Journal of Experimental Biology and Agricultural Sciences, August - 2020; Volume – 8(4) page 418 – 425

Journal of Experimental Biology and Agricultural Sciences

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ISSN No. 2320 – 8694

VALUING AND CONTROLLING THE ECONOMIC LOSSES FROM RED PALM WEEVILS (Rhynchophorus ferrugineus) IN RIYADH, SAUDI ARABIA

Adel M. Ghanem1, Khalid N. Alrwis1, Othman S. Alnashwan1, Sahar A. Kamara2, SharafAldin B. Ahamed1*, Nageeb M. Aldawdahi1

1Agricultural Economics Department, College of Food and Agricultural Sciences, King Saud University, P.O. Box 2460, Riyadh 11451. 2Agricultural Economics Research Institute, Egypt

Received – June 14, 2020; Revision – August 04, 2020; Accepted – August 19, 2020 Available Online – August 25, 2020

DOI: http://dx.doi.org/10.18006/2020.8(4).418.425

KEYWORDS ABSTRACT

date palm The current study was carried out to estimate the economic losses caused by red palm weevils in Riyadh, KSA. A well-planned questionnaire and personal interviews from 200 date palm farmers carried out for Red palm weevil primary data collection. Bernoulli or binomial distribution methodology and standard errors at 95% Economic losses confidence level used for estimating the value of removed palm trees. Results of the study revealed that the average incidence of red palm weevils in the sampled farms was 42.5 percent. Due to heavy infestation, 20 Palm value to 167 palm trees were removed from the various studied farms, this ranged, 3.94 percent of the total and 9.28 percent of the total infested palm trees. Due to the rapid spread of red palm weevils and removal of Saudi Arabia severely infested palms, date palm production reduced between 20.0 to 35.1 percent at a confidence level of 95% in the sampled farms. In case of Riyadh region, this decline in date production ranged between 20.57

and 32.83. Further, the value of removed date palms ranged between 85.65 to 715.15 thousand riyals in 2017. Across Saudi Arabia, this value was about 43.23 million riyals in 2016 and 2017. The result of the current study recommends the necessity of adopting the principle of integrated management of the control program of red palm weevil in the Kingdom of Saudi Arabia.

* Corresponding author All the articles published by Journal of Experimental Biology and Agricultural Sciences are licensed under a E-mail: [email protected] (Sharaf Aldin B. Ahamed) Creative Commons Attribution-NonCommercial 4.0

International License Based on a work at www.jebas.org. Peer review under responsibility of Journal of Experimental Biology and Agricultural Sciences.

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Valuing and controlling the economic losses from red palm weevils in Riyadh, Saudi Arabia 419

