Full Text: 1 Introduction Dates are the most important fruit crops in the agricultural economy of the Kingdom of Saudi Arabia. The number of palm tree farms reached about 123.3 thousand trees in 2017, spread over 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 thousand hectares (Ministry of Environment, Water, and Agriculture, 2017). The date production reached 754.76 thousand tons, with a value of 4.3 billion dollars which represents 53.55% of the total value of plant production in 2017 (Ministry of Environment, Water, and Agriculture, 2017). In 2017, the volume of Saudi date exports amounted to 147.42 thousand tons and was valued at 703 million riyals, accounting for 36.3% of the total value of 1939 million riyals in Saudi agricultural exports (General Authority for Statistics, 2017). Dates are an integrated diet containing a high proportion of nutrients, minerals, and vitamins. Dates also used for manufacturing sucrose and molasses, other dates, which are not suitable for human consumption, entered into the feed industry (Berbandi, 2007). Further, palm trees wood used as firewood for winter heating, carpentry and construction, decorative purposes, and in the manufacture of cardboard and paper (Berbandi, 2007). Palm leaves also used in the manufacture of chairs and roofing houses, and ropes (Berbandi, 2007). The red palm weevil is considered one of the most damaging pests which affecting palm trees under the age of 15year, trees with soft trunks are more susceptible to this insect attack. Palm weevils first appeared in the Qatif province in 1987 and then spread to the rest part of the Kingdom of Saudi Arabia. The number of infested palm trees was 14.91 thousand; among these about 9.58 thousand palm trees were treated and 5.33 thousand palm trees removed in 2016. In 2017, this number of the infected tree was 13.59 thousand; of them, 8.83 thousand palm trees were treated and 4.77 thousand palm trees were removed. The danger of palm weevils is difficult to detect in the early stages of infestation, but this could be diagnosed through some symptoms such as pigmented brownish and malodorous trees, wilted and yellowing leaves (Baqi & Farouk, 2015). The incomplete removal of infested palms in the Al-Muzahmiya governorate led to a delay in the elimination of the infestation, which stopped after 3.6 years despite the operation of pheromone traps and preventive spraying (Ministry of Environment, Water, and Agriculture, 2017). Further, Ibrahim (2011) described the red palm weevil as the hidden enemy, where the infestation is closely associated with the injury of the palm stalk digger, which creates the appropriate places for egg-laying. The infection of this insect causes the palm tree emptied of its hardness, and made vegetable sap dries up. The insect damages the offshoots and palm trees died during 1-2 years. The insect passes through several stages, starting with laying eggs, which hatch after 3-6 days and turn into larvae. The larvae develop between 1-3 months and then turn into the complete insect, ranging in length from 3.5 to 4 cm and all stages of this insect live within the infested palm trunk (Ibrahim, 2011). Al-Zafran & Lugma (2000) carried out a study and suggested that removing infected palm trees, running pheromone traps and preventive spraying of pesticides reduced this insect infection in one year in the Baha region and three years in the Medina region. These researchers suggested that effective measure of red palm weevil control are (i) behavioral control by toxic traps, pheromone and photonics traps, (ii) mechanical control by removing the infested trees, pruning and removing weeds and grasses, (iii) chemical control by the use of pesticides, (iv) biological control by multiplying the biological enemies of the insect and (v) legislative control by the issuance of laws and legislation to prevent the entry and spread of insects. The study of the Al-Asfour (2012) dealt with the environmental and vital aspects of red palm weevil in the State of Bahrain. This study showed that the highest activity of the insect was from January to March, and the lowest activity in September, there is a significant negative correlation between the temperature and the activity of the weevil. The average infestation rate was 2%. This study recommended the need of pruning the date palms during the periods of low phase activity of saplings, spraying of pesticides in high activity periods (Sayed & Ali 1995). These researchers also favor the adoption of integrated insect control strategy and utilization of GIS to improve the performance of control. Further, Abbass & Gadalla (2015) discussed the effect of some agricultural practices on the level of red palm weevil infestation in Egypt. This study showed that palm-containing air roots are more susceptible to red palm weevils than non-air roots. Besides, the rate of red palm weevil infestation increased among palms, which are constantly in moisture condition, as well as among palms containing aerosols, as compared to the palms with removed air aerosols and subsequently treated with sulfur. Finally, FAO (2017) prepared a report on the framework strategy for the eradication of palm weevils. It can be implemented through the drafting of a charter for cooperation and coordination of national, regional, and global efforts to support the integrated and sustainable management program for controlling the red palm weevil, reducing