Abstract:

【Aim】 The aim of this study is to determine the type, morphology and distribution of antennal sensilla of Thrips hawaiiensis (Thysanoptera: Thripidae) at various developmental stages. 【Methods】 The antennal morphology and structure and the type, morphology and distribution of antennal sensilla of female and male adults, nymphs, pre-pupae and pupae of T. hawaiiensis were observed by using the scanning electron microscopy (SEM). 【Results】 The antenna of adult T. hawaiiensis is composed of scape, pedicel and a long flagellum with five flagellomeres (I-V). The mean length of antennae of female and male adults is 263.70±5.78 and 225.79±8.92 μm, respectively. The length of antennae increases with the growth of T. hawaiiensis. There are seven types of sensilla, i.e., Bhm bristles (BB), sensilla campaniformia (SCa), sensilla chaetica (SChI, SChII), sensilla trichodea (ST), sensilla basiconica (SBI, SBII, SBIII), sensilla coeloconica (SCo) and sensilla cavity (SCav), and two cuticular structures, i.e., microtrichia (mt) and cuticular denticles (cd), on the antenna of adults. The antenna of prepupae is conical, has no distinct segmentation and can move freely, with the mean length of 138.81±6.29 μm. The pupal antenna is cylindricalshaped pressing against the cephalo-thoracic back and immobile, and has no obvious segmentation, with a mean length of 213.07±6.30 μm. The antenna of the 1st and 2nd instar nymphs is composed of scape, pedicel and a flagellum with four flagellomeres (I-IV), with the mean length of 122.48±1.72 and 134.58±3.75 μm, respectively. There are eight types of sensilla ［BB, SCa, SCh (SChI, SChII), SB (SBI, SBII), SCo, SCav, ST, and unusual sensillum (US)］ and two cuticular structures ［cd and ligulate structure (LS)］ on the antenna of the 1st instar nymphs. There are seven types of sensilla ［BB, SCa, SCh (SChI, SChII), ST, SB (SBI, SBII), SCo, and SCav］ and one cuticular structure (cd) on the antenna of the 2nd instar nymphs. 【Conclusion】 In this study, the antenna and the morphology and distribution of antennal sensilla of T. hawaiiensis at various developmental stages were observed and comprehensively described, and the functions of antennal sensilla were inferred. The results lay a theoretical foundation for further research on the physiological functions of antennal sensilla of thrips.

Key words: Thrips hawaiiensis; antenna, morphology, antennal sensilla, cuticular structure, scanning electron microscopy