1 Introduction The insect passes through several stages, starting with laying eggs,

which hatch after 3-6 days and turn into larvae. The larvae develop Dates are the most important fruit crops in the agricultural between 1-3 months and then turn into the complete insect, ranging economy of the Kingdom of Saudi Arabia. The number of palm in length from 3.5 to 4 cm and all stages of this insect live within tree farms reached about 123.3 thousand trees in 2017, spread over the infested palm trunk (Ibrahim, 2011). an area of 108.13 thousand hectares and representing 74.2% of areas with fruit and about 10.7% of the total crop area of 1011.4 Al-Zafran & Lugma (2000) carried out a study and suggested that thousand hectares (Ministry of Environment, Water, and removing infected palm trees, running pheromone traps and Agriculture, 2017). The date production reached 754.76 thousand preventive spraying of pesticides reduced this insect infection in tons, with a value of 4.3 billion dollars which represents 53.55% of one year in the Baha region and three years in the Medina region. the total value of plant production in 2017 (Ministry of These researchers suggested that effective measure of red palm Environment, Water, and Agriculture, 2017). In 2017, the volume weevil control are (i) behavioral control by toxic traps, pheromone of Saudi date exports amounted to 147.42 thousand tons and was and photonics traps, (ii) mechanical control by removing the valued at 703 million riyals, accounting for 36.3% of the total infested trees, pruning and removing weeds and grasses, (iii) value of 1939 million riyals in Saudi agricultural exports (General chemical control by the use of pesticides, (iv) biological control by Authority for Statistics, 2017). multiplying the biological enemies of the insect and (v) legislative control by the issuance of laws and legislation to prevent the entry Dates are an integrated diet containing a high proportion of and spread of insects. The study of the Al-Asfour (2012) dealt with nutrients, minerals, and vitamins. Dates also used for the environmental and vital aspects of red palm weevil in the State manufacturing sucrose and molasses, other dates, which are not of Bahrain. This study showed that the highest activity of the insect suitable for human consumption, entered into the feed industry was from January to March, and the lowest activity in September, (Berbandi, 2007). Further, palm trees wood used as firewood for there is a significant negative correlation between the temperature winter heating, carpentry and construction, decorative purposes, and the activity of the weevil. The average infestation rate was 2%. and in the manufacture of cardboard and paper (Berbandi, 2007). This study recommended the need of pruning the date palms Palm leaves also used in the manufacture of chairs and roofing during the periods of low phase activity of saplings, spraying of houses, and ropes (Berbandi, 2007). pesticides in high activity periods (Sayed & Ali 1995). These researchers also favor the adoption of integrated insect control The red palm weevil is considered one of the most damaging pests strategy and utilization of GIS to improve the performance of which affecting palm trees under the age of 15year, trees with soft control. trunks are more susceptible to this insect attack. Palm weevils first appeared in the Qatif province in 1987 and then spread to the rest Further, Abbass & Gadalla (2015) discussed the effect of some part of the Kingdom of Saudi Arabia. The number of infested palm agricultural practices on the level of red palm weevil trees was 14.91 thousand; among these about 9.58 thousand palm infestation in Egypt. This study showed that palm-containing trees were treated and 5.33 thousand palm trees removed in 2016. air roots are more susceptible to red palm weevils than non-air In 2017, this number of the infected tree was 13.59 thousand; of roots. Besides, the rate of red palm weevil infestation increased them, 8.83 thousand palm trees were treated and 4.77 thousand among palms, which are constantly in moisture condition, as palm trees were removed. well as among palms containing aerosols, as compared to the The danger of palm weevils is difficult to detect in the early stages palms with removed air aerosols and subsequently treated with of infestation, but this could be diagnosed through some symptoms sulfur. Finally, FAO (2017) prepared a report on the framework such as pigmented brownish and malodorous trees, wilted and strategy for the eradication of palm weevils. It can be yellowing leaves (Baqi & Farouk, 2015). The incomplete removal implemented through the drafting of a charter for cooperation of infested palms in the Al-Muzahmiya governorate led to a delay and coordination of national, regional, and global efforts to in the elimination of the infestation, which stopped after 3.6 years support the integrated and sustainable management program for despite the operation of pheromone traps and preventive spraying controlling the red palm weevil, reducing its harmful effects on (Ministry of Environment, Water, and Agriculture, 2017). the environment and food security, and mitigating its social and economic impact on rural communities. Further, Ibrahim (2011) described the red palm weevil as the hidden enemy, where the infestation is closely associated with the Preliminary estimation indicated that date farmers in the KSA injury of the palm stalk digger, which creates the appropriate suffered losses of 15 million dollars in 2015. Due to the places for egg-laying. The infection of this insect causes the palm severity of the infestation, the Ministry of Environment, Water, tree emptied of its hardness, and made vegetable sap dries up. The and Agriculture focused on the red palm weevil, and insect damages the offshoots and palm trees died during 1-2 years. approximately 37.67 million palm trees were examined in

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2017. The Ministry of the Interior also intervened and issued a Further, the equation for the value of removed palm trees due to . circular to confiscate any offshoots being transferred without a the severity of red palm weevil infestation was calculated by metal wire stamped with the seal of the Ministry of calculating the present value of net income from palm trees during Environment, Water, and Agriculture and a certificate their economic lifetime as follows (Swingler, 2014): confirming that they were free of the pest. However, there is no 푛 퐶 1 − (1 + 𝑖)−푛 doubt that the spread of the date palm weevil infestation leads 푃푉 = = 퐶 (1 + 𝑖)푘 𝑖 to a decline in date production and losses in capital assets 푘=1 (palm trees). This study aimed to study the negative effects of the red palm weevils spread and to find out effective ways to Where 푛 = number of periods, 퐶 = Value of net cash flows, 𝑖 = control it in the Riyadh area. Moreover, the study also focused effective periodic interest rate, or rate of return. on, determining the current status of red palm weevils and the The current study collected data from the (i) statistical book issued by reasons for their spread in Riyadh, estimation of the economic the Statistics and Information Department of the Ministry of losses caused by this pest, and propose effective means of Environment, Water, and Agriculture in Saudi Arabia, and (ii) the integrated management of palm weevil control in the Riyadh. report of Export Statistics issued by the General Authority for 2 Materials and Methods Statistics.