its harmful effects on the environment and food security, and mitigating its social and economic impact on rural communities. Preliminary estimation indicated that date farmers in the KSA suffered losses of 15 million dollars in 2015. Due to the severity of the infestation, the Ministry of Environment, Water, and Agriculture focused on the red palm weevil, and approximately 37.67 million palm trees were examined in 2017. The Ministry of the Interior also intervened and issued a circular to confiscate any offshoots being transferred without a metal wire stamped with the seal of the Ministry of Environment, Water, and Agriculture and a certificate confirming that they were free of the pest. However, there is no doubt that the spread of the date palm weevil infestation leads to a decline in date production and losses in capital assets (palm trees). This study aimed to study the negative effects of the red palm weevils spread and to find out effective ways to control it in the Riyadh area. Moreover, the study also focused on, determining the current status of red palm weevils and the reasons for their spread in Riyadh, estimation of the economic losses caused by this pest, and propose effective means of integrated management of palm weevil control in the Riyadh. 2 Materials and Methods This study adopted the Bernoulli distribution, also known as the binomial distribution of econometric analyses (Gujarati, 1979; William, 2003), and standard errors at the 95% confidence in the determination of the percentage or probability of the existence of red palm weevils in the Riyadh region. When estimating the proportion or probability of palm weevils, the estimate accompanied by standard errors used when estimating Confidence intervals as follows: Standard error of probability at 95% confidence level 95% confidence interval for probability =   Where P is the percentage of red palm weevil infestation,(1-P) the probability of non-infestation, N is the size of the research sample. Further, the equation for the value of removed palm trees due to the severity of red palm weevil infestation was calculated by calculating the present value of net income from palm trees during their economic lifetime as follows (Swingler, 2014): PV=k=1nC(1+i)k=C1-(1+i)-ni Where n  = number of periods, C  = Value of net cash flows, {\displaystyle \,n\,}Wwwi  = effective periodic interest rate, or rate of return. The current study collected data from the (i) statistical book issued by the Statistics and Information Department of the Ministry of Environment, Water, and Agriculture in Saudi Arabia, and (ii) the report of Export Statistics issued by the General Authority for Statistics. The study also relied on primary data collected by administering questionnaires to and interviewing a random sample of 200 date production farmers in the Riyadh region in Saudi Arabia. This area was selected as it accounts for the largest volume of date production and comprises 7.03 million palm trees, representing 24.61% of the total number of palm trees in 2015 in the Kingdom of Saudi Arabia (General Authority for Statistics, 2016). 3 Results and Discussion 3.1 Current status of red palm weevils in the Riyadh region Status of red palm weevils in studied research sample farms is given in the tables (1) and (2), it is clear from these data that the number of infested palm trees in studied farms ranged from 115 to 2984 palms, with an average of 1078 palm trees. Given the number of palm trees in the farm, the incidence of red palm weevils ranged between 22.8% and 70.2%, with an average of 42.5% and a coefficient of variation reaching 39.15%. From the probability 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 95% confidence level. Because of the severity of red palm weevil infestation, the number of palm trees removed, ranging from 20 to 167 palms per farm, with an average of 100 palm trees. Further, the age of removed date palm trees ranged between 10 and 21years, with an average of 15.5 years. The percentage of removed date palms out of the total number of palm trees in a farm ranged between 3.93% and 3.97%, with an average of 3.94 % and a coefficient of variation reaching 0.54%. The proportion of the removed date palms in the total number of palm trees in the farms of the Riyadh region ranged between 1.24 % and 6.64 % at the 95% confidence level. The percentage of removed date palms in the total number of infested palms ranged from 5.93% to 21.05%, with an average of 9.28 % and a coefficient of variation of 56.23%. Further, the probability distribution of the percentage of removed palms out of the total number of infested palm trees in the Riyadh region ranged between 5.26 % and 13.30 % at a confidence level of 95%. The decrease in the number of removed palm trees attributed to the effective role of the Ministry of Environment, Water, and Agriculture in fighting red palm weevils. Due to the spread of red palm weevils and the removal of severely damaged date palm trees, date production in the research sample farms decreased at rates ranging between 20.0% and 35.1%, with an average of 26.7% and a coefficient of variation of 16.63%. Probability distribution test showed that the decline in date production in the Riyadh region ranged between 20.57% and 32.83% at a confidence level of 95%. 