Comparative life table of Aphis craccivora (Hem.: Aphididae) on host plant, Robinia pseudoacacia under natural and laboratory conditions

-The cowpea aphid, Aphis craccivora Koch, is an important pest of Robinia pseudoacacia Frisia. Life table parameters of A. craccivora were determined under natural (16- 33ºC and 32-89% RH, respectively) and laboratory (25 ± 1ºC, RH of 70 ± 5% and a photoperiod of 16:8 h (L: D) conditions. The data were analyzed using the age-stage, two-sex life table theory. Each experiment was replicated 45 times for each condition. There was significant differences between the survivorship, fecundity and longevity of the A. craccivora in laboratory and natural conditions. Under natural conditions, A. craccivora had a significant shorter nymphal developmental time, adult longevity and life span than those reared under laboratory conditions. However, the intrinsic rate of increase (r), net reproductive rate (R0), the finite rate of increase (λ) and gross reproductive rate (GRR) under laboratory conditions, were higher than those obtained in field, the higher mean generation time (T) was found in the field. All in all, the results of this study showed that two different conditions (field and laboratory) had significant influence on developmental times and life table parameters of A. craccivora and it is hard to escape the obvious conclusion that we must prevent the unsuitable extrapolation of laboratory results to field applications. The results obtained here, could also help us to understand the population dynamics of A. craccivora under field condition and to develop effective integrated pest management (IPM) programs

Consumer decision making styles amongst young generation in Malaysia

Recently, the effect of external factors on consumer decision making styles (CDMS) and their importance to consumer behavior has investigated by some of researchers. There are two main objectives of this study. Firstly, to examine (CDMS) of young generation in Malaysia; the research used Sproles and Kendall's (1986) consumer style inventory (CSI) on a sample of 325 Malaysian females and males. External factors (demographic, geographic and group influence) have been applied to understand consumer decision making styles. As a result of the factor analysis, four factors found to be the most suitable representation of young-adults in this study:, the research demonstrated that there is a relationship between consumer decision making styles and purchase intention (PI)

Larval age-specific searching efficiency of Aphidoletes aphidimyza (Dip.: Cecidomyiidae) preying on different densities of Aphis craccivora (Hem.: Aphididae)

Searching efficiency (a') (attack rate) and handling time are two major components of natural enemiesâ functional response and are usually used to evaluate their effectiveness. The age-specific searching efficiency of Aphidoletes aphidimyza (Rondani) was studied during its larval stage. The experiment was conducted in terms of age-specific functional response to the varying density (5, 10, 20, 40, 60 and 80) of third instar nymphs of Aphis craccivora (Koch) at 23 ± 1 °C, 70 ± 5% R.H. and a photoperiod of 16: 8 h (L: D). Parameter estimates for logistic regressions showed a type III functional response at all larval ages to the varying density of A. craccivora. The age-specific handling times (Th) were estimated using Rogers random-attack equation, varied with the age of larval predator. The searching efficiency showed a similar and increasing trend at all predator larval ages. The estimated maximum rates of predation (T / Th) for the total larval stage were inversely related to prey density. It was concluded that A. aphidimyza, with type III functional response in all its larval stage, could be considered as a highly effective biological agent in suppressing and regulating A. craccivora population

Prey Density Dependent Life Table of Aphidoletes Aphidomyza Rondani (Dip., Cecidomyiidae) Feeding on Aphis Craccivora Koch (Hem., Aphididae) under Laboratory Conditions