This study adopted the Bernoulli distribution, also known as the The study also relied on primary data collected by administering binomial distribution of econometric analyses (Gujarati, 1979; questionnaires to and interviewing a random sample of 200 date William, 2003), and standard errors at the 95% confidence in the production farmers in the Riyadh region in Saudi Arabia. This area was determination of the percentage or probability of the existence of selected as it accounts for the largest volume of date production and red palm weevils in the Riyadh region. When estimating the comprises 7.03 million palm trees, representing 24.61% of the total proportion or probability of palm weevils, the estimate number of palm trees in 2015 in the Kingdom of Saudi Arabia accompanied by standard errors used when estimating Confidence (General Authority for Statistics, 2016). intervals as follows: 3 Results and Discussion P(1 P) Standard error of probability at 95% confidence level  1.96 * N 3.1 Current status of red palm weevils in the Riyadh region P(1 P) 95% confidence interval for probability = P 1.96 * Status of red palm weevils in studied research sample farms is given in N the tables (1) and (2), it is clear from these data that the number of Where P is the percentage of red palm weevil infestation,(1-P) the infested palm trees in studied farms ranged from 115 to 2984 probability of non-infestation, N is the size of the research sample. palms, with an average of 1078 palm trees. Given the number of

Table 1 Descriptive analysis of the number of infested, removed, and treated date palms in the Riyadh region.

Standard Coefficient of Statement Minimum Maximum Average deviation variance (%) Area planted with palm trees per hectare 5.6 50.0 29.5 14.83 50.27

Total number of palms in the farm 504 4250 2537 1250.51 49.29

Number of infested palms 115 2984 1078 1011.32 93.81

Number of treated palms 95 2817 984 1001.76 101.80 The number of infested palms is very severe and has 20 167 100 51.93 55.24 been eliminated Average age of removed palms 10 21 15.5 3.45 22.26

Percentage of infested palms 22.8 70.2 42.5 16.64 39.15 Percentage of date palm trees removed out of total 3.93 3.97 3.94 0.02 0.54 number of palm trees per farm Percentage of date palms removed out of total number 5.93 21.05 9.28 5.37 56.23 of infested palms Percent decrease in date production 20.0 35.1 26.7 4.44 16.63 Source: Collected from questionnaire compiled in 2017

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Valuing and controlling the economic losses from red palm weevils in Riyadh, Saudi Arabia 421

Table 2 Probability distribution of the percentage of infested palm trees, removed date palms, and percent decrease in date production

Percentage of removed Percentage of removed Rate of palm Percent decline in date palms out of total date palm trees out of Statement weevil the production of number of palm trees in total number of infested infestation dates the farm palm trees Probability that problem may exist 0.425 0.0394 0.093 0.267

Probability that problem may not exist 0.575 0.961 0.907 0.733

Standard error 0.035 0.014 0.021 0.031

Standard error at 95% confidence level 0.069 0.027 0.040 0.061 The problem may be at 95% confidence interval for the probability that problem 0.425 0.069 0.03940.027 0.0930.040 0.2670.061 exists Percentage of problem exists at 95% confidence level:

