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The Greenbug Schizaphis graminum (Rondani), one of the major pests of cereals, overwinter as adults and nymphs in temperate regions. The aphid population increases in early spring as the weather conditions become favorable, but it gradually decreases in mid-June as air temperature rises. Adult aphid colonies were acclimated to measure cold tolerance at 20, 15, 10, 5, and 0 C for one week. In contrast, other colonies were acclimated to measure heat tolerance at 20, 25, and 30 C for one week and 35 C for two days. Then, the lowest temperature resulting in 50% mortality (LLT50) and the highest temperature resulting in 50% mortality (ULT50) of tested populations were defined. Moreover, changes of sugars and polyols were studied at the end of ea
Rapid cold hardiness in response to sudden decline in air temperature plays an important role in the aphid survival. Rapid cold hardiness is a phenomenon that increases insect’s survival at sub-zero temperatures following a brief exposure to low temperatures above 0 C. In this regard, the cabbage aphid Brevicoryne brassicae (L.) is able to increase its cold hardiness gradually during cold season and produce large population on host plants in Brassicaceae family. In this research, rapid cold hardiness of B. brassicae, and its effects on development time, longevity and fecundity were investigated. Direct transfer of aphids from 20 C to a series of sub-zero temperatures for 2 h, resulted in a LT80 (estimated temperature required to kill 80%
Plant secondary metabolites influence the feeding in insects through several modes of action. In this study, the physiological effects of erucin isothiocyanate were investigated on the elm leaf beetle?Xanthogaleruca luteola?(M?ller) (Coleoptera: Chrysomelidae) via impact on crustacean cardioactive peptide (CCAP) and midgut digestive enzymes. Third instar larvae of elm leaf beetle were fed on leaves impregnated with erucin for three days. The results showed that erucin decreased?α-amylase, lipase, and protease release. Western blot analysis and competitive ELISA showed that erucin decreased CCAP content of the midgut, brain, and hemolymph. Moreover, incubation of dissected midgut with CCAP and also its injection into the hemocoel increased
The contact insecticidal activity of in natura and maltodextrin/Angum gum nanoencapsulated essential oils of Eucalyptus globulus Labill and Zataria multiflora Bioss was evaluated against the third instar larvae of Ephestia kuehniella (Lepidoptera: Pyralidae). The essential oil from E. globulus exhibited an average yield of 1.19%, and presented 1,8-cineol (59.08%) as the major component, while Z. multiflora essential oil, with an average yield of 1.5%, was characterized by thymol (26.12%) and carvacrol (25.31%) as the main components. The encapsulated particles presented spherical morphology with regular and homogeneous external surfaces, ranging from 60 to 130 nm in diameter. Laboratory bioassays estimated the contact LC50 of
The antifeedant activity of nanoemulsion formulation of arugula Eruca sativa Mill. oil was studied against elm leaf beetle Xanthogaleruca luteola (M?ller)(Col.: Chrysomelidae chrysomelidae Subject Category: Organism Namessee more details) under laboratory conditions at 25?1 C, 75?5% RH, and LD 16: 8 hours. Ingestive LC 50 values of the oil were studied in third instar larvae. Then, physiological parameters were evaluated following 24, 48, and 72 hours post feeding at LC 50 level. LC 50 values 24, 48 and 72 hours after application were 4.940, 3.791, and 2.938 mg mL-1, respectively. Arugula oil at LC 50 level decreased the nutritional indices including efficiency of conversion of ingested food, relative growth rate growth rate Subject Categor
The sugar beet moth, Scrobipalpa ocellatella (Boyd), one of the most severe sugar beet pests, causes quantitative and qualitative yield losses late in the autumn. Previously, it was shown that low temperature and short‐day photoperiod together cause diapause induction in pupae. Here, the interaction of the critical elements of the diapause induction, including the period (PER), timeless (TIM), prothoracicotropic hormone (PTTH), and ecdysteroid titer, were investigated. Immunohistochemistry results showed that the number of period immunoreactivity (PER‐ir) and TIM‐ir cells in nondiapause pupae (NDP) was lower than in the brain of the diapause pupae (DP). Moreover, the number of PER‐ir and TIM‐ir cells in the protocerebrum and opti
The Russian wheat aphid Diuraphis noxia (Kurdjumov) and melon aphid Aphis gossypii Glover are known as winter and summer active species, respectively. It is hypothesized that differences in the aphids’ seasonal activities might be related to their response to temperature extremes and different physiological mechanisms. To study the aphids’ thermal tolerance variations and mode of their physiological basis, they were cold acclimated at 20, 15, 10, 5, and 0??C for 168?h (7 days) and heat acclimated at 20, 25, 30??C for 168?h and 35??C for 48?h. At the end of each thermal regime, survival at low and high temperatures was determined, and changes in sugars and polyols and heat shock protein 70 (Hsp70) were investigated. D. noxia was more col
