Morphology and Distribution of Antennal Sensilla of the Bean Bug Riptortus pedestris (Hemiptera: Alydidae)

ABSTRACT

The bean bug, Riptortus pedestris is a major pest of bean pods and some tree fruits in north-east Asian countries. Scanning electron microscopy was conducted to investigate the morphology and distribution of antennal sensilla of R. pedestris to help in understanding the sensory mechanisms of the bug. Average antennal lengths of male and female R. pedestris were 11.00 mm and 9.84 mm, respectively, consisting of four distinct segments, scape, pedicel, basiflagellum, and distiflagellum. Based on the gross appearance, the antennal sensilla were classified into four major types (trichodea, basiconica, chaetica, and coeloconica), which could be further classified into four trichoid, three basiconic, four chaotic, and two coeloconic subtypes, based on their size, tip shape, presence of socket, and surface structure. Among them, two subtypes of trichoid sensilla, all three subtypes of basiconic sensilla, four subtypes of chaetic sensilla and two subtypes of coeloconic sensilla had numerous pores along the surface, suggesting their olfactory function. Nine subtypes (2 trichoid, 1 basiconic, 4 chaetic, and 2 coeloconic subtypes) showed a distinct socket structure at the base. Among the four antennal segments, the distiflagellum possessed highest number of sensilla. Trichoid sensilla were most abundant, followed by basiconic, chaetic, and coeloconic sensilla. Each subtype of sensilla exhibited distinct distribution profile along the four antennal segments. Two subtypes of trichoid sensilla, one subtype of basiconic sensilla and one subtype of chaetica sensilla were distributed on scape, pedicel, and basiflagellum, whereas distribution of other subtypes of sensilla was confined to basiflagellum and distiflagellum. Microsc. Res. Tech., 2016. © 2016 Wiley Periodicals, Inc.

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