Agricultural land use and its disruption of natural landscapes threaten the provision of ecosystem services, such as biological control by natural enemies, because of habitat simplification and management intensification. However, most studies that evaluate the effect of local management practices rarely identify and include other important predictors such as landscape compositional values. We studied the effect of adding flower strips at farms on the control of aphids in a seminatural habitat (SNH) gradient. We found significantly less aphids on farms with flower strips and more SNH at the second sampling date as well as a greater proportion of mummies with flowers early in the season, with a greater proportion of mummies at a greater %SNH at the end of the season. Foraging predators responded to the %SNH of farms without flowers only on the second sampling date, which coincided with their highest mean abundances. Our data suggests that aphid parasitism was enhanced by flowers, having a potential effect early in the season, which ultimately explained the reduction in aphid numbers thereafter. On the other hand, the effects perceived on predator abundances seemed to be more date- and landscape-sensitive. Flower strips of faba beans and buckwheat in the field as well as the %SNH surrounding farms positively affected Diaeretiella rapae and could therefore be an important management strategy to decrease Brevicoryne brassicae densities in brassica crops.

Plant diversity strategies promote positive effects on the delivery of ecosystem services by establishing winter refuges and other food resources for populations of natural enemies. Cover crops are encouraged as a sustainable practice able to stimulate the early recruitment of natural enemies. However, there is insufficient evidence of the dispersal of natural enemies between added vegetation habitats and targeted crops in orchards. Here we study the genetic diversity and population genetic structure of a plum aphid parasitoid using microsatellite markers developed specifically for Aphidius platensis. We seek 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 population persistence of parasitoids.

A key aspect of climate change’s impact on organisms lies in understanding their ability to adapt to shifting and stressful environmental conditions. Insects, such as parasitoid wasps, are particularly vulnerable due to limited heat tolerance. Adaptive strategies during mass rearing may enhance the efficacy and resilience of commercially reared biocontrol agents. This study assessed the effects of constant and fluctuating temperature regimens across four generations of mass-reared aphid parasitoids, examining their fitness traits and parasitism success under three thermal environments: colder [10 °C], standard [20 °C], and heat stress [28 °C]. Parasitoids reared under fluctuating temperatures [day/night: 25 °C/17 °C] showed increased parasitism, but reduced progeny survival compared to those reared at a constant temperature [20 °C]. Fluctuating regimens encouraged greater parasitism under heat stress, whereas constant regimens yielded intermediate parasitism across thermal environments, reflecting a pattern consistent with the evolution of specialist–generalist trade-offs. These findings underscore the value of developing adaptive temperature-rearing strategies for mass-rearing systems of parasitoids that more accurately simulate field conditions, improving their performance under climate stress. Future research involving diverse temperature regimens should deepen our understanding of trait trade-offs, such as survival and fecundity, and aid in identifying optimal thermal profiles to maximize efficacy in mass-rearing parasitoid wasps and their performance at the field level.

A key aspect of climate change’s impact on organisms lies in understanding their ability to adapt to shifting and stressful environmental conditions. Insects, such as parasitoid wasps are particularly vulnerable due to limited heat tolerance. Adaptive strategies during mass rearing may enhance the efficacy and resilience of commercially reared biocontrol agents. This study assessed the effects of constant and fluctuating temperature regimens across four generations of mass-reared aphid parasitoids, examining their fitness traits and parasitism success under three thermal environments: colder [10°C], standard [20°C], and heat stress [28°C]. Parasitoids reared under fluctuating temperatures [day/night: 25°C /17°C] showed increased parasitism, but reduced progeny survival compared to those reared at a constant temperature [20°C]. Fluctuating regimens encouraged greater parasitism under heat stress, whereas constant regimens yielded intermediate parasitism across thermal environments, reflecting an evolutionary pattern consistent with the specialist-generalist trade-off. These findings underscore the value of evolutionary responses in developing adaptive rearing strategies that more accurately simulate field conditions, improving the performance of augmentative biological control under climate stress. Future research involving diverse fluctuating temperature regimes should deepen our understanding of trait trade-offs, such as survival and fecundity, and aid in identifying optimal thermal profiles to maximize resilience and efficacy in parasitoid wasps.