Population Genetic Differences Between Two Cucurbit Leaf Beetles With Contrasting Feeding Preferences

The Aulacophora beetles are pests closely associated with cucurbit plants. However, research on the fine-scale population genetics of species within this genus remains limited. This study employed mitogenome data from 211 individuals (102 A. indica and 109 A. lewisii) to examine the population genetic patterns of these two common cucurbit pests, which exhibit distinct dietary preferences (A. indica and A. lewisii). Our analysis revealed that the polyphagous A. indica exhibited significantly higher genetic diversity than the oligophagous A. lewisii (p < 0.001). Populations of A. indica showed lower genetic differentiation (F _ST = 0.089) and higher gene flow (N _m = 212.901), with no correlation between genetic differentiation and geographic isolation (p = 0.587). In contrast, populations of A. lewisii displayed higher genetic differentiation (F _ST = 0.186) and lower gene flow (N _m = 62.860), consistent with the isolation by distance (IBD) model (p < 0.001). These significant differences suggest that dietary breadth may play a key role in shaping population genetic characteristics. Neutrality tests revealed signals consistent with either recent population expansion or positive selection in both species, suggesting that human-mediated crop cultivation may have influenced their genetic diversity and structure.