Elucidating the dynamic impacts of double cropping rice on arthropod pests and natural enemies in single cropping rice

BACKGROUND: Agro-landscape structure affects the population dynamics of crop pests and natural enemies alike. In southern China, rice is typically cultivated under either double cropping rice (DCR) or single cropping rice (SCR) systems. Although each system is preferred to variable extent by pestiferous herbivores or natural enemies, this phenomenon has not been comprehensively studied. Here, we investigated the dynamics of pests and natural enemies across 19 individual SCR fields embedded within landscape mosaics of varying DCR and semi-natural habitat coverage in Jiangxi, China. Within each field, we established plots with and without insecticide applications. RESULTS: Overall, DCR coverage negatively affects in-field abundance of planthopper (Hemiptera: Delphacidae) pests and natural enemies, and predator richness during early season, particularly in insecticide-unsprayed plots. During late season, DCR coverage positively affects abundance of other rice pests in insecticide-unsprayed plots. Compared to DCR, semi-natural habitat coverage has stronger effect on natural enemy populations. Hence, although DCR and semi-natural habitat influence a preventative management of rice pests in SCR systems, their effects are temporally variable and context-dependent. CONCLUSION: Our study underscores a need for more nuanced area-wide management strategies that holistically consider rice growth stages, landscape-level organismal flows, and insecticide-induced disturbances at the field level.