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1.
Demographic parameters of Diuraphis noxia (Mordvilko) and its parasitoid, Diaeretiella rapae (McIntosh) were investigated under laboratory conditions at temperatures of 20 ± 1°C, 60 ± 5% relative humidity of 60 ± 5% and a photoperiod of 16: 8 (light: dark) hours. The survival rates (lx ) and the life expectancy (ex ) at the beginning of adult emergence were 86% and 25.81 days for D. noxia and 100% and 7.36 days for D. rapae, respectively. Based on the Weibull distribution parameters, the survival curves were type I for both D. noxia and D. rapae, which indicates that mortality mostly occurred in older stages. The r m-values in aphid and parasitoid were obtained as 0.22 ± 0.002 and 0.19 ± 0.003 day?1, respectively. Mean generation time (T) and doubling time (DT) were 15.93 ± 0.202 and 3.15 ± 0.031 days for the aphid and 15.33 ± 0.071 and 3.67 ± 0.054 days for the parasitoid, respectively. The R0 -values of D. noxia and D. rapae were evaluated 33.19 ± 0.961 and 18.07 ± 0.761 females/female/generation, respectively. The gross and net fecundity rates were 59.21 ± 1.94 and 32.825 ± 0.972 nymphs/female/day for the aphid and 37.59 ± 1.46, and 33.8 ± 1.51 eggs/female/day for the parasitoid, respectively. The results of this research indicated that D. rapae is an adequate parasitoid for control of Russian wheat aphid.  相似文献   

2.
Greenbug, Schizaphis graminum (Rondani), is one of the injurious aphids of cereals in various regions of the world. This study has measured the life table parameters of the greenbug on six barley genotypes at 25 ± 2 °C, 55 ± 10% RH and 16:8 L:D in greenhouse. According to the results, significant differences were not observed for aphids’ developmental times among the genotypes. Also, the nymphs underwent no mortality on any of the tested genotypes. The longevity of the aphids was obtained from 23.7 to 35.9 days. The least mean number of offsprings was on Raihan cultivar and the highest on line13 (Legia/CWB117-5-9-5). R0 value was significantly higher on line 20 (Mall-4-3094-2//Alpha/Cum/3/Victoria/ICB01-1368-0AP) and line 13 than on the Raihan cultivar. However, the rm and λ values were significantly higher on line 44 (Sls/Bda//Sararood-1) than on Raihan cultivar. T (mean generation time) and DT (doubling time) values of the Raihan cultivar were longer than the other genotypes. Results of this research indicated that among the tested genotypes, the Raihan cultivar is the most unsuitable host for greenbug aphid and lead to the decrease of greenbug population growth.  相似文献   

3.
To understand the influence of four mulberry varieties on the development and reproduction of the European red spider mite, Panonychus ulmi (Koch) (Prostigmata: Tetranychidae), age-stage two-sex life tables of P. ulmi on Goshoerami, KNG, Chinese white and Rokokuyaso varieties were constructed under ambient laboratory conditions during summer season of the year with an average temperature of 26.22 ± 2.23 °C, relative humidity of 70 ± 5% and photoperiod of 14:10 h (L: D). Panonychus ulmi developed comparatively better on KNG and Goshoerami varieties than the other two varieties, as indicated by high fecundity (45.05 ± 1.89 and 41.23 ± 1.66 eggs female?1, respectively) and intrinsic rate of increase (0.165 ± 0.01 and 0.168 ± 0.03 day?1, respectively). Lowest intrinsic rate of increase (r) was observed on Chinese white and Rokokuyaso (0.055 ± 0.03 and 0.057 ± 0.10 day?1, respectively). Total development time of immature females was shortest on KNG than on the other varieties. Immature survival was significantly higher on KNG and Goshoerami varieties (76.76 ± 7.59 and 72.96 ± 8.21%, respectively) and was lower on Chinese white and Rokokuyaso (46.76 ± 9.00 and 43.32 ± 8.71%, respectively). Based on all the above parameters, KNG and Goshoerami were found as most suitable varieties for P. ulmi than Chinese white and Rokokuyaso.  相似文献   

