Insects often rely on olfaction to communicate with conspecifics. While the chemical language of insects has been deciphered in recent decades, few studies have assessed how changes in atmospheric greenhouse gas concentrations might impact pheromonal communication in insects. Here, we hypothesize that changes in the concentration of atmospheric carbon dioxide affect the whole dynamics of alarm signaling in aphids, including: (1) the production of the active compound (E)-β-farnesene (Eβf), (2) emission behavior when under attack, (3) perception by the olfactory apparatus, and (4) the escape response. We reared two strains of the pea aphid, Acyrthosiphon pisum, under ambient and elevated CO concentrations over several generations. We found that an increase in CO concentration reduced the production (i.e., individual content) and emission (released under predation events) of Eβf. While no difference in Eβf neuronal perception was observed, we found that an increase in CO strongly reduced the escape behavior expressed by an aphid colony following exposure to natural doses of alarm pheromone. In conclusion, our results confirm that changes to greenhouse gases impact chemical communication in the pea aphid, and could potentially have a cascade effect on interactions with higher trophic levels.

a b s t r a c tWorldwide economic losses associated with Rhagoletis fruit flies (Diptera: Tephritidae) require an effective means of control. Most conventional insecticides used to control fruit flies have been banned, and fruit producers are seeking new economical fruit fly control options. Bait stations can be a suitable alternative, provided they are affordable, effective and pest-specific. Semiochemicals are important for fruit flies to locate their host fruit and to reproduce. They could therefore be good candidates to improve existing bait stations. In this literature review, we summarize the available data on Rhagoletis semiochemicals, including (1) the kairomones involved in fruit location, (2) mating and sex pheromones and (3) oviposition and host marking pheromones. We present the latest data on the chemical composition of these semiochemicals, as well as some field applications that have been successful at Rhagoletis fly control. Based on the available data on the semiochemicals of Rhagoletis species and other Tephritid flies, we believe that the association of an efficient food attractant with early applications of host marking pheromones could reduce the risk of oviposition that usually occurs rapidly after emergence. Also, traps baited with sex pheromones and/or fruit-associated kairomones could attract and kill emerging individuals. However, analytical work has still to be conducted, as most Rhagoletis semiochemicals have yet to be identified.

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