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The oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae), is one of the most important economic pests in tropical and subtropical areas of the world, where it causes serious damage to fruit production. This study aimed to investigate the criteria for dividing the instars of B. dorsalis, which will be fundamental for the control and forecasting of development rates, as well as the development of efficient control measures for B. dorsalis. Five morphological variables, including the body length, the length and width of mouth hooks, and the length and width of the pharyngeal sclerite of the larvae, were measured. The Crosby growth rule was used in determining that B. dorsalis has 3 instars. The length of the pharyngeal sclerite is the best morphological variable for distinguishing the instars of B. dorsalis, whereas the length and the width of mouth hooks and the width of the pharyngeal sclerite can be used as additional characteristics. There was an overlap in the body length bet...

The insect male accessory glands/ejaculatory duct (MAG/ED) are important tissues of the male reproductive system. The MAG/ED's functions in reproduction have been well studied in Drosophila (Diptera: Drosophilidae) but remain largely unknown in the important agricultural pest Bactrocera dorsalis (Hendel) (Diptera: Tephritidae). In the present study, we re-assembled the transcriptome datasets of B. dorsalis's fat body, testis, and MAG/ED and compared these tissue-specific transcriptomes. Clean reads from these transcriptome data sets were de novo re-assembled and clustered into 31,782 unigenes (average 922 bp). In total, 21,306 unigenes were functionally annotated by Blasting against online databases. Comparative transcriptomic analysis identified numerous genes that were identified with the expressed tissue-bias patterns. Some MAG/ED-specific genes potentially involved in spermatozoa motility and capacitation (e.g., perlucin, glucose dehydrogenase, lipase), mating regulation (pheromone-binding protein—related protein), and immunity (lectin) were identified in B. dorsalis. The expressions of some of these genes were further validated by realtime quantitative polymerase chain reaction at transcriptional level. All of these identifications will help us to explore the physiological regulation of mating and reproduction in B. dorsalis in the future.

Juvenile hormone (JH) plays an important role in regulating growth, development, and reproduction of insects. Three key enzymes, namely, JH esterase (JHE), JH epoxide hydrolase (JHEH), and JH diol kinase (JHDK), are involved in JH degradation. In this study, we identified the full-length cDNAs of the 3 genes BdJHEH2, BdJHEH3, and BdJHDK encoding JHEH and JHDK from the oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae). We used quantitative real-time polymerase chain reaction to investigate mRNA expression profiles of these 3 genes in various development stages and tissues, and in response to both 20-hydroxyecdysone (20E) and starvation. Both BdJHEH2 and BdJHDK were highly expressed during the larval–pupal transition, whereas BdJHEH3 was mainly expressed in the early 3rd instars. All 3 genes were highly expressed in 7-d-old and 10-d-old adults, but exhibited sex-specific expression patterns. BdJHEH2 was highly expressed in fat body, whereas BdJHEH3 and BdJHDK were most abundant in Malpighian tubules. In response to 20E exposure, the 3 genes were significantly up-regulated at various time points compared with the control. However, the transcript levels of BdJHDK decreased significantly during the initial exposure to 20E. After starvation treatment, expression of BdJHEH2 and BdJHEH3 significantly decreased, whereas BdJHDK was up-regulated. No significant change was observed after feeding resumption. These 3 genes have distinct roles in regulating growth and development of B. dorsalis. ResumenLa hormona juvenil (JH) juega un papel importante en la regulacion de crecimiento, el desarrollo y la reproduccion de los insectos. Tres enzimas clave, JH esterasa (JHE), JH epoxido hidrolasa (JHEH), y JH diol quinasa (JHDK), estan implicadas en la degradacion de JH. En este estudio, hemos identificado los ADNc de longitud completa de los 3 genes BdJHEH2, BdJHEH3 y BdJHDK que codifican JHEH y JHDK de la mosca oriental de la fruta, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae). Se utilizo PCR cuantitativa en tiempo real para investigar los perfiles de expresion de mRNA de estos 3 genes en diferentes estadios de desarrollo y tejidos, y en respuesta a tanto 20-hidroxiecdisona (20E) y la inanicion. Tanto BdJHEH2 y BdJHDK fueron altamente expresado durante la transicion larval-pupal, mientras que BdJHEH3 se expreso principalmente en el 3er estadio temprano. Todos los 3 genes fueron altamente expresado en los adultos de 7 dias de edad y de 10 dias de edad, pero exhiben patrones de expresion especificos al sexo. BdJHEH2 fue altamente expresado en la grasa corporal, mientras que BdJHEH3 y BdJHDK fueron mas abundantes en los tubulos de Malpighi. En respuesta a la exposicion 20E, los 3 genes fueron significativamente hasta reguladas en varios puntos de tiempo en comparacion con el control. Sin embargo, los niveles de transcripcion de BdJHDK disminuyeron significativamente durante la exposicion inicial a 20E. Despues del tratamiento de inanicion, la expresion de BdJHEH2 y BdJHEH3 disminuyo significativamente, mientras que BdJHDK su regulacion aumento. No se observo ningun cambio significativo despues de la reanudacion de la alimentacion. Estos 3 genes tienen funciones distintas en la regulacion del crecimiento y el desarrollo de B. dorsalis. View this article in BioOne