Maximum 49.35% 6.64% 13.30% 32.83%

Minimum 35.65% 1.24% 5.26% 20.57%

Source: Compiled and calculated from the data given in Table 1. palm trees in the farm, the incidence of red palm weevils ranged Probability distribution test showed that the decline in date between 22.8% and 70.2%, with an average of 42.5% and a production in the Riyadh region ranged between 20.57% and coefficient of variation reaching 39.15%. From the probability 32.83% at a confidence level of 95%. distribution test of red palm weevil incidence in the Riyadh region, it is clear that incidence ranged between 35.65% and 49.35% at the 3.2 Factors affecting the infection of red palm weevils 95% confidence level. The probability distribution test related to the causes of red palm Because of the severity of red palm weevil infestation, the weevil infection in the studied research farms of the Riyadh are number of palm trees removed, ranging from 20 to 167 palms given in the tables (3) and (4), All these data are presented at a per farm, with an average of 100 palm trees. Further, the age of confidence level of 95%. From the results of the study, it can be removed date palm trees ranged between 10 and 21years, with revealed that (i) difficulty in achieving quarantine (92 percent an average of 15.5 years. The percentage of removed date farmers) and control in the movement of pests (98 percent farmers) palms out of the total number of palm trees in a farm ranged are some of the most important reasons of spreading red palm between 3.93% and 3.97%, with an average of 3.94 % and a weevils, (ii) the percentage of date farmers who suffer from a lack coefficient of variation reaching 0.54%. The proportion of the of effective means of early detection of red palm weevils ranged removed date palms in the total number of palm trees in the from 82.9% to 92.1%, (iii) the proportion of date farmers who farms of the Riyadh region ranged between 1.24 % and 6.64 % suffer from insufficient human and financial resources allocated to at the 95% confidence level. The percentage of removed date control palm weevils ranged between 71.7% and 83.3%, (iv) the palms in the total number of infested palms ranged from 5.93% percentage of date farmers who suffered from the unavailability of to 21.05%, with an average of 9.28 % and a coefficient of fully integrated biological control are ranged from 61.0% to variation of 56.23%. Further, the probability distribution of the 74.0%, (v) the proportion of date farmers who have lacking percentage of removed palms out of the total number of knowledge about the environmental factors sensitivity of the palm infested palm trees in the Riyadh region ranged between 5.26 weevils ranged between 48.1% and 61.9%, and (vi) the percentage % and 13.30 % at a confidence level of 95%. The decrease in of date palm farmers who delayed controlling palm weevils ranged the number of removed palm trees attributed to the effective from 38.1% to 51.9%. role of the Ministry of Environment, Water, and Agriculture in fighting red palm weevils. 3.3 Estimating of economic losses caused by red palm weevils

Due to the spread of red palm weevils and the removal of severely The economic losses caused by red palm weevils in the Riyadh damaged date palm trees, date production in the research sample region represented by both the decrease in date production and by the farms decreased at rates ranging between 20.0% and 35.1%, with value of palm trees eliminated due to the severity of their infestation. an average of 26.7% and a coefficient of variation of 16.63%. The current study revealed that the incidence of red palm weevils

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Table 3 Relative importance of causes of spread of red palm weevils

. Statement Frequency %

The difficulty of guarantee and control of the movement of the pests 190 95.0

Lack of effective means of early monitoring of red palm weevils 175 87.5

Insufficient human and financial resources to control palm weevils 155 77.5

Inability to fully implement integrated biological control 135 67.5 Lack of knowledge of the behavior of palm weevils when exposed to heat and other 110 55.0 environmental factors

Delay in the control of palm weevils 90 45.0 Source: Collected from questionnaire compiled in 2017.

Table 4 Probability distribution test of causes of red palm weevils in the Riyadh region

The difficulty of Lack of Insufficient Inability to Lack of guarantee and effective human and fully knowledge of Delay in the Statement control of the means of financial implement the behavior control of movement of the early resources for biological of palm palm weevils pests monitoring control control weevils Probability that problem may 0.95 0.875 0.775 0.675 0.55 0.45 exist Probability that problem may 0.05 0.125 0.225 0.325 0.45 0.55 not exist. Standard error 0.015 0.023 0.03 0.033 0.035 0.035 Standard error at 95% 0.03 0.046 0.058 0.065 0.069 0.069 confidence level The problem may be at 95% 0.950.03 0.8750.046 0.7750.058 0.6750.065 0.550.069 0.45 0.069 confidence level Percentage of problem exists at

95% confidence level:

Maximum 98.0% 92.1% 83.3% 74.0% 61.9% 51.9%

Minimum 92.0% 82.9% 71.7% 61.0% 48.1% 38.1% Source: Compiled and calculated from the data in Table 3

