Initiation of vitellogenesis by blood feeding is essential for egg maturation in ticks. Nutrients derived from the blood meal are utilized by female ticks to synthesize the yolk protein precursor vitellogenin (Vg). Engorged Ornithodoros moubata ticks can synthesize Vg whether mated or virgin, thus O. moubata is an excellent model for studying the relative roles of blood feeding and mating in tick vitellogenesis. Injection of rapamycin into engorged O. moubata resulted in a reduction of ovarian growth and yolk accumulation in the oocytes of mated females. OmVg expression in the midgut and fat body and protein concentrations in the hemolymph significantly decreased in mated ticks after injection with rapamycin, indicating that inhibition of the nutrient-sensing target of rapamycin (TOR) pathway disrupts egg maturation at the levels of Vg expression and synthesis. These results suggest that the TOR-signaling pathway induces vitellogenesis in response to nutritional stimulation after a blood meal in O. moubata and is functionally independent of the mating-induced pathway.

Research on vector-associated microbiomes has been expanding due to increasing emergence of vector-borne pathogens and awareness of the importance of symbionts in the vector physiology. However, little is known about microbiomes of argasid (or soft-bodied) ticks due to limited access to specimens. We collected four argasid species (Argas japonicus, Carios vespertilionis, Ornithodoros capensis, and Ornithodoros sawaii) from the nests or burrows of their vertebrate hosts. One laboratory-reared argasid species (Ornithodoros moubata) was also included. Attempts were then made to isolate and characterize potential symbionts/pathogens using arthropod cell lines. Microbial community structure was distinct for each tick species. Coxiella was detected as the predominant symbiont in four tick species where dual symbiosis between Coxiella and Rickettsia or Coxiella and Francisella was observed in C. vespertilionis and O. moubata, respectively. Of note, A. japonicus lacked Coxiella and instead had Occidentia massiliensis and Thiotrichales as alternative symbionts. Our study found strong correlation between tick species and life stage. We successfully isolated Oc. massiliensis and characterized potential pathogens of genera Ehrlichia and Borrelia. The results suggest that there is no consistent trend of microbiomes in relation to tick life stage that fit all tick species and that the final interpretation should be related to the balance between environmental bacterial exposure and endosymbiont ecology. Nevertheless, our findings provide insights on the ecology of tick microbiomes and basis for future investigations on the capacity of argasid ticks to carry novel pathogens with public health importance.

Abstract This expert opinion considers the physiological processes regulating reproduction and immune responses in the soft tick, Ornithodoros moubata, and the potential impact of climate change.

Invasion of the exotic Bactrocera dorsalis (Hendel, 1912) (Tephritidae) has drastically reduced the abundance and distribution of native Ceratitis anonae Graham, 1908 (Tephritidae) and false codling moth Thaumatotibia leucotreta (Meyrick, 1913) (Tortricidae) in Nigeria. There is an overlap in resource use among the three frugivorous insects which could result in interspecific competition. Knowledge of the population dynamics and distribution of the three frugivorous insects in the study area is lacking and such data are indispensable for effective management of the tephritid and tortricid pests. The population dynamics and distribution of the three frugivorous insects were investigated to predict the route of invasion and the outcome of interactions among the three frugivorous insects. Bactrocera dorsalis occurred in all the seven Local Government Areas (LGAs) sampled while C. anonae and T. leucotreta occurred together in two LGAs and separately in two other LGAs. The population of B. dorsalis is significantly higher than either C. anonae or T. leucotreta in the study area. The three frugivorous insects are negatively associated with one another but only the association between B. dorsalis and C. anonae was significantly different. Bactrocera dorsalis invaded the study area from southern Nigeria and C. anonae is being driven towards northern Nigeria.

: Differences in rates of diapause induction are thought to produce differences in the distribution of flies. Therefore, we investigated differences in the day length for entering diapause and effective chill treatment for termination of pupal diapause in Parasarcophaga similis and Boettcherisca peregrina flies found in Japan. Results showed maximum rates of diapause incidence for P. similis colonies from Sapporo, Tokyo and Nagasaki were 98% under 13L : 11D at 20°C, 100% under 11L : 13D and 80% under 10L : 14D, respectively. Diapause incidences for B. peregrina colonies from Tokyo and Nagasaki were 100% and 98% under 13L : 11D at 20°C. Emergence rates for diapausing pupae of P. similis (Sapporo) chilled at 4°C then transferred to diapause-terminating conditions at 27°C (16L : 8D) or 20°C (11L : 13D) were 65% and 80%. In B. peregrina (Tokyo), chill treatment was effective for 89% emergence. Adult P. similis (Sapporo) flies emerging from pupae that experienced chill treatment laid larvae that entered diapause at an incidence of 99.5%, whereas adult B. peregrina (Tokyo) laid 22% larvae destined for diapause. These flesh flies appear to move into new environments by successfully developing the ability to emerge at lower temperatures and possibly avoiding the maternal effect.

