Control of thrips in cucumber by Nesidiocoris tenuis-banker plant system

Abstract: Biological control agents (BCAs) are usually introduced after planting or after pests are observed. However, it is difficult to determine the appropriate time to introduce BCAs, since insects are not easily observed because of their very small size. Therefore, banker plant systems have been proposed as a solution for the control of insect pest, especially of aphid parasitoids. Thrips are the most important pests in cucumber because of the direct and indirect damages that they cause to the plants. Nesidiocoris tenuis is an extensively used BCA in Europe, primarily in tomato. Due to the polyphagous characteristics of N. tenuis, it may also be a good BCA against thrips in cucumber. In addition to insect pests, N. tenuis feeds on plant species used as banker plants, and thus, no alternative prey is required in a N. tenuis-banker plant system. In this study, we aimed to develop a N. tenuis-banker plant system for controlling thrips in cucumber by using garden verbena Verbena x hybrida and fairy fan-flower Scaevola aemula as banker plants for N. tenuis and investigate its effectiveness based on the population density of N. tenuis and thrips. The results showed that the presence of banker plants resulted in higher population densities of N. tenuis and lower population densities of thrips suggesting that in the presence of banker plants N. tenuis more effectively controlled thrips on cucumber plants. However, since the control ability of N. tenuis itself seems not enough, these case study implied that integrated control is important to control thrips completely.