Sexually dimorphic morphology, feeding behavior and gene expression profiles in cotton aphid Aphis gossypii

BACKGROUND

Sexual dimorphism exists in most insects. However, related knowledges in aphids were less. In this study, we identified the sexual dimorphic differences in morphology, feeding behaviors, and gene expression between sexual female and male of cotton aphid through electron microscope, electrical penetration graph technique, and RNA sequencing.

RESULTS

All the males were alate with slender reddish yellow body, and abdominal yellow‐white stripes, whereas all the sexual females were apterous with a pudgy green body. The sensillum types of antennae were identical between the two sexes, but males had more sensilla, which might be due to the significantly longer male antennae than sexual females. In terms of feeding behavior, male spent more time probing mesophyll cells and phloem sieve and salivating into phloem sieve. In contrast, sexual female spent more time in ingesting of the xylem sap. A total of 510 and 724 genes were specifically expressed in sexual female or male, respectively, which were significantly enriched in signaling pathways related to reproduction for sexual female (such as ovarian steroidogenesis, oxytocin signaling pathway) and energy and flight for male (such as thermogenesis, insulin signaling pathway). Moreover, 8551 differentially expressed genes between the two sexes were identified, in which 3720 up‐regulated genes in sexual female were mostly enriched into signaling pathways of metabolism and energy such as thermogenesis and TCA cycle.

CONCLUSION

This study provides insight into sexual dimorphism of aphids and lays a foundation for revealing the molecular mechanism underlying these differences between two sexes of cotton aphid.

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