Acari are arthropods with the conserved features of an exoskeleton that require the shedding of cuticle for growth. Steroid hormones, ecdysteroids, regulate the mechanisms necessary for growth and development. Acari lack juvenile hormones, so they utilize ecdysteroids as the solo lipophilic hormone throughout their life for molting as well as for reproduction. Although some research on ecdysteroidogenesis has been conducted in the Acari, two important questions remain unclear: the active form of ecdysteroid and sites for ecdysteroidogenesis. The active form of ecdysteroids in Acari is controversial. Analysis by mass spectrometry confirms that most Acari use 20-hydroxyecdysone (20E), but the spider mite Tetranychus urticae (Koch) (Acari: Tetranychidae) uses Ponasterone A (25-deoxy-20-hydroxyecdysone). Analyses of ecdysteoridogenic genes provide clear evidence that the ovary is the primary site of ecdysteroidogenesis in both immature and mature ticks. In this review, the known functions of ecdysteroids are summarized and recent progress on ecdysteroidogenesis is introduced.

In tritrophic interactions between cucumber plants, the cucumber moth Diaphania indica Saunders (Lepidoptera: Crambidae) and a larval parasitoid Apanteles taragamae Viereck (Hymenoptera: Braconidae), female A.taragamae may use herbivore-induced plant volatiles (HIPVs) to locate their host. However, the specific compound or blend of chemicals attracting A.taragamae remains unknown. In this study, differences in volatiles released from uninfested, mechanically damaged and host-infested cucumber plants were examined by the headspace volatile collection method. Responses of the larval parasitoid A.taragamae to the volatile extracts were examined in a four-arm olfactometer. We also investigated the attraction of female A.taragamae to a single compound identified as an HIPV from host-infested cucumber plants. Parasitoids discriminated between the volatiles from uninfested, host-infested and mechanically damaged plants. Chemical analysis of headspace volatiles from host-infested cucumber plants showed that (E,E)--farnesene was released as a major component (73.1%). When (E,E)--farnesene was tested alone in the range of 1.7-170ng, female parasitoids responded to17ng only. Therefore, tritrophic interactions between A.taragamae and D.indica appear to be partly mediated by (E,E)--farnesene.

The exotic Bactrocera dorsalis and the native Ceratitis anonae infest citrus and constitute a threat to citrus production in Nigeria. The immature stages of the two species are difficult to differentiate morphologically and share the same fruit in the study area. A 658 bp portion of the COI gene was amplified and sequenced in 88 life stages of the species using LCO1490/HCO2198 primers. The enzymes RsaI, Sau3AI and Hsp92II were used to construct banding patterns distinguishing life stages of B. dorsalis from C. anonae. DNA barcoding confirmed the species to be B. invadens syn. n. B. dorsalis and C. anonae. Rsa I produced bands of 322 and 336 bp in B. dorsalis and 201 and 457 bp in C. anonae. Sau3AI produced bands of 103, 144 and 364 bp in B. dorsalis and 164 and 471 bp in C. anonae. Hsp92II produced fragment lengths of 137 and 521 bp in B. dorsalis and 110, 231 and 290 bp in C. anonae. The identification method was confirmed by DNA barcoding and molecular phylogenetic analysis. All the life stages within a species produced the same banding patterns with the enzymes. This molecular method will be applied at quarantine checkpoints for interception of the invasive B. dorsalis. It will also be crucial for early detection of infestation and in creating and maintaining fruit fly exclusion zones by implementation of appropriate management programmes for B. dorsalis and C. anonae infesting citrus in Nigeria.

Ecdysteroids play an essential role in the regulation of the molting processes of arthropods. Nuclear receptors of the spider Agelena silvatica that showed high homology with other arthropods especially in the functional domains were identified, two isoforms of ecdysone receptor (AsEcRA, AsEcRB), retinoid X receptor (AsRXR) and two isoforms of E75 (AsE75A, AsE75D). AsEcR and AsRXR mRNA did not show major changes in expression but occurred throughout the third instar nymphal stage. AsE75DBD was low or non-existent at first then showed a sudden increase from D7 to D10. On the other hand, AsE75D was expressed in the first half and decreased from D6 to D10. Ecdysteroid titers showed a peak on D6 in A. silvatica third instar nymphs. LC-MS/MS analysis of the ecdysteroid peak revealed only 20-hydroxyecdysone (20E) was present. The 20E peak on D6 and increase in AsE75DBD from D7 is likely a result of ecdysteroids binding to the heterodimer formed with constant expression of the AsEcR and AsRXR receptors. These findings indicate the mechanisms regulating molting widely conserved in insects and other arthropods also similarly function in spiders. (c) 2017 Elsevier Inc. All rights reserved.

