Fruit ßies (Diptera: Tephritidae) are among the most important pests of fruits and vegetables. In this study, the typology, number, size, and distribution pattern of sensilla on tarsi and ovipositors of six fruit ßy species, including Bactrocera cucurbitae Coquillett, Bactrocera diaphora (Hendel), Bactrocera dorsalis Hendel, Bactrocera minax (Enderlein), Bactrocera scutellata (Hendel), and Bactrocera tau (Walker), were analyzed by scanning electron microscopy techniques. The tarsi of these six fruit ßy species are equipped with three types of trichoid sensilla (1, 2, and 3), chaetica sensilla, and basiconic sensilla. Two types of sensilla, trichoid sensilla (4 and 5) and campaniform sensilla, are identiÞed on the ovipositors of the female fruit Þles. In addition, the possible functions of these sensilla are discussed in light of previously published literature, and the trichoid sensilla (1, 2, and 3) on the tarsi, and trichoid sensilla (4 and 5), as well as campaniform sensilla on the ovipositors are considered as mechanoreceptor. The basiconic sensilla might have an olfactory function, and the chaetica sensilla were suggested as a mechano-or olfactory/gustatory neurons. Future functional tarsi and ovipositors morphology and electrophysiological of tarsi and ovipositors studies are needed to conÞrm these proposed functions.
Fruit flies (Diptera: Tephritidae) are important pests of many fruits and vegetables. In this study, the external morphology, types, and distribution of antennal sensilla in both male and female adults of the six fruit fly species, including Bactrocera tau (Walker), Bactrocera dorsalis (Hendel), Bactrocera cucurbitae (Coquillett), Bactrocera minax (Enderlein), Bactrocera diaphora (Hendel), and Bactrocera scutellata (Hendel), were observed by using scanning electron microscopy. The antennae of the six fruit fly species consist of a basal scape, pedicel, and an elongated flagellum. Arising from the proximal dorsal ridge of flagellum there is an arista consisting of two short basal segments and a long thin distal segment. Six distinct morphological types of sensilla are recorded in both sexes, including microtrichial sensilla, sensilla chaetica, sensilla trichoid, sensilla basiconica, short type of sensilla basiconica, and sensilla coeloconica. The abundance and distribution of these six sensilla types on the antennae of both sexes are recorded. In addition, the possible functions of the above-mentioned sensilla types are discussed in light of previously published literature. The functions include the mechanoreception of microtrichial sensilla, sensilla chaetica, and sensilla trichoid; olfactory functions of sensilla basiconic, and sensilla coeloconica; and thermoreception of the short type of sensilla basiconica. Future functional antennal morphology and electrophysiological studies are needed to confirm these proposed functions.
Glutathione S-transferases (GSTs) play central roles in phase II detoxification of both xenobiotics (drugs, insecticides, and herbicides) and endogenous compounds in almost all living organisms. In this study, we successfully purified the GSTs from the citrus red mite, Panonychus citri, by affinity chromatography on Glutathione Sepharose 4B and compared the biochemical characterizations of the purified GSTs from three field populations [beibei (BB), wanzhou (WZ), and zhongxian (ZX)]. SDS-PAGE revealed that the molecular weight of GSTs from three populations consisted of two subunits of 27.3 and 26.1 kDa. The specific activity of the purified GSTs from the WZ and ZX populations was increased 1.5- and 3.8-fold, respectively, compared with the BB population. Accordingly, the pyridaben susceptibility of WZ and ZX populations was less compared with BB population. Kinetic analyses showed that the WZ and ZX populations had higher substrate specificity compared with the BB population based on the values of k (cat) and k (cat) /K (m) to both reduced glutathione (GSH) and 1-chloro-2,4-dinitrobenzene (CDNB). The in vitro inhibition studies of GSTs indicated that the I (50) values of pyridaben from WZ and ZX populations of P. citri expressed 1.6- and 4.4-fold decreases, respectively, compared to the I (50) value of pyridaben from the BB population. In conclusion, all evidence suggested that the purified GSTs may partially contribute to the susceptibility of acaricide pyridaben in field populations of P. citri.
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