Effect of Neem Pesticide (Achook) on Midgut Enzymatic Activities and Selected Biochemical Compounds in the Hemolymph of Lesser Mulberry Pyralid, Glyphodes Pyloalis Walker (Lepidoptera: Pyralidae)

Synthetic organic compounds and those of plant origin used in insect pest control are known to affect digestive enzymes and biochemical compounds. The lesser mulberry pyralid Glyphodes pyloalis Walker is a monophagous and dangerous pest of mulberry that has been recently observed in Guilan province, northern Iran. In this study the effect of the neem formulation, Achook (0.03% azadirachtin) was studied on nutritional physiology and gut enzyme activity of the lesser mulberry pyralid G. pyloalis. The LC25, LC50, and LC90 values on 4th instar larvae were estimated as 113.6, 256.84, and 1,210.02 ppm, respectively. The neem insecticide exhibited a significant antifeedant activity when used at the highest concentration. When G. pyloalis larvae were provided with mulberry leaves treated with the neem extract, all nutritional indices, except approximate digestibility, decreased. Neem was found to affect digestive enzyme activities in the midgut of treated larvae. When larvae were fed on treated leaves, biochemical compounds in the hemolymph, such as protein, lipid, and glucose decreased but the amount of uric acid increased compared with the control

Toxicity and physiological effect of essential oil of Artemisia annua (Labiatae) on Agriolimax agrestis L. (Stylommatophora: Limacidae)

Essential oil of Artemisia annua L. was investigated to find out its toxicity and physiological aspects on the slug Agriolimax agrestis, in controlled conditions (8±1°C, 75±5 RH and 14:10 LD). The slugs received different concentrations of essential oil treated radish leaves in methanol, while the control received methanol alone. LC10, LC30, LC50 and LC90 values were estimated at 4.67, 5.3, 5.81, 7.25%, respectively. The effect of the essential oil on some important enzymatic components like; cytochrome P450 monnooxygenase, acid phosphatase, alkaline phosphatase, lipase, amylase and protease were significantly increased compared to the control. These results indicate that the plant Artemisia annua L. not only shows toxicity but also shows some irreversible effect on some important biochemical components and deserves further investigation

Inhibition of Digestive α-Amylases from Chilo Suppressalis Walker (Lepidoptera: Crambidae) by a Proteinaceous Extract of Citrullus Colocynthis L. (Cucurbitaceae)

The striped rice-stem borer, Chilo suppressalis (Walker) is one of the most important pest of rice worldwide. In this study, a proteinaceous extract from Citrullus colocynthis L. shows various degrees of inhibition to digestive α-amylases of C. suppressalis. Digestive α-amylases of larvae were inhibited by different concentrations (approximately 50%) of C. colocynthis amylase inhibitor (CCAI). One of the isozymes totally disappeared and the sharpness of another decreased on native-PAGE electrophoresis. The pH dependency of inhibition revealed that the enzyme was inhibited in a wide range of pH from 7-10, and the optimal pH of the enzyme occurred in lepidopteran larvae. The highest inhibition of α-amylase by CCAI was observed at 25°C; the temperature near the optimal temperature of amylolytic activity. A time-course experiment demonstrated that enzymatic activity was the highest, 30 min after the onset of the experiment, when the highest inhibition occurred. The enzyme kinetic studies using Lineweaver-Burk analysis, revealed a mixed inhibition of CCAI on α-amylase activity. The current study is the first basic one using α-amylase inhibitor against C. suppressalis. This study opens the way for transgenic rice varieties containing inhibitors

Effect of Thymus vulgaris L. and Origanum vulgare L. essential oils on toxicity, food consumption, and biochemical properties of lesser mulberry pyralid Glyphodes pyloalis Walker (Lepidoptera: Pyralidae)

