In the present study, the toxicity and physiological disorders of the essential oil isolated from Artemisia annua flowers were assessed against one of the main insect pests of mulberry, Glyphodes pyloalis Walker, announcing one of the safe and effective alternatives to synthetic pesticides. The LC50 (lethal concentration to kill 50% of tested insects) values of the oral and fumigant bioassays of A. annua essential oil were 1.204 % W/V and 3.343 μL/L air, respectively. The A. annua essential oil, rich in camphor, artemisia ketone, β-selinene, pinocarvone, 1,8-cineole, and α-pinene, caused a significant reduction in digestive and detoxifying enzyme activity of G. pyloalis larvae. The contents of protein, glucose, and triglyceride were also reduced in the treated larvae by oral and fumigant treatments. The immune system in treated larvae was weakened after both oral and fumigation applications compared to the control groups. Histological studies on the midgut and ovaries showed that A. annua essential oil caused an obvious change in the distribution of the principal cells of tissues and reduction in yolk spheres in oocytes. Therefore, it is suggested that the essential oil from A. annua flowers, with wide-range bio-effects on G. pyloalis, be used as an available, safe, effective insecticide in the protection of mulberry.
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>.
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