Nutritional indices of the willow leaf beetle, Plagiodera versicolora (Coleoptera: Chrysomelidae) on different host plants

Nutritional indices of the willow leaf beetle, Plagiodera versicolora Laicharting, third instar larvae and adults were studied on four host plants including Salix alba L., Salix aegyptica L., Populus caspica Bornm.and Populus alba L.at ۲۲ ± ۲ ºC, ۷۰ ± ۱۰% R.H., and a photoperiod of ۱۶:۸ h (L: D). The results showed that the highest consumed food by the larvae and adults (۱۴۸.۵ ± ۱۸.۰ and ۱۷۵.۲۱ ± ۴.۵۱ mg dry weight, respectively) was on P. caspica. The larvae fed on S. alba and S. aegyptica had the highest efficiency of conversion of ingested food (ECI) (۲.۳ ± ۰.۳۳ and ۲.۲۳ ± ۰.۶۷%, respectively) and efficiency of conversion of digested food (ECD) (۲.۵ ± ۰.۳۵ and ۲.۴۱ ± ۰.۷۲%, respectively). Approximate digestibility (AD) of larvae was the highest on P. caspica and P. alba (۹۸.۵۱ ± ۰.۲۵ and ۹۸.۱۴ ± ۰.۱%, respectively). The lowest relative consumption rate (RCR) of the larvae and adults was on S. alba (۰.۱۴ ± ۰.۰۰۱ and ۰.۱۳ ± ۰.۰۰۶ mg/mg/day, respectively). ECI and ECD values of the adults fed on various host plants were not significantly different. Adults fed on P. caspica had the highest values of RCR (۰.۵۹ ± ۰.۰۱ mg/mg/day), relative growth rate (RGR) (۰.۰۲ ± ۰.۰۰۸ mg/mg/day) and AD (۹۸.۷۲ ± ۰.۲۴%). These results demonstrated the higher feeding performance of the willow leaf beetle on P. caspica and its poorer performance on P. alba.

Keywords:

nutritional indices , willow leaf beetle , Plagiodera versicolora , host plants