Chemical Composition of Essential Oils from Leaves and Fruits of Juniperus foetidissima and Their Attractancy and Toxicity to Two Economically Important Tephritid Fruit Fly Species, Ceratitis capitata and Anastrepha suspensa

The present study analyzed the chemical composition of Juniperus foetidissima Willd. essential oils (EOs) and evaluated their attractancy and toxicity to two agriculturally important tephritid fruit flies. The composition of hydrodistilled EOs obtained from leaves (JFLEO) and fruits (JFFEO) of J. foetidissima was analyzed by GC–FID and GC–MS. The main compounds were α-pinene (45%) and cedrol (18%) in the JFLEO and α-pinene (42%), α-thujone (12%), and β-thujone (25%) in the JFFEO. In behavioral bioassays of the male Mediterranean fruit fly, Ceratitis capitata (Wiedemann), both JFLEO and JFFEO showed strong attraction comparable to that observed with two positive controls, Melaleuca alternifolia and Tetradenia riparia EOs. In topical bioassays of the female Caribbean fruit fly, Anastrepha suspensa (Loew), the toxicity of JFFEO was two-fold higher than that of JFLEO, with the LD50 values being 10.46 and 22.07 µg/µL, respectively. This could be due to differences in chemical components between JFLEO and JFFEO. The JFFEO was dominated by 48% monoterpene hydrocarbons (MH) and 46% oxygenated monoterpenes (OM), while JFLEO consisted of 57% MH, 18% OM, and 20% oxygenated sesquiterpenes (OS). This is the first study to evaluate the attractancy and toxicity of J. foetidissima EOs to tephritid fruit flies. Our results indicate that JFFEO has the potential for application to the management of pest tephritid species, and further investigation is warranted.

New records of flies of the genus Tephritis (Diptera: Tephritidae) from the Caucasus and Transcaucasia, with notes on other tephritid species

New distributional data are provided for four species of the genus Tephritis Latreille, 1804, Sphenella marginata (Fallén, 1814) and Ensina sonchi (Linnaeus, 1767) (Diptera: Tephritidae). Tephritis separata Rondani, 1871 and T. mutabilis Merz, 1992 are recorded for the first time from Armenia and Transcaucasia, T. anthrax S. Korneyev et Evstigneev, 2019, from North Ossetia, and T. valida (Loew, 1858), from North Ossetia and Kabardino-Balkaria. Host plants are recorded for the larvae of each species, with Leontodon asperrimus (Willd.) Endl. being recorded for the first time as a host plant of T. mutabilis, and Caucasalia macrophylla (M. Bieb.) B. Nord. (= Senecio platyphyllus DC.) and Senecio kolenatianus C.A. Mey., as host plants of S. marginata. The morphological details of all six species of flies are illustrated in colour photos.

Comparative genomic and transcriptomic analyses of chemosensory genes in the citrus fruit fly Bactrocera (Tetradacus) minax

The citrus fruit fly Bactrocera (Tetradacus) minax is a major and devastating agricultural pest in Asian subtropical countries. Previous studies have shown that B. minax interacts with plant hosts via the efficient chemosensory system. However, the molecular components of the B. minax chemosensory system have not been well characterized. Herein, we identified a total of 25 putative odorant-binding receptors (OBPs), 4 single-copy chemosensory proteins (CSPs) and 53 candidate odorant receptors (ORs) using a newly generated whole-genome dataset for B. minax. This study significantly extended the chemosensation-related gene profiles (particularly, OBPs and ORs) in six other tephritid species. Comparative transcriptome analysis of adult B. minax and Bactrocera dorsalis showed that there were 14 highly expressed OBPs (FPKM > 100) in B. dorsalis and 7 highly expressed ones in B. minax. The expression level of CSP3 gene and CSP4 gene was higher in B. dorsalis than that in B. minax. Comparative genomic and transcriptomic analyses of chemosensory genes in the citrus fruit fly B. minax provided new insights for preventive control of this agriculture important pest and closely related species.

Host Plant and Antibiotic Effects on Scent Bouquet Composition of Anastrepha ludens and Anastrepha obliqua Calling Males, Two Polyphagous Tephritid Pests

In insects, the quality of sex pheromones plays a critical role in mating success and can be determined by the ability of larvae/adults to accrue chemical precursors. We tested the host-quality-effect hypothesis by analyzing the chemical composition of scent bouquets emitted by calling males of two polyphagous tephritid species (Anastrepha ludens and A. obliqua) that originated from 13 fruit species representing diverse plant families. In A. ludens, we worked with an ancestral host (Rutaceae), nine exotic ones (Rutaceae, Anacardiaceae, Rosaceae, Solanaceae, Lythraceae), and two species never attacked in nature but that represent candidates for host-range expansion (Solanaceae, Myrtaceae). In A. obliqua, we tested an ancestral, a native, and an exotic host (Anacardiaceae), one occasional (Myrtaceae), and one fruit never attacked in nature (Solanaceae). We identified a core scent bouquet and significant variation in the bouquet’s composition depending on the fruit the larvae developed in. We also tested the possible microbial role on the scent bouquet by treating adults with antibiotics, finding a significant effect on quantity but not composition. We dwell on plasticity to partially explain our results and discuss the influence hosts could have on male competitiveness driven by variations in scent bouquet composition and how this could impact insect sterile technique programs.

