Submitted to: Biocontrol
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/11/2011
Publication Date: 2/3/2012
Citation: Ramirez-Romero, R., Sivinski, J.M., Copeland, C.S., Aluja, M. 2012. Are individuals stemming from thelytokous and arrhenotokous populations equally adept as biocontrol agents? Orientation and host searching behavior of a fruit fly parasitoid. Biocontrol. 57:427-440. Interpretive Summary: Fruit flies infest hundreds of fruit and vegetables and are responsible for trade barriers wherever they occur. The mass-rearing and release of natural enemies is an effective means of their area-wide control, but can be relatively expensive. Expenses could be lowered if all-female parasitoid strains could be established in production facilities. Scientists at the USDA-ARS, Center for Medical, Agricultural and Veterinary Entomology, Gainesville, Florida, and collaboration with colleagues at the Instituto de Ecologia, Xalapa, Vercruz, Mexico, compared the ability of all-female and bisexual strains of a fruit fly parasitoid to locate and attack their hosts. The all-female strains was as efficient and so is viable candidate for augmentative biocontrol.
Technical Abstract: Hymenopteran parasitoids generally reproduce by arrhenotoky, whereby males develop from unfertilized eggs and females from fertilized eggs. A minority reproduce by thelytoky, whereby all-female broods are derived from unfertilized eggs, and this is often the result of infection with the bacteria Wolbachia. Thelytokous populations are potentially of interest for augmentative biological control programs since the exclusive production of females could significantly lower the costs of mass rearing insects. Behavioral traits are a major component of parasitoid performance as biological control agents, but few studies have addressed the behavior of thelytokous populations. Here, we examined orientation to host odors and close-range host foraging in Wolbachia-infected thelytokous and arrhenotokous populations of the fruit fly parasitoid Odontosema anastrephae Kieffer (Hymenoptera: Figitidae). Orientation behavior to fruit of individuals stemming from both populations of wasps was compared in a two-choice olfactometer. We found that during the first hours following release, thelytokous wasps exhibited a significantly greater response to various odorant sources. However, after a 24h exposure period no significant differences were detected when comparing individuals stemming from thelytokous/arrhenotokou populations. In a second series of experiments we studied the host searching behavior of females in the presence of infested or non-infested guavas (fruit with or without Anastrepha ludens Loew [Diptera: Tephritidae] larvae). The times spent on fruit detection and, foraging on the outside and inside of the fruit were not different between populations, with one exception. In the presence of infested guavas, thelytokous wasps arrived sooner than arrhenotokous wasps. Individuals of both populations exhibited similar stereotyped behavioral sequences vis-à-vis guava treatments, with only slight deviations being detected. These results suggest that individuals stemming from thelytokous and arrhenotokous populations have similar abilities to search for and find tephritid larvae,which opens the door for additional research aimed at ascertaining cost savings in mass rearing and field performance of female-only populations.