4.
Genetic variability among 122 Rhynchosporium secalis isolates collected from barley in three regions of Tunisia was investigated using host differentials, amplified fragment length polymorphism (AFLP), and microsatellite markers. The isolates were collected from a widely grown scald-susceptible barley cultivar Rihane and a range of local landrace cultivars in geographically distinct regions with different agroclimatic conditions. Pathotypic diversity (the proportion of unique pathotypes) was high in R. secalis populations from the high (100% diversity), moderate (95%), and low (100%) rainfall areas of Tunisia, and from both Rihane (which is the sole variety grown in the high rainfall region) and local landraces (which predominate in the low rainfall area). This may reflect a general adaptability for aggressiveness and suggests that the widely grown cultivar Rihane has exerted little or no selection pressure on the pathogen population since its release in 1983. Genotypic diversity (GD), defined as the probability that two individuals taken at random had different genotypes, was high for populations from Rihane, local landraces, and different agro-ecological zones (GD = 0.96–0.99). There was low genetic differentiation among pathogen populations from different host populations (G ST ≤ 0.08, θ ≤ 0.12) and agro-ecological zones (G ST ≤ 0.05, θ ≤ 0.04), which may be partly explained by gene flow due to the movement of infected stubble around the country. There was no correlation (r = 0.06, P = 0.39) between virulence phenotype and AFLP haplotype. A phenetic tree revealed groups with low bootstrap values that did not reflect the grouping of isolates based on host, pathotype, or agro-ecological region. The implications of these findings for R. secalis evolutionary potential and scald-resistance breeding in Tunisia are discussed.  相似文献   

5.
Chrysoperla carnea (Steph.) is a general predator reared in industrial scale. Different eggs of moth were used to rear C. carnea, but stabled moth colony needed expensive equipment and is costly. In this research, we surveyed appropriate diet to mass rearing. For this purpose, 100 same old (24H) eggs of C. carnea, separately, were selected randomly from the mass culture of C. carnea which was reared on the egg of flour moth Anagasta kuehniella (Zeller), artificial diet and semi-artificial diet under laboratory conditions (25 ± 5°C, 65 ± 5% RH and L–D: 16–8). These results showed reduction process ex (expectation of life table at age X) and the survival curve was convex (K-Strategy). Also Lx in appearing of adults that fed on egg of flour moth, artificial diet and semi-artificial diet were 0.76, 0.4 and 0.9 which implied that 24, 60 and 10% of cohort were dead before reaching adult stage. Eggs produced by each female were recorded daily until all females died. The parameters were estimated using Carey’s (1993) method. Gross (GRR) and net (R0) reproductive rates of predator on A. kuehniella, artificial diet and semi artificial diets were 225.5 ± 3.45, 72.4 ± 3.5, 267.8 ± 4.8 and 180.12 ± 2.3, 24.33 ± 4.3, 254.05+3.3 (female/female/generation), respectively. Mean generation time (T), Doubling time (DT), Intrinsic rate of increase (rm ) and Finite rate of increase (λ) of predator on A. kuehniella, artificial diet and semi artificial diet were 31.9 ± 0.71, 42.87 ± 0.45, 29.79 ± 0.57 (days); 4.27 ± 0.03, 9.36 ± 0.06, 3.74 ± 0.05 (days); 0.162 ± 0.001, 0.074 ± 0.003, 1.185 ± 0.002; and 1.175 ± 0.001, 1.076 ± 0.002, 1.203 ± 0.002 (female/female/day), respectively. This research indicated that semi-artificial diet is a suitable prey for the predator.  相似文献   

