Extrinsic and intrinsic competition of two egg parasitoids of Piezodorus guildinii (Hemiptera: Pentatomidae)

CINGOLANI, M.F.; BARAKAT, M.C.

Gramado (RS, Brasil)

Congreso; XXVII Congresso Brasileiro y X Latinoamericano de Entomologia; 2018

Sociedad Entomologica Brasileira

In the search for hosts, parasitoids may experience competition between adults exploitingthe same host (extrinsic), or between larvae developing inside the host (intrinsiccompetition). An intrinsically inferior competitor may coexist with an intrinsically superiorone, if it has better abilities to locate host. Extrinsically superior parasitoids have greaterability to locate hosts, and intrinsically superior ones have a shorter preimaginaldevelopment, giving a competitive advantage in physiological suppression. Piezodorusguildinii (Hemiptera: Pentatomidae) is an important soybean pest, and its main naturalenemies 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 wasevaluated in a 6cm Petri dish. There was no difference in the time it took for each speciesto find and contact eggs, nor in the time elapsed between contacting and parasitizingeggs. 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 daysmore long-lived than those of T. urichi. In the laboratory, both species exhibited similarabilities in locating hosts, although there are many factors that can affect parasitoidsbehavior in field, and that cannot be adequately represented in the microcosm oflaboratory experiments. Although we didn´t find differences in the development times ofthe two species, we have detected (personal observations) that preimaginal developmentof T. urichi is somewhat shorter than that of T. podisi. Probably, the time window ofobservation of our assays (12hs) was too large to denote this difference. Understandingcompetitive interactions between parasitoids is important to improve the biological controlof the pest.