تقی زاده

Life table parameters of Lipaphis erysimi (Kaltenbach) (Hemiptera: Aphididae) were determined on four canola (Brassica napus L.) cultivars (Nathalie, Neptune, Danube, and Okapi) at 25±1 ˚C, 60±5% RH, and 16L:8D hours photoperiods. Data were analyzed using the female age-specific life table. There were significant differences in duration of nymphal developmental time and fecundity of aphid on the experimental canola cultivars. The shortest (7.13±0.07 day) and longest (8.91±0.15 day) nymphal developmental time were on Nathalie and Okapi, respectively. The rm value of L. erysimi ranged between 0.30 on Nathalie and 0.21 day-1 on Okapi. The highest values of rm (0.30±0.00 day-1), R0 (30.62±1.35 offspring), finite rate of increase (1.35±0.01 day-1), and the lowest mean generation time (11.54±0.12 days) and DT (2.34±0.03 days) were recorded on Nathalie. Shorter nymphal developmental time, longer adult longevity as well as greater intrinsic rate of increase, net reproductive rates, finite rate of increase, fecundity and survivorship revealed that this pest performed well on Nathalie, Neptune and Danube cultivars. Consequently, the results indicated that canola cultivars had significant effect on life table parameters of L. erysimi and the Nathalie, Neptune, and Danube cultivars were suitable hosts for population growth of the pest.

Development of economic activities, population growth, people’s daily increasing business, and improvement of life standards has caused to increase in the demand for natural environments and tourism. The scarcity of these resources and insufficiency of capital resources for the reviving and establishing of the proper recreational environment, have orientated the management of natural resources to appraise the resources and to use people's participation. This study determines factors motivating visitors’ willingness to pay for Elgoli and Mashrouteh parks in Tabriz city. To this end, the contingent valuation method and two-stage Hekman approach are utilized. Also their willingness to pay to visit these parks is estimated. The required data gathered in summer 2008 through questionnaire and interviewing 261 visitors. The results revealed that monthly income, number of family members, sexuality, and degree of individual’s satisfaction from social security status, and the number of times that they visit the park over one year, are the effective factors. Moreover, the variables of duration each visit, monthly income, education and age of the visitors is identified as effective variables on the individual’s willingness to pay. The results showed that average of the willingness to pay is 2231 Rls for per visitor. Based on the results, the most effective variable is the satisfaction of social security. Therefore increasing the social security condition can be highly influence the attractive of these parks.