6.
Efficiency of imidacloprid and thiametoxam on population growth parameters of Aphis gossypii Glover (Hemiptera: Aphididae) was assessed using three bioassay methods including; residual, starvation and FAO dip methods. Aphids were assayed under laboratory conditions at 23 ± 2°C, photoperiod of 16:8 (L:D) and 70% relative humidity. Aphids were transferred to sprayed leaves and Petri dishes in residual and starvation methods, respectively. There was no feeding for the aphids in starvation method. In FAO dip method, insects were dipped for 5 s in pesticide solutions and then transferred to fresh leaves. Results revealed that LC50 values calculated with the starvation and residual methods were respectively 15 and 11% more than FAO dip method (for imidacloprid) and 22 and 18% (for thiametoxam). The LC50 value in starvation method was 3% more than the residual method. Calculated LC50 in starvation and residual methods with imidacloprid respectively caused 160 and 34% increase in intrinsic rates of increase (r m) and net reproductive rate (R 0) in comparison with FAO dip method. Generation time (T) and doubling time (DT) were respectively 59 and 62% less than those in FAO dip method. In contrast, thiametoxam (LC50 concentration) in starvation and residual method lead to 9 and 67% increase in r m and R 0 parameters compared to FAO dip method. However T and DT were respectively 65 and 92% less than mentioned parameters in FAO dip method. There was not any significant difference between life table parameters calculated by residual and starvation bioassay methods.  相似文献   

7.
We focused on the influence of different temperature amplitudes on development and reproduction of the two-spotted spider mite, Tetranychus urticae Koch, at a 16:8 (L:D) h photoperiod and 60–95 % RH. The temperature amplitudes varied from 0 to 24 °C in steps of 6 °C; i.e. 22 ± 0, 22 ± 3, 22 ± 6, 22 ± 9 and 22 ± 12 °C. Temperature changed every 24 h between a low and an upper value, but without changing the average temperature (22 °C). The number of eggs laid by five females for 24 h was slightly lower at 22 ± 12 °C than at constant temperature (22 ± 0 °C), and egg hatchability differed among the five temperature regimes. Developmental time at 22 ± 0 °C was shorter than that at 22 ± 3 and 22 ± 6 °C, but longer than that at 22 ± 9 and 22 ± 12 °C. The oviposition period, total fecundity per female and adult longevity gradually decreased with increasing amplitudes. Sex ratio was similar at all five temperature regimes. The intrinsic rate of natural increase (r m) was affected by temperature amplitude and the r m-values at all amplitudes except 22 ± 12 °C were higher than that at constant temperature. Thus, this study showed that variable temperature regimes influence population growth rates of T. urticae and that large amplitude regimes are stressful for this species.  相似文献   

8.
The greenbug, Schizaphis graminum (Rondani) (Hemiptera: Aphididae) has been known as a major pest of small grains, particularly wheat, worldwide. In this study, the effect of new wheat cultivar (Pishgam) for cold regions on biological characteristics of greenbug was investigated in a greenhouse at 25 ± 2 °C, 55 ± 10% relative humidity and a photoperiod of 16:8 h (L:D). The raw data were analysed based on the age-stage, two-sex life table. The intrinsic rate of increase (r), the finite rate of increase (λ), the net reproduction rate (R0) and the mean generation time (T) of greenbug were 0.313 ± 0.0019, 1.36 ± 0.0027 females/female/day, 83.33 ± 0.331 females/female and 14.11 ± 0.09 days, respectively. The life expectancy of a nymph is 43.57 days. The maximum reproductive value of females is on the 16th day which coincides with the total pre-reproduction period counted from birth. Hence, the present results may provide helpful information for comprehensive IPM programme of greenbug on this variety in cold regions of Iran. Result revealed that nymphal survival rate of the aphid was 100% on studied cultivar like that on sensitive host plant cultivar.  相似文献   

