Blood serum and BSA, but neither red blood cells nor hemoglobin can support vitellogenesis and egg production in the dengue vectorAedes aegypti

Abstract

Aedes aegypti is the major vector of dengue, yellow fever and chikungunya viruses that put millions of people in endemic countries at risk. Mass rearing of this mosquito is crucial for strategies that use modified insects to reduce vector populations and transmission of pathogens, such as sterile insect technique or population replacement. A major problem for vector mosquito mass rearing is the requirement of vertebrate blood for egg production since it poses significant costs as well as potential health hazards. Also, regulations for human and animal use as blood source can pose a significant obstacle. A completely artificial diet that supports egg production in vector mosquitoes can solve this problem. In this study, we compared different blood fractions, serum and red blood cells, as dietary protein sources for mosquito egg production. We also tested artificial diets made from commercially available blood proteins (bovine serum albumin (BSA) and hemoglobin). We found that Ae. aegypti performed vitellogenesis and produced eggs when given whole bovine blood, serum, or an artificial diet containing BSA. Conversely, egg production was impaired after feeding of the red blood cell fraction or an artificial diet containing only hemoglobin. We also found that egg viability of serum-fed mosquitoes were comparable to that of whole blood and an iron supplemented BSA meal produced more viable eggs than a meal containing BSA alone. Our results indicate that serum proteins, not hemoglobin, may replace vertebrate blood in artificial diets for mass mosquito rearing.

Artificial Diets for Mosquitoes

“…Gonzales et al (2015) tested Pitts’ 200 mg/mL BSA/PBS meal and compared it to whole bovine blood, washed bovine red blood cells, serum, and commercially available bovine hemoglobin, to determine whether vitellogenesis and offspring viability can be supported in Ae. aegypti [32]. She found that the BSA/PBS meal was comparable to whole bovine blood in terms of engorgement rates, and the number of eggs laid and retained in the ovaries.…”

“…Conversely, Gonzales and coworkers (2015) found that a meal containing only washed bovine red blood cells, predominately hemoglobin proteins, or bovine hemoglobin (200 mg/mL of dried bovine red blood cells dissolved in phosphate buffered saline) failed to support egg production in Ae. aegypti [32]. Hemoglobin at higher concentrations also acted as a phagosuppressor, significantly reducing engorgement rates in a concentration-dependent manner.…”

“…They also found that radiolabeled iron bound to ferritin was retained by 15% and most of it was found in the eggs (~77%). Gonzales and coworkers (2014) found that the addition of iron(III)chloride to a BSA-based artificial diet significantly increased egg viability and hatch rates from 15.2 ± 5.2 to 33.1 ± 12.3 [32]. …”

“…The artificial blood meals used by Pitts (2014) and Gonzales et al (2015) used BSA, fraction V (Research International Products) at 200 mg/mL as the main protein source [32,61]. BSA is the price-driving ingredient in these diets because the other ingredients are added at relatively small concentrations.…”

“…In order to replace vertebrate blood, an artificial blood meal should meet the following standards [32]: Females must readily ingest the meal in sufficient amounts.It must support vitellogenesis.It must support large egg batches.The competitiveness of offspring should be comparable to wild mosquitoes.Mosquito behavior and immunity should not be affected.It must not interfere with Wolbachia symbionts (only important for Wolbachia endosymbiont-driven techniques).…”