عنوان مقاله [English]
Introduction: Increase of world population, lack of food sources, and need for food security, protection of agricultural products against losses, drought, pests, and diseases, all seems to be necessary more than ever. During the years, grains have been the main food of humans, especially wheat, barley, rice, and corn. So production and storage of these products is important for societies. One of the main problems in this field is protecting the grains in stores until consuming or planting them again. Annually, over hundreds of millions tons of grains are lost by pests present in stores and not observing the scientific principles of storing. Control of insects and pests during storage as a destructive factor of stored products by harmless methods is necessary. There are restrictions in use of chemically control methods against pests in stores. Therefore in recent decades, physically control methods have attracted a lot of attentions. The purpose of using physically control methods is eliminating pests with minimum destructive effect on the environment. These methods directly affect on pests or change their living situations and create an unsafe environment for them. One of the tools that indirectly affect pests is ultrasonic waves. Ultrasonic waves are mechanical waves which can properly penetrate in air and porous areas. These waves are completely safe for the environment and cause no damage to the environment. Ultrasonic waves as new safe strategy in insect control can prepare unsafe areas for annoying insects and agricultural pests. The main characteristics of ultrasonic waves are safe for humans and environment.
Materials and Methods: In this study, experiments were carried out to assess the repellent impact of ultrasonic waves on one important storage pest, red flour beetle (Tribolium castaneum Herbs). The system, which produces ultrasonic waves, includes distributor of ultrasonic waves, power supply, central processor, oscillator, display, Perry amplifier, amplifier, keyboard, and step motor. In this system, all parts are connected with each other. After doing pretests at different frequencies and times, frequencies of 30, 35, 40, 45, and 50 kHz and radiation times of 3, 6, 12, and 24 h were selected as the most appropriate levels of variables. So these levels were used for doing the main tests on red beetle samples of flour. to study the effect of ultrasonic waves on red beetles, a factorial experiment was done based on completely randomized block design with three replications. To study the repellent and absorbent effects of ultrasonic waves, 20 red beetles were placed in 150 g flour into plastic tubes. The tubes have 10 cm diameter and 50 cm length. The odorless and flavourless oil was rubbed to the beginning and end of tubes in order to count the number of beetles. Because they trap into oil while exiting the tubes. The insects, which go toward the radiation source of waves, were as absorbent effect of waves. On the contrary, the insects that go against the radiation source and try to get out of flour were considered as repellent effect of waves.
Results and Discussion: The results of this research showed that ultrasonic waves can give red beetles away from the flour. It showed that insects tend very much to escape from the environment So they use all directions to get out of the environment. Analysis of variance showed that the frequency variable with the level of 95% probability independently had a significant effect on the pests escape. The results showed that in frequency of 35 kHz during 6 hours radiation intervals have highest repellency and escaping of pest from the nutrient medium with less energy consumption. The study showed that the application of ultrasonic waves in pests control can reduce the fumigant pesticides which are an important factor in environmental, food storage and consumers pollution.
Conclusions: The present study indicates that physically control method with ultrasonic wave is a safe, harmless, and accommodated method with the environment. It can be used in storehouses and grain depots. So this method can be placed in consolidated management program of pests in stores. To make sure about the proper and precise performance of this system, more researches are needed to be done in this field.