of S. zeamais and the prolonged effect of the more toxic alcohol incorporated in a paint on its survival. 1-heptyn-3-ol was the most toxic alcohol tested (LC₅₀ = 0.74 μL/L). In the presence of food, the fumigant toxicity of 1-heptyn-3-ol was lower (LC₅₀ = 14.73 μL/L). Also, the non-phytotoxic effect of 1-heptyn-3-ol was determined. When the 1-heptyn-3-ol was included in the polyvinyl paint, the toxic effect was prolongated in the time, causing even 80% mortality at 14th day. Regarding the repellent effect of 1-heptyn-3-ol, it was observed that this alcohol included in the bioactive paint, in the presence of food, presented a repellency similar to that determined for the pure compound, in the absence of food, and greater than the repellency determined for the pure compound in the presence of food. In conclusion, compounds such as 1-hetpyn-3-ol is a potential candidate for insecticidal formulations that allow adequate management of S. zeamais in stored grain. This study presents a preliminary design of a biopaint with insecticidal and repellent activity against the pest insect S. zeamais.