Akademik Veri Yönetim Sistemi
JOURNAL OF THE ENTOMOLOGICAL RESEARCH SOCIETY, cilt.11, ss.1-15, 2009 (SCI-Expanded)
An oligophagous leaf beetle, Agelastica alni (L., 1758) (Coleoptera: Chrysomelidae), often occurs in outbreak densities and utilizes both alders and willows in Europe. It was reported on alder and hazel in Turkey and its outbreaks on alder occur almost every year in the middle and eastern Black Sea regions of the country where hazel plantations cover huge areas. Nitrogen utilization, and degradation of some plant secondary metabolites by A. alni larvae fed with leaves of alder (Alnus glutinosa (L.) Gaertn. ssp. glutinosa), babylon willow (Salix babylonica L.) and hazel (Corylus avellana L.) with varying nutritional status were investigated. Larvae of this species were fed leaves of these plants that had been fertilized (NPK) and not been fertilized. Larval nitrogen utilization was determined to calculate the nitrogen utilization efficiency (NUE). The effects of some secondary metabolites of leaves of the plants on the digestion efficiency of A. alni larvae were tested. It was determined that A. alni larvae balanced its nitrogen utilization to some degree, despite the increase of nitrogen content of the leaves. Although the nitrogen content changed from 2,97% to 4,33 in hazel, from 2,47 % to 3,68 in babylon willow, from 4,27 % to 5,34 in young alder, from 4,04 % to 4,66 in older alder, the efficiency of nitrogen utilization of larvae changed from 16,54% to 12,77, from 11,92 % to 13,86, 22,72 % to 24,53, and 21,09 % to 23,71, respectively. In addition, the correlation between the changed N content of the treated leaves and the nitrogen utilization of the larvae that fed on them was negative (except from the larvae fed on unfertilized leaves of C. avellana) in all plants and treatments. The statistical analysis indicated that the approximate digestibility (AD) of the larvae was not affected by these secondary compounds (r(2)<0.7, P < 0.05). On the other hand, the degradation ratio of proanthocyanidin (condensed tannin) and total phenolics by A. alni larvae was determined as 3381 %. These results lead to the interpretation that metabolites had no measurable effects on A. alni larvae, or alternatively, the larvae utilized regulatory mechanisms to overcome the undesirable effects of these compounds. This study also indicated that larvae of A. alni have developed nitrogen homeostasis, which may involves a decrease of predation risk.