Thrips (Thripidae: Thysanoptera) are little hemimetabolous insects with recognizable cigar-shaped bodies. Thrips are small insects, with an adult body size ranging from about 0.5 to 15 mm (Goldarazena, 2011). Thrips cause several problems for various fruits and vegetables. They impact the young leaves, flowers, and young fruits of the strawberry (Allen and Gaede, 1963), mangosteen (Thongjua and Thongjua, 2013), and aubergine (Kawai, 1990). Additionally, they have an impact on a variety of vegetables, including cucumbers, tomatoes, and sweet peppers (Rosenheim et al., 1990; Welter et al., 1990; Shipp et al., 1998; Hao et al., 2002). Thrips affect the leaves and flowers of fruits and vegetables and reduce their production (Devi and Roy, 2017). Moreover, they lower the market value of fruits and vegetables by damaging their appearance (Heinz et al., 1992). In this way, thrips consequently lower the quality of fruits and vegetables and result in lost revenue. Thrips affect the mangosteen (
Several studies show that different methods are utilized for thrips control in different countries; for example, in Japan, South Florida, UK, and Brazil people use chemical methods to control the thrips (Raetano et al., 2003; Smit et al., 2005; Cannon et al., 2007). In Japan and UK, people use biological methods for thrips control (Rodriguez et al., 2003; Smit et al., 2005). Physical method and integrated pest management (IPM) methods (e.g., mass trapping by using sticky traps) are used by the people in Venezuela and Japan (Salas, 2004; Yano, 2018). However, several studies suggest that these methods utilized in different countries have negative effects on the environment and human health (Cannon et al., 2007; Zhang et al., 2008). Therefore, an environment-friendly method needs to be developed to control the thrips. It is well known that various environmental factors affect the thrips density and distribution such as humidity, rainfall, temperature, and wind (Thongjua and Thongjua, 2015), but humidity is the one that affect the most (Waiganjo et al., 2008). There is a negative relationship between humidity and thrips numbers (Akram et al., 2013; Thongjua and Thongjua, 2015); it means that high humidity can reduce the numbers of thrips inside mangosteen canopy. Therefore in this study, we would like to develop and use a smart watering system to control thrips numbers through controlling humidity inside the mangosteen canopy.
Farmers may increase their mangosteen productivity and receive more benefit by using this smart watering method inside mangosteen canopy. Previously, smart watering systems has been used by people in several countries for various purposes. For example, smart watering systems were utilized in mango orchards in Spain to control the irrigation process and in China to control the soil moisture content, respectively (Wei et al., 2017; Zuazo et al., 2021). In Thailand and India, several fruit and vegetable orchards have better irrigation process due to the use of smart watering systems (Sikka et al., 2016; Musik, 2020). In Thailand, smart watering system is used to control the humidity in mangosteen orchard (Malee et al., 2022). Smart sensing systems were created in New Zealand and Australia for monitoring nitrate levels in ground and surfacewater used in agricultural purposes (Alahi et al., 2017a, 2017b, 2018a, 2018b, 2018c, 2022). In these countries, smart watering systems were developed for monitoring the water quality in aquaculture and agriculture (Akhter et al., 2021a, 2021b).
Thong Hong mangosteen garden in Phrom Khiri district (latitude: 8° 12′ N and longitude: 99° 28′ E), Nakhon Si Thammarat province, Thailand was selected to conduct this study. The size of this garden is 13.837 acres, and there are 700 trees. The trees are approximately 8 to 9 m long, and the distances between the trees are 7 to 8 m. The study area is shown in Figure 1.
In this study, we have developed and used a smart watering system to control humidity as well as thrips inside mangosteen canopy. Figure 2 demonstrates that the system consisted of open-close water pumps, a control room with magnetic contactor and switches for switching between manual and automatic systems, smart phone (android), a microcontroller board, Bluetooth, Wi-Fi, sensors (Modbus TRU RS485 SHT20), and a Thingcontrol application. In this system, the magnetic contactor in the control room was connected to the smartphone (Android) and with a microcontroller board by Thingcontrol application and Wi-Fi. A magnetic contactor controlled the open-close pumps, and the magnetic contactor was automatically controlled by a smartphone (Android). Figure 3 illustrates a mangosteen garden's automatic water management system controlled by a microcontroller board. The system was designed and developed from March 2021 to March 2022.
We had two treatments in this study: (i) a control system and (ii) an automatic water management system. The conventional watering system was used in the control system, where the farmers provided water at the bottom of the trees for only half an hour (11.00 am–11.30 am) every day. Here, two trees were randomly selected, and one sensing system was installed in each tree (Fig. 4). In control, there was no smart watering system. Similarly, two trees were randomly selected in the automatic water management system. One sensing system was installed in each tree and a smart watering system was used (Figs. 4 and 5). In this area, humidity (%) falls below 80% from 9.00 am to 5.00 pm (Malee et al., 2022), and low humidity increases the number of thrips inside the mangosteen canopy (Akram et al., 2013). That is why we controlled the smart watering system to provide water inside the mangosteen canopy every hour (from 9.00 am to 5.00 pm) for 15 min. Figure 6 demonstrates the watering inside the mangosteen canopy.
