Gonotrophic Status, Follicular Development, Sperm Presence, and Sugar-Feeding Patterns in a Hybomitra lasiophthalma Population (Diptera: Tabanidae)

Parity, stage of follicular development, and presence of sperm and fructose or sucrose were monitored during two consecutive years in a population of Hybomitra lasiophthalma</it> (Macquart). Females were collected in canopy traps with or without carbon dioxide. The trap catch increased four times with carbon dioxide (CO2). Presence or absence of CO2 had no significant effect on parity rates, prevalence of sperm and fructose, and the stage of primary follicular development within nulliparous (nullipars) and parous flies (pars). The percentage of parous flies was 38% (n = 306) in 1980 and 20% (n = 818) in 1981. The presence of 93% host-seeking nullipars with terminal follicles at stage II suggested that the population studied in southwestern Quebec was anautogenous. Sperm was found in 83% and fructose in 84% of specimens dissected (n = 1,124); sperm presence was significantly higher in pars (89%) than in nullipars (81%).