Toxic and persistent effect of oregano's essential oil against zabrotes subfasciatus (Coleoptera: Bruchidae)in stored dry beans (Article)= [Efecto tóxico y persistente del aceite esencial del orégano contra zabrotes subfasciatus (Coleoptera: Bruchidae)en frijol almacenado]

Zabrotes subfasciatus (Coleoptera: Bruchidae), is one of the most destructive species with greater abundance and distribution in stored beans Phaseolus vulgaris L., causing great economic losses in Sonora, Mexico. Control of this pest has been based mainly on the use of broad-spectrum synthetic insecticides. Their intensive application has caused insect resistance, environmental pollution and impact on human health, therefore increasing research to control it has the aim of developing safe alternatives with potential to replace synthetic insecticides, while not being harmful. We studied the toxic effect and persistence of the essential oil (EO)of Lippia palmeri (Watson)(Verbenaceae)on Zabrotes subfasciatus (Boheman)in stored beans. The EO was compared between plant leaves collected from two locations: Puerto of Oregano (POEO)and Alamos Sonora (AEO). Beans were treated with 0, 0.135, 1.35, 4.0, and 8.0 µl/g of EO and infested with Z. subfasciatus. Mortality, oviposition, insect emergence, and percentage of damaged grain were assessed for 4 months. The POEO caused greater mortality, and both EOs showed ovicidal effects that persisted for 2 months with the 1.35 µl/g dose. Moreover, lethal effects after 3 months of storage at 4 and 8 µl/g were observed, either in insect emergence or damaged grain. This seems to be caused by the persistence of the essential oils carvacrol, thymol, and p-cymene in the Lippia palmeri samples.