Morphology and function of ovipositorial and tarsal sensilla of female Asian citrus psyllid

Abstract

AbstractThe Asian citrus psyllid (ACP), Diaphorina citri Kuwayama (Hemiptera:Psyllidae), is one of the most important pests of citrus plants worldwide, due to be the dominant vector of the devastating citrus disease Huanglongbing (HLB). Selection of suitable oviposition site is a crucial event of phytophagous insect life. Usually, the chemical and physical characteristics of a host plant were recognized by sensilla on the ovipositor and tarsi of a phytophagous insect after settling on a plant surface. In this study, the morphology, number, and distribution pattern of the ovipositorial and tarsal sensilla of adult female psyllids, were observed by scanning electron microscopy (SEM) techniques. The effect of these sensilla on oviposition was investigated by sensilla deactivation using hydrochloric acid (HCl). The results showed that sensilla trichoid (ST), sensilla chaetica (ChS) and sensilla basiconica (SB) were distributed on ovipositor, while sensilla trichoid (ST) were distributed on the external genitalia. Sensilla chaetica (ChS) and basiconica (SB) were mainly distributed on the end of the ovipositor back plate, and on the base of the sternum. On tarsus, sensilla trichoid (ST), sensilla chaetica (ChS), sensilla triangular (TeS) and sensilla ear ball (SE) were observed. However, whole tarsal segments were covered with Böhm's mane, which was arranged in a circular line. Oviposition assay revealed that a significantly lower number of eggs were laid on the Murraya paniculata seedlings confined by the psyllids with deactivated ovipositorial sensilla followed by protarsal sensilla, mesotarsal sensilla and hindtarsal sensilla. These results suggested that the ovipositorial and tarsal sensilla of citrus psyllid have an important role in the oviposition.