1. Introduction
The Pestman In-Ground Bait System is designed for the continuous protection of buildings and is an innovative alternative to traditional soil barrier techniques. It has been successfully used in many famous buildings, such as the Wisteria House in Taipei and the Hong Kong Museum of History. The system operates on the principle of monitoring – treatment – re – monitoring, allowing for the detection and elimination of termite infestations while minimizing environmental impact.
As an alternative to the banned termiticides chlordane and mirex, the Pestman system was first installed in Jiangsu, Anhui, and Hunan provinces in China for building termite control. This study focused on evaluating the effectiveness of the Pestman in-ground bait system in controlling Coptotermes formosanus in Changde City in China, with the aim of providing valuable insights for the transition from traditional chemical control methods to integrated pest management (IPM) strategies.
2. Materials and Methods
2.1 Experimental Object
Coptotermes formosanus was selected as the experimental object.
2.2 Experimental Equipment
The Pestman in-ground bait system, which includes monitoring wood strips, bait stations, and hexaflumuron bait, was used in the experiment.
2.3 Experimental Site
The experiment was conducted in the artificial mixed forest of fir and camphor trees in the green belt of Taolin Hotel in Changde City in China.
2.4 Experimental Design Principle
A dead Metasequoia glyptostroboides tree, suspected to be the main nest site of formosanus, was chosen as the experimental location. Three underground bait stations without any bait were installed in a circular pattern around the base of the tree, within a 0.5 m radius, starting from the end of November 2009. The effectiveness of the monitoring wood strips in attracting termites was first evaluated. Once a sufficient number of termites were captured, they were transferred to the Pestman In-Ground Bait Station for further study.
2.5 Experimental Methods
2.5.1 Installation of Bait Stations
Three Monitoring Wood Strips without bait were buried in a fan – shaped pattern around the base of the damaged Metasequoia glyptostroboides tree. The stations were spaced approximately 0.5 m apart and contained monitoring wood strips. The stations were covered with a thin layer of soil to prevent damage and theft.
2.5.2 Evaluation of the Attraction Effect of Monitoring Wood Strips
After the installation of the Monitoring Wood Strips, the covers were opened and inspected every two weeks in winter and once a week in spring. The presence of termites on the monitoring wood strips was recorded, and the trapping rate was calculated based on the number of strips with termite feeding activity. The correlation between the trapping rate and environmental temperature was also analyzed.
2.5.3 Determination of the Feeding Rate of Termites on the Pestman In-Ground Bait Station
When a significant number of termites were attracted to the monitoring wood strips, they were transferred to the Pestman In-Ground Bait Station. The amount and progress of termite feeding on the Pestman In-Ground Bait Station were observed every 2 – 3 days. The time when each bait station was placed and consumed was recorded to calculate the number of days required for consumption. The weight of the bait stations was measured, and the amount of bait was determined by subtracting the weight of the plastic container. The average daily consumption of the bait stations was calculated to analyze the feeding rate of the termites.
2.5.4 Analysis of the Preference and Feeding Continuity of Termites for the Pestman In-Ground Bait Station
After termites were successfully attracted to the bait stations, two of the stations had their monitoring wood strips replaced with Pestman In-Ground Bait Station, while the remaining station continued to use monitoring wood strips for comparison. The feeding behavior of the termites was observed every three days, and the Pestman In-Ground Bait Station and monitoring wood strips were replaced when consumed. The number of times the termites were transferred, the number of Pestman In-Ground Bait Station replacements, the interruption of feeding, and the feeding rate of the new monitoring wood strips were recorded. The average daily consumption of the bait boxes was compared with that of the monitoring wood strips to evaluate the termites’ preference for the Pestman In-Ground Bait Station.
2.5.5 Measurement of the Proportion Change of Workers and Soldiers in the Pestman In-Ground Bait Station
When termites were transferred to the Pestman In-Ground Bait Station, the proportion of workers and soldiers was counted. The number of termites in each box was approximately 40 – 50, with soldiers accounting for about 8%. The proportion of workers and soldiers was estimated during each feeding rate observation. After the experiment, the changes in the proportion of workers and soldiers were analyzed.
2.5.6 Evaluation of the Effectiveness of the Pestman System
After the trapping and killing process, the activity of formosanus around the experimental site was monitored monthly for three months. If termites were detected, the Pestman In-Ground Bait Station was used again for control. If no termite activity was observed, the experiment was concluded.
3. Experimental Results and Analysis
3.1 Effect of Temperature on the Trapping Rate of Monitoring Wood Strips
From November 2008 to July 2009, termite feeding activity was first observed in the Monitoring Wood Strips in late April 2009. The meteorological data indicated that the temperature was relatively low from November 2008 to April 2009, with an average daily temperature below 15 °C. After April, the temperature increased, and the average daily temperature exceeded 19 °C. The results demonstrated that when the average daily temperature reached 19 °C, the monitoring wood strips had a strong ability to attract termites. At 21 °C, the trapping rate reached 100%, and the attraction ability remained high with increasing temperature. In contrast, when the temperature was below 15 °C, the trapping rate was low, and termite feeding activity was minimal.
