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ISSN : 1598-5504(Print)
ISSN : 2383-8272(Online)
Journal of Agriculture & Life Science Vol.52 No.4 pp.25-29
DOI : https://doi.org/10.14397/jals.2018.52.4.25

A Study on the Use of Unmanned Aerial Vehicles for Chestnut Insect Pests Control

Chong-kyu Lee*
Dept. of For. Res., Gyeongsang National Univ. of Sci. and Tech., Jinju, 52725, Korea
Corresponding author: Chong-Kyu Lee Tel: +82-55-751-3243 Fax: +82-55-751-3241suam7@gntech.ac.kr
January 26, 2018 February 26, 2018 March 16, 2018

Abstract


The purpose of this study was to examine the damage rate of insect pests on chestnut orchards. and to investigate the effects of varying methods of insect pests control. The results revealed that there was a statistically significant(p<0.05) difference among early-ripenign, middleripening, and late-ripening cultivars. The damage rate of Dichocrocis punctiferalis was highest in early-ripening cultivars(24.22%), followed by middle-ripening(22.71%) and late-ripening(20.25%). The damage rate of Curculio sikkimensis was highest in late-ripening cultivars(24.52%), followed by middle-ripening(22.61%) and early-ripening(19.96%). There was a statistically significant(p<0.05) difference in damage rates after insect pests control. Two methods of insect pests control, using either helicopter or an unmanned drone, were used. The results revealed significant differences (p<0.05) between D. punctiferalis and C. sikkimensis. Changes in the damage rates of D. punctiferalis after drone control were 8.97%~9.62%, and that after helicopter control was 14.82~15.94%, which was 20.25%~24.22% significant difference(p<0.05) from control site. Changes in damage rates of C. sikkimensis after drone spraying was 6.77~7.72%, and that after helicopter spraying was 12.62~14.94%, which was 19.96~24.52% significant difference(p<0.05) from control sites. Control effects of D. punctiferalis by drone spraying was 59.06% and helicopter spraying was 30.82%. Control effects of C. sikkimensis by drone spraying was 66.97% and helicopter spraying was 40.78%.



초록


    Gyeongnam National University of Science and Technology

    Introduction

    Chestnuts are an important income source in Korea, with more than 60,000 tons per year being produced yielding 101.1 billion won in yearly income. In recent years, the demand for chestnuts in the international market as well as the domestic market has risen consistently. It is considered that the production of food that meets the demand of the consumer has come inevitably, and the chestnut production in Korea is predominant in Hadong, Sancheong, Jinju, Hapcheon of Gyeongnam, Gongju of Chungnam, and Gwangyang of Jeonnam. Reduction in chestnut production has led to income declines in chestnuts production caused by the damage incurred by Dichocrocis punctiferalis during ripening.

    D. punctiferalis is a insect pests that damages chestnuts, causing 20~30% of damage every year, and a decrease in annual income of around 30 billion won(Lee, 2011). It is known that D. punctiferalis damages the fruits of trees such as peaches(Needlay et al., 1983) and damages ripening chestnuts(Lee et al., 1997; 1998; Choi, 1998). As a chestnut pest, D. kuriphilus caused serious damage to native chestnut trees(Kang et al., 1978). Both a study on control using artificially synthesized sex pheromones for ripening chestnut orchards(Torth et al., 1992) and on control of D. punctiferalis(Kang et al., 1978; Choi, 1993; Lee, 2009; 2011) have been conducted, but there is a lack of information verifying the effects of different insect control methods. On a large-scale chestnut orchard, farmers depend on chemical control using a helicopter, and small-scale farms have almost direct control of chemicals. In recent years, the aging of farmers has created many difficulties in insect pests control. Hence, there is a need to understand the optimal timing for insect pests control.

    This study was carried out to verify the effects of insect pests control on chestnut tree using the advanced technology of an unmanned drone as a tool for future pest control.

    Materials and methods

    1 Selection of study sites and period

    The area that managed best with the interest of the cultivator where chestnut trees were collectively cultivated was selected. Three sites(1 site per 1 ha) were selected among the five locations, such as Jinju city Micheonmyeun Obangri San 13, as the test sites. Three study sites for helicopter treatment area and control area each were selected in the same way (Table 1). The survey was conducted from April to November 2017.

