Submitted to: Journal of Insect Behavior
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/16/2009
Publication Date: 5/22/2009
Citation: Aluja, M., Ovruski, S.M., Guillen, L., Orono, L.E., Sivinski, J.M. 2009. Comparison of the host searching and oviposition behaviors of the tephtitid (Diptera) parasitoids Aganaspis pelleranoi and Odontosema anastrephae (Hymenoptera: Figitidae, Eucoilinae). Journal of Insect Behavior. 22:423-451. Interpretive Summary: Species of natural enemies that occur in the same place must differ in their methods of finding and obtaining hosts in order to survive together. Understanding these differences can be important to deciding which biological control agent to employ in any particular set of circumstances. 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 two related parasitoids that attack pest fruit flies. They found that one specialized in feeding larvae and the other on larvae at rest. Thus both could be released without concerns for competition between them.
Technical Abstract: We compared the host-searching and oviposition behaviors of two Neotropical figitid parasitoids (Hymenoptera) that exploit the same resource: ripe fruit infested by fruit fly larvae (Tephritidae) that have fallen to the ground. Sexually mature Aganaspis pelleranoi (Brèthes) and Odontosema anastrephae Kieffer females were exposed individually, under no choice conditions, to four types of fruit: 1) Clean, intact guavas, Psidium guajava L. (no fruit fly larvae, no perforations); 2) clean, with artificial perforations; 3) artificially infested (with larvae), no perforations; 4) infested with artificial perforations. A behavioral transition matrix and sequence diagram of the following behaviors was constructed: walking on fruit, detection of larvae via the antennae, tarsi or aculeus, fruit perforation and penetration, and oviposition. Overall, we found that infested fruit (intact and with artificial perforations) elicited the most activity in the females of both species and that A. pelleranoi females exhibited a significantly more diverse behavioral repertoire (i.e., more transitions) and were significantly more active than O. anastrephae females. Females of both species penetrated the fruit in search of larvae by biting through the epi- and mesocarp, but O. anastrephae remained inside for significantly longer periods (up to eight hours). A. pelleranoi females used both their antennae and tarsi to detect larvae but the use of these structures varied depending on context: in infested fruit tarsi were used preferentially (usually while standing still) while in uninfested fruit, antennae were mainly used (usually while walking). In the case of O. anastrephae females the reverse pattern was usually observed with antennae most commonly used to detect larvae in infested fruit. We discuss our findings in light of their evolutionary, ecological and practical implications.