Two new Chinese Cryptocercus (Blattodea: Cryptocercidae) species, C. arcuatus sp. nov. and C. convexus sp. nov., are described together with photographs. This description includes the external structure of the adults and structures of the female genitalia. A comparative study of female genitalia was based on the 5 Chinese species in the family Cryptocercidae. Significant differences in female genitalia of Cryptocercidae are summarized. A key to these 5 species and a checklist of the species of Cryptocercus worldwide are provided.

Polyandry is widespread among insects but male accessory gland products can influence the propensity of former mates to copulate later with other males. In addition, females may receive nutritional supplements in accessory gland fluids that substantially increase fitness regardless of whether re mating has been inhibited. In this study, we investigated polyandry in female Bactrocera dorsalis (Hendel) (Diptera: Tephritidae) and the relationship between remating and male accessory gland contents. Similar to other fruit flies, 2 kinds of accessory glands were observed in male B. dorsalis. Male mesodermal accessory glands expanded significantly in length and area when copulation finished. A remating refractory period occurred in B. dorsalis females, but it did not differ in duration following copulations with either virgin or non-virgin males. Besides, we found that virgin females lived longer, but produced much fewer eggs than mated females. Remating with a refractory period resulted in more eggs being laid and offspring produced than continuous exposure to 2 mates. In addition, females in the continuous presence of 2 males produced significantly more offspring than females with only 1 male present. We also observed that increases in male and female age reduced the rate of fertilization. These results indicated that multiple matings increased the fitness of B. dorsalis females, although remating inhibition existed in B. dorsalis fruit flies. It is the great reproductive ability of B. dorsalis that enable flourishing populations to occur in wild.

Phenoloxidase (PO) is a multicopper enzyme, which plays an important role in melanin synthesis. PO is necessary for defense against intruding microorganisms and parasites, and is important in wound healing and cuticle pigmentation. As a specific inhibitor of PO, kojic acid (KA) is commonly used to characterize the functional properties of PO. In this study, we investigated the effect of KA on PO activity during the development of the oriental fruit fly, Bactrocera dorsalis, which is a destructive pest of many horticultural crops. After feeding on a KA-containing artificial diet, the larval and pupal developmental periods were significantly prolonged. In addition, the larvae did not grow to normal size and rates of pupation and emergence were decreased when B. dorsalis larvae had been fed with KA-containing diet for 6 days. Compared to the control, PO activities from whole bodies of B. dorsalis were inhibited, so did in larval cuticles. Consistent with these, kinetic analysis showed that the catal...

A new Allacta xizangensis sp. nov. (Blattodea: Ectobiidae: Pseudophyllodromiinae) is described and assigned to the polygrapha species group. Four known species, A. robusta, A. bimaculata, A. transversa, A. ornata, are re-described and illustrated based on type material and specimens kept in the collection of Southwest University (SWU), Sun Yat-Sen University (SYSU), Hebei University (HBU), China and Institute of Zoology, Chinese Academy of Sciences (IZCAS) and the Russian Academy of Sciences (ZIN). The hitherto unknown male of A. transversa is described with a special display of its genitalia. A key is given to identify the males of Allacta from China. The tarsomere ultrastructure of all the legs of A. ornata was examined by scanning electron microscopy.

