ARS | Publication request: Effect of host diet and adult parasitoid diet on egg load dynamics and egg size of braconid parasitoids attacking Anastrepha ludens

Submitted to: Physiological Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 20, 2011
Publication Date: June 1, 2012
Citation: Cicero, L., Sivinski, J.M., Aluja, M. 2012. Effect of host diet and adult parasitoid diet on egg load dynamics and egg size of braconid parasitoids attacking Anastrepha ludens. Physiological Entomology. 57:1471-1479.

Interpretive Summary: Invasive fruit flies infest hundreds of fruits and vegetables and are responsible for trade restrictions wherever they occur. Parasitoids, either introduced or mass-reared and augmented, are an important component of their control. Scientists at the USDA-ARS Center for Medical, Agricultural and Veterinary Entomology, Gainesville, Florida, in collaboration with colleagues at the Instituto de Ecologia (Xalapa, Veracruz, Mexico) examined the role of both the diets of the host-fly and the adult fruit fly parasitoids in determining the number and size of offspring eggs and time it takes for these eggs to mature, i.e., if nutrition influenced female capacity to reproduce. While there were affects, these were often minor and usually short lived. It appears these species are relatively resilient to nutritional shortfalls, perhaps because the eggs are small, with little yolk and thus cheap to produce. This information could be used to optimize parasitoid mass-rearing and lower the costs associated with maintaining certain colonies.

Technical Abstract: The quantity and quality of host nutrients can affect fitness-related traits in hymenopteran parasitoids, including oogenesis. We predicted that increasing host quality would positively influence oogenesis-related traits in synovigenic parasitoids, and that increasing quality of adult parasitoid diet could positively affect the same parameters, potentially compensating for development on low-quality hosts. Four braconid parasitoid species with contrasting life histories were reared on diets of low (Anastrepha ludens Loew larvae rared in mango) or high quality (artificial diet). Adult parasitoids were provided with high (honey ad libitum) low (honey every other day) or lowest quality (guava pulp) diet. Generalist species that naturally encounter host quality variance were predicted to be more flexible in dealing with nutrient shortfalls than specialized species. Contrary to predictions, in some cases low quality hosts yielded parasitoids with higher egg loads (Opius hirtus Fisher, Diachasmimorpha longicaudata Ashmead). However, as predicted, high quality adult diet had a positive effect on egg load (Utetes anastrephae Viereck), egg size (Doryctobracon crawfordi Viereck) and egg maturation rate (D. longicaudata, O. hirtus and U. anastrephae). Generalist species D. longicaudata varied egg load and maturation rate depending on host quality and adult diet, respectively. Evidence of the combined effect of both factors on parasitoid fertility was found for the specialist species O. hirtus. Egg-related effects of nutritional variance on these koinobiont parasitoids with low nutrient-provisioned eggs may be lower than reported for idiobionts with well provisioned eggs. We examine the theoretical and practical implications of these findings.