Semiochemical and Vibrational Cues and Signals Mediating Mate Finding and Courtship in Psylloidea (Hemiptera): A Synthesis

Abstract

Mate finding and courtship involve complex interactions that require close coordination between individuals of the opposite gender. Well-organized signalling systems, sometimes involving a combination of signal modalities, are required to convey species-specific and individual information to members of the opposite gender. Previous studies of psyllids have focused on single-signal modalities and have largely ignored the potentially interdependent nature of different types of signals. Several studies have shown that semiochemicals play a role in psyllid mate finding. However, long-range semiochemical sex attractants, such as the highly volatile sex pheromones used by many Lepidoptera (molecular weights <300), are yet to be identified. The compounds identified thus far, namely 13-methylheptacosane (from Cacopsylla pyricola) and dodecanoic acid (from Diaphorina citri), seem to have short range activity or no activity under field conditions. The possible role played by cuticular hydrocarbons in psyllid courtship remains largely ignored. Conversely, many psyllid species rely on vibrational signals for mate finding and mate assessment during courtship. This apparent disproportional reliance on vibrational rather than semiochemical signals suggests that vibrational signals have been more influential in sexual selection in psyllids. However, male fitness, female choice and benefits accrued from selecting fitter males remain poorly understood.

Male Psyllids Differentially Learn in the Context of Copulation

“…In an effort to slow the spread of the disease in citrus growing regions worldwide, considerable research on the behavior and ecology of D. citri has focused on the reproductive biology and mate finding behavior of this devastating agricultural pest species. Psyllids are known to use multi-modal communication to detect mates within a complex host plant environment [4,5]. Vibrational communication is widespread among Hemiptera [6,7,8] and in addition to functioning as an independent communication method, appears to modulate other forms of communication including long-range attraction and short-range courtship pheromone production [5,8,9].…”

“…Females then reply, facilitating their location by males on the host plant [11,13]. This appears common among most psyllid species [5] although the characteristics of their vibrational calling is likely species specific [14]. In an effort to exploit the dueting behaviors of reproductive D. citri , artificial female calling devices are being developed for use in the field as a form of mating disruption [13,15,16,17].…”

“…It is likely that these pheromones function as short-distance cues used after vibrational communication has allowed long-distance detection along the plant surface. At least three other psyllid species are known to use female produced sex-pheromones to attract mates including Cacopsylla bidens [5], C. pyricola [20], and Bactericera cockerelli [21]. However, there is some evidence to suggest that different psyllid species use semiochemicals in a manner that is species specific [5].…”

Apple Proliferation Phytoplasma Influences the Pattern of Plant Volatiles Emitted Depending on Pathogen Virulence

“…Some species of psyllid have been shown to use semiochemicals in interspecific and intraspecific communication (Soroker et al, 2004;Mayer et al, 2011;Gross, 2013;Weintraub and Gross, 2013;Lubanga et al, 2014). While sex pheromones may play a role in mate location in some species of psyllid, it appears that vibrational signals may be even more important and perhaps effective for mate location and selection (Eben et al, 2014;Lubanga et al, 2014;Wood et al, 2015).…”

“…While sex pheromones may play a role in mate location in some species of psyllid, it appears that vibrational signals may be even more important and perhaps effective for mate location and selection (Eben et al, 2014;Lubanga et al, 2014;Wood et al, 2015). Psyllid behaviors related to aggregation will be important to elucidate to better understand the epidemiology of phytoplasmas.…”