Ultra-structural characterization of the genitalial sensilla of Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Psyllidae)

Asian citrus psyllid (ACP), Diaphorina citri Kuwayama, transmits the causal pathogen of the citrus disease huanglongbing (HLB). Wing-borne vibrations of substrate are believed to mediate acoustic communication in D. citri. Observations of D. citri indicate that adults of both sexes oscillate their abdomen dorso-ventrally on both host plants and within olfactometers prior to mating. We examined the external morphology of the sensilla present on the subgenital plates and genital regions of D. citri adults with scanning electron microscopy (SEM) to gain insight into the their function with respect to communication. Furthermore, we determined the putative functions of the identified sensilla using transmission electron microscopy (TEM). Both sexes of D. citri possessed three types of morphologically distinct aporous sensilla trichoidea (AST) on dorsal, ventral and lateral sides of their subgenital plates. The shape, external morphology and array of AST were similar in both sexes. However, males possessed more AST than females. Male D. citri possessed uniporous sensilla in addition to aporous sensilla. Collectively, our results suggest that abdominal oscillations contribute to mate finding behavior in D. citri. Aporous sensilla may function as mechanoreceptors whereas uniporous sensilla may function as chemoreceptors.