Trehalase plays a critical role in metabolic processes by catalyzing the hydrolysis of trehalose to glucose. In this study, we cloned and characterized a full-length cDNA encoding membrane-bound trehalase in the oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae) and named it as BdTre2. BdTre2 contained an open reading frame (ORF) of 1842 bp,which encoded a putative 613 amino acids. Alignment analysis revealed that the deduced protein sequence of BdTre2 had about a 70% identity to Tre2 of most dipteran insects, suggesting that this gene was conserved in the evolution of the Diptera. Phylogenetic analysis showed that the deduced protein of BdTre2 was more homologous to the trehalase2 gene than insect trehalase1 gene. The expression pattern in different developmental stages and tissues of BdTre2 in B. dorsalis was measured by quantitative real-time PCR (qPCR), and the results showed that BdTre2 was strongly expressed in the adult stage, particularly in the midgut. Concurrently, ...

Summary Diaphorina citri Kuwayama (Hemiptera: Liviidae) is a phytophagous insect and the vector of the bacterium ‘Candidatus' Liberibacter asiaticus. This is the likely causal pathogen of huanglongbing, which results in decline and possible death of citrus trees. It has been shown that host plants can affect the detoxification enzyme profile of arthropods. Here, we examined the effect of rearing D. citri on various host plant species with respect to activity of general esterases (ESTs), glutathione S-transferases (GST), and cytochrome P450 monooxygenases (P450s). These enzymes were selected because they are known to metabolize a wide diversity of insecticides and are known to directly contribute to resistance in D. citri. We reared D. citri on Citrus sinensis L., Bergera koenigii L. and Murraya paniculata (L.) Jacq. (Sapindales: Rutaceae). Following 12 generations of rearing, the activities of EST, GST, and P450 enzymes were compared between the colonies raised on the different host plants. The GST activi...

Housekeeping genes are thought to be consistently expressed in different tissues, and therefore they are commonly used as references to normalize qPCR data. But the expression of these genes has proved to be affected by certain experimental conditions. In this study, we evaluated the stability of 9 housekeeping genes of economically important pest, Bactrocera dorsalis, under the stress of β-Cypermethrin insecticide. Variations in gene expression were identified both in the whole bodies of larvae and in their midguts. The expression level of each housekeeping gene was shown to be quite different in different tissues, and suggested that the expression stabilities of these genes were differentially affected by toxicity stress. The stability of EF1α was evaluated both in the whole body and in the midgut by geNorm ana Norm finder and in both analyses it proved to be the best reference gene. The folds of changes of expression of the housekeeping genes normalized by EF1α were in accordance with the eval...

The 20-hydroxyecdysone (20E) plays a critical role in a series of biological processes, via the ecdysone receptor/USP heterodimeric complex in arthropod. In order to clarify the regulatory mechanism of 20E, we characterized a full-length cDNA encoding a putative ecdysone receptor isoform B1 and named it as BdEcR-B1 in the oriental fruit fly, Bactrocera dorsalis. The BdEcR-B1 gene was 3,111 bp long, with an open reading frame of 2,304 bp, which encoded 767 amino acids with a predicated molecular weight of 83.3 kDa and an isoelectric point of 6.74. Alignment analysis revealed that the deduced protein sequence had 80% identity to EcR-B1 isoforms of various dipteran species, indicating that this gene was highly conserved during the evolution of the Diptera. Phylogenetic analysis suggested that BdEcR-B1 was orthologous to the EcR-B1 proteins identified in other insect species. Quantitative real-time PCR showed that BdEcR-B1 was expressed at all tested developmental stages, and the expression of BdEcR-...

Glutathione S-transferases (GSTs) were purified from 3 developmental stages of Bactrocera minax through glutathione-agarose affinity chromatography, and characterized subsequently using the Michaelis-Menten kinetics toward the artificial substrates 1-chloro-2, 4-dinitrobenzene (CDNB) and reduced glutathione (GSH), respectively. Compared to the counterparts of third instar larva and adult, the highest specific activity of the purified GSTs towards CDNB was observed in the pupae. Although the specific activities of purified enzymes varied among 3 developmental stages, the purification yields were similar. SDS-PAGE revealed only one band at 23 kDa for all 3 stages. GSTs of the adults exhibited the highest Km value towards CDNB, while for GSH the pupae possessed the highest Km. The optimum temperature and pH for CDNB conjugation of the 3 stages were 37 °C and 7.5, respectively. Inhibition kinetics showed that ethacrynic acid, bromosulfalein, diethyl maleate, tetraethylthiuram disulfide and curcumin p...

