The seasonal abundance and population density of emerged moths of Synanthedon myopaeformis Borkh. (Lepidoptera : Sesiidae) from infested apple trees at Berket El Saba district, Menoufia governorate during 2015 and 2016 years exhibited that the emerged moths continued all year round where, nine emergence peaks were recorded throughout year months. The highest number of emerged moths was observed during the summer months (40.96% and 41.26% at 2015 and 2016 seasons, respectively) and the highest monthly percentage of emerged moths was recorded in August. The highest number of emerged moths were recorded at the basic stem region 0-50cm above the ground surface, while the least number of emerged moths was found at the height 150-200cm and there was significant positive correlation between minimum & maximum temperatures and number of emerged moths, while the correlation was negative between RH% and number of emerged moths. The obtained results indicated that the minimum & maximum temperatures and RH% were responsible for 71.67% and 73.71% of changes population during the successive periods at 2015 and 2016, respectively.
Field trails were undertaken to determine the seasonal abundance and population fluctuations of key insect pests infesting caraway, cumin and chamomile plants. The most pests associated with these plants were Myzus persicae (Sulzer), Aphis craccivora Koch and Thrips tabace Lindeman. The most numerous pests on caraway plants were T. tabace. It constituted about 45.47% and 62.85% out of the grand total of pests in 2013 and 2014 seasons, respectively. Whereas M. persicae was the most dominant insect pest on cumin plants, constituting about 60.97% and 58.92% out of grand total of pests in first and second seasons, respectively. On chamomile crop M. persicae was the numerous pest as compared with the other insect pests (54.17% and 71.70%). The highest level of abundance was recorded during March and April. Temperature and relative humidity significantly affected the population densities of these pests. The dominant predators were Coccinella undecimpunctata Reiche, Scymnus interruptus Gaeze, Orius spp., Chrysoperla carnea [Stephens] Paedrus alfirri Kock, Syrphus corolla F. and true spiders. These predators attained their maximum population densities during February and March.
Accelerated life tests are commonly utilized in manufacturing industries to induce early failures of highly reliable products. In this paper, estimation and optimal design issues of multiple ramp-stress accelerated life tests are discussed for the generalized half-normal distribution. Assuming inverse power model as a life-stress relationship, the maximum likelihood estimates of the parameters, as well as Fisher information matrix are derived. In addition, the methods of least square, moments, Bayes are used for estimating the model parameters. The optimal proportion of test units allocated to each stress level is obtained under D and A-optimality criteria. A sensitivity analysis of the optimal allocation to misspecification of the model parameters is carried out. Furthermore, a real data set is used to show the application of the generalized half-normal distribution in reliability studies. Finally, a Monte Carlo simulation study is carried out to examine the performance of the estimation methods and the optimality criteria.
Population trends of certain piercing-sucking insects infesting wheat i.e. Thrips sp L., Empoasca spp and its associated coccinellid predator Coccinella undecimpunctata was determined by using yellow sticky traps (YST), direct count and sweep net methods on wheat fields. The tested taxa exhibited one seasonal peak only/each. By using YST both Thrips sp and Empoasca spp showed that their peaks at March 5 with a general average of 242.5 and 12.25 individuals/ 1 YST, respectively. No or very few numbers of C. undecimpunctata were collected by this method. Concerning the direct count method, Thrips sp and C. undecimpunctata exhibited their peaks at February 26 with a general average of 10.50 and 19.50 individuals/10 wheat tillers, respectively. However, Empoasca spp is completely disappeared. By using sweep net both Thrips sp and Empoasca spp revealed that semi-equal peaks at early and mid-February, while C. undecimpunctata peak was appeared one to four weeks later. Concerning the effectiveness of the used sampling methods it is appeared that yellow sticky traps can be used successfully to determine thrips populations. However, the direct count inspection can be considered as the most suitable method for determining coccinellid population trends. On the other hand, sweep net can be used as a successful method for determining Thrips sp, Empoasca spp and C. undecimpunctata in wheat fields.
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