Effect of geographic origin of Spodoptera exigua (Lepidoptera: Noctuidae) and sugar beet cultivar on nutritional indices of this pest
Keywords:beet armyworm, feeding performance, geographic population, host cultivar
Nutritional indices of three geographic populations (Miandoab, Moghan and Kalposh) of the fifth instar of Spodoptera exigua (Lepidoptera: Noctuidae) on four sugar beet cultivars (Dorothea, Rozier, Persia and Perimer) were evaluated at 25 ± 1 °C, 65 ± 5 % RH and a 16:8 L:D photoperiod. The estimates of all the nutritional indices were affected by the interaction effect of the geographic population and the sugar beet cultivars. Miandoab population reared on Dorothea, and Moghan and Kalposh populations reared on Perimer had the highest approximate digestibility (AD). Miandoab and Kalposh populations reared on Rozier showed the highest efficiency of conversion of ingested food (ECI) and efficiency of conversion of digested food (ECD) values. Moghan population reared on Persia showed the lowest AD values and the highest ECI and ECD values. The present study showed that the nutritional indices of three populations, in most cases, were significantly different from with other, due to different environmental conditions that the pest collected from there. It is concluded that both geographic origins of the pest and host cultivar affected the nutritional indices of S. exigua larvae.