Early life nutritional quality effects on adult memory retention in a parasitic wasp

Nutritional quality during early life can affect learning ability and memory retention of animals. Here we studied the effect of resource quality gained during larval development on the learning ability and memory retention of 2 sympatric strains of similar genetic background of the parasitoid Trichogramma brassicae: one uninfected and one infected by Wolbachia. Wolbachia is a common arthropod parasite/mutualistic symbiont with a range of known effects on host fitness. Here we studied, for the first time, the interaction between resource quality and Wolbachia infection on memory retention and resource acquisition. Memory retention of uninfected wasps was significantly longer when reared on high quality hosts when compared to low quality hosts. Furthermore, uninfected wasps emerging from high quality hosts showed higher values of protein and triglyceride than those emerging from low quality hosts. In contrast, the memory retention for infected wasps was the same irrespective of host quality, although retention was significantly lower than uninfected wasps. No significant effect of host quality on capital resource amount of infected wasps was observed, and infected wasps displayed a lower amount of protein and triglyceride than uninfected wasps when reared on high quality hosts. This study suggests that the nutritional quality of the embryonic period can affect memory retention of adult wasps not infected by Wolbachia. However, by manipulating the host’s obtained capital resource amount, Wolbachia could enable exploitation of the maximum available resources from a range of hosts to acquire suitable performance in complex environments

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

Feeding indices and enzymatic activities of carob moth Ectomyelois ceratoniae (Zeller) (Lepidoptera: pyrallidae) on two commercial pistachio cultivars and an artificial diet

Feeding indices and enzymatic activities of Ectomyelois ceratoniae (Zeller) were studied in a growth chamber under controlled conditions (29 ± 2 °C, relative humidity of 70 ± 5% and a photoperiod of 16:8 (L:D) hours) on two commercial Pistachio cultivars (Akbari and Kalequchi) and an artificial diet. Feeding indices of E. ceratoniae larvae differed significantly on three hosts (P < 0.05). The relative consumption rate was calculated to be 5.36 ± 0.009, 11.10 ± 1.49 and 10.631 ± 0.599 (mg/mg/day) on artificial diet, Akbari and Kalequchi cultivars, respectively. Carob moth larvae reared on Akbari cultivar showed the highest efficiency of conversion of digested food (ECD) (5.64 ± 0.43). The highest amount of efficiency of conversion of ingested food (ECI) was obtained on artificial diet but approximate digestibility (AD) was the lowest on this diet. The highest enzymatic activities of alpha-amylase, general proteases and lipase were observed in the midgut of larvae reared on artificial diet. Total protein and lipid value were highest in larvae that were reared on artificial diet

Digestive α-amylase of Bacterocera oleae Gmelin (Diptera: Tephritidae): Biochemical characterization and effect of proteinaceous inhibitor

Digestive α-amylase of Bacterocera oleae larvae was characterized and treated by an inhibitor to gain a better understanding of the degradation of nutritional molecules as a potential target for controlling the pest. Presence of α-amylase was confirmed in the gut of olive fruit fly through the use of a negative control in dinitrosalicylic acid procedure. An optimal pH of 5 was found for amylolytic activity in the gut. The enzyme had optimal activity in a broad range of temperatures 20–45 °C. Among used cations and specific inhibitors, Ca2+, phenylmethylsulphonyl fluoride (PMSF) and ethylene glycol-bis (β-aminoethylether) N,N,N′,N′-tetraacetic acid (EGTA) had statistical differences on amylolytic activity indicating the presence of amino acid triad and Ca2+ in active site of the enzyme. A proteinaceous α-amylase inhibitor was extracted from Polygonum persicaria, a medicinal plant, that widely grows in North of Iran. IC50 value of PPAI was 0.062 mg/ml (i.e. 0.062 mg/ml of extracted inhibitor inhibited 50% of amylolytic activity in the gut of B. oleae larvae) and was temperature and pH dependent. The use of enzyme inhibitors from different plant sources may serve as an important pest control strategy via plant breeding programs. Identification of genes responsible for these inhibitor proteins could be a first step to provide a resistant variety of olive

Evaluation of Origanum vulgare L. essential oil as a source of toxicant and an inhibitor of physiological parameters in diamondback moth, Plutella xylustella L. (Lepidoptera: Pyralidae)

The effect of essential oil of Origanum vulgare L. a medicinal plant was studied on toxicity, physiology and biochemical characteristics of diamondback moth Plutella xylustella L. in controlled condition. The LC10, LC30 and LC50 values were estimated 0.234, 0.710 and 1.528 percent (v/v) respectively for 3rd instar larvae. Repellency of essential oil under LC10 and LC30 concentrations was 22.8 ± 6.64 and 49.8 ± 6.95 percent respectively. Effect of plant essential oil on feeding efficiency was also evaluated under LC10 and LC30 concentrations. Approximately Digestibility (AD), Efficacy of Conversion of Ingested Food (ECI), Efficacy of Conversion of Digested Food (ECD), Relative Consumption Rate (RCR) and Relative Growth Rate (RGR) of the treated larvae showed a significant difference compared with the control. The effectiveness of plant essential oil on digestive enzymes under LC50 concentration for the survivors after 24 and 48 h after treatment was analyzed. Total protein and triglycerides were decreased significantly compared with the control. Activity of alkaline phosphatase and protease in treated larvae decreased compared with the controls. The lipase was increased 24 h after treatment compared with the control. Significant differences in detoxifying enzymes such as glutathione S-transferase and esterase were noted compared to controls. It is concluded that the essential oil used in the present experiment shows toxicity in higher doses. It is also concluded that the essential oil used did show considerable changes in repellency, feeding efficiency, reduced larval weight and changes in biochemical properties which may nominate it for further investigation in key insect pests

Effects of a Lectin from Polygonum Persicaria L. on Pieris Brassicae L. (Lepidoptera: Pieridae)

In the current study, the entomotoxic effects of a lectin, extracted from Polygonum persicaria, were determined on Pieris brassicae larvae. The purified molecule significantly decreased larval survival, weight, and mass protein. Different concentrations of P. persicaria agglutinin (PPA) (0.5, 1 and 2 mg/ml) significantly decreased nutritional indices including: the efficiency of conversion of ingested food (ECI), the efficiency of conversion of digested food (ECD), and approximate digestibility (AD) in a dose-dependent manner. There was a significant decrease in larval α-amylase activity after larval fed on PPA. The decreased activity was found in both the biochemical assessment and gel electrophoresis; sharpness of one isozyme decreased and another completely disappeared. Meanwhile, PPA significantly decreased activities of glucosidases mainly β-glucosidase. Fed of P. brassicae larvae on different concentrations of PPA, significantly decreased activity of TAG-lipase in both the biochemical assessment and gel electrophoresis. It was found that alkaline phosphatase (ALP) and acid phosphatase (ACP) were also affected by PPA but concentrations of 1 and 2 mg/ml showed statistical differences compared to the control. General and specific proteolytic activities statistically decreased after larvae fed on different concentrations of PPA. Results of our study could bring attention to this molecule, showing it to be a safe and efficient control of the pest worldwide