Oregano oil (Lippia berlandieri) from different origins for the control of Sitophilus zeamais Motschulsky and its impact on quality of stored maize seed

Abstract

In Mexico, synthetic chemical pesticides are usually used to reduce post harvest losses in maize storage, which often lead to issues of pathogens resistance and environmental pollution. Thus, alternatives are needed for the conservation of grains and seeds in storage. In the present study the insecticidal effect of five oregano oils (Lippia berlandieri) of plants collected in Durango, Chihuahua and Coahuila in northeastern Mexico was evaluated to control the maize weevil (Sitophilus zeamais Motschulsky) in stored maize seed, as well as its effect in the physiological quality of the seed. A split plot design was used, the data were analyzed using the SAS statistical package (2007) and the mean comparison was performed using LSD < test (p 0.05). The essential carvacrol oil of Salaices, Chihuahua and Durango’s oregano oil caused a cumulative mortality of 100 % in the first sampling; while in the second one, the Chihuahua oregano oil reached a mortality rate of 98.33 %. The Durango and Chihuahua oils had the highest mortality with 100 and 98.66 % in the third sampling. Most insect mortality was achieved with the application of oregano oil to 250 and 300 ppm. In the physiological quality of the seed, all the treatments except carvacrol of Salaices Chihuahua, allowed a greater than 90 % germination, an average length greater than 9 cm of plumule and an average length of radicle up to 13 cm.