9.
Green peach aphids, Myzus persicae (Sulz.) (Hemiptera: Aphididae), obtained from pepper fields, were colonized on susceptible pepper plants in a growth chamber. The development, survivorship, and life table parameters of the green peach aphid were evaluated on nine peppers cultivars as follows: Almuden, Bilano, Bird, Cabezo, de la Sierra, Eppo, Jaen, Raza, and Yatasto at controlled conditions (20?±?1°C; about 70% RH; 14h photophase). The development times of immatures ranged from 6.1 days on Yatasto to 11.4 days on Jaen, whereas immature survival was close to 100% on all cultivars. The intrinsic rate of increase (r m ) for green peach aphid on Bilano and Yatasto were the highest. Jackknife estimates of r m varied from 0.281 to 0.174 females/female/day on Yatasto and Jaen, respectively. The mean population generation times (T) on these hosts ranged from 13.7 to 22.7 days. The highest net reproductive rates (R 0 ) were on Bird and Bilano (63.8 and 62.89 females/female/generation, respectively) and the lowest on De la Sierra and Almuden (34.1 and 38.7, respectively). Because of the high coefficient of determination (R 2) values in Gompertz and Weibul models, survival data from different cultivars had a good fit to both models. The results pointed Jaen, Almuden, and Raza cultivars as the least suitable host plants, indicating that they were the most resistant to M. persicae among the cultivars we tested.  相似文献   

10.
Lysiphlebus testaceipes (Cresson) (Hymenoptera: Braconidae, Aphidiinae) has constituted a well-studied parasitoid insect model, but very little is known about the host-instar suitability of aphid for the wasp so far. One of the hosts of L. testaceipes is Aphis gossypii Glover (Hemiptera: Aphididae). The latter is a serious aphid pest to vegetable production in Benin. Therefore, the objectives of our study were to: (1) examine the oviposition behavior of L. testaceipes on A. gossypii; (2) investigate the host-instar suitability of A. gossypii for L. testaceipes; and (3) compare the life table parameters of A. gossypii with aphids parasitized by L. testaceipes and unparasitized aphids (control). The study was conducted in a laboratory at 26 ± 1 °C in petri dishes and revealed that the parasitoid utilized up to seven stabbing stings to handle and oviposit, particularly in older A. gossypii. In aphids parasitized at the third instar, the net reproductive rate R o as well as the intrinsic rate of natural increase r m was significantly lower (2.119 ± 0.272 and 0.110 ± 0.018) compared to the control (15.529 ± 1.287 and 0.272 ± 0.008), respectively (p < 0.01).  相似文献   

11.
Gaeolaelaps aculeifer (Canestrini, 1883) is a soil-dwelling predatory mite with potential for use as a biological control agent of fungus gnats (Diptera: Sciaridae) in mushroom production. The life table, predation rate and population growth rate of G. aculeifer on a diet of larvae of the sciarid fly, Lycoriella auripila, at 23?±?1°C, 60?±?5% RH and a photoperiod of 0:24 (L:D)?h was investigated. The results revealed that the duration of egg, larva, protonymph, deutonymph, females and males of G. aculeifer were 3.8?±?0.1, 1.4?±?0.1, 3.9?±?0.1, 4.1?±?0.1, 67.7?±?2.8 and 60.3?±?3.1 days, respectively. Net reproductive rate (R0) was 54.8?±?7.1 offspring, intrinsic rate of increase (r) was 0.12?±?0.01 offspring day?1, finite rate of increase (λ) was 1.13?±?0.01 day?1and mean generation time (T) was 32.3?±?0.6 days. The predator consumed a mean of 0.08?±?0.05, 1.73?±?0.18, 3.16?±?0.28 and 75.9?±?7.1 third instar L. auripila larvae during the larval (1.3?±?0.1 days), protonymph (3.9?±?0.1 days), deutonymph (4.1?±?0.1 days) and adult (52.6?±?2.2 days) stages. Population parameters and consumption rates suggest that G. aculeifer has good potential as a biological control agent of L. auripila in mushroom production.  相似文献   