Nicotinic acetylcholine receptors (nAChR) play major roles in the fast synapse cholinergic transmission in the insect central nervous system, and they are recognized as potential target sites for insecticides. In this study, the full-length cDNA sequence of the nAChR alpha6 subunit (Bdorα6) was isolated and characterized from the oriental fruit fly, Bactrocera dorsalis, using the Rapid Amplification of cDNA Ends (RACE) technique. The Bdorα6 cDNA was 2020 bp long, containing an open reading frame of 1467 bp, which encodes 488 amino acid residues with a predicated molecular mass of 55.6 kDa. Homology analysis indicated that Bdorα6 has typical features of a nAChR α subunit. Phylogenetic analysis with other insect nAChR subunits suggested that Bdorα6 was most closely related to Dα6 of Drosophila melanogaster. The developmental changes and tissue-specificity of the relative expression levels of Bdorα6 were investigated using quantitative real-time PCR. The highest expression level was observed in the ...

A change in temperature may be responsible for a variety of physiological stress responses in organisms, which are often associated with enhanced generation of reactive oxygen species (ROS) leading to oxidative damage. In the present study, the lipid peroxidation (LPO) levels of the oriental fruit fly, Bactrocera dorsalis (Hendel), were measured under thermal stress conditions of the relatively low (-5, -2.5, 0, and 5 °C) or high (35, 37.5, and 40 °C) temperatures. Subsequently, the time-related effect of thermal stress on activity of antioxidant enzymes including catalase (CAT), glutathione-S-transferases (GSTs), peroxidase (POX), superoxide dismutase (SOD), and total antioxidant capacity (T-AOC) were systematically determined. The results showed that LPO levels increased significantly in a time-dependent manner under thermal stress. The activities of CAT, GSTs, and SOD were significantly enhanced and likely provided a defense mechanism against oxidative damage due to the accumulation of ROS. PO...

Several members of the Tephritidae (Diptera) are destructive pests of fruits and vegetables. This study used scanning electron microscopy to analyze the external morphology, typology, size, and distribution of maxillary palpus sensilla of both female and male adults of 6 fruit fly species, Bactrocera cucurbitae (Coquillett), B. diaphora (Hendel), B. dorsalis (Hendel), B. minax (Enderlein), B. scutellata (Hendel), and B. tau (Walker). The palpus is equipped with sensilla chaetica, sensilla basiconica, and microtrichia. In addition, the possible functions of the sensillum types are discussed. Probable functions include the mechanoreception of sensilla chaetica and microtrichia, and olfaction of sensilla basiconica. Future functional morphology and electrophysiological studies are needed to confirm these proposed functions.

Nine field collected populations of Panonychus citri from Chinese citrus orchards were assayed for susceptibility to pyridaben and the alternative acaricide azocyclotin and activity of glutathione S-transferases (GSTs). The results showed that populations from Pujiang, Wanzhou, and Pengshan exhibited a low level of sensitivity to pyridaben, but demonstrated a high level of sensitivity to azocyclotin. The correlation coefficient between GSTs activities and the LC50 of pyridaben was r = 0.93 while the correlation coefficient between GSTs activities and the LC50 of azocyclotin was r = 0.03. The Vmax value of CDNB (1-chloro-2, 4-dinitrobenzene) in populations from Beibei, Jintang, Pengshan, Wanzhou, and Zhongxian exhibited a: 2.5-, 11.6-, 7.0-, 5.1-, and 6.4-fold increase in resistance, respectively, relative to the pyridaben susceptible population. In addition, azocyclotin was the most sensitive inhibitor of the GSTs compared with the EA (ethacrynic acid) and pyridaben, based on the values for I 50....

Seasonal abundance of the Asian citrus psyllid, Diaphorina citri Kuwayama, was studied weekly in two orange jasmine [Murraya paniculata (L.) Jack] plots in southern Florida from October 1998 to October 1999. Psyllid populations occur throughout the season on orange jasmine in southern Florida. Population peaks were observed in October, November, and December in 1998, and May and August in 1999. Psyllid population levels were positively related to the availability of new shoot flushes which were in turn related to the weekly minimum temperature and rainfall. Natural enemies were not key factors in regulating populations during the study period. The populations of adult psyllids were also studied weekly on potted orange jasmine and grapefruit (Citrus paradisi Macfadyen) plants from June 1999 to July 2000. The population levels of psyllid on both host plants were not significantly different and general population trends on the two hosts were similar over time. Continuous shoot flushes produced by orange jasmine could play an important role in maintaining high populations of this insect when new shoot flushes were not available in the commercial citrus groves.