Contribution of midgut bacteria to blood digestion and egg production in aedes aegypti (diptera: culicidae) (L.)

<p>Abstract</p> <p>Background</p> <p>The insect gut harbors a variety of microorganisms that probably exceed the number of cells in insects themselves. These microorganisms can live and multiply in the insect, contributing to digestion, nutrition, and development of their host.</p> <p>Recent studies have shown that midgut bacteria appear to strengthen the mosquito's immune system and indirectly enhance protection from invading pathogens. Nevertheless, the physiological significance of these bacteria for mosquitoes has not been established to date. In this study, oral administration of antibiotics was employed in order to examine the contribution of gut bacteria to blood digestion and fecundity in <it>Aedes aegypti</it>.</p> <p>Results</p> <p>The antibiotics carbenicillin, tetracycline, spectinomycin, gentamycin and kanamycin, were individually offered to female mosquitoes. Treatment of female mosquitoes with antibiotics affected the lysis of red blood cells (RBCs), retarded the digestion of blood proteins and reduced egg production. In addition, antibiotics did not affect the survival of mosquitoes. Mosquito fertility was restored in the second gonotrophic cycle after suspension of the antibiotic treatment, showing that the negative effects of antibiotics in blood digestion and egg production in the first gonotrophic cycle were reversible.</p> <p>Conclusions</p> <p>The reduction of bacteria affected RBC lysis, subsequently retarded protein digestion, deprived mosquito from essential nutrients and, finally, oocyte maturation was affected, resulting in the production of fewer viable eggs. These results indicate that <it>Ae. aegypti </it>and its midgut bacteria work in synergism to digest a blood meal.</p> <p>Our findings open new possibilities to investigate <it>Ae. aegypti</it>-associated bacteria as targets for mosquito control strategies.</p

Mecanismos de transferência de massa na desidratação osmótica de goiaba em soluções de sacarose, sucralose e açúcar invertido Mass transfer mechanisms during the osmotic dehydration of guava in sucrose, sucralose and inverted sugar solutions

O objetivo deste trabalho foi avaliar o efeito da concentração de soluções de sacarose, sucralose e açúcar invertido sobre a cinética da desidratação osmótica de pedaços de goiaba. Frações de 1/12 do fruto foram imersas em soluções de sacarose a 0,5 e 0,4 g mL-1; de sacarose a 0,3 g mL-1 + sucralose a 0,2 g L-1 e em xarope de açúcar invertido, a 50 ºC, por 2 h, sob agitação de 60 min. A solução de açúcar invertido promoveu maior perda de água e redução de massa nas amostras de goiaba submetidas à desidratação osmótica. O melhor desempenho foi obtido para o tratamento em solução de sacarose a 0,4 g mL-1; com perda de água e redução de massa semelhantes aos valores obtidos na imersão em solução de sacarose a 0,5 g mL-1 e ganho de sólidos similar ao observado em solução de sacarose a 0,3 g mL-1.The present work aimed at investigating the effect of sucrose, sucralose and inverted sugar solutions on the kinetics of osmotic dehydration of guava pieces. The fruits were cut in twelfths and immersed in sucrose solutions at 0.5 and 0.4 g mL-1; of sucrose at 0.3 g mL-1 + sucralose at 0.2 g L-1 and in inverted sugar syrup for 2 h at 50 ºC, under agitation of 60 min. The undiluted inverted sugar solution promoted the highest levels of water loss and weight reduction in osmo-dehydrated guava pieces. The best overall performance was achieved by immersing guava pieces in sucrose solutions at 0.4 g mL-1 which led to water loss and mass reduction of similar values attained with sucrose solutions at 0.5 g mL-1; whereas maintaining the same level of solids gain achieved with sucrose solutions at 0.3 g mL-1