Neuroecology of Alcohol Preference in Drosophila

In this review, we highlight sources of alcohols in nature, as well as the behavioral and ecological roles that these fermentation cues play in the short lifespan of Drosophila melanogaster. With a focus on neuroethology, we describe the olfactory detection of alcohol as well as ensuing neural signaling within the brain of the fly. We proceed to explain the plethora of behaviors related to alcohol, including attraction, feeding, and oviposition, as well as general effects on aggression and courtship. All of these behaviors are shaped by physiological state and social contexts. In a comparative perspective, we also discuss inter- and intraspecies differences related to alcohol tolerance and metabolism. Lastly, we provide corollaries with other dipteran and coleopteran insect species that also have olfactory systems attuned to ethanol detection and describe ecological and evolutionary directions for further studies of the natural history of alcohol and the fly.

Nitrogen Fixation and Diazotrophic Community in Plastic-Eating Mealworms Tenebrio Molitor L.

Mealworms, the larvae of a coleopteran insect Tenebrio molitor L., are capable of eating, living on and degrading the non-hydrolyzable vinyl plastics as sole diet. However, vinyl plastics are carbon-rich but nitrogen-deficient. It remains puzzling how plastic-eating mealworms overcome the nutritional obstacle of nitrogen limitation. Here, we provide the evidence for nitrogen-fixation activity within plastic-eating mealworms. Acetylene reduction assays illustrate that the nitrogen-fixing activity ranges from 12.3 ± 0.7 to 32.9 ± 9.3 nmol ethylene·h− 1·gut− 1 and the corresponding fixed nitrogen equivalents of protein are estimated as 8.6 to 23.0 µg per day per mealworm. Nature nitrogen isotopic analyses of plastic-eating mealworms provide further evidence for the importance of nitrogen fixation as a new nitrogen source. Eliminating the gut microbial microbiota with antibiotics impairs the mealworm’s ability to fix nitrogen from atmosphere, indicating the contribution of gut microbiota to nitrogen fixation. By using the traditional culture-dependent technique, PCR and RT-PCR of nifH gene, nitrogen-fixing bacteria diversity within the gut was detected and the genus Klebsiella was demonstrated to be an important nitrogen-fixing symbiont. These findings first build the relationship between the plastic degradation (carbon metabolism) and nitrogen fixation (nitrogen metabolism) within mealworms. Combined with previously reported plastic-degrading capability and nitrogen-fixing activity, mealworms may be potential candidates for up-recycling of plastic waste to produce protein sources.

Two Splice Isoforms of Leptinotarsa Ecdysis Triggering Hormone Receptor Have Distinct Roles in Larva-Pupa Transition

Insect ecdysis triggering hormone (ETH) receptors (ETHRs) are rhodopsin-like G protein-coupled receptors. Upon binding its ligand ETH, ETHR initiates a precisely programed ecdysis behavior series and physiological events. In Drosophila melanogaster, the ethr gene produces two functionally distinct splicing isoforms, ethra and ethrb. ETH/ETHRA activates eclosion hormone (EH), kinin, crustacean cardioactive peptide (CCAP), and bursicon (burs and pburs) neurons, among others, in a rigid order, to elicit the behavioral sequences and physiological actions for ecdysis at all developmental stages, whereas ETH/ETHRB is required at both pupal and adult ecdysis. However, the role of ETHRB in regulation of molting has not been clarified in any non-drosophila insects. In the present paper, we found that 20-hydroxyecdysone (20E) signaling triggers the expression of both ethra and ethrb in a Coleopteran insect pest, the Colorado potato beetle Leptinotarsa decemlineata. RNA interference (RNAi) was performed using double-stranded RNAs (dsRNAs) targeting the common (dsethr) or isoform-specific (dsethra, dsethrb) regions of ethr. RNAi of dsethr, dsethra, or dsethrb by the final-instar larvae arrested larva development. The arrest was not rescued by feeding 20E. All the ethra depleted larvae stopped development at prepupae stage; the body cavity was expanded by a large amount of liquid. Comparably, more than 80% of the ethrb RNAi larvae developmentally halted at the prepupae stage. The remaining Ldethrb hypomorphs became pupae, with blackened wings and highly-expressed burs, pburs and four melanin biosynthesis genes. Therefore, ETHRA and ETHRB play isoform-specific roles in regulation of ecdysis during larva-pupa transition in L. decemlineata.

