OBJECTIVE To determine the intensity of Pediculus capitis infestation (abundance) among Argentinean schoolchildren. Children's sex and social stratum were analyzed as modifiers of the general prevalence and degree of parasitism. METHODS The study included 1,370 schoolchildren (692 girls, 678 boys) from 26 schools of the province of La Rioja (21 public schools, five private schools). Classic p...

Both deleterious mutations and parasites have been acknowledged as potential selective forces responsible for the evolutionary maintenance of sexual reproduction. The pluralist approach to sex proposes that these two factors may have to interact synergistically in order to stabilize sex, and one of the simplest ways this could occur is if parasites are capable of causing synergistic epistasis b...

trissolcus grandis thomson is a solitary egg parasitoid of sunn pest, eurygaster integriceps puton. although widely distributed, it has often been overlooked in field surveys. our objectives were to develop an efficient rearing technique for t. grandis, and to determine the basic bionomics and demographic parameters, necessary for future augmentative biological control programs. exposure of 0-4...

Assuming the existence of tick parasitism in humans in the State of Pará, an aggregate observational study was developed along a transversal line in three cities of the State, during two years. Interviews and examinations of 2,160 townspeople and tourists were carried out, without discrimination of ethnic, sex, age, or social status, and classified for effects analyzed for four bands of age, si...

Sexual selection theory proposes that males suffer reduced immune function and increased parasitism as costs of expressing sexual signals. Life-history theory proposes that females suffer the same costs because of inherent trade-offs between reproduction and self-maintenance. Mechanistically, each theory invokes an energetic tradeoff, although few experiments have directly compared these costs ...