The realized fecundity of hymenopteran parasitoids has often been used to predict their potential success in the biological control of agricultural pests. However, as demonstrated by recent theoretical and empirical work, fitness costs associated with reproduction in this taxon have led to disparate life-history strategies with wide-ranging biological implications (e.g., longevity, dispersal, host specificity). Therefore, when eggs are matured and laid may be just as important an assessment tool as how many eggs are laid. Nowhere may this be more important than in the Aphelinidae, whose members have been traditionally viewed as utilizing a strongly synovigenic maturation strategy. Recent evidence suggests that Eretmocerus eremicus Rose & Zolnerowich, a parasitoid of the sweetpotato whitefly, Bemisia tabaci (Gennadius), employs an oogenesis mode falling much closer to the pro-ovigenic end of this continuum. Females eclose with a large egg complement (approximately 53) that remains constant during the first 2 d of adult life. This is in direct contrast to other observed aphelinids, which possess a small maximum egg load (approximately 12-14) and a significant maturation phase during this time period. E. eremicus also exhibits oosorption after 2 d when deprived of host meals, a process that appears to function in somatic maintenance. These results, taken in conjunction with the comparatively short adult lifespan of this species (approximately 8 d), suggest that E. eremicus is largely limited reproductively by host encounter rate rather than egg load. Current projects concern the relationship between potential and realized fecundity in E. eremicus and how the dynamics of this relationship may change over time. It is believed that the reproductive strategy employed by this parasitoid may help explain observed gender-biased dispersal patterns that appear to limit its usefulness in controlling B. tabaci populations under certain agricultural and ecological conditions.
Species 1: Hymenoptera Aphelinidae Eretmocerus eremicus
Keywords: egg load, Aphelinidae
The ESA 2001 Annual Meeting - 2001: An Entomological Odyssey of ESA