Cebos feromonales para la captura de Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae) en cultivos de maíz adyacentes a cultivos de fresas

El gusano cogollero, Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae), es una de las principales plagas del maíz y el sorgo, además de que este insecto empieza a ser una amenaza para el cultivo de fresa en Michoacán, México. Debido al daño que puede causar este insecto, es necesario contar con un sistema de monitoreo de sus poblaciones para detectar infestaciones tempranas e implementar su control a tiempo. Bajo este escenario, el uso de trampas cebadas con feromona sexual puede ser útil para atraer a los machos. En este estudio, se comparó la efectividad de una feromona desarrollada a partir de poblaciones mexicanas de S. frugiperda contra cuatro formulaciones comerciales, tres formuladas en el extranjero y una en México, en cultivos de maíz adyacentes a cultivos de fresas. También, se evaluó el efecto del color de la trampa en las capturas de S. frugiperda, usando uno de los cebos que presentó mayores capturas. Las trampas cebadas con cebo optimizado para poblaciones mexicanas (EcoTap) y con el cebo comercial formulado en el país (Phero-SF) fueron las que capturaron más machos de S. frugiperda y menos insectos no blancos, comparado con las trampas cebadas con los otros cebos. Uno de los hallazgos inesperados fue la captura de machos del gusano cortador, Agrotis ipsilon (Hufnagel) (Lepidoptera: Noctuidae), por las trampas cebadas con EcoTap o Phero-SF. El color de la trampa no fue una variable significativa para la captura de machos de S. frugiperda o A. ipsilon. Estos resultados pueden ser de importancia para el desarrollo de un sistema de monitoreo o trampeo masivo de S. frugiperda en las regiones mexicanas donde el maíz y sorgo son los principales cultivos, o en aquellos orgánicos de fresas que pueden estar amenazados por este insecto polífago.The fall armyworm, Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae), is one of the main pests of maize and sorghum, in addition this insect begins to be a threat for strawberry crops in Michoacán, Mexico. Thus, it would be worth to have a monitoring system to detect early infestations of S. frugiperda and implement their control in time. Under this scenario, the use of traps baited with the sex pheromone may be useful to catch males. In this study, we compared the effectiveness of a pheromone lure developed from Mexican populations of S. frugiperda against four commercial lures, three formulated abroad and one in Mexico, in maize crops adjacent to strawberries ones. Additionally, we analyzed the effect of the trap color. It was found that the traps baited with lure optimized for Mexican populations (EcoTap) or with the commercial lure formulated in Mexico (Phero-SF) captured more S. frugiperda males and less non-target insects compared to traps baited with the other lures. One unexpected finding was the caught of black cutworm males, Agrotis ipsilon (Hufnagel) (Lepidoptera: Noctuidae), by the traps baited with EcoTap or Phero-SF lures. The trap colour did not have a significant effect on the capture of S. frugiperda or A. ipsilon males. The results obtained here may be used for monitoring or mass trapping S. frugiperda in the Mexican regions where maize and sorghum are the main crops or in organic strawberry crops that may be threatened by this polyphagous insect

Inhibition of the responses to sex pheromone of the fall armyworm, Spodoptera frugiperda

Trifluoromethyl ketones reversibly inhibit pheromone-degrading esterases in insect olfactory tissues, affecting pheromone detection and behavior of moth males. In this work, (Z)-9-tetradecenyl trifluoromethyl ketone (Z9-14:TFMK), a closely-related analogue of the pheromone of the fall armyworm, Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae), was prepared and tested in electroantennogram and field tests as possible inhibitors of the pheromone action. The electroantennogram parameters, amplitude, and the repolarization time of the antennal responses of S. frugiperda males were affected by Z9-14:TFMK vapors. Exposure of male antennae to a stream of air passing through 100 μg of the ketone produced a significant reduction of the amplitude and an increase of 2/3 repolarization time signals to the pheromone. The effect was reversible and dose-dependent. In the field, the analogue significantly decreased the number of males caught when mixed with the pheromone in 10:1 ratio. The results suggest that Z9-14:TFMK is a mating disruptant of S. frugiperda and may be a good candidate to consider in future strategies to control this pest.We also thank MICINN for a FPI fellowship to R. Gago, and CONACYT (project 84072) and CICYT (project AGL 2009-13452-C02-01) for financial support.Peer reviewe

Inhibition of electrophysiological response to the pheromone of the fall armyworm, Spodoptera frugiperda

In the search for new control methods for the fall armyworm (FAW), Spodoptera frugiperda (Lepidoptera: Noctuidae), we present the inhibition of the electroantennographic (EAG) response to the pheromone by 3-octylthio-1,1,1-trifluoropropan-2- one (OTFP). As a member of the trifluoromethyl ketones, OTFP is a potent inhibitor of serine esterases, particularly those of insect antennae. Exposure of antennal receptors to OTFP vapors resulted in a decreased amplitude and 2/3 repolarization time (2/3 RT) of the EAG response to the pheromone. The effect was reversible, with the amplitude and repolarization time being recovered upon suppression of the treatment. The non-fluorinated analogue 3-octhylthiopropan-2-one (OTP) did not affect either the amplitude or the 2/3 RT of the EAG response to the pheromone, confirming the key role played by fluorine atoms in this type of chemical. These results may be the basis for new behavioral studies with the aim of considering OTFP in future management strategies of the FAW.We acknowledge CONACYT (project 84072) and CICYT (project AGL 2006-13489-C02-01) for financial support.Peer reviewe