The essential oils of Thymus vulgaris L. and Origanum vulgare L. were investigated for their toxicity and physiological aspects on the lesser mulberry pyralid Glyphodes pyloalis Walker in controlled condition (24±1°C, 75±5% RH and 16L : 8D). The leaf disc method was used to study acute toxicity, the effect of LC10, LC30, and LC50 on the feeding efficiency of 4th instar larva, and biochemical indices. The essential oil doses of LC10, LC30 and LC50 were estimated to be 0.107%, 0.188% and 0.279% for T. vulgaris, and 0.67%, 1.173% and 1.728% for O. vulgare, respectively. The results showed that T. vulgaris was more toxic than O. vulgare. The essential oil sublethal dose LC30 affected the nutritional indices of 4th instar larvae of G. pyloalis. The essential oils reduced total protein, carbohydrate, and lipid. Some concentrations of essential oils changed the activity level of α-amylase, protease, lipase, general esterases, and glutathione S-transferase (GST) but others showed no effect on these enzymes. It was concluded that the used essential oil concentrations were both toxic to G. pyloalis and showed irreversible effects on key metabolic processes, therefore, the used essential oil concentrations may be considered as alternatives to the classic pest control agents

Effect of Artemisia annua L. essential oil on toxicity, enzyme activities, and energy reserves of cotton bollworm Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae)

The essential oil of Artemisia annua L., a weed collected from northern Iran, was studied for its toxicity and physiological aspects on 4th instar larva of the cotton bollworm Helicoverpa armigera Hübner in controlled conditions (26±1°C, 65±10% RH and 16 L : : 8 D h). The artificial diet was used as a medium for investigating the toxicity and the effect of LC10, LC30, LC50, and LC90 on the feeding efficiency of 4th instar larva. The essential oil in doses of LC10, LC30, LC50, and LC90 were estimated to be 2.01%, 3.86%, 6.07%, and 18.34%, respectively. The activity of α-amylase, protease, lipase, general esterases, and glutathione S-transferase and protein, triglyceride, glucose for treated larva were measured. The results showed that all of these parameters were decreased compared with the control. Hence, A. annua essential oil is suggested as a botanical for controlling this important pest of field crops

Effect of Citrullus colocynthis L. (Cucurbitaceae) agglutinin on gene expression of caspases in Ectomyelois ceratoniae Zeller (Lepidoptera: Crambidae)

The larvae of Ectomyelois ceratoniae Zeller were reared on the artificial diets containing 2% of Citrullus colocynthis L. (Cucurbitaceae) lectin and control to find any changes in gene expression of caspases. Specific primers were designed to amplify genes of six found caspases including Caspase 1, 2, 3, 4, 5 and 6. RNA of both treatments were extracted and cDNA molecules were synthesized prior to gene expression. Results of quantitative real-time polymerase chain reaction revealed that expression of all caspases in the fed larvae by 2% of lectin increased in comparison with control except for caspase 1 as 2.99, 5.7, 17.13, 23.18, 10.44-fold. These results are consistent with our previous studies on the lower activities of digestive enzymes that are due to death of midgut cells followed by binding of lectin molecule

Changes in cellular immune responses of Chilo suppressalis Walker (Lepidoptera: Crambidae) due to pyriproxyfen treatment

The effects of pyriproxyfen were determined on the cellular immunity and phenoloxidase activity in the 4th instar larvae of Chilo suppressalis Walker. The bioassay results revealed the effective concentrations of: 10L : 18C, 30L : 72C and 50L : 190C μg · ml–1. The sole effect of 18 and 72 μg · ml–1 concentrations at intervals of 1–3 h caused a higher number of total hemocytes in the treated larvae than the control, but the reverse results were observed after 6–24 h. The number of plasmatocytes was lower than that of the control for intervals of 3–24 h but the number of granulocytes was higher than the control after 1–3 h although no significant differences were observed at the other times. In the treated larvae, the activities of phenoloxidase were higher and lower than those of the control after 1–3 h and 6–24 h, respectively. The combined effects of pyriproxyfen and the entomopathogenic fungus, Beauveria bassiana isolate B3 caused higher numbers of total hemocytes, plasmatocytes, and granulocytes in the treated larvae by use of the three concentrations of pyriproxyfen, at intervals of 6 and 12 h. Although the numbers of nodules in the larvae treated with concentrations of 18 μg · ml–1 were higher than those of other treatments, the overall numbers were lower than those of the control. Finally, the activity of phenoloxidase in the treated larvae was higher than that of the control, at intervals of 6 and 12 h post-treatment. Findings of the current study indicate an intervening role of pyriproxyfen in the cellular immunity of C. suppressalis to entomopathogenic objects

