Novel simple method to collect alarm pheromone from brown citrus aphid, Toxoptera citricida (subfamily Aphididae)

Aphid cornicles are unique defensive tube-like organs found only in aphids on the posterior surface of their abdomen. Cornicles secrete defensive fluid as a mechanical protection and thus it provides direct fitness. When natural enemies attack aphid, the aphid daubs them with a sticky cornicle secretion, which hardens upon contacting the natural enemy and glues its appendages (such as mouth part, antennae, leg. etc.). This gives the chance to aphid to escape from the predation. While aphid secretes the defensive fluid, it also emits volatile alarm pheromone that is confined in the defensive fluid. The alarm pheromone is emitted by an individual to warn clone-members through chemical signaling. In their turn, the clone-members respond to the signal by stop feeding and leave the area of feeding to escape from the predator. Accordingly, alarm pheromone was found to provide indirect fitness or inclusive fitness. Although different alarm pheromones were identified in different aphid species, the sesquiterpene trans- β-farnesene was found to be the only alarm pheromone in many of subfamily Aphididae species. Different methods were used to identify and study the effects of the alarm pheromone on aphid fitness such as crushing –insect but the collection included natural enemy or plant. In fact, including other factors in pheromone collection such as plant, soil, or solvents affect the results. Moreover, including predator in the collection or crushing aphid will also affect the results. In these methods the produced alarm pheromone inside the body will be collected not only the released which is emitted only when aphids face stressful conditions or danger. In current study, we collected the alarm pheromone EBF in naïve live brown citrus aphid, Toxoptera citricda (subfamily Aphididae) using novel method without using any bio-stress factor or crashing the insects.