Project description:Among the parasites of insects, endoparasitoids impose a costly challenge to host defenses because they use their host’s body for the development and maturation of their eggs or larvae, and ultimately kill the host. Tachinid flies are highly specialized acoustically-orienting parasitoids that release first instar mobile larvae which burrow into the host’s body to feed. We investigated the possibility that Teleogryllus oceanicus field crickets employ post-infestation strategies to maximize survival when infested with the larvae of the parasitoid fly Ormia ochracea. Using crickets from the Hawaiian island of Kauai, where the parasitoid is present, and crickets from the Cook Islands (Mangaia), where the parasitoid is absent, we evaluated fitness consequences of infestation by comparing feeding behavior, reproductive capacity, and survival of males experimentally infested with O. ochracea larvae. We also evaluated genetic mechanisms underlying host responses by comparing gene expression in crickets infested with fly larvae for different lengths of time with that of uninfested control crickets. We observe some differences in fitness (spermatophore production) and survival (total survival time post-infestation) between populations. However, for both traits significant population effects 1) were not associated with the slope of the response to different numbers of larvae and 2) only emerged from models containing body condition at one but not both time points evaluated. Gene expression patterns also revealed population differences in response to infestation. We did not find evidence for consistent differences in genes associated with immunity or stress response. Taken together, these results suggest that coevolution with the fly does not strongly select for either post-infestation resistance or tolerance of parasitoid larvae in male crickets.

2020-06-02 | GSE151539 | GEO

Project description:Rapid convergent evolution in wild crickets

| PRJEB6032 | ENA

Evolutionarily conserved but mechanistically diverse piRNA defense against gypsy in insect ovaries

Project description:Organisms possess highly adaptive defence systems to silence rapidly evolving mobile genetic elements such as transposons. While individual transposons may appear and disappear over time, the evolutionary stability of the defence pathways targeting them remains unclear. In the ovarian somatic cells of Drosophila, envelope-carrying gypsy LTR retrotransposons are silenced by the piRNA pathway, which relies solely on Piwi - an evolutionary derivative of an Aubergine/Piwi gene duplication specific to flies. Recent studies, however, have revealed that envelope-carrying gypsy elements are widespread across metazoans and particularly abundant in insect genomes. This prompted us to investigate whether and how the piRNA pathway targets ovarian somatic gypsy elements in other insects. We found that Aedes and Anopheles mosquitoes, as well as stingless bees and crickets, all express piRNAs targeting gypsy elements in ovarian somatic cells, indicating a continuous arms race for more than 400 million years of insect evolution. Interestingly, we found that Aedes aegypti activate the same set of piRNA clusters in ovarian somatic cells as in other somatic tissues where they are known to target RNA viruses. This suggests that piRNA-based antiviral defence in mosquitoes may have originated from the ovarian somatic piRNA pathway. Moreover, we discovered that the mechanisms of piRNA biogenesis in ovarian somatic cells differ among insects: slicing-independent phasing dominates in dipterans, ping-pong amplification in bees, and slicing-dependent phasing in crickets. These findings indicate that distinct piRNA pathways have independently evolved at different timepoints to silence the same class of retrotransposons in insect evolution.

2025-09-17 | GSE305623 | GEO

Cricket Genomics

Project description:Genomics of Rapid Evolution in Field Crickets

| PRJEB24786 | ENA