ABSTRACT: Acoustic Insecticides’ against Malaria: Can genetically engineered mosquitoes be used as acoustic ‘drones’ to jam mating communications in Anopheles swarms?
Project description:Malaria mosquitoes acoustically detect their mating partners within large swarms that form transiently at dusk. Indeed, male malaria mosquitoes preferably respond to female flight tones during swarm time. This phenomenon implies a sophisticated context- and time-dependent modulation of mosquito audition, the mechanisms of which are largely unknown. Using transcriptomics, we identify a complex network of candidate neuromodulators regulating mosquito hearing in the species Anopheles gambiae. Among them, octopamine stands out as auditory modulator during swarm time. In-depth analysis of octopamine auditory function shows that it affects the mosquito ear on multiple levels: it modulates the tuning and stiffness of the flagellar sound receiver and controls the erection of antennal fibrillae. We show that two α- and β-adrenergic-like octopamine receptors drive octopamine’s auditory roles and demonstrate that the octopaminergic auditory control system can be targeted by insecticides. Our findings highlight octopamine as key for mosquito hearing and mating partner detection, and as a potential novel target for mosquito control.
Project description:Queens of social insects make all mate-choice decisions on a single day, except in honeybees whose queens can conduct mating flights for several days even when already inseminated by a number of drones. Honeybees therefore appear to have a unique, evolutionarily derived form of sexual conflict: a queen’s decision to pursue risky additional mating flights is driven by later-life fitness gains from genetically more diverse worker-offspring but reduces paternity shares of the drones she already mated with. We used artificial insemination, RNA-sequencing and electroretinography to show that seminal fluid induces a decline in queen vision by perturbing the phototransduction pathway within 24-48 hours. Follow up field trials revealed that queens receiving seminal fluid flew two days earlier than sister queens inseminated with saline, and failed more often to return. These findings are consistent with seminal fluid components manipulating queen eyesight to reduce queen promiscuity across mating flights.
Project description:Changes in gene expression in whole Anopheles gambiae female bodies between virgin mosquitoes and females samples at 2h, 6h, and 24h after mating.
Project description:In this RNA-seq study, we compared the antennal transcriptomes of sexually mature drones (males) and time-trained foragers (females) of Apis mellifera collected at different times of day and different activity states. The goals of our project was to provide a more comprehensive description of gene expression differences between drone and forager antennae. Most studies on insect antennal transcriptome still focus on identifying and reporting genes involved in odorant binding and detection. In contrast, we also aimed at identifying so far unrecognised molecules, not directly involved in odorant detection, but likely playing an important role in peripheral olfactory processing. We also wanted to explore whether daily changes in gene expression and correlations between gene expression levels and behavioral activity might be a fruitful approach to identify additional genes involved in odorant reception. Apis mellifera drones perform mating flight in the afternoon around 14:00 hour (h) in Bangalore, India. During their daily mating flight activity, drones were caught at the hive entrance and color marked on the thorax. On the next day color-marked drones were collected at two different time points: 9:00 (inactive) and 14:00 h (active). Honey bee foragers can be trained to visit a food source at a specific time of the day. In this study, an A. mellifera colony was transferred in an enclosed outdoor flight cage to train the foragers to visit a feeder at a specific time of the day. A sucrose reward (1M sucrose solution) was presented either from 8:00 to 10:00 h (morning training) or from 13:00 to 15:00 h (afternoon training) for 10 consecutive days. On the 8th, 9th and 10th day of training, foragers visiting the feeder were marked on their thorax with different colors, one type of color each day, to identify the frequently visiting foragers. On the 11th day, the feeder was not presented and the foragers that had all 3 color marks were collected at 9:00 and 14:00 h. All the samples were immediately flash frozen in liquid nitrogen. Collected samples were transferred from liquid nitrogen onto dry ice and the entire antennae (i.e. scape, pedicel and flagellum) were cut off. We pooled 10 antennae from 5 bees per sample and extracted total RNA using Trizol method. Antennal transcriptomes of drones (n=3 per time point), morning-trained foragers (n=2 per time point) and afternoon-trained foragers (n=2 per time point) were sequenced at 2 different time points (9:00 h and 14:00 h).
Project description:Since Anopheles gambiae female mosquitoes mate only once in their lifetime, and store sperm received from males potentially for weeks, genes and pathways regulated by mating in the sperm storage organ (spermatheca) to preserve sperm function may represent new targets for vector control. The transcriptional response to mating in the spermatheca was investigated using Agilent two-color microarrays. Spermathecae from mated females were collected 24 h after mating and compared to age-matched virgins. 4 biological replicates were performed.
Project description:Honey bee drones, queens and workers have vastly different phenotypes. Here we profile the the expression level of mRNAs and microRNAs of honeybee, drones, queens and workers at the L5 larval stage (91 hours +/- 1).
