Phytophagous insects, including Asian citrus psyllids (Diaphorina citri Kuwayama), use multiple sensory modalities (vision, olfaction, and gustation,) to locate and accept host plants. We explored incorporation of several sensory cues into a multi-modal attract-and-kill device (AK device) using a three-dimensional shape to increase visibility, as well as elements of color, attractant, phagostimulant, UV reflectant, and toxicant. Attraction of adult D. citri to the device was mediated by a combination of a highly reflective yellow cylinder, a UV reflectant compound (magnesium oxide), and an odorant blend as a short-range attractant. The device surface was coated with a slow-release wax matrix (SPLAT™) augmented with a phagostimulant consisting of a 3-component blend (formic acid, acetic acid, and para-cymene) and an insecticide (β-cyfluthrin). Psyllids landing on the device attempted to feed from the wax matrix, became intoxicated, died, and fell from the device. The device remained fully active over a period of 12 weeks partly because dead psyllids or nontargets did not adhere to the surface as occurs on adhesive yellow sticky cards, the industry standard. Laboratory and field assays showed that the device attracted and killed significantly more adult D. citri than ordinary yellow sticky cards. This device or a future iteration based on the design elements of this device is expected to contribute to sustainable and environmentally appropriate management of D. citri by exploiting the psyllid’s innate behavioral responses to visual, olfactory, and gustatory stimuli.

The Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae), is the vector of the bacterium responsible for huanglongbing, a deadly plant disease affecting citrus worldwide. We investigated the effects of wind direction and speed on flight duration and direction of D. citri, as well as the effects of temperature and barometric pressure on sustained flight duration of D. citri. Experiments were performed with laboratory flight mills and wind tunnels. Flight activity of D. citri increased with increasing temperature. Of the few insects that flew at 18°C, most performed short duration flights (<60 s). When exposed to temperatures between 21 and 28°C, D. citri performed long duration flights (>60 s). In addition, the distance covered increased with temperature. Interestingly, males were more sensitive to cold temperature and flew significantly shorter distances than females at 21 and 25°C. Barometric pressure recorded before and during the flight mill experiment suggested that decreasing pressure reduced distance flown by D. citri. Flight direction was strongly influenced by wind. In wind tunnel experiments where psyllids were challenged to reach citrus leaf flush positioned either downwind or upwind, most D. citri moved downwind when exposed to continuous airflow. In a subsequent experiment, we challenged psyllids to pulsed wind blowing at higher speeds. In this case, most psyllids progressed upwind, suggesting upwind movement by psyllids during pauses within pulsed airflow. Collectively, the results indicate that D. citri are able to modify their flight behavior in response to abiotic factors.

1 Invasive ambrosia beetles in the Euwallacea nr. fornicatus species complex (Coleoptera: Curculionidae: Scolytinae) threaten avocado production in multiple countries. These pests are currently monitored with lures containing quercivorol;-copaene was also recently discovered to be an effective attractant. 2 We investigated dispersal behaviour of female E. nr. fornicatus in two Florida avocado groves using mark-release-recapture experiments and laboratory flight mills. Additionally, we estimated the sampling range of quercivorol and -copaene lures deployed alone and in tandem. 3 The two-component lure recaptured 31.2% of marked beetles, which was significantly more than quercivorol (11.2%) or -copaene (8.8%) alone. Contour analysis indicated that wind speed and direction can influence the number of females that disperse, as well as the direction and distance of their flight. 4 Two methods were used to estimate sampling range and both of them indicated comparable effective ranges for the three lure treatments, with 80% of marked beetles being recaptured within 30-35 m of the release point. Average total flight distance in laboratory tests was 81.0 m in 24 h, with a maximum distance recorded at 400 m. 5 The combination of quercivorol and -copaene lures provides the best detection of pest E. nr. fornicatus in Florida, with a recommended trap spacing of approximately 30 m in surveillance programmes for this pest in avocado groves.