Drought Stress Promotes <i>Aphis gossypii</i> Growth but Decreases Host Attractiveness in Melon

ABSTRACT Drought stress is a significant environmental factor that affects plant physiology and growth, leading to considerable detrimental effects on crop productivity. Cucumis melo , which is widely cultivated for its economic value, is particularly susceptible to water scarcity. Aphis gossypii is the major pest impacting melon crops due to both the direct damage it causes and its ability to transmit several plant viruses. We investigated whether water‐deficit (WD) and well‐watered (WW) regimes affect aphid fitness, host preference, alighting behaviour and responses to plant volatiles. In antibiosis assays, the pre‐reproductive period (PRP) was longer in aphids reared on WW regime (7.47 ± 0.13 days) than on WD (6.53 ± 0.19 days; p &lt; 0.001). Similarly, mean generation time (Td) was longer under WW regime (10.12 ± 0.18 days) than under WD (8.85 ± 0.26 days, p &lt; 0.001). In contrast, aphids exhibited higher intrinsic rates on WD regime ( r m = 0.463 ± 0.013) than on WW (0.409 ± 0.008; p &lt; 0.001). Mean relative growth rate (RGR) showed the same pattern, being higher under WD regime (0.539 ± 0.015) compared with WW (0.475 ± 0.009, p &lt; 0.001). In dual choice, higher numbers of alate aphids and nymphs were recorded on WW regime. In free‐choice settlement assays, adult aphid preference differed between watering regimes and across time, with greater alate settlement and nymph production—particularly after 48 h—on WW regime. Olfactometry assays showed no aphid response to plant water status. Overall, our results indicate that aphid alighting on melon plants is driven primarily by visual rather than olfactory cues, with WW regime being more attractive than WD. However, once aphids settle on WD regime, population growth is enhanced relative to WW. Thus, when both plant types co‐occur, aphids preferentially colonise WW regime, although higher population growth may occur on water‐stressed hosts.