EFFECT OF QUIESCENCE IN AE. KOREICUS FITNESS AND PHYSIOLOGY

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INTRODUCTION. The emergence and spread of new alien mosquito species have recently been documented in Europe. In addition to the well-known invasion of Aedes albopictus, several studies have focused on monitoring and controlling other invasive Aedes species, such as Aedes koreicus and Aedes japonicus. Over the past decade, Ae. koreicus and Ae. japonicus have expanded their range and become permanently established in several areas of northern Italy. Considering that both species are potential vectors of important arboviruses, their dispersal and establishment in new areas may pose a growing threat to human and animal health. Invasive Aedes mosquitoes are characterized by a strong ability to spread—often facilitated by human-mediated transport—and to adapt to novel environmental conditions. The aim of our study was to expand current knowledge on the distribution and prevalence of Ae. koreicus in northeastern Italy, with particular attention to its ecological adaptation to temperature. Mosquito embryonic development is influenced by multiple environmental factors, among which temperature exerts the strongest effect on embryonic growth and survival. MATERIALS AND METHODS. To better understand the acclimation capacity of Ae. koreicus, we investigated the effects of egg quiescence under different time and temperature conditions. Eggs of Ae. koreicus were maintained under quiescent conditions for 4, 11, or 20 weeks at four constant temperatures: 8, 16, 24, and 28 °C. After each quiescence period, eggs were hatched at 24 °C and several fitness parameters were evaluated, including egg hatching patterns, percentage of egg hatchability, survival rate of first instar larvae, larval developmental time, pupation rate, longevity, fecundity, and adult wing length. Moreover, energetic resources (protein, lipid, and triglyceride contents) were analysed in both first instar larvae and newly emerged females. RESULTS AND CONCLUSION. Quiescence temperature, duration, and their interaction significantly influenced egg hatching patterns and overall Ae. koreicus fitness. Lower storage temperatures (8–16 °C) promoted long-term egg viability and delayed hatching across multiple flooding cycles, whereas higher temperatures (24–28 °C) induced rapid but short-lived hatching responses and reduced long-term viability. Embryonic viability was negatively affected by triglyceride depletion. However, larvae with reduced lipid content exhibited prolonged developmental time, resulting in adult females with higher lipid reserves. Consequently, prolonged quiescence at lower temperatures increased adult size and female fecundity. Overall, these results suggest that temperature-dependent quiescence plasticity may enhance the ability of Ae. koreicus to persist across variable environments, with important implications for its population dynamics and its potential role as a disease vector.

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