The behavioural responses of Apanteles taragamae, a larval parasitoid of the cucumber moth Diaphania indica, to the volatiles of cucumber plants was investigated in a four-arm olfactometer. Females and males were given a choice between several odour sources that included (1) clean air, (2) uninfested, (3) host-infested, and (4) mechanically damaged cucumber plants. Females and males showed different preferences for volatiles emanating from these plants. Females responded significantly longer to the volatiles from uninfested plants than clean air, and to host-infested plants than uninfested plants. There were no significant differences in female responses to the volatiles from mechanically damaged and uninfested plants. Males responded significantly longer to clean air rather than uninfested plants. The volatiles from both uninfested and host-infested cucumber plants may play important roles in host habitat location of A. taragamae females.

Cotesia kariyai Watanabe (Hymenoptera: Braconidae) is a specialist larval parasitoid of Mythimna separata Walker (Lepidoptera: Noctuidae). Cotesia kariyai wasps use herbivore-induced plant volatiles (HIPVs) to locate hosts. However, complex natural habitats are full of volatiles released by both herbivorous host-and non-host-infested plants at various levels of intensity. Therefore, the presence of non-hosts may affect parasitoid decisions while foraging. Here, the host-finding efficiency of naive C. kariyai from HIPVs influenced by host-and non-host-infested maize [Zea mays L. (Poaceae)] plants was investigated with a four-arm olfactometer. Ostrinia furnacalis Guenee (Lepidoptera: Crambidae) was selected as a non-host species. One unit (1 U) of host-or non-host-infested plant was prepared by infesting a potted plant with five host or seven non-host larvae. In two-choice bioassays, host-infested plants fed upon by different numbers of larvae, and various units of host-and non-host-infested plants (infestation units; 1 U, 2 U, and 3 U) were arranged to examine the effects of differences in volatile quantity and quality on the olfactory responses of C. kariyai with the assumption that volatile quantity and quality changes with differences in numbers of insects and plants. Cotesia kariyai was found to perceive quantitative differences in volatiles from host-infested plants, preferring larger quantities of volatiles from larger numbers of larvae or plants. Also, the parasitoids discriminated between healthy plants, host-infested plants, and non-host-infested plants by recognising volatiles released from those plants. Cotesia kariyai showed a reduced preference for host-induced volatiles, when larger numbers of non-host-infested plants were present. Therefore, quantitative and qualitative differences in volatiles from host-and non-host-infested plants appear to affect the decision of C. kariyai during host-habitat searching inmultiple tritrophic systems.

Species from the genus Mayetiola are observed in the main cereal cultures of Tunisia. Some researchers have studied M. destructor that attacks wheat and M. hordei that attacks barley. However, a third important species observed in oat, M. avenae, has not been studied and is not well documented in Tunisia. A method to easily separate the species is needed to clarify the occurrences of these gall midge species. This study aimed to first distinguish between the three species of gall midges by molecular characterization and second to reveal the phylogenetic relationships within and between the three species of Mayetiola collected from 5 different regions of northern Tunisia. To achieve these purposes, two regions of the mitochondrial DNA, cytochrome oxidase subunit I gene, and the 16S rRNA gene were amplified by polymerase chain reaction and sequenced. For each marker, a set of 75 individuals were used for DNA analysis. Phylogenetic trees were created using the DNA sequences of all samples from the 3 species. Results showed significant separation of the three different species into dissimilar clades. Each clade contained only specimens from the same species. Differences were observed between DNA sequences of the same species. The differences within the same species were not representative of geographical variations but coexisted within a population Therefore, using the COI and 16S rRNA genes as markers can clearly separate M. avenae, M. destructor and M. hordei.

We evaluated the utility of DNA barcodes for identifying Thaumatotibia leucotreta (Meyrick) infesting sweet oranges in Nigeria. Approximately 658 bp of the mitochondrial gene cytochrome oxidase subunit I (COI) was amplified, sequenced, and analyzed for 32 adult samples, eight from each of the four geopolitical zones of Nigeria. All of the samples had identical sequences except for two, both of which showed a transition from "G" to "A" at position 433 bp. DNA barcodes of specimens from Nigeria showed 100% similarity with sequences of T. leucotreta in the Barcode of Life Database (BOLD) from Kenya and South Africa; all the Nigerian samples cluster with T. leucotreta from BOLD with a bootstrap support of 90. DNA barcoding is consistent with identifications of the samples based on morphology.

