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PHYTOPARASITIC NEMATODES ASSOCIATED WITH ORNAMENTAL PLANTS IN RIYADH REGION, CENTRAL SAUDI ARABIA
No full textA survey of phytoparasitic nematode genera was conducted in the rhizosphere of 55 ornamental plants (herbaceous, trees and shrubs) in Riyadh region, central Saudi Arabia from February 1999 to June 2001. A total of 453 soil and room samples were collected, and 200 cm3 soil subsamples were assayed for nematodes. A variety of twenty phytoparasitic nematode genera were extracted and identified from the rhizosphere of surveyed plants in general. These genera is a descending order of frequency were; Helicotylenchus (43.7%), Tuylenchorhyachus (41.1%), Meloidogyne (37.1%), Aphelenchus (24.9%), Tylenchus (24.3%), Rotylenchulus (21.4%), Criconemella (20.5%), Heniericonenioides (11.7%), Aphelenchoides (6.6%), Ditylenchus (5.7%), Paratrichodorus (5.5%), Pratylenchus (4.9%), hoplolamus (4.2%), Trichodorus (3.3%), Xiphinema (3.9%), Longidarus (1.8%), Hemicycliophora and Paratylenchus (0.9% each), Rotylenchus (0.7%) and Psilenchus (0.2%). Most of nematode genera were present at population densities of 10-100 nematodes /100cm3 soil, but a relatively high population densities were found with Parylenchus on Codiaeum varigatum, Meloidogyte javanica on Rosmarinus officinalis and Helicotylenchus on Matthiola incona (3442, 1528 and 1366 nematodes /100 cm3 soil, respectively). According to the prominence value (PV), the most prominent nematodes in general were; Parvatylenchus, Helicotylenchus, Meloidogyne, Rotylenchulus and Criconemella. Meloidogyne javanica was identified from galled herbaceous ornamental plants and 15 ornamental trees and shrubs, whereas M. arenaria was only identified from galled roots of Dahlia variabilis and Clerodendron inerme. This is the first extensive survey of phytonenatodes associated with ornamental plants in Saudi Arabia including many new host records (especially for root-knot nematodes) in the country
Settlement and Performance Evaluation of Apis mellifera yemenitica in Relation to Beewax Foundation Use in Modern Hives
No full textTwenty indigenous (Apis mellifera yemenitica) honeybee colonies were transferred from the traditional log hives into modern movable frame (Langstroth) hives and divided into 4 Groups. Each group was provided with a modified frame to assess the effect of frame-type on colony settlement, wax secretion, sugar syrup and pollen consumption, sealed brood area, honey and pollen storage. Role of sugar syrup and pollen patty feeding was also evaluated for easy Apis mellifera yemenitica establishment in modern hives under Riyadh conditions. In treatment A and B where the frames were provided with complete wax foundation sheets and one inch wide wax foundation stripe, respectively showed complete colony`s settlement. In treatments C the wired frame without wax foundation sheet and in treatment D where the frames were without wire and wax foundation sheets out of 5 could settle only 3 and 2- Apis mellifera yemenitica colonies respectively. The food consumption rate remained high in treatment B followed by A, C and D, respectively whereas the sealed brood area, honey and pollen storage were found maximum in treatment A followed by B, C and D, respectively. The dimensions of the hive cells were found different in frames with the wax foundation sheet and without wax foundation sheet. The bees constructed larger cells 27/sq. inch in frames with wax foundation sheets and smaller cells 34/sq. inch in frames without wax foundation sheets
Performance Evaluation of Naturally Mated and Instrumentally Inseminated Honeybee (Apis mellifera L.) Queens in Field Colonies
