Department of Horticulture, Foshan University, Foshan, China.
College of Agronomy, Jiangxi Agricultural University, Nanchang, China.
PLoS One. 2020 Jun 3;15(6):e0234030. doi: 10.1371/journal.pone.0234030. eCollection 2020.
Diaphorina citri Kuwayama is the most economically important citrus pest which is the primary vector of Candidatus Liberibacter spp. causing citrus greening (huanglongbing, HLB) disease. To better understand the developmental and structural changes of antennae and antennal sensilla in D. citri nymphs, we investigated the antennal morphology, structure and sensilla distribution of the five nymphal stages of D. citri using scanning electron microscopy. The antennae of the five different nymphal stages of D. citri were filiform in shape, which consisted of two segments in the first-, second- and third-instar nymphs; three segments in the fourth- and fifth-instar nymphs. The length of their antennae was significantly increased with the increase of the nymphal instar, as well as the total number of antennal sensilla. Ten morphological sensilla types were recorded altogether. They were the long terminal hair (TH1), short terminal hair (TH2), sensilla trichoidea (ST), cavity sensillum 1 (CvS1), cavity sensillum 2 (CvS2), sensilla basiconica 1-3 (SB1-3), sensilla campaniform (SCA) and partitioned sensory organ (PSO). Also, the distribution of antennal sensilla in each nymphal stage of D. citri was asymmetrical. The SBs only occurred on the antennae of the third-, fourth- and fifth-instar nymphs. Only one CvS2 was found in the third- and fifth-instar nymphs, and one SCA in the fourth- and fifth-instar nymphs, respectively. The possible roles of the nymphal antennal sensilla in D. citri were discussed. The results could contribute to a better understanding of the development of the sensory system, and facilitate future studies on the antennal functions in D. citri nymphs.
柑橘木虱 Diaphorina citri Kuwayama 是最重要的柑橘害虫，也是引起柑橘黄龙病（HLB）的候选韧皮杆菌属的主要载体。为了更好地了解柑橘木虱若虫触角和触角感器的发育和结构变化，我们使用扫描电子显微镜研究了柑橘木虱五个若虫龄期的触角形态、结构和感器分布。柑橘木虱五个不同若虫龄期的触角均呈丝状，一、二、三龄若虫由两段组成，四、五龄若虫由三段组成。随着若虫龄期的增加，触角的长度显著增加，触角感器的总数也随之增加。总共记录了 10 种形态感器类型。它们是长端毛（TH1）、短端毛（TH2）、毛形感器（ST）、腔感器 1（CvS1）、腔感器 2（CvS2）、感觉锥形感器 1-3（SB1-3）、钟形感器（SCA）和分区感觉器官（PSO）。此外，柑橘木虱各若虫龄期的触角感器分布不对称。SB 仅出现在三、四、五龄若虫的触角上。三、五龄若虫各有一个 CvS2，四、五龄若虫各有一个 SCA。讨论了若虫触角感器在柑橘木虱中的可能作用。这些结果有助于更好地了解感觉系统的发育，并促进未来对柑橘木虱若虫触角功能的研究。
