Abstract
Several parasitoids attacking the same host may lead to competition. Adult parasitoids' abilities to find, parasitize and defend hosts determine resource's retention potential. In soybean, two egg parasitoid species, Telenomus podisi and Trissolcus urichi (Hymenoptera: Platygastridae), compete on the egg masses of Piezodorus guildinii (Hemiptera: Pentatomidae) one of the major pest of this crop. We evaluated parasitoid's abilities to exploit hosts' footprints; and parasitoid's behavior when competing for the same host. Both arena residence time and retention time were similar for T. podisi and T. urichi on male or female host footprints. In its turn, T. urichi reentered the area contaminated with P. guildinii more times and staid longer in it than T. podisi. Furthermore, when competing for the same egg mass, each parasitoid species won (was in possession of the host by the end of the experiment) half of the replicates, and the number of times each wasp species contacted host in the first place was similar, without affecting replicate outcome (who ultimately won). Both species started agonistic and non-agonistic encounters. This study provides information about the potential interspecific competition between these parasitoids, which contributes to evaluate the compatibility of multiple natural enemies' biological control programs for stink bugs.
Highlights
Competition is an interaction that occurs among two or more individuals of the same or different species, which arises when the supply of a scarce resource does not satisfy the immediate needs of individuals.Insect parasitoids have a very specialized life cycle that includes an immature stage that develops on or within a single host, killing that host
When analyzing the arena residence time wasps that were exposed to control treatment remained significantly less time on the arena than wasps exposed to host traces, regardless wasp species or host gender. Both T. podisi and T. urichi staid just about half a minute exploiting the arena in the control treatment before leaving (H = (5;N=180) 114.622; p
We removed control treatment from analysis and there were no differences in the arena residence time of T. podisi and T. urichi towards stink bug traces generated by female or male hosts (H(3;N=120)=6.206; p
Summary
Insect parasitoids have a very specialized life cycle that includes an immature stage that develops on or within a single host, killing that host. Competition can occur between adult parasitoids (extrinsic competition), i.e. interactions between females searching for or exploiting hosts, as well as between immature parasitoids (intrinsic competition), i.e. between larvae developing in the same host (Zwölfer 1971). Zwölfer (1971) classified parasitoids as ‘‘extrinsically superior’’ if they have better skills in host location and ‘‘intrinsically superior’’ if they have better skills in larval competition. He argued that the superior dispersal capabilities of poorer intrinsic competitors are important in explaining coexistence (Fugitive species hypothesis)
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