Ten Widely Used Canola Genotypes: A Complex of Highly Resistant and Susceptible Hosts to Feeding Spodoptera exigua

The nutritional indices are an important tool in evaluating herbivore responses to variation in host nutritive properties. The current study was conducted to unveil the effects of ten canola cultivars (Brassica napus L.) ('Opera', 'Licord', 'Okapi', 'Talaye', 'Zarfam', 'Modena', 'SLM046', 'Sarigol', 'RGS(003)' and 'Hayula(420)') on consumption and utilization indices of the Spodoptera exigua (Hubner) larvae. The results revealed significant differences in nutritional indices of different larval instars of S. exigua fed on the mentioned canola cultivars. The highest value of Digestion Ability of food (AD) for the third and fourth instars was observed on Licord (86.57% and 83.08%, respectively), and for the fifth instars was on Opera (68.79%). The Relative Growth Rate (RGR) and Relative Consumption Rate (RCR) in the fifth instar larvae were significantly greater on Opera, Okapi and Talaye, whereas the lowest values of Conversion Efficiencies (ECI and ECD) were recorded on these cultivars. The highest ECI was observed in the larvae that consumed RGS(003) (24.27%), Hayula(420) (20.36%), and Sarigol (19.17%). Furthermore, the larvae reared on Okapi exhibited the highest RGR, which confirms high susceptibility of this cultivar. Based on the obtained results, Okapi, Talaye and Opera were the cultivars susceptible to S. exigua.