Diurnal patterns and impact of temperature on activity of Nesidiocoris tenuis

Abstract: The zoophytophagous mirid bug Nesidiocoris tenuis (Reuter) (Hemiptera: Miridae), which is widely distributed around the world, is used as a biological control agent against tiny insect pests such as whiteflies and thrips. In order to improve the effectiveness of biological control by this species, the ecology of the species in diverse field environments needs to be further elucidated. Although the long-term seasonal variation in emergence of N. tenuis has been investigated in various fields around the world, there are no reports on their activity time or diurnal activity in shorter periods of time than a day. To enhance their activity and/or effectiveness as a biocontrol agent, the use of HIPVs or purple light has been proposed as a method to properly move N. tenuis to pest infestation sites. However, if their activity depends on factors such as time and temperature, the effects of these methods cannot be properly assessed. In this study, we investigated the amount of their daily activity by using the locomotor activity monitor (LAM10, TriKinetics Inc., MA, USA). The results showed that the activity was higher during the dark period and showed a daily cycle. The behavior was most active at 25 ℃, and the activity was significantly lower at lower temperatures. In summary, N. tenuis is active at night, and they are less active at low temperatures. These results suggest that nighttime heating in the greenhouses will be important for their full potential as a biocontrol agent.