Effect of Vegetational Diversification on the Gene Flow of Natural Enemies in a plum orchard

Abstract

Vegetational diversification strategies promote positive effects on ecosystem service provision by establishing winter refuges and alternative food resources for natural enemy populations. Cover crops are encouraged as a sustainable practice that can stimulate the early recruitment of natural enemies. However, evidence of the dispersion of natural enemies between added vegetation habitats and target crops within orchards is missing in the literature. Here, we study the genetic populational diversity and its structure of a plum aphid parasitoid using novel microsatellite markers designed specifically for Aphidius platensis. We seek to understand the genetic structure and gene flow of the parasitoid wasps to understand whether parasitoid wasps are able to shift between alternative and target aphid hosts (winter vs. spring hosts) developing on winter oat cover crops, spontaneous vegetation, and the target plum trees in an organic orchard system. Our results supported aspects of our hypotheses by providing evidence that added habitat diversity, through a cereal cover crop, can act as banker plants of parasitoid populations for the dispersion of migrants within a fruit orchard, which could favor suppression efficiency of orchard pests, as well as enable the population persistence of parasitoids.