Genotype-Associated Variation in Nutritional Indices of Helicoverpa armigera (Lepidoptera: Noctuidae) Fed on Canola

In this study, the nutritional indices of the larval stages of Helicoverpa armigera (Hübner) were determined on ۱۰ canola (Brassica napus L.) genotypes (Talaye, Opera, Licord, Modena, SLM۰۴۶, Hayula۴۲۰, Zarfam, Okapi, RGS۰۰۳ and Sarigol) at ۲۵±۱˚C, ۶۰±۵% RH and a photoperiod of ۱۶: ۸ (L: D) hours. The third instar larvae reared on Talaye showed the highest value of Efficiency of Conversion of Ingested food ECI and Efficiency of Conversion of Digested food ECD (۷.۰۰۵±۰.۶۳۲ and ۸.۹۷۲±۱.۸۶۲, respectively). However, the lowest value of ECI and ECD was on Licord (۰.۵۰۳±۰.۰۱۷ and ۲.۵۰۷±۰.۴۴۹, respectively). The highest (۰.۷۷۸±۰.۰۹۱) and lowest (۰.۵۹۴±۰.۰۵۹) Relative Growth Rate (RGR) of the fourth instar larvae were obtained on SLM۰۴۶ and Sarigol, respectively. Results indicated that the highest values of ECI and ECD for fourth instar larvae were on Talaye (۶.۳۰۰±۰.۵۸۵ and ۸.۸۸۰±۱.۹۵۴, respectively). The lowest value of the Relative Consumption Rate (RCR) and Approximate Digestibility (AD) of the fifth instar was recorded on Modena (۵.۱۹۳±۰.۶۲۹ and ۳۸.۶۲۵±۱۱.۳۴۰, respectively). The ECI and ECD values of the fifth larval instar were the highest on Talaye (۹.۸۹۳±۰.۸۸۹ and ۱۹.۶۵۵±۰.۹۶۶, respectively). The highest value of RCR and AD of the sixth instar was on Okapi (۷.۷۸۱±۰.۶۶۵ and ۸۲.۲۲۳±۱.۹۲۲, respectively). Among different genotypes tested, the highest ECI and ECD of the whole larval instars (۱۲.۳۲۳±۰.۳۱۰ and ۳۲.۳۵۷±۵.۵۰۸, respectively) were observed on Talaye and the lowest ones (۵.۹۴۷±۰.۲۵۷ and ۶.۹۲۲±۰.۳۲۰, respectively) were on Okapi. Together, Talaye and Okapi were the most suitable and unsuitable genotypes, respectively, for H. armigera larvae.

Keywords:

Approximate digestibility , Brassica napus , Digested food , Ingested food , Relative growth rate