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Various factors, including the insect host, diet, and surrounding ecosystem can shape the structure of the bacterial communities of insects. We have employed next generation, high-throughput sequencing of the 16S rRNA to characterize the bacteriome of wild Zeugodacus (Bactrocera) cucurbitae (Coquillett) flies from three regions of Bangladesh. The tested populations developed distinct bacterial communities with differences in bacterial composition, suggesting that geography has an impact on the fly bacteriome. The dominant bacteria belonged to the families Enterobacteriaceae, Dysgomonadaceae and Orbaceae, with the genera Dysgonomonas, Orbus and Citrobacter showing the highest relative abundance across populations. Network analysis indicated variable interactions between operational taxonomic units (OTUs), with cases of mutual exclusion and copresence. Certain bacterial genera with high relative abundance were also characterized by a high degree of interactions. Interestingly, genera with a low relative abundance like Shimwellia, Gilliamella, and Chishuiella were among those that showed abundant interactions, suggesting that they are also important components of the bacterial community. Such knowledge could help us identify ideal wild populations for domestication in the context of the sterile insect technique or similar biotechnological methods. Further characterization of this bacterial diversity with transcriptomic and metabolic approaches, could also reveal their specific role in Z. cucurbitae physiology.

In this research work, nanocomposite coatings of nickel reinforced with graphene oxide (GOs) were produced by electrodeposition on steel substrate discs from the modified Watts bath. The resultant coatings were evaluated in terms of their surface morphology by atomic force microscopy and thermomechanical and electrochemical corrosion characteristics. The electrodeposited coatings showed variation in the electrochemical and thermomechanical behavior as the function of GO content where they show the optimum characteristics for 0.1 wt.% GO. The relatively lower concentrations of GO produced composites with greater surface homogeneity and lower roughness, whereas when the GO content is increased, the coatings show increased surface roughness. Electrochemical corrosion resistance of nickel is increased by incorporation of GO up to 0.1 wt.% due to decreased grain boundary area in the coatings and the uniform dispersion of the nanophase ensured by prior probe sonication and magnetic stirring during the co-deposition. The nickel composite coatings with 0.1 wt.% GO also showed improved thermomechanical behavior with higher recovery at 473 K.

BackgroundVarious endosymbiotic bacteria, includingWolbachiaof 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 ofWolbachia,Spiroplasma,ArsenophonusandCardiniumamongBactrocera,DacusandZeugodacusflies of Southeast Asian populations, and to genotype any detectedWolbachiastrains.ResultsA specific 16SrRNAPCR 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.Wolbachiainfections were identified inBactrocera dorsalis,B. correcta,B. scutellarisandB. zonata, with 12.2–42.9% occurrence, Entomoplasmatales inB. dorsalis,B. correcta,B. scutellaris,B. zonata,Zeugodacus cucurbitaeandZ. tau(0.8–14.3%) andCardiniuminB. dorsalisandZ. tau(0.9–5.8%), while none of the species tested, harbored infections withArsenophonus. Infected populations showed a medium (between 10 and 90%) or low (Wolbachia, 2 to 33% for Entomoplasmatales and 5 to 45% forCardinium.Wolbachiaand 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.Cardiniuminfections were identified in both countries but only in subtropical populations. Phylogenetic analysis revealed the presence ofWolbachiawith some strains belonging either to supergroup B or supergroup A. Sequence analysis revealed deletions of variable length and nucleotide variation in threeWolbachiagenes.Spiroplasmastrains were characterized as citri–chrysopicola–mirum and ixodetis strains while the remaining Entomoplasmatales to the Mycoides–Entomoplasmataceae clade.Cardiniumstrains were characterized as group A, similar to strains infectingEncarsia pergandiella.ConclusionsOur results indicated that in the Southeast natural populations examined, supergroup AWolbachiastrain infections were the most common, followed by Entomoplasmatales andCardinium. In terms of diversity, most strains of each bacterial genus detected clustered in a common group. Interestingly, the deletions detected in threeWolbachiagenes were either new or similar to those of previously identified pseudogenes that were integrated in the host genome indicating putative horizontal gene transfer events inB. dorsalis,B. correctaandB. zonata.

