Effect of four varieties of mulberry on biochemistry and nutritional physiology of mulberry pyralid, Glyphodes pyloalis Walker (Lepidoptera: Pyralidae)

Abstract

The effects of four mulberry varieties (Kenmochi, Ichinose, Shin Ichinose, Mahalii) on nutritional indices and digestive proteolytic and amylolytic activities of <em>Glyphodes pyloalis</em> Walker (Lepidoptera: Pyralidae) were determined at 24±1°C, 75±5% RH and a photoperiod of 16:8 L:D. Fifth instar larvae reared on Shin Ichinose showed the highest efficiency of conversion of digested food and efficiency of conversion of ingested food (3.82±0.16% and 3.11±0.07%, respectively). Approximate digestibility values of the fourth instar larvae were highest (95.23±0.73%) and lowest (91.77±1.45%) on Kenmochi and Shin Ichinose, respectively. The fifth instar larvae fed on Kenmochi had the highest consumption index (4.6±0.73) and lowest relative growth rate (0.03±0.10), respectively. Our results showed that the highest protease activity in optimal pH was on Malalii variety (0.97 U/mg) and the lowest was on Kenmochi (0.75 U/mg). In addition, the highest amylase activity in optimal pH was on Mahalii (0.17 U/mg) and lowest on Kenmochi (0.103 U/mg). Specific proteolytic analysis showed that larvae feeding on Mahalii had the highest activity of trypsin and elastase (2.30 and 2.13 U/mg, respectively). This research showed that plasticity in food utilization and enzyme activity is functionally relevant to host plant cultivars. The results of nutritional indices and activity of digestive enzymes indicated that Kenmochi was an unsuitable host for feeding of <em>Glyphodes pyloalis</em>.