Determination of insecticidal activity of Heliopsis longipes A. Gray Blake, an endemic plant of Guanajuato state oleh Alejandro Hernández Morales, Jackeline Lizzeta Arvizu Gómez, Blanca Estela Gómez Luna, Enrique Ramírez Chávez, María del Rosario Abraham Juárez, Gerardo Martínez Soto, Jorge Molina Torres