In each tree of both treatments, one yellow sticky trap sheet (dual-sided 25 × 20 cm) was hung for 24 hr to collect thrips which is shown in Figure 7. Collecting thrips using yellow sticky trap sheet is common in many countries (Heinz et al., 1992; Boonham et al., 2002; Affandi et al., 2008; Aliakbarpour and Rawi, 2011; Devi and Roy, 2017). In Thailand also, the farmers use these traps to catch and reduce thrips numbers inside mangosteen canopy. We hung the sheet between 9 and 10 am, and counted thrips numbers the next day at the same time. The thrips get attached easily at both sides of the yellow sheet and cannot fly away (Boonham et al., 2002; Aliakbarpour et al., 2011). After removing each sheet from each tree, the thrips were identified by eye observation and circled with a permanent marker which is shown in Figure 8. Afterwards, the thrips numbers were counted from both sides of the sheet and data were recorded. The size (length) of randomly selected five thrips was measured and their size range was 1.2–3.9 mm, as shown in Figure 9. This experiment was conducted from 24th June to 3rd July, 2022.
In this study, humidity (%) data were also collected simultaneously when thrips data were collected. Thingcontrol company's (
We assessed the normality of the data before starting the analysis. Parametric statistics were used when normality or other assumptions of parametric tests were met. Independent sample
It was observed that mean (± SE) humidity (%) was different between control and automatic water management systems (Fig. 11). In control system, humidity (%) was significantly lower than in automatic water management system (
It was observed that thrips numbers per yellow sticky trap (dual-sided 25 × 20 cm) were significantly higher in the control system than in the automatic water management system (
There was a negative relationship between humidity (%) and thrips numbers (Spearman's correlation coefficient (
In this study, a smart watering system was developed and used for controlling humidity and thrips inside the mangosteen canopy. Previously, smart watering systems were created and employed in several fruit orchards (i.e., chestnut tree gardens, durian gardens, and mangosteen gardens) for controlling irrigation processes and various climatic factors (Mota et al., 2018; Musik, 2020; Malee et al., 2022). It was observed that our system increased humidity as well as reduced thrips numbers effectively inside mangosteen canopy. In a previous study (Malee et al., 2022), it was observed that a smart watering system was able to control humidity inside fruit orchards. However, it was not tested whether the system could control thrips numbers or not. It has been assumed that smart watering system can control thrips density through increasing humidity inside fruit orchards since there is a negative relationship between humidity and thrips numbers (Akram et al., 2003; Thongjua and Thongjua, 2015; and this study).
Thrips are more prevalent and more capable of destroying orchard fruits when there is low humidity. They impact the young leaves, flowers, and young fruits of the strawberry (Allen and Gaede, 1963), mangosteen (Thongjua and Thongjua, 2015), and aubergine (Kawai, 1990). Additionally, they impact a variety of vegetables, including cucumbers, tomatoes, and sweet peppers (Rosenheim et al., 1990; Welter et al., 1990; Shipp et al., 1998; Hao et al., 2002). Cucumbers can be infected by thrips in two different ways: they can have scars, or their shape can be changed, which reduces their production (Rosenheim et al., 1990). Another study found that thrips infections in cucumbers reduced the quantity of tendrils and leaves which increased plant fatality (Welter et al., 1990). In tomatoes and sweet peppers, thrips can produce silvery and bronzy colors which damage the appearance of vegetables and lower their market value (Shipp et al., 1998). Thrips directly damage the vegetables through eating their leaves and blooms. It changes the carbon allocation in these plants (Rosenheim et al., 1990; Shipp et al., 1998). Thrips consequently lower the quality and quantity of the fruits and vegetables, resulting in lost revenue. In Thailand, mangosteen are exported to many countries like China, Hong Kong, Canada, Taiwan, and Japan (Ongkunaruk et al., 2011; Pankeaw et al., 2011) due to the increasing demand for this fruit on worldwide markets. The value or market demand of mangosteen depends on the quality of the fruits. If thrips outbreak develops in mangosteen orchards when the fruits are young, they produce scars on the fruit's surface (Thongjua and Thongjua, 2015). Sometimes severely damaged skin can inhibit fruit development, resulting in smaller-sized fruits than normal. Thrips also causes translucent flesh disorder, and fruit gamboge. All of these problems reduce their market value inside and outside of Thailand. However, high humidity inside the mangosteen canopy creates an unsuitable environment for thrips populations and can reduce them by eliminating both adult and larval populations (Thongjua and Thongjua, 2015). That is why it was important for us to develop a smart watering system for increasing the humidity in mangosteen orchards and control thrips numbers.
The present study developed and used a smart watering system to control thrips effectively through increasing humidity inside mangosteen canopy. This system can be used by the farmers effectively to control the thrips population inside other fruit and vegetable orchards. For this reason, this system needs to be familiar and socialized with the farmers who culture mangosteen and other fruits in Thailand and other countries thus they can realize the importance of the system for controlling humidity and thrips numbers. Through using this system, they will be able to increase the quality and quantity of the fruits and earn more money.