The life table provides an integrated and comprehensive description of development times, survivorship, and reproduction of a population. Life table parameters of aphidophagous midge, Aphidoletes aphidimyza Rondani (Dip., Cecidomyiidae) on different densities (5, 10, 20, 40, 60, 80) of third instar nymphs of Aphis craccivora Koch as prey, were studiedat (25±1°C, 70±5% relative humidity (RH) and a photoperiod of 16L : 8D h). There were no significant differences among the adult pre-ovipositional periods (APOP) at different prey densities. The total pre-ovipositional period (TPOP) of female A. aphidimyza was reduced significantly as prey density increased. The oviposition period was significantly different at varying prey densities. It was 4.333±0.211 and 5.625±0.324 days at the lowest and highest prey densities, respectively. Female longevity was also significantly different at varying prey densities. Fecundity was directly dependent on prey density (R2 = 0.990). The lowest fecundity was obtained at a density of 5 prey (52.5±1.544 eggs) and the highest was at a density of 80 prey, per day (121.375±4.301 eggs). The intrinsic rate of increase (r) was prey density dependent (R2 = 0.958), and ranged from 0.122±0.017 to 0.193±0.014 d-1 as prey density increased. The net reproductive rate (R0) was significantly increased as prey density increased. The peak reproductive values showed that female aphidophagous midges at the age of 15, 16, 17, 18, and 19 days made the highest contribution to the population at different prey densities. It was concluded that the increase in the densitits of third instar nymphs of A. craccivora had significant effects on demographic parameters of A. aphidimyza

OccupationalHearing NImpairmentoise-induced Hearing Loss and Hypertension Associated with Long Term Occupational Exposure to Noise

Background and aims  &nbsp;Noise induced hearing loss is a permanent,usually, bilateral hearing  impairment due to long term exposure to high levels of noise and exposure of workers to noise  represents one of the most common occupational hazards. Although noise has also been suggested  to increase the prevalence of hypertension, evidence for this association is not conclusive. This historical cohort study was undertaken to evaluate the auditory effects of noise and to further examine the hypothesis that a link between noise exposure and hypertension exists.   Methods  &nbsp;The study population consisted of 140 healthy male employees from a local petrochemical industry with history of past and present exposure to noise and 140 matched healthy male unexposed individuals from the same industry (referent group). Aquestionnaire with 40 questions concerning age, sex, weight, height, length of employment, workplace noise  level and history of hypertension was administered. Furthermore, subjects were physically examined, their blood pressure were taken under normal resting position and underwent audiometry testing. Similarly, sound pressure level and octave band analyzing in different stations  of workplace carried out for every employee, and then Leq calculated. Data were analyzed by  SPSS 13, using student's t test and Chi-square.   Results   The prevalence of hearing impairment in this study was 38.5 percent among exposed  and 7.8 percent among unexposed group and the difference was statistically significant  (p<0.0001). Similarly, the prevalence of hypertension in exposed group was significantly higher  than that of unexposed group.   Conclusion   These findings while provide corroborative evidence to further substantiate the  notion that exposure to noise is associated with hearing impairment, they also support the  proposition that long term occupational exposure to noise appears to be a risk factor for arterial hypertensio

NT-4 Gene Expression of Male Wistar Rat’s Sciatic Nerve Fiber: The Effect of Decreased Activity on the Form of Spinal Nerve Ligation

Background & Objectives: Painful neuropathy is a state resulting from somatosensory disease or injury. Neurotrophins such as NT-4 are crucial for neural growth and development and protect the integrity of function and structure of nervous system. Paying heed to the importance of physical activity in neural plasticity, this study focuses on the investigation of chronic effect of decreased activity on the form of spinal nerve ligation on NT-4 gene expression of male Wistar rat&rsquo;s sciatic nerve fiber. Materials & Methods: Ten adult male Wistar rats in the weight range of 250&plusmn;30 gr were randomly divided into two groups, including one healthy control group (C) and one group with decreased physical activity (SNL). Over six weeks, neuropathic pain behavior tests were conducted continually in both groups. At the end of the sixth week, the changes in NT-4 gene expression in sciatic nerve were measured with Real time technique. Results: The behavioral tests demonstrated that spinal nerve ligation induced thermal hyperalgesia and mechanical allodynia in the SNL group. Decreased pain threshold was observed throughout the study period (p<0.05). Additionally, in comparison with the C group, NT-4 gene expression in sciatic nerve fiber was significantly higher in the SNL group (p<0.05). Conclusion: In the present study, it was discovered that the decreased activity in the form of SNL is associated with increased NT-4 gene expression in the experimental group. With respect to the physiologic functions of NT-4 in nervous system, this elevation is probably a mechanism for neurogenesis in the injured area, and based on the previous studies, it seems that the increased activity could enhance the increased NT-4 gene expression and accelerate neurogenesis