Body Colour of the Cotton Aphid Aphis gossypii Glover Mediates Consumption Preference of the Lady Beetle Coccinella septempunctata L.

Aphids in different colours have varying attack risks by natural enemies. Distinct colour morphs, from yellow to dark green, often coexist in the colonies of the cotton aphid, Aphis gossypii Glover. However, it remains unclear whether their predation risks differ. Here, we first found that, on cotton leaves, an adult seven‐spotted lady beetle Coccinella septempunctata L., consumed significantly more dark green morphs than yellow morphs, and dark green morphs had significantly higher escape rates than yellow morphs. In a glass Petri dish with a green background, the probability of dark green morphs consumed by an adult C. septempunctata was also significantly higher than that of yellow morphs. These results suggest a higher consumption risk for dark green morphs. Then, we investigated the cues that regulate lady beetle's prey selection. Under light conditions, adult C. septempunctata consumed significantly more dark green morphs, which was not observed under dark conditions, indicating that the lady beetles can use visual cues to distinguish between two morphs. Given that body colour and size are the major external differences between the two morphs, we further evaluated their roles in regulating lady beetle's prey selection by drawing dark green and yellow dots to simulate two morphs. Compared to the control area without dots, adult C. septempunctata spent significantly more time searching in the area with dark green or yellow dots. When dots in both colours were present, regardless of dot sizes, the lady beetles spent significantly more time searching in the area with dark green dots. However, there was no significant difference in searching time between the areas containing dots in the same colour but different diameters. These findings demonstrate that, in A. gossypii , dark green morphs suffer a higher predation risk from adult C. septempunctata than yellow morphs, mainly due to the body colour.