Myroides albus sp. nov., isolated from the gut of plastic-eating larvae of the coleopteran insect Zophobas atratus

A bacterial strain, BIT-d1T, was isolated from the gut of plastic-eating larvae of the coleopteran insect Zophobas atratus. Its taxonomic position was analysed using a polyphasic approach. Cells were white-pigmented, Gram-stain-negative, non-motile, long rods without flagella. The 16S rRNA gene sequence (1401 bp) of strain BIT-d1T showed highest similarity (98.0%) to Myroides pelagicus SM1T and 96.6~92.6 % similarity to the other species of the genus Myroides . The results of phylogenetic analyses, based on the 16S rRNA gene, concatenated sequences of six housekeeping genes (gyrB, dnaK, tuf, murG, atpA and glyA) and genome sequences, placed strain BIT-d1T in a separate lineage among the genus Myroides , family Flavobacteriaceae . The major isoprenoid quinone was menaquinone-6 (MK-6) and the major fatty acids were C15 : 0 iso, C17 : 0 iso 3-OH and summed feature 9 (comprising iso-C17 : 1 ω9c and/or C16 : 0 10-methyl), which were similar to other members in the genus Myroides. In silico DNA–DNA hybridization and average nucleotide identity calculations plus physiological and biochemical tests exhibited the genotypic and phenotypic differentiation of strain BIT-d1T from the other members of the genus Myroides . Therefore, strain BIT-d1T is considered to represent a novel species within the genus Myroides , for which the name Myroides albus sp. nov is proposed. The type strain is BIT-d1T (=CGMCC 1.17043T=KCTC 72447T).

First record of the sisal weevil, Scyphophorus acupunctatus, in Cyprus

In May 2013, numerous adults of a coleopteran insect species that later was identified as the sisal weevil, Scyphophorus acupunctatus (Coleoptera: Curculionidae), were accidentally captured in both pitfall and funnel traps placed across Cyprus for the monitoring of red palm weevil, Rhynchophorus ferrugineus (Coleoptera: Curculionidae). S. acupunctatus was found for the first time in the Germasogeia area of the Limassol district (34°71′81″N, 33°08′56″E) and in the Kissonerga area of the Paphos district (34°81′67″N, 32°40′00″E). During 2013 and early 2014, numerous adults of this species were also collected from red palm weevil traps from all over Cyprus

Transcriptome analysis reveals candidate genes involved in luciferin metabolism inLuciola aquatilis(Coleoptera: Lampyridae)

Bioluminescence, which living organisms such as fireflies emit light, has been studied extensively for over half a century. This intriguing reaction, having its origins in nature where glowing insects can signal things such as attraction or defense, is now widely used in biotechnology with applications of bioluminescence and chemiluminescence. Luciferase, a key enzyme in this reaction, has been well characterized; however, the enzymes involved in the biosynthetic pathway of its substrate, luciferin, remains unsolved at present. To elucidate the luciferin metabolism, we performed ade novotranscriptome analysis using larvae of the firefly species,Luciola aquatilis. Here, a comparative analysis is performed with the model coleopteran insectTribolium casteneumto elucidate the metabolic pathways inL. aquatilis. Based on a template luciferin biosynthetic pathway, combined with a range of protein and pathway databases, and various prediction tools for functional annotation, the candidate genes, enzymes, and biochemical reactions involved in luciferin metabolism are proposed forL. aquatilis. The candidate gene expression is validated in the adultL. aquatilisusing reverse transcription PCR (RT-PCR). This study provides useful information on the bio-production of luciferin in the firefly and will benefit to future applications of the valuable firefly bioluminescence system.