The size of larval rearing container modulates the effects of diet amount and larval density on larval development in Aedes aegypti.

Mass-rearing of mosquitoes under laboratory conditions is an important part of several new control techniques that rely on the release of males to control mosquito populations. While previous work has investigated the effect of larval density and diet amount on colony productivity, the role of the size of the container in which larval development takes place has been relatively ignored. We investigated the role of container size in shaping life history and how this varied with density and food availability in Aedes aegypti, an important disease vector and target of mass-rearing operations. For each treatment combination, immature development time and survival and adult body size and fecundity were measured, and then combined into a measure of productivity. We additionally investigated how larval aggregation behaviour varied with container size. Container size had important effects on life history traits and overall productivity. In particular, increasing container size intensified density and diet effects on immature development time. Productivity was also impacted by container size when larvae were reared at high densities (1.4 larva/ml). In these treatments, the productivity metric of large containers was estimated to be significantly lower than medium or small containers. Regardless of container size, larvae were more likely to be observed at the outer edges of containers, even when this led to extremely high localized densities. We discuss how container size and larval aggregation responses may alter the balance of energy input and output to shape development and productivity.

Optimizing CRE and PhiC31 mediated recombination in Aedes aegypti.

Introduction: Genetic manipulation of Aedes aegypti is key to developing a deeper understanding of this insects' biology, vector-virus interactions and makes future genetic control strategies possible. Despite some advances, this process remains laborious and requires highly skilled researchers and specialist equipment. Methods: Here we present two improved methods for genetic manipulation in this species. Use of transgenic lines which express Cre recombinase and a plasmid-based method for expressing PhiC31 when injected into early embryos. Results: Use of transgenic lines which express Cre recombinase allowed, by simple crossing schemes, germline or somatic recombination of transgenes, which could be utilized for numerous genetic manipulations. PhiC31 integrase based methods for site-specific integration of genetic elements was also improved, by developing a plasmid which expresses PhiC31 when injected into early embryos, eliminating the need to use costly and unstable mRNA as is the current standard. Discussion: Here we have expanded the toolbox for synthetic biology in Ae. aegypti. These methods can be easily transferred into other mosquito and even insect species by identifying appropriate promoter sequences. This advances the ability to manipulate these insects for fundamental studies, and for more applied approaches for pest control.

Ethanol drinking reduces extracellular dopamine levels in the posterior ventral tegmental area of nondependent alcohol-preferring rats.

Moderate ethanol exposure produces neuroadaptive changes in the mesocorticolimbic dopamine (DA) system in nondependent rats and increases measures of DA neuronal activity in vitro and in vivo. Moreover, moderate ethanol drinking and moderate systemic exposure elevates extracellular DA levels in mesocorticolimbic projection regions. However, the neuroadaptive changes subsequent to moderate ethanol drinking on basal DA levels have not been investigated in the ventral tegmental area (VTA). In the present study, adult female alcohol-preferring (P) rats were divided into alcohol-naive, alcohol-drinking, and alcohol-deprived groups. The alcohol-drinking group had continuous access to water and ethanol (15%, vol/vol) for 8 weeks. The alcohol-deprived group had 6 weeks of access followed by 2 weeks of ethanol deprivation, 2 weeks of ethanol re-exposure, followed again by 2 weeks of deprivation. The deprived rats demonstrated a robust alcohol deprivation effect (ADE) on ethanol reinstatement. The alcohol-naïve group had continuous access to water only. In the last week of the drinking protocol, all rats were implanted with unilateral microdialysis probes aimed at the posterior VTA and no-net-flux microdialysis was conducted to quantify extracellular DA levels and DA clearance. Results yielded significantly lower basal extracellular DA concentrations in the posterior VTA of the alcohol-drinking group compared with the alcohol-naive and alcohol-deprived groups (3.8±0.3nM vs. 5.0±0.5nM [P<.02] and 4.8±0.4nM, [P<.05], respectively). Extraction fractions were significantly (P<.0002) different between the alcohol-drinking and alcohol-naive groups (72±2% vs. 46±4%, respectively) and not significantly different (P=.051) between alcohol-deprived and alcohol-naive groups (61±6% for the alcohol-deprived group). The data indicate that reductions in basal DA levels within the posterior VTA occur after moderate chronic ethanol intake in nondependent P rats. This reduction may result, in part, from increased DA uptake and may be important for the maintenance of ethanol drinking. These adaptations normalize with ethanol deprivation and may not contribute to the ADE.