No full textApis mellifera queens were reared to evaluate the performance of Naturally Mated (NM) and instrumentally inseminated (II) queens, using Doolittle grafting method. A group of twelve queen cells was introduced to five frames nucleus colonies and virgins allowed to mate naturally. A second group of 14 queen cells was confined to cages and instrumentally inseminated once with 8 μl of semen and placed back to their assigned nucleus colonies. At oviposition, nucleus colonies for both groups were transferred into a standard Langstroth hive filled with empty combs, and all colonies were allowed to build up naturally into full-size colonies. A perusal of the data presented a slightly higher survival rate in NM queens but binary logistic regression test revealed no significant differences between the survival rates of both NM and II queens that ended up with 5 NM (41%) and 3 II (21.4%) queens after 23-months. A detail probe of ANOVA also indicated no significant difference in brood production which were recorded 1274.4 and 1304.3cm2 2-months after colony establishment, 1585.2 and 1534.6 cm2 during April 1997, and 1674.9 and 1541.5cm2 during spring 1998 for NM and II queens respectively. Likewise, honey production for NM remained statistically at par with that of II queens and was recorded 251.7 and 241.1 lbs. during fall season 1996 and 314.2 and 297.5 lbs. during fall 1997 for NM and II queens respectively
Spatial distribution of predators and prey affect biological control of twospotted spider mites, Tetranychus urticae Koch (Acari: etranychidae), using Phytoseiulus persimilis Athias-Henriot (Acari: Phytoseidae) on impatiens greenhouses
No full textThe twospotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), initially occurs as localized populations or “hot spots” in commercial greenhouses. Growers concerned about mite damage are often advised to focus on “hot spots”, either with chemicals or natural enemies. However, many growers spread natural enemies evenly around the greenhouse. I investigated the impact of spider mite distribution among plants on population growth and plant damage and on the effectiveness of biological control by the predatory mite, Phytoseiulus persimilis Athias-Henriot (Acari: Phytoseiidae) under two predator release strategies: broadcast or point (localized) application. The experimental unit consisted of 16 impatiens plants arranged in a square. Each unit was started with the same numbers of spider mites, but spider mites were distributed either evenly (the total number of spider mites was divided equally among the 16 plants in the unit) or clumped (the total number of spider mites was divided equally among the 4 central plants). The clumped distribution simulated a “hot spot.” Predators were released at an overall 1:4 predator:prey ratio based on the total number of spider mites in a unit, but were released in either an even or clumped pattern. Within nine days after predator release, spider mite populations were reduced in all treatments, but only in the clumped spider mite-clumped predator treatment were spider mite populations reduced to undetectable levels. In the other spider mite-predator treatments, predators reduced spider mites more quickly in the even-even and even-clumped treatments than in the clumped-even treatment. By 18 days after predator release, spider mites were eliminated in all treatments, but a reduction in average plant damage occurred only in treatments in which the predator release pattern matched the spider mite distribution (i.e., even-even or clumped-clumped) with the greatest reduction in the even-even treatment. my results suggest that there is an advantage to releasing predators in “hot spots” at a recommended predator:prey ratio. If more uniform predator releases are made, overall predator numbers need to be kept sufficiently high so that the recommended predator:prey ratio of 1:4 shown to prevent damage on impatiens is achieved in higher-density spider mite patches
REVISION OF GENUS SCHIZOSTHETUS AND REDESCRIPTION OF TYPE SPECIES S. LYRIFORMIS
No full textSchizosthetus (Athias-Henriot, 1982) is a genus of the family Parasitidae which is associated with bark beetles. One of the reasons that encouraged this study was solving the confusion that has been shown in some previous studies in distinguishing this mite in the genus level. Moreover, one of the past recommendations was to investigate different collections of this genus in North and Central America and compare these to old world taxa.