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

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>

Effect of heavy metals (Cd, Cu, and Zn) on feeding indices and energy reserves of the cotton boll worm Helicoverpa armigera Hübner (Lepidoptera: Noctuidae)

Third-instar larvae of Helicoverpa armigera Hübner (Lepidoptera: Noctuidae) were exposed to 12.5, 25, and 50 mg/kg concentrations of cadmium (Cd). The third-instar larvae were also exposed to 25, 50, and 100 mg/kg concentration of copper (Cu), and 25, 50, and 100 mg/kg concentrations of zinc (Zn). The heavy metal concentrations were each introduced separately into the artificial diet of the third-instar larvae. The third-instar larvae were 24 h old at the start of the treatment. The larvae were maintained in controlled conditions (26±1°C, 65±10% RH and 16L : 8D h) for 7 days. The feeding indices and the level of total protein, glycogen, cholesterol, and triglyceride were measured after the treatments. The results showed that high concentrations of Cd significantly increased approximate digestibility (AD). The relative growth rate (RGR) was significantly enhanced with a 25 mg/kg concentration of Cu. Efficiency of conversion of the ingested food (ECI%) increased significantly with lower concentrations of copper (25 and 50 mg/kg). The amount of cholesterol was also enhanced with 12.5 and 25 mg/kg concentrations of cadmium while the amount of triglyceride was significantly reduced in all Cd treatments. Glycogen, protein, and cholesterol were significantly enhanced in all Cu treatments. The amount of triglycerides at 25 and 50 mg/kg of Cu was significantly increased. Glycogen in all Zn treatments was significantly increased. Protein and cholesterol levels showed significant reduction with a 25 and 50 mg/kg concentration of zinc while triglyceride was enhanced with a 50 mg/kg concentration of Zn. It is clear from the present results that the presence of such heavy metals in the environment has an intense impact on H. armigera as far as food consumption and biochemical indices are concerned. Therefore, a need is shown for a more comprehensive study on the life table and immunology of this insect, under the presence of heavy metals

Proteolytic activity in the midgut of the crimson speckled moth Utethesia pulchella L. (lepidoptera: arctiidae)

Samples were prepared from the midgut of 4th instar larvae of the crimson speckled moth Utethesia pulchella L. to find proteolytic activity and properties. Result revealed the presence of high proteolytic activity in the midgut when taking into account specific proteinases including trypsin-like, chymotrypsin-like, elastase and two exopeptidase (aminopeptidase and carboxipeptidase). The optimal pH of general protease was 8 and 7 when using azocasein and hemoglobin as general substrates, respectively. The optimal temperature of the total proteolytic activity in the midgut of U. pulchella was 25°C and 30°C when using azocasein and hemoglobin, respectively. Proteolytic activity was inhibited significantly by soybean trypsin inhibitor (SBTI), phenylmethylsulfonyl fluoride (PMSF), trypsin inhibitor (TLCK), chymotrypsin inhibitor (TPCK) and Phenanthroline. These results provide evidences for the presence of serine proteinases as the major proteases in the midgut of U. pulchella; a key rangeland pest in warm climates. The interaction between digestive proteases and protease inhibitors have potentially important consequences for pest management programs