Seasonal Abundance and Diversity of Fruit Flies (Diptera: Tephritidae) in Three Types of Plant Formations in Western Burkina Faso, West Africa

Fruit flies are significant insect pests, worldwide. Tephritid species diversity and their seasonal abundance were investigated over 2 yr (May 2017 to May 2019) in Western Burkina Faso. A mass trapping experiment consisting of 288 Tephri Trap types, operating with four types of parapheromones comprising methyl eugenol, terpinyl acetate, trimedlure, and cue lure and an insecticide (Dichlorvos), was used for attracting and killing insects. Plant formations including natural fallows, mango orchards, and agroforestry parks in each of the six study sites were selected for data collection. Twenty-nine tephritid species belonging to 10 genera were identified. Fourteen fruit fly species were identified for the first time in Burkina Faso. The genera Ceratitis MacLeay (Diptera : Tephritidae) and Dacus Fabricius (Diptera: Tephritidae) with, respectively, 14 and 7 species recorded were the most represented. The dominant species caught was the invasive Bactrocera dorsalis Hendel (Diptera: Tephritidae) followed by Ceratitis cosyra Walker (Diptera: Tephritidae) and Ceratitis silvestrii Bezzi (Diptera: Tephritidae). The fruit fly population density was very high during the rainy season, with peaks occurring in June or July. The fruit fly species were generally more abundant during the hot and rainy seasons than during the cold and dry seasons. The highest diversity was recorded in natural fallows, as compared with the mango orchards and agroforestry parks. Tephritid species found refuge in the mango orchards during the dry and cold periods. The results of that investigation may be used for developing a sustainable pest management strategy for commercial orchards.

Worldwide Phylogeography of Ceratitis capitata (Diptera: Tephritidae) Using Mitochondrial DNA

The Mediterranean fruit fly, Ceratitis capitata (Weidemann), is one of the most economically important tephritid species worldwide. It has spread across six geographic regions as a result of successful invasions and continues to cause substantial losses to agricultural communities. Our study examined 1,864 flies originating from 150 localities, using mitochondrial DNA sequencing methods. We tested for population structure and revealed the genetic diversity for 1,592 specimens gathered from 144 wild fly collections from 46 countries representing the entire geographic range for this species. We also include in this study 272 Sterile Insect Technique (SIT) specimens from four SIT facilities. We recovered 202 haplotypes from the current sampling and updated previously published work to reveal a total of 231 haplotypes for this pest. These data show population structure at and below the regional level for these collections, shedding light on the current demographics for this species. We observed four common haplotypes, seen among 62% of the samples sequenced that have worldwide distribution. Three haplotypes were seen in SIT flies, with one seen as the predominant haplotype. Our work showed that two of the haplotypes were private to SIT flies, not present among wild fly collections. However, a third haplotype common among wild fly collections was also seen in one SIT facility but at a low frequency based on the current sampling. We provide guidance on the interpretation of these methods for the source estimation of current and future infestations.

DNA barcoding reveals a species group of the genus Campiglossa (Diptera, Tephritidae, Tephritinae) with recognition of a new species from East Asia and previously unknown females of Campiglossa coei (Hardy)

While analyzing DNA barcodes of all the Korean and some East Asian tephritid species in conjunction with the barcode sequences available from BOLD Systems (www.boldsystems.org), the large and taxonomically enigmatic genus Campiglossa was recovered as a monophyletic clade, together with the genera Dioxyna and Homoeotricha, which are here synonymized for that reason. Ten major lineages are also recognized within the Campiglossa clade: producta group, loewiana group, sororcula group, irrorata group, achyrophori group, difficilis group, luxorientis group, magniceps group, arisanica group, and misella group. Here, more detailed taxonomic accounts are provided for the misella group, including four DNA analysis-recovered members: C. coei, C. misella, C. paramelaenasp. nov., and C. melaena. A single morphological synapomorphy is proposed for this species group: the presence of a large mid-anterior dark wing marking in males with associated structural modification (more apically positioned crossvein R-M than in females). Based on the morphological characteristics, two presumptive members that are only known from male specimens are further recognized: C. pishanica and C. propria from China. A full description of C. paramelaenasp. nov., and a redescription of C. coei, for which only males were previously known, are provided. For all the included species, a taxonomic key, diagnoses, and photographs to aid their accurate identification are given. Finally, C. favillacea is synonymized with C. coei and C. roscida with C. misella, and C. coei and C. pishanica resurrected from the synonymy of C. misella.