12.
Fertility life table parameters were assessed for five populations (strains) of two Trichogramma species, T. embryophagum Hartig and T. principium Sugonyaev & Sorokina, collected from eggs of the carob moth Ectomyelois ceratoniae (Zeller) in Iranian pomegranate orchards. Four combinations of two constant temperatures (25°C, 30°C) and two relative humidity levels (50% RH, 70% RH) were used. The overall intrinsic rate of natural increase (rm) was significantly decreased with decreased relative humidity but was uninfluenced by temperature. The highest and lowest rm values were observed in T. embryophagum from Qum (0.34 ± 0.004) and T. embryophagum from Varamin (0.13 ± 0.01), respectively. Two‐way interaction analyses revealed that the strains had significantly different responses in their rm values at different temperatures and relative humidities. In general, rm values were significantly higher at 25°C and 70% RH than at 30°C and 50% RH. The Qum strain of T. embryophagum was the most promising candidate to be considered as a biocontrol agent against E. ceratoniae due to its high reproductive rate (0.27 ± 0.01) at conditions (30°C and 50% RH) similar to the actual climatic conditions in Iranian pomegranate orchards during the major part of the growing season.  相似文献   

13.
Proteins from the fresh roots of Stemona tuberosa (Stemonaceae) were extracted into 20 mM phosphate buffer, pH 7.2/0.1 M NaCl, precipitated with 90% saturation ammonium sulfate, and enriched by diethylaminoethanol (DEAE) cellulose. The protein eluted as a single main peak from the unbound fractions (ST-1), and appeared as a single band with superoxide dismutase (SOD) activity after native polyacrylamide gel electrophoresis (PAGE) resolution and zymogram development. ST-1 was classified as SOD due to its strong inhibition by HCN and H2O2. The amino acid sequence of three tryptic peptides of ST-1 matched with the SOD isozymes from Ananas comosus and Solanum lycopersicum. The SOD consisted of at least two heterologous protein subunits with molecular mass of 17.6 and 31.5 kD, respectively, and had an optimal SOD activity at pH 5 and over a temperature range of 0–50°C. MgCl2, MnCl2, and HgCl2 were strongly inhibitory at all concentrations tested. The SOD activity was completely negated in the presence of 0.5 mM SDS or 5 mM HgCl2. The relationship between riboflavin and nitroblue tetrazolium (NBT) on SOD activity was linear, giving K m and V max values of the purified SOD of 62.414 ± 0.015 M and 101.010 ± 0.022 µmol/min/mg protein for NBT and 27.389 ± 0.032 M and 38.167 ± 0.021 µmol/min/mg protein for riboflavin, respectively.  相似文献   

14.
The English grain aphid, Sitobion avenae (Fabricius), is a severe pest of wheat plants in temperate countries. Therefore, we carried out primary screening to assess the resistance or susceptibility of 23 commonly grown wheat varieties to this aphid at greenhouse and laboratory conditions in Iran. Also, population attributes of this aphid were evaluated on six wheat varieties, namely Saysonz, Arta, Moghan3, Zagros, Sardari and Shirodi. The aphids were colonized on the Hirmand wheat variety in a growth chamber at 20 ± 1°C, 60 ± 5% R.H. and a photoperiod of 14:10 (L:D). The tested varieties were grouped into three major classes including A (e.g., Shirodi, Falat and Moghan2), B (e.g., Sardari, Zagros and Tagan) and C (e.g., Arta, Saysonz, Moghan3 and Pishtaz). Also, the results of the life history traits showed that the developmental time of nymphal stage ranged from 7.5 days on Zagros to 10.8 days on Saysonz. The intrinsic rate of increase (r m ) of S. avenae varied from 0.133 (day−1) on Saysonz to 0.210 (day−1) on Shirodi. Jackknife estimates of other population parameters on these varieties were evaluated. As a result, our findings showed that the varieties Saysonz, Arta and Moghan3 were partially resistant against S. avenae, whereas Shirodi, Zagros and Sardari were relatively susceptible.  相似文献   

