A field-collected intersex Aedes albopictus with female-like blood-feeding and a male genotype.

Sexual dimorphism in Aedes albopictus is typically strict, with blood-feeding restricted to females. Here, we report a rare field-collected intersex Ae. albopictus captured by human-landing catch in Guangzhou, China. Morphological examination revealed a structurally intact piercing-sucking proboscis, intermediate antennal whorled setae, and male-type claspers, although maxillary palp asymmetry and other cephalic traits could not be conclusively assigned to female morphology due to tissue condition. Blood was visible in the abdomen at the time of capture; however, molecular identification of the blood meal was unsuccessful, likely due to limited blood volume and tissue partitioning during DNA extraction. DNA sequencing of the male-determining gene Nix confirmed a genotypic male individual. These observations indicate region-specific disruption of sexual differentiation and suggest that genotypic males may occasionally exhibit female-like blood-feeding under rare circumstances. This study highlights the developmental plasticity of sexually dimorphic traits in mosquitoes and provides insights into the potential limits of rigid sex-specific feeding behavior.