Detection and characterization of bacterial endosymbionts in Southeast Asian tephritid fruit fly populations

Background Various endosymbiotic bacteria, including Wolbachia of the Alphaproteobacteria, infect a wide range of insects and are capable of inducing reproductive abnormalities to their hosts such as cytoplasmic incompatibility (CI), parthenogenesis, feminization and male-killing. These extended phenotypes can be potentially exploited in enhancing environmentally friendly methods, such as the sterile insect technique (SIT), for controlling natural populations of agricultural pests. The goal of the present study is to investigate the presence of Wolbachia, Spiroplasma,Arsenophonus and Cardinium among Bactrocera,Dacus and Zeugodacus flies of Southeast Asian populations, and to genotype any detected Wolbachia strains. Results A specific 16S rRNA PCR assay was used to investigate the presence of reproductive parasites in natural populations of nine different tephritid species originating from three Asian countries, Bangladesh, China and India. Wolbachia infections were identified in Bactrocera dorsalis, B. correcta, B. scutellaris andB. zonata, with 12.2–42.9% occurrence, Entomoplasmatales in B. dorsalis, B. correcta, B. scutellaris, B. zonata,Zeugodacus cucurbitae and Z. tau (0.8–14.3%) and Cardinium in B. dorsalis andZ. tau (0.9–5.8%), while none of the species tested, harbored infections with Arsenophonus. Infected populations showed a medium (between 10 and 90%) or low (< 10%) prevalence, ranging from 3 to 80% for Wolbachia, 2 to 33% for Entomoplasmatales and 5 to 45% for Cardinium. Wolbachia and Entomoplasmatales infections were found both in tropical and subtropical populations, the former mostly in India and the latter in various regions of India and Bangladesh. Cardinium infections were identified in both countries but only in subtropical populations. Phylogenetic analysis revealed the presence ofWolbachia with some strains belonging either to supergroup B or supergroup A. Sequence analysis revealed deletions of variable length and nucleotide variation in three Wolbachia genes. Spiroplasma strains were characterized as citri–chrysopicola–mirum and ixodetis strains while the remaining Entomoplasmatales to the Mycoides–Entomoplasmataceae clade.Cardinium strains were characterized as group A, similar to strains infecting Encarsia pergandiella. Conclusions Our results indicated that in the Southeast natural populations examined, supergroup A Wolbachia strain infections were the most common, followed by Entomoplasmatales and Cardinium. In terms of diversity, most strains of each bacterial genus detected clustered in a common group. Interestingly, the deletions detected in three Wolbachia genes were either new or similar to those of previously identified pseudogenes that were integrated in the host genome indicating putative horizontal gene transfer events in B. dorsalis, B. correcta and B. zonata.

The oesophageal diverticulum of Dirioxa pornia studied through micro-CT scan, dissection and SEM studies

Background Dirioxa pornia (Diptera, Tephritidae) (Island fly) is an Australian native species related to a number of pestiferous fruit flies but, unlike many of the pest species, has not been studied extensively due to its non-pest status. However, due to D. pornia’s apparent reliance on the bacteria for survival it is an ideal species to undertake studies into interaction between Tephritid species and bacteria associated with the intestinal tract. The oesophageal diverticulum, which is a blind-ended protrusion of the oesophagus, has been studied, described and characterised in many other Tephritid species. Unlike many other species where the oesophageal diverticulum has been observed the organ was only observed in male D. pornia. It is speculated that this sexual dimorphism the organ may be the primary location to host beneficial bacteria in the involved in the production of the nuptial gift and the mating success of this Tephritid species. In case of D. pornia, however, no study on any area of the digestive system has been conducted. This study was conducted to locate and characterize the oesophageal diverticulum in D. pornia. A virtual dissection of the alimentary tract was made through micro-computer tomography studies. These studies were followed by dissection and scanning microscopy studies to elucidate the presence of bacteria. Results The oesophageal diverticulum of D. pornia is part of the foregut and distends from the oesophagus within the head of the fly. The shape of the oesophageal diverticulum corresponds with the Ceratitis type. Scanning microscopy studies of the oesophageal diverticulum show rod-shaped bacterial cells residing along with yeast cells in the lumen. The organ was only observed in male specimens. Conclusions This study classifies the oesophageal diverticulum of D. pornia under the “Ceratitis type” of oesophageal diverticula in Tephritid species. The study also proves that micro-CT scanning is possible to locate soft tissues in Tephritid species and the Avizo® Fire software can be successfully used to visualize 3 dimensional (3D) images from x-rays. The methods used in this experiment can be used in future studies for visualising soft tissues of adult Tephritid species through micro tomography. There is sexual dimorphism with the organ only found in males. Finally this study shows that bacteria are present in the oesophageal diverticulum of D. pornia.