15.
The present study investigated the magnitude of diurnal variation in back squat and bench press using the MuscleLab linear encoder over three different loads and assessed the benefit of an active warm-up to establish whether diurnal variation could be negated. Ten resistance-trained males underwent (mean ± SD: age 21.0 ± 1.3?years, height 1.77 ± 0.06?m, and body mass 82.8 ± 14.9?kg) three sessions. These included control morning (M, 07:30?h) and evening (E, 17:30?h) sessions (5-min standardized warm-up at 150?W, on a cycle ergometer), and one further session consisting of an extended active warm-up morning trial (ME, 07:30?h) until rectal temperature (Trec) reached previously recorded resting evening levels (at 150?W, on a cycle ergometer). All sessions included handgrip, followed by a defined program of bench press (at 20, 40, and 60?kg) and back squat (at 30, 50, and 70?kg) exercises. A linear encoder was attached to an Olympic bar used for the exercises and average force (AF), peak velocity (PV), and time to peak velocity (tPV) were measured (MuscleLab software; MuscleLab Technology, Langesund, Norway) during the concentric phase of the movements. Values for Trec were higher in the E session compared to values in the M session (Δ0.53?°C, P < 0.0005). Following the extended active warm-up in the morning (ME), Trec and Tm values were no different to the E values (P < 0.05). Values for Tm were lower in the M compared to the E condition throughout (P < 0.05). There were time-of-day effects for hand grip with higher values of 6.49% for left (P = 0.05) and 4.61% for right hand (P = 0.002) in the E compared to the M. Daily variations were apparent for both bench press and back squat performance for AF (3.28% and 2.63%), PV (13.64% and 11.50%), and tPV (?16.97% and ?14.12%, where a negative number indicates a decrease in the variable from morning to evening). There was a main effect for load (P < 0.0005) such that AF and PV values were larger at higher masses on the bar than lower ones and tPV was smaller at lower masses on the bar than at higher masses for both bench press and back squat. We established that increasing Trec in the M–E values did not result in an increase of any measures related to bench press and back squat performance (P > 0.05) to increase from M to E levels. Therefore, MuscleLab linear encoder could detect meaningful differences between the morning and evening for all variables. However, the diurnal variation in bench press and back squat (measures of lower and upper body force and power output) is not explained by time-of-day oscillations in Trec.  相似文献   

16.
Objectives: To evaluate the effect of ubiquinone and combined antioxidant therapy on mitochondrial function in non-proliferative diabetic retinopathy (NPDR) in a randomized, double-blind, phase IIa, placebo-controlled, clinical trial. Three groups of 20 patients were formed: Group 1, ubiquinone; Group 2, combined therapy; and Group 3, placebo (one daily dose for 6 months).

Methods: Fluidity of the submitochondrial membrane in platelets was determined by examining intensity of fluorescence between the monomer (Im) and excimer (Ie). Hydrolytic activity of the mitochondrial F0F1-ATPase was evaluated with the spectrophotometric method.

Results: Normal, baseline submitochondrial membrane fluidity, 0.24 ± 0.01 Ie/Im, was significantly diminished in the three study groups vs. normal values (P < 0.0001); placebo, 0.14 ± 0.01 Ie/Im; ubiquinone, 0.14 ± 0.01 Ie/Im; and combined therapy, 0.13 ± 0.00 Ie/Im. Afterward, it increased significantly (P < 0.0001), the ubiquinone group 0.22 ± 0.01 Ie/Im, combined therapy group, 0.19 ± 0.01 Ie/Im; with no changes the placebo group. Baseline hydrolytic activity of the F0F1-ATPase enzyme increased in the three study groups vs. normal values (184.50 ± 7.84 nmol PO4), placebo, 304.12 ± 22.83 nmol PO4 (P < 0.002); ubiquinone, 312.41 ± 25.63 nmol PO4 (P < 0.009); and combined therapy, 371.28 ± 33.50 nmol PO4 (P < 0.002). Afterward, a significant decrease the enzymatic activity: ubiquinone, 213.25 ± 14.19 nmol PO4 (P < 0.001); and combined therapy, 225.55 ± 14.48 nmol PO4 (P < 0.0001).