led to a decline in the production of dates in the Riyadh region, wages, and operating and production costs) amounting to 41.72 and it ranging between 20.57% and 32.83% at a confidence level thousand riyals/ha, the net income of the research sample farms is of 95%. Estimating the net farm income depend on the life of estimated as 37.66 thousand riyals/ha, that is, 437.91 riyals/palm. palm tree, in current study revenue and production costs of the research farm samples was estimated by keeping average age Palm Value = Net Income for Palm × Total discount coefficients at 10% discount rate during Palm's default life. about 40 years. According to the Attieh (1994), the actual 푛 (economic) age of a palm differs from its productive life, since 1 푉푎푙푢푒 표푓 푡ℎ푒 푝푎푙푚 = 437.91 × the latter is the age at which the palm remains productive (1 + 0.10)40 푘=1 irrespective of the type of production. = 437.91 × 9.779 = 4.28 푡ℎ표푢푠푎푛푑 푟𝑖푦푎푙푠/푝푎푙푚 It is clear from the data given in table 5 that the average productivity per hectare (ha) in the research sample farms is about removed ranged from 85.65 to 715.15 thousand riyals, with an 8.65 tons. The average selling price of the dates is 9.20 thousand average of about 428.0 thousand riyals in 2017. In Saudi Arabia, riyals/ton, and on the behalf of these data farms income was the data from the Ministry of Environment, Water, and Agriculture estimated as 79.38 thousand riyals/ha. In light of the production revealed that the total value of removed date palm trees reached At costs (depreciation of farm assets, permanent and seasonal labor the level of the research sample, the value of date palm trees 22.81

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Valuing and controlling the economic losses from red palm weevils in Riyadh, Saudi Arabia 423

Table 5 Present value of net cash flows during the original life of the palm and 20.42 million riyals in 2016 and 2017, respectively. Thus, the

Statement Year (1-40) total value of date palm trees removed reached 43.23 million riyals, or about 11.50 million dollars in 2016 and 2017 (Table 6). Agricultural income in thousands SR / ha 79.38 3.4 Integrated management of red palm weevils in the Riyadh Production costs in thousands SR / ha 41.72 region

Net farm income in thousands SR / ha 37.66 In the current study, study area farmers have been used as an Average number of palms per hectare 86 integrated management approach for the control of red palm Average net income per palm in SR 437.91 weevils. Data generated from the probability distribution test of integrated management (at the 95% confidence level) have been Total discount transactions at 10% discount rate 9.779 presented in tables (7) and (8). Most of the farmers used more than

Total current value of net income per palm in SR 4282.32 one method of red palm weevils management, among the various management practices, early monitoring of red palm weevils is one Value of palm trees removed for the research sample in thousand SR of the most effective (87.5%) means to control and this was Minimum 85.65 followed by the integrated biological control (80.5%). The third important way of red palm weevils controlling is remote sensing Maximum 715.15 and 56% of farmers favor this method of controlling. Other Average 428.0 methods, which are very commonly suggested by study area Source: Collected from the questionnaire compiled in 2017 and farmers are training on red palm weevils control (49%), use of the current value calculation law contained in this study pheromone traps (41.5%), use of biocontrol fungus (36%),

injecting palm tree trunks with pesticides and natural products (35%), use of tissue culture techniques (19%) and cutting of Table 6 Estimated value of palm trees removed in Saudi Arabia in 2016 and 2017 severely infested palm trees and disposal through burning (13.5%).

Total value of Number of Value per palm trees The implementation of the integrated management of the red palm palm trees Palm Year removed weevil program was aided by the Custodian of the two holy removed (in (thousands of (millions of thousands) SR) mosques (King Salman bin Abdul Aziz), for these 1.766 billion SR) riyals allocated in 2015 for five years. 2016 5.33 4.28 22.81 Conclusions and Recommendations 2017 4.77 4.28 20.42 Results of the current study revealed the status of red palm weevils Total 10.10 4.28 43.23 in the Riyadh region, higher incidence of this insect pestled to a Source: Compiled and calculated from the data in Table 5 decline in date production ranging from 20.57% to 32.83% at a

Table 7 Relative importance of various methods of red palm weevils controlling

Method Frequency %

Early monitoring of red palm weevils 175 87.5

Integrated biological control of red palm weevils 161 80.5

Remote sensing and geographical positioning of red palm weevils 112 56.0

Effective participation of date farmers in the palm weevil program 98 49.0

Expansion of the use of pheromone traps to eliminate palm weevils 83 41.5

Use of fungus and fungal spray to kill palm weevils that target palm tree base 72 36.0

Injection of palm tree trunks with pesticides and natural products 70 35.0

Expansion of tissue culture to produce high-quality red palm weevil-free” off shoots. 38 19.0

Severe palm cutting and disposal 27 13.5 Source: Questionnaire forms compiled in 2017