Based on the collections from many different parts of the world (United States of America, Mexico, Honduras, Guatemala, Canada, France, Germany, Sweden, and China), this study ended up with the following findings: 1. These collections can be assigned to 3 species; 2.Only one of these three species is found in all areas of North and Central America (except Oregon State). Finally, a full description of the most common North and Central American species S. lyriformis that focuses on all parts of body in all stages (especially legs, glands and lyrifissures). This description includes complete illustrations of all parts, and revision of and a key to distinguish the three species from one anothe
Optimal economic ordering policy with deteriorating items under different supplier trade credits for finite horizon case
No full textThis paper develops and solves a general finite horizon trade credit economic ordering policy for an inventory model with deteriorating items under inflation and time value of money when shortages are not allowed. The time horizon is divided into different cycles each of which has its own demand rate and its own trade credit period offered from the supplier to his retailer so that the retailer should pay his supplier before or after the end of the permissible trade credit of that cycle. Up to the end of the trade credit of a cycle, the retailer is free of charge, but he is charged on an interest for those items not being sold before this end. The retailer can also earn the interest of the money from the generated sales revenue in any cycle by depositing such revenue into an interest bearing account. The objective of the retailer is then to minimize his net total relevant costs. A closed form of this net total cost is derived and the resulting model is solved. Then rigorous mathematical methods are used to show that, under some seemingly possible conditions, there exist a unique vector of the relevant decision variables that solve the underlying inventory system. A numerical example which shows the applicability of the theoretical results is given
Optimal Control of Reverse Logistics Model with Logistic Demand and Return Rates
No full textPontryagin minimum principle (PMP) is applied in this paper to
find the optimal control of the reverse logistics model of a production
inventory system with deteriorating items. The total cost of the system
consists of the sum of holding costs of inventory levels in two different
stores, the manufacturing and remanufacturing costs, and the disposal
cost. The general solution of the controlled system is obtained. Finally,
numerical example are presented to explain the analytical solution
Numerical methods for solving the modified regularized long wave equation
No full textThis study is conducted & thesis submitted in partial fulfillment of the requirement
for the Degree of Master of Science, Department of Mathematics, College of Science, King Saud University, Riyadh, Kingdom of Saudi Arabia, April 2006GNonlinear differential equations play an important role in physical and
engineering applications, moreover numerical study of these equations are very
important as it is difficult in many cases to obtain analytic solutions. The kind
of equations we are handling in this topic are the Regularized Long Wave
equation (RLW) and the more general Modified Regularized Long Wave
equation (MRLW), such equations represent solitons which are characterized by
some conservation laws such as mass, momentum and energy.
Numerical study for these equations is included and in addition the study of
the solitary wave interactions. Finite difference and collocation method with
cubic B-splines are used in this research leading to good results. Also, the recent
method called ADM method is used to study the considered equations and the
interaction of solitons, it leads to better results than previously obtained
compared the theoretical results. Error and stability analysis of the numerical
schemes are provided and some of the results are sent for publication brief
.Summary of the results pointing out the open points for further research work.King Saud Universit
Technical Efficiency of Broiler Farms in the Central Region of Saudi Arabia: Stochastic Frontier Approach
No full text1) Department of Agricultural Economics, College of Agriculture,
King Saud University, P. O. Box 2460, Riyadh 11451, Saudi Arabia.
2) Department of Agricultural Economics, College of Agriculture,
Oklahoma State University, Stillwater, Oklahoma, U.S.A.Broiler farms are considered one of the highest priority areas that have gained major support and
incentives in the government policy. Broiler farms in Central Saudi Arabia require substantial high
investment costs and competent management. These farms have recently experienced a wide range of
technical and managerial problems. Some farms are operated at less than full capacity while others have
ceased operations. The aim here is to determine the performance of the farms that remain, to measure their
technical efficiency, and to determine if the mean technical efficiency differs between small and large
farms. The stochastic frontier approach (SFA) is used to estimate the technical efficiency of broiler farms
in the central region of Saudi Arabia by determining which farms are located on the production frontier and
which are not. The mean technical efficiency of small farms will be compared with that of large farms to
determine if policy instruments should be targeted toward small or large farms.
The technical efficiency indexes calculated from the estimated production frontiers, range from
0.53 to 0.96, with mean technical efficiency estimated to be 0.89. This implies that the broiler farms are
producing chicken to about 89 percent of the potential frontier production levels, implying that the
production is about 11% below the frontier.
The technical efficiency indexes calculated from the estimated production frontier for the small
farms range from 0.45 to 0.99, with mean technical efficiency estimated to be 0.83. This implies that the
SMALL broiler farms in the Central Region of Saudi Arabia are producing chicken to about 83% of the
potential frontier production levels, given the levels of their inputs and the technology currently being used.
technical efficiency indexes calculated from the estimated production frontiers for the large farms
2
range from 0.57 to 0.99, with mean technical efficiency estimated to be 0.82. This implies that the broiler
farms in the Central Region of Saudi Arabia are producing chicken to about 82 percent of the potential
frontier production levels, implying that the production is about 18% below the frontier
