Sex-specific physiological strategies of Dalbulus maidis (Hemiptera: Cicadellidae) for surviving overwintering stress

Abstract

Dalbulus maidis (Hemiptera: Cicadellidae), principal vector of maize stunting pathogens in the Americas, poses a major threat to maize (Zea mays L.) productivity, especially in Argentina. Adult corn leafhoppers exhibit morphophysiological traits, such as seasonal polyphenism and reproductive quiescence, to withstand unfavorable conditions. However, other physiological responses to seasonal stress remain poorly understood. In this study, we investigated sex-specific metabolic and immunological adjustments that support survival under variable environmental conditions. Adults were field collected during summer, autumn, and winter in Tucum´ an, Argentina, sexed, and processed for biochemical analysis. For fatty acid profile, adults were classified according to sex and polyphenism (yellow for summer; melanized for autumn/winter). Seasons influenced protein and lipid content, males exhibiting higher protein levels consistently across seasons (438.57 vs 342.87 μg/mg, respectively), and females accumulating more lipids during autumn (59.43 vs 41.91 μg/mg, respectively). Females stored more glycogen than males, particularly in summer (32.70 vs 17.67 μg/mg, respectively) and winter (49.89 vs 10.48 μg/mg, respectively). Phenoloxidase activity showed pronounced sex- and season-dependent variation: females invested in immune activation during colder months (11-17 U/min/mg protein), whereas males maintained consistently low enzymatic activity (6-7 U/min/mg protein). Monounsaturated fatty acids increased whereas polyunsaturated decreased in autumn-winter phenotypes, although the saturated/unsaturated ratio remained similar (0.6-0.7). Females evidenced greater metabolic flexibility and adaptive investment for overwintering, prioritizing energy storage and immune responsiveness, whereas males accumulate resources toward early reproductive efforts. This study provides novel insights into insect physiological plasticity and highlights how environmental stress shapes metabolic and immunological regulation in a major agricultural pest.