Background Symbiotic bacteria contribute to a multitude of important biological functions such as nutrition and reproduction and affect multiple physiological factors like fitness and longevity in their insect hosts. The melon fly, Zeugodacus cucurbitae (Coquillett), is an important agricultural pest that affects a variety of cultivated plants belonging mostly to the Cucurbitaceae family. It is considered invasive and widespread in many parts of the world. Several approaches are currently being considered for the management of its populations including the environmentally friendly and effective sterile insect technique (SIT), as a component of an integrated pest management (IPM) strategy. In the present study, we examined the effect of diet and radiation on the bacterial symbiome of Z. cucurbitae flies with the use of Next Generation Sequencing technologies. Results Melon flies were reared on two diets at the larval stage, an artificial bran-based diet and on sweet gourd, which affected significantly the development of the bacterial profiles. Significant differentiation was also observed based on gender. The effect of radiation was mostly diet dependent, with irradiated melon flies reared on the bran diet exhibiting a significant reduction in species diversity and richness compared to their non-irradiated controls. Changes in the bacterial symbiome of the irradiated melon flies included a drastic reduction in the number of sequences affiliated with members of Citrobacter, Raoultella, and Enterobacteriaceae. At the same time, an increase was observed for members of Enterobacter, Providencia and Morganella. Interestingly, the irradiated male melon flies reared on sweet gourd showed a clear differentiation compared to their non-irradiated controls, namely a significant reduction in species richness and minor differences in the relative abundance for members of Enterobacter and Providencia. Conclusions The two diets in conjunction with the irradiation affected significantly the formation of the bacterial symbiome. Melon flies reared on the bran-based artificial diet displayed significant changes in the bacterial symbiome upon irradiation, in all aspects, including species richness, diversity and composition. When reared on sweet gourd, significant changes occurred to male samples due to radiation, only in terms of species richness.

Additional file 1. Prevalence of reproductive bacteria in tephritid fruit fly populations from Bangladesh, China and India using a 16S rRNA gene-based PCR screening approach. Red values in the heat map indicate high occurrence and blue values low. For each genus the absolute number and the percentage (in parentheses) of infected individuals are given. The last column on the right (“Total*”) indicates the total occurrence of all three Entomoplasmatales genera.

Aedes aegypti is a major vector of arboviruses such as dengue (DENV), Chikungunya (CHIKV) and Zika (ZIKV) that may be controlled on an area-wide basis using the sterile insect technique (SIT). Larval diet is a major

Bactrocera dorsalis, the Oriental fruit fly, is one of the world's most destructive agricultural insect pests and a major impediment to international fresh commodity trade. The genetic structuring of the species across its entire geographic range has never been undertaken, because under a former taxonomy B. dorsalis was divided into four distinct taxonomic entities, each with their own, largely non‐overlapping, distributions. Based on the extensive sampling of six a priori groups from 63 locations, genetic and geometric morphometric datasets were generated to detect macrogeographic population structure, and to determine prior and current invasion pathways of this species. Weak population structure and high genetic diversity were detected among Asian populations. Invasive populations in Africa and Hawaii are inferred to be the result of separate, single invasions from South Asia, while South Asia is also the likely source of other Asian populations. The current northward invasion of B. dorsalis into Central China is the result of multiple, repeated dispersal events, most likely related to fruit trade. Results are discussed in the context of global quarantine, trade, and management of this pest. The recent expansion of the fly into temperate China, with very few associated genetic changes, clearly demonstrates the threat posed by this pest to ecologically similar areas in Europe and North America.

Effective male fruit fly attractants, such as cue lure (CL) and methyl eugenol (ME), are important in the monitoring and management of pest species through lure and kill techniques of trapping and male annihilation. However, some species are only weakly responsive to these lures, making their detection and control difficult. Zeugodacus diversus (Coquillett), a pest of cucurbit flowers in Asia, is weakly attracted to ME. Recently in Australia and Papua New Guinea, the eugenol analogues isoeugenol, methyl-isoeugenol, and dihydroeugenol were found to be effective attractants for species with a weak response to ME and CL, as well as several nonresponsive species. Additionally, studies from the early 1900s indicated that Z. diversus was attracted to isoeugenol. To determine if these eugenol analogues may be more effective attractants for Z. diversus, we field tested them in Bangladesh in comparison to ME, as well as CL and zingerone. Z. diversus was significantly more attracted to all three eugenol analogues than ME, with it most attracted to methyl-isoeugenol. Its attraction to methyl-isoeugenol was 49 times greater than its attraction to ME (respective means 23.58 flies/trap/day (FTD) and 0.48 FTD). Z. diversus was also consistently trapped at methyl-isoeugenol at all trap clearances including when populations were low, whereas it was only trapped at ME at 6 out of the 13 clearances. This study demonstrates that methyl-isoeugenol is a highly attractive lure for Z. diversus and would be a valuable inclusion as an attractant in monitoring and male annihilation programs.