Role of the plant-conspecific complex in host location and intra-specific communication of Lygus rugulipennis

Wind tunnel and vertical open Y-shaped olfactometer studies are used to test whether volatile cues from the host plant (Vicia faba), from conspecific bugs, and from a plant-conspecifics combination, would elicit behavioural responses in mated males and females of Lygus rugulipennis. In the olfactometer, females move towards volatiles from healthy plants but they do not respond to volatiles released by oviposition- and/or feeding-damaged plants without conspecifics, nor to conspecifics alone. Both in the wind tunnel and olfactometer, females respond to volatiles emitted by the plant-insect complex. By contrast, in the wind tunnel, both sexes move significantly towards damaged host plants, even if the presence of conspecifics on these plants enhances only the female response. However, the presence of eggs from conspecifics on host plants reduces the responses of both sexes in the wind tunnel. Finally, males, as well as females, are less responsive to conspecifics alone compared with damaged plants, especially when conspecifics are present on the host plants (host plant-Lygus complex). The results suggest that volatiles emitted by plants and conspecifics influence L. rugulipennis behaviour, giving information to both sexes on the presence of suitable host plants that have been colonized by other conspecifics acting as pioneers, or providing information on the presence of an already exploited host plant (presence of eggs), thus preventing competition. Males also can use this information to increase the probability of encountering mature females.