Factors influencing silhouette-trap captures of the blackfly Austrosimulium bancrofti (Taylor) (Diptera: Simuliidae) in the Australian Capital Territory

Three carbon-dioxide-baited silhouette traps of different shape were used to investigate aspects of trap-finding by Austrosimulium bancrofti (Taylor) in the Australian Capital Territory. Highly significant effects were included in a model which generated fitted estimates of the number of flies captured under defined conditions. Fitted captures indicated higher numbers were collected on two of the 15 trapping days. Low wind and high cloud cover increased trap catches. Temperature and solar flux had a quadratic effect, with fitted catches indicating that the highest numbers were captured at 19°C and 620·6 W/m2. The results were compared with trap captures of A. bancrofti 1300 km north in Queensland

Ancestral dietary change alters the development of Drosophila larvae through MAPK signalling

Studies in a broad range of animal species have revealed phenotypes that are caused by ancestral life experiences, including stress and diet. Ancestral dietary macronutrient composition and quantity (over- and under-nutrition) have been shown to alter descendent growth, metabolism and behaviour. Molecules have been identified in gametes that are changed by ancestral diet and are required for transgenerational effects. However, there is less understanding of the developmental pathways altered by inherited molecules during the period between fertilization and adulthood. To investigate this non-genetic inheritance, we exposed great grand-parental and grand-parental generations to defined protein to carbohydrate (P:C) dietary ratios. Descendent developmental timing was consistently faster in the period between the embryonic and pupal stages when ancestors had a higher P:C ratio diet. Transcriptional analysis revealed extensive and long-lasting changes to the MAPK signalling pathway, which controls growth rate through the regulation of ribosomal RNA transcription. Pharmacological inhibition of both MAPK and rRNA pathways recapitulated the ancestral diet-induced developmental changes. This work provides insight into non-genetic inheritance between fertilization and adulthood.Samuel G. Towarnicki, Neil A. Youngson, Susan M. Corley, Jus C. St. John, Richard G. Melvin, Nigel Turner, Margaret J. Morris, and J. William O. Ballar

Evolutionary history of a mosquito endosymbiont revealed through mitochondrial hitchhiking

Due to cytoplasmic inheritance, spread of maternally inherited Wolbachia symbionts can result in reduction of mitochondrial variation in populations. We examined sequence diversity of the mitochondrial NADH dehydrogenase subunit 4 (ND4) gene in Wolbachia-infected (South Africa (SA), California and Thailand) and uninfected (SA) Culex pipiens complex populations. In total, we identified 12 haplotypes (A–L). In infected populations, 99% of individuals had haplotype K. In the uninfected SA population, 11 haplotypes were present, including K. Nuclear allozyme diversity was similar between infected and uninfected SA populations. Analysis of nuclear DNA sequences suggested that haplotype K presence in uninfected SA Cx. pipiens was probably due to a shared ancestral polymorphism rather than hybrid introgression. These data indicate that Wolbachia spread has resulted in drastic reduction of mitochondrial variability in widely separated Cx. pipiens complex populations. In contrast, the uninfected SA population is probably a cryptic species where Wolbachia introgression has been prevented by reproductive isolation, maintaining ancestral levels of mitochondrial diversity. Molecular clock analyses suggest that the Wolbachia sweep occurred within the last 47 000 years. The effect of Wolbachia on mitochondrial dynamics can provide insight on the potential for Wolbachia to spread transgenes into mosquito populations to control vector-borne diseases