3.2 Feeding Rate of Termites on the Pestman In-Ground Bait Station
During the trapping and killing process from April to July 2010, a total of 15 Pestman In-Ground Bait Stations were used. The consumption of each bait box was analyzed based on the number of days required for consumption and the amount of bait in each box. In the initial stage of the experiment, the feeding rate of the termites on the Pestman In-Ground Bait Station was relatively low. However, after approximately 26 days of feeding, the consumption reached its maximum. Subsequently, the feeding rate decreased due to the death of a large number of workers caused by the insect growth regulator. Eventually, the consumption ceased when all the workers died.
3.3 Preference and Feeding Continuity of Termites for the Pestman In-Ground Bait Stations
During the experiment, the monitoring wood strips in two bait stations were replaced with Pestman In-Ground Bait Station, and the remaining station continued to use monitoring wood strips. Before the installation of the Pestman In-Ground Bait Stations, the monitoring wood strips had a good feeding rate. However, after the replacement, the termites no longer fed on the remaining monitoring wood strips. The Pestman In-Ground Bait Stations had a 100% feeding rate until the termite colony died, and there was no interruption in feeding during the replacement process. Although the average daily consumption of the Pestman In-Ground Bait Stations was approximately eight times that of the monitoring wood strips, considering the large number of worker deaths in the later stage of the experiment, it is believed that the termites had a greater preference for the Pestman In-Ground Bait Stations. Therefore, the Pestman In-Ground Bait Station exhibited excellent termite – attracting and feeding – continuity properties.
3.4 Proportion Change of Workers and Soldiers in the Pestman In-Ground Bait Stations
During the trapping and killing process, the proportion of workers and soldiers in the termite group feeding in the Pestman In-Ground Bait Stations was observed and analyzed. Initially, the proportion of workers and soldiers in the Pestman In-Ground Bait Stations was similar to that in the natural state. However, after approximately 20 days of feeding, the proportion of workers began to decrease, while the proportion of soldiers increased. This change was due to the death of workers caused by the insect growth regulator, which affected the balance of the termite group.
4. Discussion
4.1 Correlation between Temperature and Termite Trapping
Temperature and season have a significant impact on the feeding behavior of formosanus. In cold winters, the low temperature reduces termite activity, making it difficult for the monitoring wood strips to attract termites. In contrast, in spring, when the temperature rises, termite activity increases, and the monitoring wood strips can effectively capture a sufficient number of termites for control. This study confirmed that the optimal trapping temperature in the Changde area is above 15 °C. Future research should investigate the potential effects of humidity and soil texture on termite trapping, as well as the influence of wood material on the trapping rate.
4.2 Feeding Rate of Termites on the Pestman In-Ground Bait Stations
Although the termites were manually transferred to the Pestman In-Ground Bait Stations, their strong preference for the bait led to an increasing feeding rate in the first half of the experiment. This may be attributed to the recruitment of additional workers by the transferred termites. In the second half of the experiment, the feeding rate decreased due to the death of workers caused by the insect growth regulator.
4.3 Preference and Feeding Continuity of Termites for the Pestman In-Ground Bait Stations
The termites exhibited a higher consumption of the Pestman In-Ground Bait Stations compared to the monitoring wood strips and ceased feeding on the latter after being introduced to the Pestman In-Ground Bait Stations. This behavior may be due to several factors. Firstly, the cellulose in the Pestman In-Ground Bait Stations is a high – quality food source for termites, and the insecticide hexaflumuron does not repel them, leading to an addictive effect. Secondly, the compressed granular form of the bait conforms to the termites’ feeding behavior, increasing their consumption. Finally, the presence of additives in the Pestman In-Ground Bait Stations may also contribute to the termites’ preference and continuous feeding. However, further research is needed to confirm these hypotheses, as the limited number of Pestman In-Ground Bait Stations with control monitoring wood strips in this experiment may have affected the results.
4.4 Proportion Change of Workers and Soldiers in the Pestman In-Ground Bait Stations
The use of hexaflumuron in the Pestman In-Ground Bait Stations, which inhibits worker molting and causes their death, led to a change in the proportion of workers and soldiers in the termite group. The initial proportion of workers and soldiers in the Pestman In-Ground Bait Stations was similar to that in the natural state. However, as the experiment progressed, the death of workers led to an increase in the proportion of soldiers. This may be due to the colony’s response to the loss of workers, either by increasing protection or by the soldiers gathering near the food source due to insufficient food supply from the workers.
4.5 Effectiveness of the Pestman In-Ground Bait Station
The Pestman In-Ground Bait Stations demonstrated good control effectiveness against formosanus in this experiment. The observed phenomena, such as the consumption of bait, the decrease in consumption in the later stage, the increase in the proportion of soldiers, and the changes in termite behavior, were consistent with previous reports. This indicates that the Pestman In-Ground Bait Stations is an effective method for controlling formosanus in Changde City.
5. Conclusion
The experiment using the Pestman In-Ground Bait Stations to control C. formosanus at Taolin Hotel in Changde City in China lasted for 57 days. A total of 15 Pestman In-Ground Bait Stations. The insecticide hexaflumuron was used in a total amount of 150 g.
The use of only 150 g of hexaflumuron in the environment resulted in minimal pollution and was almost non – toxic to humans and animals. Compared with traditional control methods, the Pestman is more environmentally friendly and safe, which may explain why it is considered a green product.
Future research should focus on optimizing the Pestman In-Ground Bait Stations and further investigating the factors that affect its effectiveness. This will contribute to the development of more sustainable and efficient termite control strategies.
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