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Table 8 Potential distribution of red palm weevil control methods . Injection of Expansion Use of Severe Remote Effective Expansion palm tree of tissue Early Integrated fungi palm sensing participati of use of trunks with culture for monitori biological and cutting Methods and geo- on of date pheromone pesticides the ng control fungal and positioning farmers fisheries and natural production spray disposal products of offshoots Probability of using 0.875 0.805 0.560 0.490 0.415 0.360 0.350 0.190 0.135 the method Probability of not 0.125 0.195 0.440 0.510 0.585 0.640 0.650 0.810 0.865 using the method Standard error 0.023 0.028 0.035 0.035 0.035 0.034 0.034 0.028 0.024

Standard error at 95% confidence 0.046 0.055 0.069 0.069 0.068 0.067 0.066 0.054 0.047 level 95% confidence interval for the 0.875 0.805 0.560 0.490 0.415 0.360 0.350 0.190 0.135 probability of using 0.046 0.055 0.069 0.069 0.068 0.067 0.066 0.054 0.047 the method Percentage of use of

the medium at 95%

confidence level:

Maximum 92.1% 86.0% 62.9% 55.9% 48.3% 42.7% 41.6% 24.4% 18.2%

Minimum 82.9% 75.0% 49.1% 42.1% 34.7% 29.3% 28.4% 13.6% 8.8% Source: Collected and calculated from data in table 7 confidence level of 95%. In the Kingdom of Saudi Arabia, the total Master thesis submitted to the Graduate School of Gulf Arab value of the removed date palm trees was about 43.23 million University, Manama, Bahrain. riyals in 2017. The current study justified the use of the integrated red palm weevil management program in Saudi Arabia. Al-Zafran HAR, Lugma’s HEEM (2000) Effect of the removal of infested palm trees on the level of red palm weevils infectious in in some Acknowledgment infested areasin Saudi Arabia, Ministry of Agriculture, Saudi Arabia.

The authors extend their sincere appreciation to the Deanship of Attieh AMA (1994) Commercial, economic and social feasibility Scientific Research at King Saud University for supporting the studies with applications on the computer, the Egyptian work through the College of Food and Agricultural Sciences universities. Research Center. Furthermore, the authors thank the Deanship of Baqi A, Farouk N (2015) Palm weevil, Department of Plant Scientific Research at King Saud University for their technical Production and Protection, Faculty of Agriculture and Veterinary support. Medicine, Qassim University, Saudi Arabia.

Conflict Of Interest Berbandi AR (2007) The Palm Tree and its Economic Importance Authors would hereby like to declare that there is no conflict of in the Arab World, Insect and Insect Pests, First Edition, Dar interests that could possibly arise. Raslan for Printing, Publishing and Distribution, Damascus, Syria.

FAO (2017) Report of the Scientific Consultation and High-Level References Meeting of Red Palm Weevil Management, Rome, Italy, March 29-31. Abbass MK, Gadalla EG (2015) Effect of some Agricultural Operation on the level of Infestation with red Palm Weevil Gujarati D (1979) Basic Econometrics, MC Grow-Hill Rhynchophorus ferrugineus (OLIVIER) in Date Palm Farms in International Book Company, London. Egypt. Journal Plant Protection and Pathology 6 (9): 1267-1272. Ibrahim ABO (2011) Red Palm Weevil, Hidden Enemy, Journal of Al-Asfour AAA (2012) Study of some environmental and Agriculture and Water in the Arab World, Arab Center for the biological aspects of red palm weevil in the Kingdom of Bahrain. Studies of Arid Zones and Dry lands 27: 38- 46.

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Valuing and controlling the economic losses from red palm weevils in Riyadh, Saudi Arabia 425

Ministry of Environment, Water and Agriculture (2017) Studying Swingler DN (2014) A Rule of Thumb approximation for time

Crop Composition in Saudi Agriculture. value of money calculations. Journal of Personal Finance 13 (2): 57-61. Ministry of Environment, Water, and Agriculture, proxy of Planning and Budget, Department of Statistics and Information The General Authority for Statistics (2016) Detailed results of the (2017) Statistical book. agricultural census in 2015.Kingdom of Saudi Arabia.

Sayed AA, Ali AG (1995) Timing of application of certain The General Authority for Statistics (2017) Export statistics for organophosphates versus a biocide to control the 2017. ,Kingdom of Saudi Arabia. cosmopterigid, BatrachedraamydraulaMeyr. infesting date palm fruits in New Valley. Assiut Journal of Agricultural William HG (2003) Econometric Analysis, Fifth edition, New Sciences 26 (4): 253-259. York University.

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