SUSCEPTIBILITY OF THE FALL ARMYWORM, SPODOPTERA FRUGIPERDA (LEPIDOPTERA: NOCTUIDAE), AT SANTA ISABEL, PUERTO RICO, TO DIFFERENT INSECTICIDES

Although there are differences in the speed of lethal activity, most of the insecticides we tested were effective in controlling FAW. This might be attributed to regular pest scouting and applying insecticides in rotation or combination, which may have helped to delay development of resistance and, thus, to keep the FAW population susceptible to those insecticides. Moreover the dose rate study showed that applying thiodicarb, acephate, spinetoram or spinosad at the current 1 × rate is sufficient to control FAW; and higher rates should not be used. Further studies, taking into consideration the biology of the pest and the phenology of the crop to determine the right time and frequency of application of those insecticides under field conditions, could help to achieve high levels of control and prolog the effectiveness of the products. Moreover, the evaluation of insecticide susceptibility of FAW populations from different regions is important as the variability of insecticide resistance/susceptibility characteristics in FAW populations may assist in determining the origin of FAW infestations and in developing an appropriate management strategy (Pitre 1986).