Project description:Honey bee drones, queens and workers have vastly different phenotypes. Here we profile the the expression level of mRNAs and microRNAs of honeybee, drones, queens and workers at the L5 larval stage (91 hours +/- 1). For both mRNA and miRNA, we analyse five replicates for drones, queens and workers (15 replicates for mRNA and 15 for miRNA).
Project description:Oral susceptibility of Aedes aegypti mosquitoes to dengue viruses varies between different Aedes species and strains. However, the midgut-specific transcriptional profile that may produce this variation is presently obscure and was the subject of our investigation. The variation in active expression between dengue-2 susceptible (SUS) and refractory (REF) mosquitoes was investigated during the first critical 96 hours after infection Transcriptional profiles were mined from respective guts using the serial analysis of gene expression technique (SAGE) and libraries constructed from midguts obtained from mosquitoes that received a dengue-2 infected blood meal (DENV-2), a non infected blood meal (naive) or a 5% sucrose meal (SM). Here we report that variation between DENV-2 infected libraries versus respective naïve libraries revealed very few transcripts that were common and statistically significant in DENV-2 infected libraries. In addition, the expression profiles among libraries displayed up regulation of antisense transcripts especially in the SUS strain. A strong proclivity towards strain-specificity in differential expression was observed, which suggested an exclusive transcription that is likely up-regulated after DENV-2 infection Thirty Aedes aegypti female mosquitoes aged 4-5 days were transferred to 500 ml paper cups and offered a 5% sucrose meal (SM), a naïve blood meal or a dengue-2 (JAM 1409 strain) infectious blood meal, using standard artificial membrane feeders. Fully engorged females were isolated and maintained on a 5% sucrose solution ad libitum at 26oC and relative humidity till dissection
Project description:The heavy use of pesticides in intensive agricultural areas often leads to the contamination of neighbouring mosquito larvae breeding sites. Such exposure to complex agrochemical mixtures can affect the tolerance of mosquitoes larvae to insecticides. The objective of this study was to determine whether agrochemical pollutants found in Anopheline larval breeding sites can affect the tolerance of adults to Fludora® Fusion, a novel vector control insecticide formulation combining two insecticides with distinct modes of action. An. gambiae larvae were exposed to a sub-lethal dose of a mixture of agrochemical pesticides representative of a region with an intense agricultural activity in Ivory Coast. Comparative bioassays with Fludora® Fusion and its two insecticide component (deltamethrine and clothianidin) were carried out between adult mosquitoes exposed or not to the agrochemicals at the larval stage. A transcriptomic analysis through RNA sequencing was subsequently performed in larvae and adults in order to highlight the molecular mechanisms underlying the phenotypic changes observed. Bioessais revealed a significant increased tolerance of adult females to clothianidin (2.5-fold) and Fludora® Fusion (2.2-fold) following larval exposure to agrochemicals. No significant increased tolerance to deltamethrin was observed suggesting that pesticide exposure affects the efficacy of the Fludora® Fusion mixture mainly through mechanisms acting on clothianidin tolerance. Transcriptomic analysis revealed the potential of agrochemicals to induce various resistance mechanisms including cuticle proteins, detoxifications activities and altered insecticide sequestration. These results suggest that though Fludora® Fusion has a good potential for vector control, its efficacy may be locally affected by the ecological context. The present study also suggests that, although the complex interactions between the use of agrochemicals and vector control insecticides are difficult to decipher in the field, they still must be considered in the frame of insecticide resistance management programmes.
Project description:Honey bee colonies were maintained in an apiary at the University of British Columbia. During the summer of 2018, 40 queens were reared from a single colony and half were allowed to open mate, while the other half were kept as virgins in plastic queen cages. Two weeks after emergence, the virgin queens were given two, eight-minute carbon dioxide treatments on 2 sequential days, then re-introduced to their nucleus colonies. This process stimulates virgin queens to begin laying71, and we conducted these treatments in order to minimize the physiological differences between virgin and mated queens. Virgin and mated queens were retrieved from their nucleus colonies and half of each (10) were subjected to heat-shock (42 ͦC, 2 h), and then maintained at 30 ͦC for 2 d. The other half were held only at 30 ͦC for 2 d. Four to six weeks after mating, the queens were anesthetized with carbon dioxide, beheaded, then their spermathecae (including the tracheal net) were removed with fine forceps. Both ovaries were also removed and weighed. During the same summer, 200 drones from a different colony in the same apiary were collected and maintained in the laboratory overnight at ambient temperature with excess syrup (50% sucrose). The next day, semen was harvested with glass capillaries according to the methods described above. Because many drones were not sexually mature, 60 semen samples (out of the 200 drones) were collected. Capillaries were placed in petri dishes and half (30) were heat-shocked as described above, then kept at 25 ͦC for 2 d. The other half were only kept at 25 ͦC for 2 d. Ten samples from each experimental group were used for sperm viability assays as described above.