Discussion: Mitochondrial dysfunction significantly improved in groups of NPDR patients treated with antioxidants.  相似文献   

17.
The predatory mite Typhlodromips swirskii (Athias–Henriot) is commonly used to suppress pest populations of thrips and whitefly in commercial greenhouses. Many generalist phytoseiid mites can be reared on astigmatid factitious prey. This study investigated the life table parameters of T. swirskii to the astigmatid mite Suidasia medanensis (Oudemans) and the capture success ratio of T. swirskii to different life stages of the prey. Juvenile development time and survival was 5.01 ± 0.10 days and 93 %, respectively. The intrinsic (r m ) and finite (λ) rates of increase were 0.222 and 1.249, respectively, with average oviposition rate of 1.71 ± 0.07 eggs/female/day. The capture success ratio of T. swirskii to S. medanensis was: eggs > freeze killed adults > nymphs > live adults. Typhlodromips swirskii was concluded to exhibit good population growth rates with S. medanensis as prey and, a prey population with predominance of eggs and nymphs to be advantageous to the predator due to an unidentified defence mechanism of adult prey.  相似文献   

18.
The effect of five African nightshade (Solanum sp.) species on the biological and demographic parameters of the tomato spider mite, Tetranychus evansi Baker and Pritchard, was examined in the laboratory at 25 ± 1°C, 70–80% RH and 12L:12D photoperiod. Duration of each development stage, reproduction rate, longevity, intrinsic rate of natural increase (r m), and doubling time (DT) of the tomato spider mite on the five nightshade species were calculated. The results indicated that S. villosum, S. scabrum, S. tarderemotum and S. americanum are more suitable for T. evansi due to a shorter developmental period, longer adult longevity, higher reproduction and intrinsic rate of natural increase ranging between 0.180 and 0.196 females/female/day compared with S. sarrachoides which cannot support T. evansi populations as the r m (−0.063 females/female/day) and DT were negative on this host. Differences in developmental time and life table parameters among the other host plants were not significant.  相似文献   

19.
Demographic statistics for the ladybeetle Scymnus syriacus Marseul (Coleoptera: Coccinellidae) were investigated when reared on the green citrus aphid, Aphis spiraecola Patch (Homoptera: Aphididae), fed on two host plants: spirea (Spirea sp.) and Thompson orange (Citrus sinensis cv. Thompson) under laboratory conditions (25 ± 1°C, 65 ± 5% relative humidity and 16 h light : 8 h dark). Mean developmental times from egg to adult were 20.32 ± 0.18 and 22.07 ± 0.15 days for spirea and Thompson orange, respectively. The survival rate from egg to adult was higher for spirea (85%) than for Thompson orange (72.5%). The oviposition periods were 41.8 ± 2.47 and 39.71 ± 2.6 days and the total number of eggs per female were 657.6 ± 29.5 and 587.9 ± 32.6 on spirea and Thompson orange, respectively. Fertility life tables were also constructed to compare the effects of host plants. The intrinsic rate of increase (rm) on spirea was higher than that on Thompson orange. Jackknife estimates of rm varied from 0.149 on spirea to 0.133 on Thompson orange. The mean population generation times on these host plants were 38.16 and 40.65 days, respectively. These results indicate that spirea‐fed A. spiraecola is more suitable for S. syriacus, producing a higher survival rate and shorter developmental time.  相似文献   

20.
Two larval instars of Carcinops pumilio (Erichson) were identified from a frequency distribution of the head capsule measurements. The total developmental time from egg to adult emergence averaged 20.5 ± 0.1 days at 30 °C. The 2nd instar was the longest, accounting for 39% of the total development time. The 1st instar larvae sustained the highest mortality of 26% whilst there was no mortality in the pupal stage. The immature stages sustained about 50% mortality before adult emergence. The adult females of C. pumilio can live for 140 days and the rate of survival was high in the young adults but decreased as the beetles aged. Newly emerged adults survived for 25.5 ± 0.4 days without feeding. The sex ratio was 0.48 females: 0.52 males. The intrinsic rate of natural increase (rm) was 0.065, the generation time (T) was 50.019 days and the net reproduction rate (Ro) was 20.191.  相似文献   

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