CONICET | Buscador de Institutos y Recursos Humanos

In the search for hosts, parasitoids may experience competition between adults exploiting the same host (extrinsic), or between larvae developing inside the host (intrinsic competition). An intrinsically inferior competitor may coexist with an intrinsically superior one, if it has better abilities to locate host. Extrinsically superior parasitoids have greater ability to locate hosts, and intrinsically superior ones have a shorter preimaginal development, giving a competitive advantage in physiological suppression. Piezodorus guildinii (Hemiptera: Pentatomidae) is an important soybean pest, and its main natural enemies are the oophagous parasitoids Telenomus podisi and Trissolcus urichi(Hymenoptera: Platygastridae). Our objectives were to compare the ability of wasps tolocate host eggs, and larval development time of both parasitoids. Host eggs location was evaluated in a 6cm Petri dish. There was no difference in the time it took for each species to find and contact eggs, nor in the time elapsed between contacting and parasitizing eggs. In turn, there were no differences in average development time of larvae, pupae, and the entire preimaginal period. Adult females of T. podisi were, on average,10 days more long-lived than those of T. urichi. In the laboratory, both species exhibited similar abilities in locating hosts, although there are many factors that can affect parasitoids behavior in field, and that cannot be adequately represented in the microcosm of laboratory experiments. Although we didn´t find differences in the development times of the two species, we have detected (personal observations) that preimaginal development of T. urichi is somewhat shorter than that of T. podisi. Probably, the time window of observation of our assays (12hs) was too large to denote this difference. Understanding competitive interactions between parasitoids is important to improve the biological control of the pest.