    1.1 Methods

    The Chunpung-1(W1910 mm × H650 mm) model was used for pest treatment. The treatment was applied once at the end of July and twice at the end of August, which is the emergence period of D. punctiferalis. For the chemical treatment, three sites were treated using an unmanned drone, and the other three sites were treated using a helicopter. Afterwards, the effects of the treatment were analyzed and compared with three control sites. The chemical treatment used was tacrolifide liquid wettable powder, diluted 1,000 times.

    The effects of treatment on D. punctiferalis and Curculio sikkimensis were investigated by randomly sampling 500 seedlings in the treatment area.

    2 Damage rate per insect pests control method

    For the survey of damage rates per control method, 500 chestnuts were randomly collected as early-ripening cultivars in unmanned drone, helicopter, and control sites. Different species were selected per different harvest seasons in early September, late September, and early October. After collection, damaged chestnuts were sorted and damage rates of D. punctiferalis and C. sikkimensis were computed and compared per site.

    3 Statistics

    The statistical analysis was performed by the SAS system using the mean value of the damage rates by treatment and chestnut maturity. An ANOVA was performed to determine the damage rate between treatments, and for derived significant results, Duncan’s Multiple Range Test was performed to verify the difference between treatments(SAS, 1989).

    Results and Discussion

    1 Damage rate of chestnut fruits

    Damage rates of D. punctiferalis and C. sikkimensis, which are known to cause most damage to chestnut during harvesting season(KFRI, 1991; 1995), were investigated(Table 2).

    Damage rates were computed per ripening period, and analysis revealed that there was a statistically significant difference between early-ripening, middleripening, and late-ripening cultivars(p<0.05). The damage rate of D. punctiferalis was highest in early-ripening cultivars(24.22%), followed by middle-ripening(22.71%), and late-ripening cultivars(20.25%). The damage rate of C. sikkimensis was highest in late-ripening cultivars (24.52%), followed by middle-ripening(22.61%), and early-ripening cultivars(19.96%).

    These results imply that because the emergence period of D. punctiferalis is early to mid. August (KFRI, 1995; Lee et al., 1998; Lee, 2011), the ripening period for early-ripening cultivars coincides with the emergence period, resulting in high hatching rates and increased damage. For C. sikkimensis, the emergence period is early September(KFRI, 1991; 1995). Since the ripening period of early-ripening cultivars does not coincide with the emergence period of this insect pest, the damage rate is relatively low. On the other hand, the ripening period of middle and late-ripening cultivars coincides with this emergence period, resulting in higher hatching rates and increased damage.

    2 Change in damage rates after treatment

    Changes in damage rates per treatment method were compared with the control site(Table 3, Table 4). The comparative results showed that the damage rate of the D. punctiferalis was lowest at 8.97~9.42% in sites using drones and 14.82~15.94% in sites using helicopters, which was 20.25~24.22% lower than that of the control site. There was a statistically significant difference(p<0.05) for each treatment method. The damage rate of C. sikkimensis(KFRI, 1991) was lowest at 6.77~7.72% in the site treated using a drone and 12.62~14.94% in the site treated using a helicopter, which was 19.96~24.52% lower than that of the control site. There was a statistically significant difference(p<0.05) for each treatment method. Therefore, since drone insect pests control reduces the damage rate more significantly than that using a helicopter, this particular method can save costs and increase the efficiency of current insect pests control methods. The current insect pests control method is performed by spraying the chemicals above tree height. Hence, the amount of chemicals landing on trees is less than that sprayed by drones, causing significant differences between the two treatment methods.

    3 Control value of chestnut insect pests by treatment method

    The control effects of drone and helicopter treatment methods are shown in Table 5. The effect on D. punctiferalis was 50.95% and 30.82%, with drone treatment having a higher impact. Control effects on C. sikkimensis were 66.97% and 40.78%, with drone treatment having a higher impact as well. A study by Lee(2009) showed similar control effects to those in this study, 23.81% and 28.9%, respectively. On the other hand, in this study the control effect by drone treatment was greater than that by the helicopter treatment. These results imply a potential future application of drones in the insect pests control industry, but continuous future research is needed.

    Acknowledgement

    This work was supported by Gyeongnam National University of Science and Technology Grant in 2017.

    Figure

    Table

    The chestnut orchards of study sites

    Damage rate of chestnut fruits by D. punctiferalis and C. sikkimensis in chestnut orchards in 2017

    Change in the damage rate of D. punctiferalis in treated chestnut orchards by treatment method

    Change in the damage rate of C. sikkimensis in treated chestnut orchards by treatment method

    Control effects(%) of chestnut insect pests by treatment method

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