In most aphid species, facultative parthenogenetic reproduction allows rapid growth and formation of large single-genotype colonies. Upon predator attack, individual aphids emit an alarm pheromone to warn the colony of this danger. (E)-β-farnesene (EBF) is the predominant constituent of the alarm pheromone in Myzus persicae (green peach aphid) and many other aphid species. Continuous exposure to alarm pheromone in aphid colonies raised on transgenic Arabidopsis thaliana plants that produce EBF leads to habituation within three generations. Whereas naive aphids are repelled by EBF, habituated aphids show no avoidance response. Similarly, individual aphids from the habituated colony can revert back to being EBF-sensitive in three generations, indicating that this behavioral change is not caused by a genetic mutation. Instead, DNA microarray experiments comparing gene expression in naive and habituated aphids treated with EBF demonstrate an almost complete desensitization in the transcriptional response to EBF. Furthermore, EBF-habituated aphids show increased progeny production relative to EBF-responsive aphids, with or without EBF treatment. Although both naive and habituated aphids emit EBF upon damage, EBF-responsive aphids have a higher survival rate in the presence of a coccinellid predator (Hippodamia convergens), and thus outperform habituated aphids that do not show an avoidance response. These results provide evidence that aphid perception of conspecific alarm pheromone aids in predator avoidance and thereby bestows fitness benefits in survivorship and fecundity. Therefore, although habituated M. persicae produce more progeny, EBF-emitting transgenic plants may have practical applications in agriculture as a result of increased predation of habituated aphids.aphid | (E)-beta-farnesene | Hippodamia convergens | microarray | sesquiterpene R apid population growth of aphids is facilitated by their parthenogenetic lifestyle, which often results in the establishment of large single-genotype colonies in the field. In agricultural settings, aphid populations can be controlled with natural enemies such as coccinellid beetles and parasitoid wasps. Despite the effectiveness of biological control, behavioral responses to the threat of predation may allow aphids to persist as pests. Aphid avoidance of predators involves the production of an alarm pheromone. Across a remarkable diversity of aphids, the alarm pheromone contains a mixture of compounds with (E)-β-Farnesene (EBF) as the predominant component (1-3). Detection of EBF results in an array of aphid escape behaviors that, depending on the species and developmental stage, can include flying, walking away, and dropping off the plant.EBF is a volatile sesquiterpene released from cornicles on the aphid's abdomen (4). When an aphid is attacked, it can release EBF in a range of concentrations, depending on the stress that is encountered, as well as the specific species, lineage, and developmental stage of the aphid itself (5-10). EBF-treated Acyrthosiphon pisum do no...

Isometric and allometric scaling of floral organs in North American Oenothera section Lavauxia drive variation in breeding system. Multiple developmental paths to intermediate phenotypes support the likelihood of multiple mating system transitions.