The effects of host plants on the feeding indices and chemical activities of elm leaf beetle, Xanthogaleruca luteola (Muller) (Coleoptera: Chrysomelidae)

Elm leaf beetle (ELB), Xanthoga leruca luteola (Muller), is considered as one of the most important and destructive phytophagous pests of Ulmus species in the north of Iran. In the current study, the effects of three host plants including Ulmus carpinifolia, U. carpinifolia var. umbraculifera, and Zelkova carpinifolia, on feeding indices and biochemical processes of ELB were examined under controlled conditions (25 ± 2 °C; 14:10 LD; 65% RH). The results showed that the highest efficiency of conversion of ingested food (ECI) (23.11±1.36 %) and efficiency of conversion of digested food (ECD) belonged to U. carpinifolia (79.9±4.12 %) and the lowest to Z. carpinifolia (p≤0.05). Relative growth rate (RGR) and approximate digestibility (AD) in U. carpinifolia var umbraculifera and U. carpinifolia were similar to each other. The highest consumption index (CI) belonged to U. carpinifolia var. um braculifera and the lowest to Z. carpinifolia (1.93±0.029, 1.47±0.054), respectively (p≤0.05). Significant differences were found among enzymatic activities of acid (ACP) and alkaline phosphatases (ALP), aspartate aminotransferases (AST and ALT) and lactate dehydrogenase (LDH) in the haemolymph of X. luteola larvae reared on three different host plants. The highest activities of LDH (33±0.58), AST (10074.7±25.25) and ALT (1053.75±5.6) were found in larvae fed on U. carpinifolia (p≤0.05). Also, the highest amount of protein and triglyceride (TAG: 126.5±0.866) was found in larvae fed on U. carpinifolia. The results show that all enzymatic activities significantly decreased on Z. carpinifolia compared with other host plants (p≤0.05). These results indicated that U. carpinifolia is the most appropriate host plant for larvae of X. luteolaas evidenced by the highest nutritional indices as well as activities of enzymatic component in intermediary metabolism.