On the other hand, C. carnea larvae did encounter and even successfully attacked prey on inflorescences, suggesting potential to control P. cannabis populations on flowering medicinal cannabis. The results from the present and previous studies on hairy plants, showed that the morphology of the natural enemy and the type of glandular trichomes are key factors regarding the mobility and predation success of biological control agents . Finally, it is important to note that the very distinct predation strategies exhibited by the larvae of the two predators should also be taken into consideration when interpreting our results. On one hand, the larvae of A. aphidimyza are furtive predators, usually positioned in the center of the aphid colony and thus, they do not have to cover long distances for exploiting their prey . On the other hand, the larvae of C. carnea employ an active searching strategy causing significant disturbance in the aphid colonies and thus they have to cover longer distances for exploiting their prey . Finally, it is important to highlight the fact that females of A. aphidimyza readily oviposited on medicinal cannabis plants infested by P. cannabis. Previous studies tested the oviposition of A. aphidimyza as influenced by plant trichomes and found a higher number of eggs laid on potato varieties with higher trichome density .
A positive association between the cannabis aphid colony size and the number of eggs laid by female A. aphidimyza has been reported in previous studies with other aphid species on different host plants cannabis drying racks. This result confirms that A. aphidimyza females respond to the cannabis aphid infestations and is reassuring regarding the biocontrol potential of this predator against P. cannabis. Since ancient times, Cannabis has been extensively utilized by humans for a variety of uses, such as textiles, paper, food, medicine, biofuel or recreational drugs. Cannabis has been an integral part of human life since its domestication and continues into the present . However, research on the uses and applications of this plant significantly decreased and almost ceased in the mid-20th century when the species and its varieties were declared illegal in most Western countries, regardless of the concentrations of psychoactive compounds . Therefore, one of the most ancient crops, long-valued for its multiple uses, became largely ignored during the last 50 years. Thus, compared with other crop plants, Cannabis has not fully benefited from modern scientific technologies, which has created a major knowledge gap that remains to be filled .
The last decade has witnessed a revival of interest in Cannabis research, especially in relation to the genetic and phytochemical features of the different varieties and to its evolutionary origin, domestication and further geographic diffusion . For example, the use of modern methods of molecular analysis has helped clarify the taxonomy of the Cannabis complex and its genetic modifications over time as a result of artificial selection during the domestication process . Palynological and archeological records have been used mostly to identify the geographical center of origin of Cannabis, its center of domestication and further human-driven diffusion patterns throughout the world. Modern global and regional databases and associated handling facilities, notably geographic information system tools, have been instrumental in this type of research . This paper briefly reviews the newly available information on the center of origin and the center of domestication of Cannabis and its further worldwide dispersal, with a focus on Europe,cannabis grow tray where spatiotemporal diffusion patterns remain controversial, and the Iberian Peninsula, which represents a knowledge gap regarding the tempo and mode of Cannabis arrival and diffusion.
Previous reviews on the subject date from roughly a decade ago . A review including the research developed on Cannabis during the last decade, which has been fundamental for setting the present standards of knowledge, is lacking. This is especially true for the meta-analyses and molecular phylogenetic investigations developed during the last five years. The present review represents an updated outlook on the evolution, domestication and worldwide diffusion of Cannabis that includes the latest developments on this topic. The review begins with a brief section regarding the current state of Cannabis taxonomy, ecology, phenology and human uses. The next section discusses the evolutionary center of origin and the time of appearance of the original wild Cannabis, followed by similar geographic and chronological considerations on Cannabis domestication and diffusion of its cultivated forms. The next section focuses on Europe, where domestication and diffusion patterns are still under discussion.