Influence of hematocrit variation on <i>Cimex lectularius</i> (Hemiptera: Cimicidae) development and reproduction

The common bed bug, Cimex lectularius L. (Hemiptera: Cimicidae), is an obligately hematophagous insect with a broad host range including humans, bats, and chickens. There are significant interspecific and intraspecific differences in hematological parameters of these hosts, yet little is known about their effects on life history traits of bed bugs. In this study, we investigate the hematocrit, or red blood cell concentration, and its effects on bed bug fitness. We conducted dose-response experiments using human blood of different hematocrits, and assessed development time, feeding rate, adult body size, egg production, and egg hatch rate. Human blood with hematocrits ranging from 35% to 50% equally supported nymphal development. However, feeding bed bug nymphs a hematocrit of 60% resulted in high mortality (78%), low feeding rate, and none of the bed bug nymphs reached the adult stage. Additionally, bed bugs fed human blood with a 20% hematocrit emerged as significantly smaller adults. These results suggest a nutritional deficiency at low (∼20%) hematocrits and toxicity at high hematocrits (∼60%). In our assessment of fecundity, we observed maximal egg production at 35-50% hematocrit and deficiencies in egg production at low (20-30%) and high (60%) hematocrits. We conclude that bed bugs are well adapted to feed on a broad range of human blood hematocrits and hypothesize that this tolerance may allow them to thrive on alternative hosts. Considering the detrimental effects of very low and high hematocrits, studies that rely on laboratory rearing of hematophagous arthropods should consider hematological parameters during experimental design.