The antifeedant activity of nanoemulsion formulation of arugula Eruca sativa Mill. oil was studied against elm leaf beetle Xanthogaleruca luteola (M?ller)(Col.: Chrysomelidae) under laboratory conditions at 25?1?C, 75?5% RH, and LD 16: 8 hours. Ingestive LC50 values of the oil were studied in third instar larvae. Then, physiological parameters were evaluated following 24, 48, and 72 hours post feeding at LC50 level. LC50 values 24, 48 and 72 hours after application were 4.940, 3.791, and 2.938 mg mL-1, respectively. Arugula oil at LC50 level decreased the nutritional indices including efficiency of conversion of ingested food, relative growth rate, efficiency of conversion of digested food, and relative consumption rate, but increased feedi
The diamondback moth, Plutella xylostella (L.)(Lepidoptera: Plutellidae) is one of the most destructive insect pests, feeding exclusively on wild and cultivated cruciferous species. The attacked plants produce considerable amount of glucosinolates in response to insects’ feeding. Herein, we studied digestive activities of P. xylostella on four different genotypes of family Brassicaceae including two canola cultivars (SLM046 and RGS003) and two cabbage cultivars (Green-Cornet and Glob-Master). The highest proteolytic and amylolytic activities of P. xylostella were observed on Green-Cornet and the lowest occurred on RGS003 and Glob-Master, respectively. The highest activity of α-glucosidase and β-glucosidases were observed on Green-Cornet
The two-spotted spider mite (TSSM), Tetranychus urticae Koch (Acari: Tetranychidae) is a serious pest of many greenhouse crops such as bean, cucumber, rose and other products. The control of this important pest has been mainly based on the use of acaricides. Phytoseiid mites are used mostly for biological control of pest mites. In this study, control of TSSM by phytoseiid predatory mites, Phytoseiulus persimilis Athias-Henriot, Amblyseius swirskii Athias-Henriot and Neoseiulus californicus McGregor was evaluated on four rose varieties including Avalanche, Dolcevita, Samurai and Sorbet in a commercial rose greenhouse. The total number of motile stages and eggs of each studied species on a leaf were counted weekly, through a zigzag sampling p
For effective integrated pest management (IPM) programs, it is essential to determine the thermal requirements and apply an accurate forecasting method based on daily degree units of pests. The present study investigated the physiological time (Degree-Days) and the number of generations of tomato leaf miner (TLM), Tuta absoluta (Meyrick) in Varamin region (Tehran, Iran) on two tomato cultivars (Cal JN3 and Early Urbana Y) under field-cage and open-field conditions during tomato growing seasons in 2015 and 2016. The environmental temperature was recorded hourly using an electronic data logger. The results indicated that TLM completed three generations during tomato growing seasons on the two tomato cultivars in both years. Degree-days for ea
Organisms are often exposed to various stresses such as heat. The diamondback moth, Plutella xylostella (L.)(Lepidoptera: Plutellidae) is a serious pest of cruciferous crops in Iran and the world. The effect of short-term temperature stress on egg stage of P. xylostella and its demographic parameters were studied under laboratory conditions. Diamondback moth eggs were exposed to 30, 35 and 40 C for durations of 2, 4, 6, 8 h and then returned to normal temperature condition (25 C). The results showed that P. xylostella eggs successfully developed to adulthood at short-term (2, 4, 6 and 8 h) high temperatures stress. The ovipositional period was significantly longer at 30 C for 8 h, 35 C for 2 h and 40 C for 4 h than for other periods of stre
The effect of different wheat cultivars (Pishtaz, Pishgam, Parsi, Sivand, Sirvan, Tajan, Zarrin, Alvand, Shahriar and Darya) on the life table parameters of the aphid Rhopalosiphum padi (L.) and its parasitoid Aphidius matricariae Haliday was determined based on the age-stage, two-sex life table theory. All experiments were implemented in a growth chamber at 25???1??C, 60???5% RH and a photoperiod of 16?L: 8 D hours. The results revealed that different wheat cultivars significantly affected development time and population parameters of the second (aphid) and third (parasitoid) trophic levels in a tritophic system. The shortest development time of R. padi was observed on both Pishgam (5.00???0.13?d) and Alvand (5.03???0.08?d). The longest de
Better performance of generalist predators, as well as an increase in their density, may be an incentive factor in the ability of the predators to exploit more than one food item or mixed diets. In this study, the effects of four pollen grains (cedar, pear, apricot, and pistachio) when provided to Neoseiulus californicus in mixed diets with prey, Tetranychus urticae, were evaluated. The result indicated that the fastest female developmental time was observed on pistachio pollen + T. urticae, together with apricot pollen + T. urticae. Females reared on the mixed diet comprising pistachio pollen reflected the longest total life span duration, while the shortest total life span was observed in those on the diet that included pear pollen. Furth