3.2 Factors affecting the infection of red palm weevils The probability distribution test related to the causes of red palm weevil infection in the studied research farms of the Riyadh are given in the tables (3) and (4), All these data are presented at a confidence level of 95%. From the results of the study, it can be revealed that (i) difficulty in achieving quarantine (92 percent farmers) and control in the movement of pests (98 percent farmers) are some of the most important reasons of spreading red palm weevils, (ii) the percentage of date farmers who suffer from a lack of effective means of early detection of red palm weevils ranged from 82.9% to 92.1%, (iii) the proportion of date farmers who suffer from insufficient human and financial resources allocated to control palm weevils ranged between 71.7% and 83.3%, (iv) the percentage of date farmers who suffered from the unavailability of fully integrated biological control are ranged from 61.0% to 74.0%, (v) the proportion of date farmers who have lacking knowledge about the environmental factors sensitivity of the palm weevils ranged between 48.1% and 61.9%, and (vi) the percentage of date palm farmers who delayed controlling palm weevils ranged from 38.1% to 51.9%. 3.3 Estimating of economic losses caused by red palm weevils The economic losses caused by red palm weevils in the Riyadh region represented by both the decrease in date production and by the value of palm trees eliminated due to the severity of their infestation. The current study revealed that the incidence of red palm weevils  led to a decline in the production of dates in the Riyadh region, and it ranging between 20.57% and 32.83% at a confidence level of 95%. Estimating the net farm income depend on the life of palm tree, in current study revenue and production costs of the research farm samples was estimated by keeping average age about 40 years. According to the Attieh (1994), the actual (economic) age of a palm differs from its productive life, since the latter is the age at which the palm remains productive irrespective of the type of production. It is clear from the data given in table 5 that the average productivity per hectare (ha) in the research sample farms is about 8.65 tons. The average selling price of the dates is 9.20 thousand riyals/ton, and on the behalf of these data farms income was estimated as 79.38 thousand riyals/ha. In light of the production costs (depreciation of farm assets, permanent and seasonal labor wages, and operating and production costs) amounting to 41.72 thousand riyals/ha, the net income of the research sample farms is estimated as 37.66 thousand riyals/ha, that is, 437.91 riyals/palm. Palm Value = Net Income for Palm × Total discount coefficients at 10% discount rate during Palm's default life. Value of the palm=437.91×k=1n1(1+0.10)40=437.91×9.779=4.28 thousand riyals/palm removed ranged from 85.65 to 715.15 thousand riyals, with an average of about 428.0 thousand riyals in 2017. In Saudi Arabia, the data from the Ministry of Environment, Water, and Agriculture revealed that the total value of removed date palm trees reached At the level of the research sample, the value of date palm trees 22.81   and 20.42 million riyals in 2016 and 2017, respectively. Thus, the total value of date palm trees removed reached 43.23 million riyals, or about 11.50 million dollars in 2016 and 2017 (Table 6). 3.4 Integrated management of red palm weevils in the Riyadh region In the current study, study area farmers have been used as an integrated management approach for the control of red palm weevils. Data generated from the probability distribution test of integrated management (at the 95% confidence level) have been presented in tables (7) and (8). Most of the farmers used more than one method of red palm weevils management, among the various management practices, early monitoring of red palm weevils is one of the most effective (87.5%) means to control and this was followed by the integrated biological control (80.5%). The third important way of red palm weevils controlling is remote sensing and 56% of farmers favor this method of controlling. Other methods, which are very commonly suggested by study area farmers are training on red palm weevils control (49%), use of 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 severely infested palm trees and disposal through burning (13.5%). The implementation of the integrated management of the red palm weevil program was aided by the Custodian of the two holy mosques (King Salman bin Abdul Aziz), for these 1.766 billion riyals allocated in 2015 for five years. Conclusions and Recommendations Results of the current study revealed the status of red palm weevils in the Riyadh region, higher incidence of this insect pestled to a decline in date production ranging from 20.57% to 32.83% at a confidence level of 95%. In the Kingdom of Saudi Arabia, the total value of the removed date palm trees was about 43.23 million riyals in 2017. The current study justified the use of the integrated red palm weevil management program in Saudi Arabia. Acknowledgment The authors extend their sincere appreciation to the Deanship of Scientific Research at King Saud University for supporting the work through the College of Food and Agricultural Sciences Research Center. Furthermore, the authors thank the Deanship of Scientific Research at King Saud University for their technical support. Conflict Of Interest Authors would hereby like to declare that there is no conflict of interests that could possibly arise.