Abundant arid natural habitats reduced aphid biocontrol by parasitoids: a case study of Gobi habitats in a desert-oasis farming ecosystem.

BACKGROUND In arid and hyper-arid regions, natural habitats with limited water availability are characterized by sparce vegetation, low host density, and harsh climatic conditions. Whether these arid natural habitats can support natural enemies and facilitate biological control in local agroecosystems is largely unknown. In this study, we determined the effects of landscape composition (the coverage of native Gobi habitats, water bodies and the Shannon's landscape diversity index) on the abundance of mummified aphids and the aphid parasitism rate in local conventional cotton fields under the desert-oasis landscape settings in southern Xinjiang, China. Additionally, to evaluate the impacts of landscape effects above on aphid control, we also investigated the relationship between parasitism rate and aphid population density. RESULTS Our results demonstrated that: (i) parasitic wasps provide unstable but effective biological control, especially in August; (ii) the in-field mummified aphid abundance and the aphid parasitism rate showed a consistent negative correlation with coverage in the local landscape of native Gobi habitat, both in July and August; (iii) the abundance of live aphids was significantly negatively correlated to aphid parasitism rate in August, which thus linked the percentage cover of high Gobi habitat with relative higher aphid pressure in local cotton fields. CONCLUSIONS Our research clarifies the impact of arid natural habitats on parasitic wasps and their pest control capabilities in arid and hyper-arid cotton growing regions. This finding provides useful information for the development of conservation biological control strategies based on habitat management in arid and hyper-arid regions. © 2025 Society of Chemical Industry.