Changes in Free Amino Acid Concentration in the Hemolymph of the Female Culex pipiens pallens (Diptera: Culicidae), After a Blood Meal

Abstract

The analysis of the free amino acids in the hemolymph of female Culex pipiens pallens L. indicated that asparagine, glutamine, glycine, leucine, serine, threonine, tyrosine, and valine noticeably increased in concentration during a blood meal digestion at 22 degrees C. The concentrations started to rise at about 4 h, reaching maximal level at 12-24 h, and then gradually returned to the prefeeding level by the fifth day after the blood meal. Before the sharp increase, the concentrations of asparagine, glutamine, glycine, serine, threonine, and tyrosine declined slightly during the first 1-2 h, probably because of hemolymph dilution by water absorbed from the blood meal. Histidine and lysine also showed a minor decrease soon after blood feeding, followed by a moderate but noticeable increase, delaying maximal concentrations until 48 h after the blood meal. Proline and alanine both exhibited a high hemolymph content and changed greatly, but with a large variation between the two samples analyzed. The changing pattern of individual hemolymph amino acids depended to a large extent upon the content of each amino acid in the blood meal given to the mosquitoes. Other free amino acids detected in the hemolymph were at very small concentrations and except for phenylalanine did not show any changes after a blood meal. The total free amino acid concentration was 50 nmol (or 6 micrograms) per microliters hemolymph before a blood meal, and increased to a maximal concentration of 88 nmol (or 11 micrograms) per microliters hemolymph at 18 h after the blood meal.