Comparative flight performance of three important pest Adelphocoris species of Bt cotton in China

The massive adoption of Bt cotton throughout China has been accompanied by outbreaks of secondary pests such as Adelphocoris spp. (Heteroptera: Miridae). The Adelphocoris group primarily consists of three species: A. suturalis, A. fasciaticollis and A. lineolatus, which greatly differ in geographical distribution and seasonal dynamics. However, the underlying drivers of these differences remain to be understood. The study of flight behaviour of these three species can yield important insight into their spatial and temporal dynamics and help explain their distribution. We examined flight propensity of the three Adelphocoris spp. under a range of biological and environmental conditions using a computer-monitored flight-mill. Gender and mating status only had minor effects on flight performance in these species, while age exerted great effects on it. Flight capacity was low for one-day-old adults and increased with age until day 10-13, then gradually decreased afterwards. Temperature and relative humidity affected flight propensity, with 20-23 degrees C and 64-68% RH considered optimal for flight of all three species. Between-species comparisons indicated that A. suturalis and A. fasciaticollis had similar flight distance and duration, which were significantly greater than for A. lineolatus. Our findings provide crucial information for understanding geographical distribution and seasonal occurrence and for developing regional forecasting and pest management protocols for Adelphocoris species.