The exotic tephritid Bactrocera invadens (syn. Bactrocera dorsalis) and the native Ceratitis species constitute serious pests and major impediment to Citrus production in Nigeria. Lack of accurate and reliable diagnostic methods independent of the life stages intercepted for both genera hampers implementation of appropriate early management programmes to avoid economic losses and delays in quarantine decision regarding these pests. We used a PCR amplification technique to successfully establish RFLP patterns of the COI coding gene to differentiate the exotic B. invadens from the native Ceratitis species infesting sweet oranges in Nigeria. The universal barcoding primer pair LCO1490/HCO2198 was used to amplify 658 bp-long fragment of the mitochondrial COI coding gene. The amplified fragment was analysed by automated direct sequencing and RFLP. Intraspecific variation in nucleotide sequences of B. invadens was very low with not more than 2 bp substitutions in four out of 31 individuals sequenced. Among the Ceratitis species intraspecific variation was also very low with at most 4 bp substitutions in few of the 32 individuals sequenced. The restriction enzymes Rsa I and Hsp92 II produced patterns that clearly and unambiguously separated B. invadens from Ceratitis spp. DNA barcoding was also used to confirm the identities of the tephritid species analysed. The molecular method established in this study will enhance easy monitoring, early detection of species involved, and implementation of appropriate management programmes that effectively reduce yield loses in Citrus production in Nigeria.

Ecdysteroidogenesis is essential for arthropod development and reproduction. Although the importance of ecdysteroids has been demonstrated, there is little information on the sites and enzymes for synthesis of ecdysteroids from Chelicerates. Ecdysteroid functions have been well studied in the soft tick Ornithodoros moubata, making this species an excellent candidate for elucidating ecdysteroidogenesis in Chelicerates. Results showed that O. moubata has at least two ecdysteroidogenic enzymes, Spook (OmSpo) and Shade (OmShd). RNAi showed both enzymes were required for ecdysteroidogenesis. Enzymatic assays demonstrated OmShd has the conserved functions of ecdysone 20-hydroxylase. OmSpo showed specific expression in the ovaries of final nymphal and adult stages, indicating O. moubata utilizes the ovary as an ecdysteroidogenic tissue instead of specific tissues as seen in other arthropods. On the other hand, OmShd expression was observed in various tissues including the midgut, indicating functional ecdysteroids can be produced in these tissues. In nymphal stages, expression of both OmSpo and OmShd peaked before molting corresponding with high ecdysteroid titers in the hemolymph. In fed adult females, OmSpo expression peaked at 8-10 days after engorgement, while OmShd expression peaked immediately after engorgement. Mated females showed more frequent surges of OmShd than virgin females. These results indicate that the regulation of synthesis of ecdysteroids differs in nymphs and adult females, and mating modifies adult female ecdysteroidogenesis. This is the first report to focus on synthesis of ecdysteroids in ticks and provides essential knowledge for understanding the evolution of ecdysteroidogenesis in arthropods.

European foulbrood is a contagious bacterial disease of honey bee larvae. Studies have shown that the intestinal bacteria of insects, including honey bees, act as probiotic organisms. Microbial flora from the gut of the Japanese honey bee, Apis cerana japonica F. (Hymenoptera: Apidae), were characterized and evaluated for their potential to inhibit the growth of Melissococcus plutonius corrig. (ex White) Bailey and Collins (Lactobacillales: Enterococcaceae), the causative agent of European foulbrood. Analysis of 16S rRNA gene sequences from 17 bacterial strains isolated by using a culture-dependent method revealed that most isolates belonged to Bacillus, Staphylococcus, and Pantoea. The isolates were screened against the pathogenic bacterium M. plutonius by using an in vitro growth inhibition assay, and one isolate (Acja3) belonging to the genus Bacillus exhibited inhibitory activity against M. plutonius. In addition, in vivo feeding assays revealed that isolate Acja3 decreased the mortality of honey bee larvae infected with M. plutonius, suggesting that this bacterial strain could potentially be used as a probiotic agent against European foulbrood.

The objective of this study was to determine the possibilities for use of thymol, a common compound in essential oils of Thymus and Origanum plants, as an alternative biopesticidal compound to control Helicoverpa armigera. Thymol was applied to Helicoverpa armigera larvae topically and also administered orally at sublethal levels to determine the effects on their reproduction and development. Thymol did affect egg development and oviposition was reduced by 9.42 and 38.86% under two different applications, respectively. Growth inhibition was also observed and 6.7% of insects were dead as larvae, 42.4% as pupae and 6.6% as pupal-adult intermediates. The present studies clearly indicate that thymol used at sublethal levels can alternatively control bollworms by altering reproductive mechanisms.

Lyme disease and relapsing fever are arthropod-borne infectious diseases caused by the genus Borrelia. ese infectious pathogens are maintained by wildlife reservoirs and are transmitted to humans by arthropod vectors. It is, therefore, impossible to eradicate these pathogens from the environment. For this reason, there is currently an international trend toward focusing on understanding the mechanisms of pathogen transmission in order to ultimately prevent disease by interrupting the route of transmission. It is the intent of this review to detail the most recent understanding of the mechanisms by which Borrelia spp. are transmitted by hard-bodied ticks.